Evaluation of biomass and vegetative characteristics of mesquite (Prosopis juliflora) afforestation in arid area of Iran

Evaluation of biomass and vegetative characteristics of mesquite (Prosopis juliflora) afforestation in arid area of Iran | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of biomass and vegetative characteristics of mesquite (Prosopis juliflora) afforestation in arid area of Iran Jaafar Hosseinzadeh, Mehdi Heydari, Ahmad Ehsani, Masoud Bazgir, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4006840/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Evaluating the degree of success in the growth, effectiveness and durability or replacement of pioneer afforestation in dry areas of the world is one of the important issues of managing these forests. We evaluated the suitability of mesquite for afforesting degraded lands in the dry climate region of Einkhosh, Ilam province, Iran by studying the influence of stand density (180 and 250 trees per ha) and age (15, 27 and 34 years) on tree development, growth and biomass, and soil quality in. We measured tree characteristics (height, crown height, collar diameter and crown area) and calculated above-ground biomass. Soil quality index was determined at two depths (0–15 and 15–30 cm) based on the measured physical, chemical and biological soil properties. The results showed that stand age and density and their interaction significantly affected stem number, crown height growth and soil quality index. The average number of stems was the highest (7.8 per hectare) in the 15-year-old stand and the lowest (1.5 per hectare) in the 34-year-old stand. Height, collar diameter, basal area growth, biomass, and competition between trees were significantly affected by stand age and its interaction with stand density (p < 0.01). The average annual growth of tree collar diameter and height with age was lowest (4.1 mm per year and 17.7 cm per year, respectively) in the 34-year-old stand. In contrast, average annual growth rates of 7.2 mm and 31 cm for collar diameter and height, respectively, in the 15-year-old stand. The surface soil quality index increased with the stand age and density, and it was highest (averaging 0.714) in the dense areas of the 34-year-old stand. In contrast, soil quality index at lower soil depths, decreased with increasing stand age, but it was still highest in the dense areas of the 34-year-old stand. The basal area at the stem collar showed a positive and strong correlation with total height, crown height, degree of competition and crown area. In general, high density mesquite afforestation plantings (250 trees per hectare) in this dry and desert area improved soil quality and increased vegetative and productivity characteristics of mesquite, especially as stands aged. Therefore, mesquite can be a suitable option for revitalization of sites in dry and sparsely vegetated areas. mesquite growth clump age density biomass soil quality Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Today, afforestation is considered a valuable approach for increasing carbon sequestration by forests, mitigating the effects of climate change and improving other ecosystem services. For these reasons, the area of forest plantations around the world has increased by more than 105 million hectares between 1990 and 2015 (FAO, 2016 ). Forest plantations play a role in providing quality, reliable water to communities, regulating the hydrological process, protecting the soil, controlling erosion and improving the landscape (Bauhus et al., 2010 ). Estimating the biomass of trees and forest plantations is important to evaluate the productivity and nutrient cycling in these ecosystems (Ishihara et al., 2015 ), their role and contribution in the global carbon cycle (MacFarlane, 2015 ), their delivery of ecosystem services (De Miguel et al., 2014) and the benefits they provide to local residents (MacFarlane, 2015 ). The goals of afforestation, according to the existing conditions in an area, may include: stabilization of sand and desertification, wood production, improvement of soil conditions and characteristics, prevention of soil erosion, protection or creation of wildlife habitat, supply of fuel and animal feed and creation of windbreaks in soil conservation (Chen et al., 2023 ; Gbadebo, 2022 ; Lucas-Borja et al., 2022 ). To choose suitable tree and shrub species for establishing forests as plantations in dry areas, it is necessary to know the local site conditions, consider socio-economic factors and be able to predict future growth and effects on soil resources. Vegetation, whether coniferous or broadleaf trees and shrubs, or grass, affects the surrounding environment, and these effects are different depending on the type of vegetation, its age and management practices (Heydari et al., 2020 ; Eslaminejad et al., 2020 ; Yuan et al., 2023 ). Attempting to establish vegetation on loose sands and sand dunes in dry areas causes changes in the physical and chemical properties of the soil, including increases in organic matter and soil nutrients (e.g., phosphorus, nitrogen and potassium) and the percentage of clay and silt, all of which creates a better environment for the activity of microorganisms, thus accelerating soil development (Kumar et al., 2017 ; Li et al., 2012 ). Of course, the degree of these improvements in the soil depends on various factors including the species used in afforestation, and the density and age of the plantation (Zhang et al., 2021 ; Stanturf et al., 2021). Suitable species and optimal plantation density still need to be evaluated in different regions. Afforestation is the planting of trees to reestablish forests in areas where the tree cover was lost. The soil is often poor in these areas and this challenges plant survival and growth (Pérez-Silos et al., 2021 ). In such a situation, one of the most important stages of forest planting in desert areas is the selection of the appropriate primary species. This choice is particularly important, because it affects the climate and soil characteristics of the region and affects the lives of the residents of the neighboring desert areas. Therefore, species selection is the most important and fundamental action to change the landscape and future of an area (Herbohn et al., 2001 ; Emam and Lubos, 2021 ). In the first World Conference on Desertification (UNCCD, 1977) in Nairobi, Kenya, the phenomenon of desertification was introduced as the main cause of destruction of natural ecosystems through reduction of biological production and soil degradation. These negative impacts can be mitigated by restoring vegetative cover through afforestation (Kulik et al., 2023 ). Protection of existing and recovery of former forests and pastures are important for sustainable development of any country experiencing desertification and other ecosystem degrading phenomenon. In arid and semi-arid regions, protecting, revitalizing, expanding and strengthening vegetation is vital to ecosystem health, productivity and sustainability, and to the well-being of people who live in these regions (Hakimovich and Alishovich, 2023 ). Establishing permanent vegetation through afforestation protects soil and increases biodiversity (Pourbabae, 1998) and increases soil carbon and nitrogen storage (Chen et al., 2010). Thus, afforestation is considered a primary method for restoring degraded lands (Cannell, 2003) and an important first step in the long-term process of improving ecosystem health, productivity and resilience (Zhu et al., 2009; Yang et al., 2012). In particular, afforestation in desert ecosystems is an important approach in land management to stop desertification and ecosystem degradation (Kulik et al., 2023 ; Hakimovich and Alishovich, 2023 ). Today, assessing the success rate in growth and effectiveness on the one hand and deciding whether to sustain or replace pioneer afforestation in the other hand, in order to accelerate the improvement of the ecosystem in arid and semi-arid regions of the world are considered important issues in the management of these primary forests (Lamb, 2018 ). Quantitative assessment of biomass production and carbon storage in forests established by afforestation is one of the important measures used to evaluate success and effectiveness in ecosystem change. Accurate estimation of tree biomass and carbon storage requires cutting and harvesting a sufficient number of trees and weighing them, which is destructive and costly (Kaonga, M.L., T.P. Bayliss-Smith, 2010). Alternatively, allometric equations can be used as a non-destructive and low-cost method to evaluate above-ground biomass of trees and stands at regional, national, continental and global levels (Peichl et al., 2007; Xiang et al., 2016 ; Zhao et al., 2021 ). A review of studies conducted to estimate biomass with different experimental, semi-empirical and theoretical methods showed that theory-based methods do not provide a better estimates of biomass in some species, including mesquite trees (Návar, 2010). In this research, we used the modified semi-experimental method of West (West et al., 1999 ) and Chojnacky's experimental method (Chojnacky et al., 2014 ) to estimate mesquite biomass based on collar diameter. Mesquite ( Prosopis juliflora ) is an important species that has been used in many afforestation projects around the world, including in the desert areas of Iran (Mbaabu et al., 2020 ; Moradi et al., 2017 ; Maundu et al., 2009 ). However, our knowledge about the success of establishment and growth of this species and its functions in different ages and climatic regions in relation to planting techniques, including different planting densities, is still incomplete. No comprehensive research has been done in the desert areas of Iran regarding changes in vegetative characteristics in stands and soil quality due to stand density and age of plantation. This research seeks to answer the following hypotheses: 1) The effect of planting age on the improvement of vegetative characteristics is greater than that of planting density. 2) Soil quality increases with the increase in the age of afforestation regardless of initial planting density. 3) With increasing age of mesquite afforestation, the trend is one of increasing biomass over time. Materials and methods area of ​​study The studied area is called Einkhosh, which is located in a relatively wide plain located southeast of Dehloran city in the south of Ilam province, Iran. The geographic location of the studied area is between 33°30′05″ N and 32°21′33″ N latitude and 47°50′24″ E and 47°36′56″ E longitude. According to the information of the closest weather station to the region (Dehloran weather station), the average annual rainfall is 297.8 mm, which is distributed irregularly throughout the year. Maximum rainfall occurs in the months of January and Bahman. There is a 7-month dry period from the middle of April to the end of November in the region based on the ambrothermic curve. The average annual temperature of the region is 26.2 degrees Celsius, the relative humidity is about 37.5%, and the average annual potential evaporation is 3857.5 mm, which is the highest in July and the lowest in January. According to De Martonn's classification, the climate of the region is dry and hot (Meteorology of Ilam Province, 2016). Experimental design and sampling Afforestation with mesquite in the Einkhosh region of Dehloran over many decades has provided an opportunity to assess plantings that span a diversity of ages. We selected three afforestation stands of different ages (15, 27 and 34 years old) for this research. In each of the stands, two density classes were identified: thin (average 180 trees per hectare) and dense (average 250 trees per hectare). Two square plots (40 x 40 m) were located randomly in each stand. In each of the plots, the characteristics of the trees including the total height and the starting height of the crown (using Sunto clinometer to the nearest cm), collar diameter (at the ground level) and crown dimensions (using tape measure with cm accuracy) were measured. Annual diameter growth, height growth and crown growth were determined by dividing the current total measure of the characteristic by the age of the planting. Then, the average annual growth of collar diameter, height, crown area and above-ground biomass (by West and Chojnacky methods) were calculated according to Chojnacky et al. ( 2014 ). The above-ground biomass was estimated using the following two allometric equations, which estimate biomass based on collar diameter (Db): Eq. 1- Semi-empirical modified equation of West et al. ( 1999 ) and Eq. 2- Empirical equation of Chojnaki et al. (2014): 1) AGB = (0.0295) D b 2.67 2) Ln (AGB) = 2.426 Ln (D b ) – 2.9255 Here, AGB is the above-ground biomass of the tree in kg and D b is the collar diameter in cm. To analyze the competitive effect of neighboring trees, a quantitative index dependent on the distance and crown size of neighboring trees was used in Eq. 3 (Hegyi, 1974 ). 3) CI= ∑ (CR j /CR i ) 1.3 /Dist ij 0.4 Here, CR is the average tree crown radius in meters, Dist ij is the horizontal distance between the neighboring trees and the target tree in meters, i and j represent the neighboring and target trees, respectively. In each of the areas, 4 random soil samples were taken from two depths of 0–15 and 15–30 cm (30 samples in total) and their soil characteristics including: chemical properties (pH, EC, percentage of organic carbon, percentage of total nitrogen and available phosphorus), physical properties (sand, silt, clay, saturated moisture and bulk density) and biological properties (basal respiration) were evaluated by standard methods in the laboratory (see Heydari et al., 2017 ). A part of each sample was kept at 4°C to check soil respiration. The total data method (Rahmanipour et al., 2014) was used to calculate the soil quality index. Statistical Analysis The mean, standard deviation and coefficient of variation were used to summarize the data and validate model assumptions. The Kolmogorov-Smirnov test was used to check for normality of the data. GLM analysis was used to test for significance in the effect of stand density and age, and their interaction on the response of vegetative characteristics.. Duncan's mean comparison test was used to compare differences among the means of the vegetative variables measured in the different afforested stands. All statistical analyses were performed using IBM SPSS ver. 22 and all graphs were drawn using Excel 2013 software. Results The results of statistical tests on the main and interaction effects of age and stand density on vegetative characteristics, growth rates and soil quality index in afforestation with mesquite is presented in Table (1). We found that effects of stand age, stand density and their interaction on stem number, crown height growth and soil quality index were significant. The average number of stems was the highest (7.8 per tree) in the 15-year-old stand and the lowest (1.5 per tree) in the 34-year-old stand. Changes in total height, collar diameter, basal area, total height growth, collar diameter growth, basal area growth, competition between stands and tree biomass were affected by the age of the stand and the interaction of age and stand density. The changes in the crown area and the average annual growth of the crown area were only influenced by the age of the stand. The average annual growth of the biomass was only influenced by the interaction effect of age and density (Table 1 ). The average annual growth of the collar diameter and height of the trees decreased with age and reached 4.1 mm and 17.7 cm in the 34-year-old stand, respectively, which differed from the 15-year-old stand where collar diameter and height averaged 7.2 mm per year and 31 cm per year, respectively. The surface soil quality index increased with the age and density of the forest stand, and it averaged 0.714 in the dense stand, which was higher than that of the thin stand (0.640). Table 1 GLM analysis of the effects of age and stand density on mesquite vegetative characteristics and soil quality index Treatments Total Height Base Diameter Basal area Crown Area Stem No. Df F Sig. F Sig. F Sig. F Sig. F Sig. Stand Age 2 131.070 .000 43.820 .000 33.239 .000 42.319 .000 104.59 .000 Density 1 .005 .942 3.005 .085 3.277 .072 .618 .433 4.492 .035 Age× Density 2 7.906 .000 5.452 .005 5.976 .003 .622 .538 25.446 .000 Treatments Height Growth Base Dia. Growth Basal area Growth Crown area Growth Crown Heigh Growth Df F Sig. F Sig. F Sig. F Sig. F Sig. Stand Age 2 276.744 .000 43.356 .000 3.367 .036 42.319 .000 27.979 .000 Density 1 1.115 .292 .593 .442 .678 .411 .618 .433 5.514 .020 Age× Density 2 5.953 .003 3.716 .026 4.812 .009 .547 .580 7.551 .001 Treatments Competition Biomass (Chojnacky) Biomass Growth Soil Quality Index-Surface Soil Soil Quality Index-Deep Soil Df F Sig. F Sig. F Sig. F Sig. F Sig. Stand Age 2 76.954 .000 29.253 .000 1.680 .189 2621.002 .000 273.868 .000 Density 1 1.981 .161 3.493 .063 .827 .364 923.005 .000 106.648 .000 Age× Density 2 5.573 .004 5.662 .004 4.719 .010 41.799 .000 7.091 .001 Bold numbers indicate the significance of the difference. Comparison of the two methods used to estimate mesquite biomass (Table 2 ) showed that there was a significant difference between the two methods and that Chojnaki's method had a lower standard deviation and standard error than West's method according to the paired sample t test. Table 2 Comparison of Chojnacki and West methods for estimating biomass and its growth rate Mean Std. Deviation Std. Error Mean T df Sig. (2-tailed) Pair 1 West Biomass 30.9527 19.02975 1.31948 9.403 207 .000 Chojnaki Biomass 29.3246 16.60601 1.15142 Pair 2 West Biomass Growth 1.2511 .82388 .05713 8.188 207 .000 Chojnaki Biomass Growth 1.1913 .72447 .05023 Vegetative characteristics The increase in the age of mesquite, regardless of the stand density, was accompanied by an increase in tree height and diameter and an increase in the crown competition between the trees, but the number of stems per tree decreased with the increase in age (Fig. 2 ). In this study, the effect of density on the average biomass of trees was not significant, but with increasing age from 15 to 27 years, we observed an increase in biomass, and after 27 years, we noted a decrease in the average above-ground biomass of mesquite (Fig. 3 ). Growth rates The interaction of stand age and density effects on growth rates in height, basal area, crown area and biomass of trees is shown in figure (4). The trend of decreasing growth in height, basal area, collar diameter, biomass, and crown height growth with increasing age is quite evident. Cown area growth lowest in the 27-year-old stand intermediate in the 34-year-old stand and highest in the 15-year-old stand. Soil quality As seen in Fig. 5 , the surface soil quality index increased with the age and density of the stand, and it was always higher in the higher density portions of the stand. In contrast to trends observed in surface soils, soil quality index decreased with increasing age of the stand in the lower soil layer sampled, but it was still higher in the dense portion of the stand at any given age. The average soil quality index increased from about 0.52 in the 15-year-old low-density plots to about 0.83 in the 34-year-old dense plots. The correlations between the studied characteristics is shown in Fig. 6 . As can be seen, the soil quality index showed a positive and significant correlation with the total height, crown height, crown diameter, degree of competition, basal area and biomass, but it showed a negative correlation with the number of stems and average annual growth. Basal area had positive and strong correlation with the total height, crown height, degree of competition and crown area. Crown area had a positive and significant correlation with height, collar diameter and degree of competition. Discussion Vegetative characteristics The high number of multi-stems in early ages can be attributed to the presence of livestock in afforestation areas and the activation of lateral buds due to grazing and cutting the terminal bud of seedlings (Cooper-Norris et al., 2023 ). The change and decrease in the number of tree stems in the following years has disrupted the process of changes in the average basal area and the average above-ground biomass of the stands, so that the biomass in the 27-year-old stand is more than that of the younger and older stands. The average above-ground biomass of 15-year-old and 27-year-old mesquite trees in this study was 98 and 139 kg, respectively, which is higher than the 58 and 111 kg presented by James Ansley et al. ( 2018 ) for Prosopis glandulosa . Stand age is also an important driver for biomass and productivity (Liu et al., 2018 ; Michaletz, Cheng, Kerkhoff, & Enquist, 2014 ). Stand age can affect biomass and productivity through increasing tree size (Pickle et al., 2007; Poorter et al., 2015 ; Barry et al., 2018 ; Becknell & Powers, 2014 ; Zhang and Chen, 2015 ). The higher density of the stand increases soil carbon storage and wood production, due to more complete crown coverage and greater use of light (Forrester et al., 2018 ; Morin, 2015 ). Changes in trunk diameter can increase or decrease productivity due to changes in light distribution between individual trees (Binkley, Stape, Bauerle, & Ryan, 2010 ; Soares et al., 2016 ; Zhang & Chen, 2015 ). The basal area at the collar showed a positive and strong correlation with the total height, crown height, degree of competition and crown area, which indicates the presence of space to grow into and reflects the dynamics of stand growth. At low densities, interactions between trees will not occur or will be weak (Forrester & Bauhus, 2016 ). As stand density increases, competitive interactions become more intense, trees occupy more growing space and use more resources such as light, water, and nutrients (Boyden, Binkley, & Senock, 2005 ; Forrester et al. al., 2013). Recent studies based on large forest inventory datasets show that stand density has stronger effects than diversity on forest productivity (Forrester & Bauhus, 2016 ; Guo & Ren, 2014 ; Paquette & Messier, 2011 ). The lack of significance between stand density and many of the independent variables is due, in part, to the relatively low tree densities sampled in this study and lower levels of inter-tree competition for light even in the higher density portions of the stands. Although the results indicate the importance of changes in the stand age compared to that in stand density in these areas, the effect of density on crown height growth (P = 0.02) and soil quality index (P = 0.000) was significant. Growth rates The results of this research showed that the average growth in total height, collar diameter, crown height, basal area and biomass of mesquite trees decreased with increasing age. It is obvious that the growth rate of trees changes with their age, due to physiological changes such as reduction in photosynthesis rate, leaf productivity and transfer of carbon sources to different parts of the plant, leaf size and gas exchange rate (Johnson & Abrams, 2009 ). The decrease in tree growth over time can be attributed to changes in the supply of required resources (light, nutrients, water), changes in the balance between photosynthesis and respiration, increased hydraulic resistance, reduced nutrient supply, or genetic changes with meristem age (Martinez et al., 2007). However, it should be noted that long-term growth patterns vary greatly between and within tree species (Brienen and Zuidema, 2006 ; Rozendaal and Zuidema, 2011 ). Ren (2020) reported that the biomass growth of acacia trees in Chinese forest plantations was rapid (from 1.60 to 185.01 tons/ha) during the first 7 years, and then decreased (to 188.69 tons/ha) during the next 27 years. Soil quality The results of this research showed that the average surface soil quality index increased from about 0.52 in the 15-year-old low-density stand to about 0.83 in the 34-year-old dense stand. The increase of surface soil quality index in forest plantations has been reported in many studies. Ren (2020) showed an increase in soil fertility during the first 34 years in Acacia plantations in China. In fact, soil quality index of the surface soil increases with increasing age and density of forest plantations, due to the increase in vegetation cover and root development that increases the accumulation of organic matter in the surface soil, and hence, the levels of nutrients and chemical elements that improve soil quality (Wang et al., 2021 and 2017 ; Zhao et al., 2021 ; Zethof et al., 2019 ). The increase in soil fertility can also be related to the increase in nitrogen fixation (Xiong et al., 2008 ). Fu et al. ( 2009 ) and Yi et al. ( 2018 ) reported that during the growth and aging process, soil microorganisms and nematode communities play a key role in improving soil physical and chemical properties. The decrease in soil quality index in the lower soil sampled in this study may be due to, the amount of total phosphorus becomes a limiting factor for carbon sequestration as the afforestation stand ages (Çomakli and Turgut, 2021 ). In general, studies have shown that hot and dry climate areas have less potential for the accumulation of soil organic carbon, total nitrogen, and total phosphors below the 20 cm soil depth and therefore the soil quality index is lower compared to soils in humid areas (Colantoni et al., 2015 ; Guo et al., 2021 ). The negative correlation between soil quality index and the average growth of vegetative characteristics of mesquite trees is related to the increase in the age of the trees and the decrease in the average growth. Conclusion We found that Chojnaki's method for estimating mesquite biomass, which had a lower standard deviation and standard error, performed better than the West method. After 27 years, we observed that height growth rate decreased due to increased competition. The significant increase in collar diameter, basal area, biomass, and surface soil quality index in the 34-year-old stand compared to the 27-year-old stand indicates there may be an opportunity to increase the volume and density of trees in the stand into the future. In general, higher density plantings (250 stems per hectare) of mesquite in afforestation plantings in this dry desert area, improve soil quality and promotes vegetative development and production as stands develop over time, and therefore mesquite is a suitable species for revival of dry and sparsely covered areas. Declarations Author Contribution J.H. Conceptualization, Methodology, Data curation, Project administration, Writing – original draftM.H. Methodology, Formal analysis, Software, Writing – review & editingA.E. Data curation, Investigation, ResourcesM.B. Validation, Writing – review & editingD.C.D. 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Pérez-Silos, I., Álvarez-Martínez, J.M. and Barquín, J., 2021. Large-scale afforestation for ecosystem service provisioning: learning from the past to improve the future. Landscape Ecology, 36, pp.3329-3343. Poorter, L., van der Sande, M. T., Thompson, J., Arets, E. J. M. M., Alarcón, A., Álvarez-Sánchez, J., Peña-Claros, M. (2015). Diversity enhances carbon storage in tropical forests. Global Ecology and Biogeography, 24, 1314–1328. https://doi.org/10.1111/geb.12364 Ren H, Yiming F., Zeyuan Z., Dafeng H., Qinfeng G., Yao H. (2020) Long‑term structural and functional changes in Acacia mangium plantations in subtropical China. Landscape and Ecological Engineering, https://doi.org/10.1007/s11355-020-00429-4 Rozendaal DMA, Zuidema PA., 2011. Dendroecology in the tropics: a review. Trees, 25(1):3–16. Soares, A. A., Leite, H. G., Souza, A. L., Silva, S. R., Lourenço, H. M., & Forrester, D. I. (2016). Increasing stand structural heterogeneity re-duces productivity in Brazilian Eucalyptus monoclonal stands. Forest Ecology and Management, 373, 26–32. https://doi.org/10.1016/j.foreco.2016.04.035 Stanturf, J.A., Botman, E., Kalachev, A., Borissova, Y., Kleine, M., Rajapbaev, M., Chyngozhoev, N. and Nyam-Osor, B., 2020. Dryland forest restoration under a changing climate in central Asia and Mongolia. Mongolian Journal of Biological Sciences, 18(2), pp.3-18. UNFCCC, 1997. Kyoto Protocol to the United Nations Framework Convention on Climate Change, Article 12. Wang C., Wang S., Fu B., Li Z., and Wu X., Tang Q. (2017): Precipitation gradient determines the trade-off between soil moisture and soil organic carbon, total nitrogen, and species richness in the Loess Plateau, China. Science of the Total Environment, 575: 1538–1545. Wang J., Zhao W., Wang G., Yang S., Pereira P. (2021): Effects of long-term afforestation and natural grassland recovery on soil properties and quality in Loess Plateau (China). Science of the Total Environment, 770: 144833. Xu Z. (2004): Incomplete complementary judgement matrix. Systems Engineering –Theory and Practice, 24: 93–97. West GB, Brown JH, Enquist BJ. 1999. A general model for the structure and allometry of plant vascular system. Nature 400:664-667 Xiang WH, Zhou J, Ouyang S, Zhang SL, Lei PF, Li JX, Deng XW, Fang X, Forrester DI (2016) Species-specific and general allometric equations for estimating tree biomass components of subtropical forests in southern China. Eur J For Res 135: 963–979. Xiong Y, Xia H, Li Z (2008) Impacts of litter and understory removal on soil properties in a subtropical Acacia mangium plantation in China. Plant Soil 304:179 Yi GT, Wang XL, Liu ZF, Cai XA, Fu SL, Zhou LX (2018) Interan nual dynamics of soil microbial biomass carbon under diferent plantations in subtropical China. Ecol Environ Sci 27:224–231 Yuan, C., Wu, F., Wu, Q., Fornara, D.A., Heděnec, P., Peng, Y., Yuan, J., Zhu, G. and Yue, K., 2023. Divergent effects of converting different types of ecosystems to tree plantations on soil water holding characteristics: A meta-analysis. Agriculture, Ecosystems & Environment, 348, p.108403. Zethof J.H., Cammeraat E.L., Nadal-Romero E. (2019): The enhancing effect of afforestation over secondary succession on soil quality under semiarid climate conditions. Science of the Total Environment, 652: 1090–1101. Zhang, T., Song, L., Zhu, J., Wang, G., Li, M., Zheng, X. and Zhang, J., 2021. Spatial distribution of root systems of Pinus sylvestris var. mongolica trees with different ages in a semi-arid sandy region of Northeast China. Forest Ecology and Management, 483, p.118776. Zhang, Y., & Chen, H. (2015). Individual size inequality links forest diversity and above-ground biomass. Journal of Ecology, 103, 1245–1252. https://doi.org/10.1111/1365-2745.12425 Zhao X., Tong M., He Y., Han X., Wang L. (2021) A comprehensive, locally adapted soil quality indexing under different land uses in a typical watershed of the eastern Qinghai-Tibet Plateau. Ecological Indicators, 125: 107445. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4006840","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":276429736,"identity":"b819d682-cc5e-4ca0-b226-1531c71eef6b","order_by":0,"name":"Jaafar Hosseinzadeh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYBACxgYeECUBIgyYGSokZKASEsRqOSPBQ1ALAwMPnGXAzNiGxMUFmBt4Dz78UWGRJ99+eOPjwnkWPPzTDjB++MFgkY/bYXzJxjxnJIoZe9KKjWduk+CRuJ3ALNnDIGHZgNsvZtKMbRKJzQw5ZtK8QC0MtxMYpIF+McBtC4+Z5M9/Eolt/G/Mf/POkeCRB9rym5AWCd4GicQeiRwzZiCDx+B2Aht+W5p5jI15jkkkzpB4ViwNZPAY3k5ss+wxwK3FsL3H8OGPmrrE+f3JGz/z1NTJyd1OPnzjR0Udbi3N2BwLjCNcGhgY5HFLjYJRMApGwSiAAgBim0YgIcQfXwAAAABJRU5ErkJggg==","orcid":"","institution":"Ilam University","correspondingAuthor":true,"prefix":"","firstName":"Jaafar","middleName":"","lastName":"Hosseinzadeh","suffix":""},{"id":276429737,"identity":"050b88f9-75d0-49f2-be64-45b7a3746a75","order_by":1,"name":"Mehdi Heydari","email":"","orcid":"","institution":"Ilam University","correspondingAuthor":false,"prefix":"","firstName":"Mehdi","middleName":"","lastName":"Heydari","suffix":""},{"id":276429738,"identity":"f9405707-7dd9-4f50-b768-12e237ebf737","order_by":2,"name":"Ahmad Ehsani","email":"","orcid":"","institution":"Ilam University","correspondingAuthor":false,"prefix":"","firstName":"Ahmad","middleName":"","lastName":"Ehsani","suffix":""},{"id":276429739,"identity":"c62d372c-5d76-45ef-ba95-7cee5d8f356b","order_by":3,"name":"Masoud Bazgir","email":"","orcid":"","institution":"Ilam University","correspondingAuthor":false,"prefix":"","firstName":"Masoud","middleName":"","lastName":"Bazgir","suffix":""},{"id":276429740,"identity":"abe64e36-19d7-4fa8-af5d-5b5334c4c236","order_by":4,"name":"Daniel C. Dey","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Daniel","middleName":"C.","lastName":"Dey","suffix":""}],"badges":[],"createdAt":"2024-03-02 18:16:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4006840/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4006840/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52122436,"identity":"2aef4cf1-a9eb-413e-a63a-5b70806561fd","added_by":"auto","created_at":"2024-03-07 05:16:41","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":82998,"visible":true,"origin":"","legend":"\u003cp\u003eThe location of the region and the stands under study near Dehloran city, Ilam province; 15 years old (a), 27 years old (b) and 34 years old (c)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/c2445d216844b2a20b15a7b5.png"},{"id":52122370,"identity":"870e4cc2-6717-44c5-8aa2-e0206bd3c0a7","added_by":"auto","created_at":"2024-03-07 05:08:41","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":8219,"visible":true,"origin":"","legend":"\u003cp\u003eThe interaction effect of stand age and density on the average number of stems and competition between trees\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/3dee03051c41a35911d4d736.png"},{"id":52122366,"identity":"46b6772e-5dbb-4249-bcb3-193096be1920","added_by":"auto","created_at":"2024-03-07 05:08:41","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":20197,"visible":true,"origin":"","legend":"\u003cp\u003eThe interaction effect of age and stand density on the vegetative characteristics of mesquite\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/b70ba88d1edf216d013f5817.png"},{"id":52122369,"identity":"75112c3d-0250-43d0-a420-f415950586e5","added_by":"auto","created_at":"2024-03-07 05:08:41","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":28887,"visible":true,"origin":"","legend":"\u003cp\u003eThe interaction effect of age and stand density on the average annual growth of mesquite vegetative characteristics\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/e1936aec2af6f2d13d7583c7.png"},{"id":52122367,"identity":"e8f1895c-259f-4837-859a-6bc4ee3f0948","added_by":"auto","created_at":"2024-03-07 05:08:41","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":10061,"visible":true,"origin":"","legend":"\u003cp\u003eThe interaction effect of age and stand density on soil quality index; surface soil (0-15 cm) and depth soil (15-30 cm)\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/01ae5e49e2093695ece4dbe5.png"},{"id":52122371,"identity":"7254989e-f671-4f63-82b0-d886bbd41d24","added_by":"auto","created_at":"2024-03-07 05:08:41","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":80191,"visible":true,"origin":"","legend":"\u003cp\u003eHeat map and correlations between the studied characteristics; Soil quality index (SQI), height (H), crown height (CRH), collar diameter (CRD), stem number (STC), degree of competition (COM), basal area (BA), crown area (CRA), crown area growth (CRAG), crown height growth (CHG), basal area growth (BAG), collar diameter growth (CDG), height growth (HGR), biomass by Chojnaki method (ChojB), biomass growth (ChojG)\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/17fced170a02b84afb79498f.png"},{"id":56716067,"identity":"2a7b07e0-bc46-47e2-a87e-19a10117a3bd","added_by":"auto","created_at":"2024-05-18 19:16:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":698358,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4006840/v1/878d5f10-1cd5-4754-86e3-b54f9c61390c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of biomass and vegetative characteristics of mesquite (Prosopis juliflora) afforestation in arid area of Iran","fulltext":[{"header":"Introduction","content":"\u003cp\u003eToday, afforestation is considered a valuable approach for increasing carbon sequestration by forests, mitigating the effects of climate change and improving other ecosystem services. For these reasons, the area of forest plantations around the world has increased by more than 105\u0026nbsp;million hectares between 1990 and 2015 (FAO, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Forest plantations play a role in providing quality, reliable water to communities, regulating the hydrological process, protecting the soil, controlling erosion and improving the landscape (Bauhus et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Estimating the biomass of trees and forest plantations is important to evaluate the productivity and nutrient cycling in these ecosystems (Ishihara et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), their role and contribution in the global carbon cycle (MacFarlane, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), their delivery of ecosystem services (De Miguel et al., 2014) and the benefits they provide to local residents (MacFarlane, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe goals of afforestation, according to the existing conditions in an area, may include: stabilization of sand and desertification, wood production, improvement of soil conditions and characteristics, prevention of soil erosion, protection or creation of wildlife habitat, supply of fuel and animal feed and creation of windbreaks in soil conservation (Chen et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Gbadebo, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Lucas-Borja et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). To choose suitable tree and shrub species for establishing forests as plantations in dry areas, it is necessary to know the local site conditions, consider socio-economic factors and be able to predict future growth and effects on soil resources. Vegetation, whether coniferous or broadleaf trees and shrubs, or grass, affects the surrounding environment, and these effects are different depending on the type of vegetation, its age and management practices (Heydari et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Eslaminejad et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Yuan et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Attempting to establish vegetation on loose sands and sand dunes in dry areas causes changes in the physical and chemical properties of the soil, including increases in organic matter and soil nutrients (e.g., phosphorus, nitrogen and potassium) and the percentage of clay and silt, all of which creates a better environment for the activity of microorganisms, thus accelerating soil development (Kumar et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Li et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Of course, the degree of these improvements in the soil depends on various factors including the species used in afforestation, and the density and age of the plantation (Zhang et al., \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Stanturf et al., 2021). Suitable species and optimal plantation density still need to be evaluated in different regions.\u003c/p\u003e \u003cp\u003eAfforestation is the planting of trees to reestablish forests in areas where the tree cover was lost. The soil is often poor in these areas and this challenges plant survival and growth (P\u0026eacute;rez-Silos et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In such a situation, one of the most important stages of forest planting in desert areas is the selection of the appropriate primary species. This choice is particularly important, because it affects the climate and soil characteristics of the region and affects the lives of the residents of the neighboring desert areas. Therefore, species selection is the most important and fundamental action to change the landscape and future of an area (Herbohn et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Emam and Lubos, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the first World Conference on Desertification (UNCCD, 1977) in Nairobi, Kenya, the phenomenon of desertification was introduced as the main cause of destruction of natural ecosystems through reduction of biological production and soil degradation. These negative impacts can be mitigated by restoring vegetative cover through afforestation (Kulik et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Protection of existing and recovery of former forests and pastures are important for sustainable development of any country experiencing desertification and other ecosystem degrading phenomenon. In arid and semi-arid regions, protecting, revitalizing, expanding and strengthening vegetation is vital to ecosystem health, productivity and sustainability, and to the well-being of people who live in these regions (Hakimovich and Alishovich, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eEstablishing permanent vegetation through afforestation protects soil and increases biodiversity (Pourbabae, 1998) and increases soil carbon and nitrogen storage (Chen et al., 2010). Thus, afforestation is considered a primary method for restoring degraded lands (Cannell, 2003) and an important first step in the long-term process of improving ecosystem health, productivity and resilience (Zhu et al., 2009; Yang et al., 2012). In particular, afforestation in desert ecosystems is an important approach in land management to stop desertification and ecosystem degradation (Kulik et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Hakimovich and Alishovich, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eToday, assessing the success rate in growth and effectiveness on the one hand and deciding whether to sustain or replace pioneer afforestation in the other hand, in order to accelerate the improvement of the ecosystem in arid and semi-arid regions of the world are considered important issues in the management of these primary forests (Lamb, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Quantitative assessment of biomass production and carbon storage in forests established by afforestation is one of the important measures used to evaluate success and effectiveness in ecosystem change. Accurate estimation of tree biomass and carbon storage requires cutting and harvesting a sufficient number of trees and weighing them, which is destructive and costly (Kaonga, M.L., T.P. Bayliss-Smith, 2010). Alternatively, allometric equations can be used as a non-destructive and low-cost method to evaluate above-ground biomass of trees and stands at regional, national, continental and global levels (Peichl et al., 2007; Xiang et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhao et al., \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). A review of studies conducted to estimate biomass with different experimental, semi-empirical and theoretical methods showed that theory-based methods do not provide a better estimates of biomass in some species, including mesquite trees (N\u0026aacute;var, 2010). In this research, we used the modified semi-experimental method of West (West et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e1999\u003c/span\u003e) and Chojnacky's experimental method (Chojnacky et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) to estimate mesquite biomass based on collar diameter.\u003c/p\u003e \u003cp\u003eMesquite (\u003cem\u003eProsopis juliflora\u003c/em\u003e) is an important species that has been used in many afforestation projects around the world, including in the desert areas of Iran (Mbaabu et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Moradi et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Maundu et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). However, our knowledge about the success of establishment and growth of this species and its functions in different ages and climatic regions in relation to planting techniques, including different planting densities, is still incomplete. No comprehensive research has been done in the desert areas of Iran regarding changes in vegetative characteristics in stands and soil quality due to stand density and age of plantation. This research seeks to answer the following hypotheses:\u003c/p\u003e \u003cp\u003e1) The effect of planting age on the improvement of vegetative characteristics is greater than that of planting density.\u003c/p\u003e \u003cp\u003e2) Soil quality increases with the increase in the age of afforestation regardless of initial planting density.\u003c/p\u003e \u003cp\u003e3) With increasing age of mesquite afforestation, the trend is one of increasing biomass over time.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e \u003cb\u003earea of ​​study\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe studied area is called Einkhosh, which is located in a relatively wide plain located southeast of Dehloran city in the south of Ilam province, Iran. The geographic location of the studied area is between 33\u0026deg;30\u0026prime;05\u0026Prime; N and 32\u0026deg;21\u0026prime;33\u0026Prime; N latitude and 47\u0026deg;50\u0026prime;24\u0026Prime; E and 47\u0026deg;36\u0026prime;56\u0026Prime; E longitude.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAccording to the information of the closest weather station to the region (Dehloran weather station), the average annual rainfall is 297.8 mm, which is distributed irregularly throughout the year. Maximum rainfall occurs in the months of January and Bahman. There is a 7-month dry period from the middle of April to the end of November in the region based on the ambrothermic curve. The average annual temperature of the region is 26.2 degrees Celsius, the relative humidity is about 37.5%, and the average annual potential evaporation is 3857.5 mm, which is the highest in July and the lowest in January. According to De Martonn's classification, the climate of the region is dry and hot (Meteorology of Ilam Province, 2016).\u003c/p\u003e\n\u003ch3\u003eExperimental design and sampling\u003c/h3\u003e\n\u003cp\u003eAfforestation with mesquite in the Einkhosh region of Dehloran over many decades has provided an opportunity to assess plantings that span a diversity of ages. We selected three afforestation stands of different ages (15, 27 and 34 years old) for this research. In each of the stands, two density classes were identified: thin (average 180 trees per hectare) and dense (average 250 trees per hectare). Two square plots (40 x 40 m) were located randomly in each stand. In each of the plots, the characteristics of the trees including the total height and the starting height of the crown (using Sunto clinometer to the nearest cm), collar diameter (at the ground level) and crown dimensions (using tape measure with cm accuracy) were measured. Annual diameter growth, height growth and crown growth were determined by dividing the current total measure of the characteristic by the age of the planting. Then, the average annual growth of collar diameter, height, crown area and above-ground biomass (by West and Chojnacky methods) were calculated according to Chojnacky et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe above-ground biomass was estimated using the following two allometric equations, which estimate biomass based on collar diameter (Db): Eq.\u0026nbsp;1- Semi-empirical modified equation of West et al. (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e1999\u003c/span\u003e) and Eq.\u0026nbsp;2- Empirical equation of Chojnaki et al. (2014):\u003c/p\u003e \u003cp\u003e1) AGB = (0.0295) D\u003csub\u003eb\u003c/sub\u003e\u003csup\u003e2.67\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e2) Ln (AGB)\u0026thinsp;=\u0026thinsp;2.426 Ln (D\u003csub\u003eb\u003c/sub\u003e) \u0026ndash; 2.9255\u003c/p\u003e \u003cp\u003eHere, AGB is the above-ground biomass of the tree in kg and D\u003csub\u003eb\u003c/sub\u003e is the collar diameter in cm.\u003c/p\u003e \u003cp\u003eTo analyze the competitive effect of neighboring trees, a quantitative index dependent on the distance and crown size of neighboring trees was used in Eq.\u0026nbsp;3 (Hegyi, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1974\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e3) CI= \u0026sum; (CR\u003csub\u003ej\u003c/sub\u003e/CR\u003csub\u003ei\u003c/sub\u003e)\u003csup\u003e1.3\u003c/sup\u003e/Dist\u003csub\u003eij\u003c/sub\u003e\u003csup\u003e0.4\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eHere, CR is the average tree crown radius in meters, Dist\u003csub\u003eij\u003c/sub\u003e is the horizontal distance between the neighboring trees and the target tree in meters, i and j represent the neighboring and target trees, respectively.\u003c/p\u003e \u003cp\u003eIn each of the areas, 4 random soil samples were taken from two depths of 0\u0026ndash;15 and 15\u0026ndash;30 cm (30 samples in total) and their soil characteristics including: chemical properties (pH, EC, percentage of organic carbon, percentage of total nitrogen and available phosphorus), physical properties (sand, silt, clay, saturated moisture and bulk density) and biological properties (basal respiration) were evaluated by standard methods in the laboratory (see Heydari et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). A part of each sample was kept at 4\u0026deg;C to check soil respiration. The total data method (Rahmanipour et al., 2014) was used to calculate the soil quality index.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe mean, standard deviation and coefficient of variation were used to summarize the data and validate model assumptions. The Kolmogorov-Smirnov test was used to check for normality of the data. GLM analysis was used to test for significance in the effect of stand density and age, and their interaction on the response of vegetative characteristics.. Duncan's mean comparison test was used to compare differences among the means of the vegetative variables measured in the different afforested stands. All statistical analyses were performed using IBM SPSS ver. 22 and all graphs were drawn using Excel 2013 software.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe results of statistical tests on the main and interaction effects of age and stand density on vegetative characteristics, growth rates and soil quality index in afforestation with mesquite is presented in Table\u0026nbsp;(1). We found that effects of stand age, stand density and their interaction on stem number, crown height growth and soil quality index were significant. The average number of stems was the highest (7.8 per tree) in the 15-year-old stand and the lowest (1.5 per tree) in the 34-year-old stand. Changes in total height, collar diameter, basal area, total height growth, collar diameter growth, basal area growth, competition between stands and tree biomass were affected by the age of the stand and the interaction of age and stand density. The changes in the crown area and the average annual growth of the crown area were only influenced by the age of the stand. The average annual growth of the biomass was only influenced by the interaction effect of age and density (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe average annual growth of the collar diameter and height of the trees decreased with age and reached 4.1 mm and 17.7 cm in the 34-year-old stand, respectively, which differed from the 15-year-old stand where collar diameter and height averaged 7.2 mm per year and 31 cm per year, respectively. The surface soil quality index increased with the age and density of the forest stand, and it averaged 0.714 in the dense stand, which was higher than that of the thin stand (0.640).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGLM analysis of the effects of age and stand density on mesquite vegetative characteristics and soil quality index\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eTotal Height\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eBase Diameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eBasal area\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eCrown Area\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003eStem No.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStand Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e131.070\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43.820\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e33.239\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e42.319\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e104.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.942\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e.085\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.277\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e.618\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e4.492\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.035\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026times; Density\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.906\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.452\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.005\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5.976\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e.622\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.538\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e25.446\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eTreatments\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eHeight Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eBase Dia. Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eBasal area Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eCrown area Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003eCrown Heigh Growth\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDf\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStand Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e276.744\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43.356\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.367\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e.036\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e42.319\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e27.979\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.292\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e.593\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e.442\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e.678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.411\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e.618\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e5.514\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.020\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026times; Density\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.953\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.716\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.026\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.812\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e.009\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e.547\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e.580\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e7.551\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eTreatments\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCompetition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eBiomass (Chojnacky)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eBiomass Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eSoil Quality Index-Surface Soil\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003eSoil Quality Index-Deep Soil\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDf\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eSig.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStand Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e76.954\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29.253\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2621.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e273.868\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.981\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.161\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e.063\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e.827\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.364\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e923.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e106.648\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026times; Density\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.573\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e.004\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.662\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e.004\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.719\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e.010\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e41.799\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e7.091\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cb\u003e.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBold numbers indicate the significance of the difference.\u003c/p\u003e \u003cp\u003eComparison of the two methods used to estimate mesquite biomass (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) showed that there was a significant difference between the two methods and that Chojnaki's method had a lower standard deviation and standard error than West's method according to the paired sample t test.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of Chojnacki and West methods for estimating biomass and its growth rate\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStd. Deviation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eStd. Error Mean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSig. (2-tailed)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePair 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWest Biomass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30.9527\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19.02975\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.31948\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e9.403\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e207\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChojnaki Biomass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29.3246\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16.60601\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.15142\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePair 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWest Biomass Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.2511\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.82388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e.05713\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e8.188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e207\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChojnaki Biomass Growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.1913\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.72447\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e.05023\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eVegetative characteristics\u003c/h3\u003e\n\u003cp\u003eThe increase in the age of mesquite, regardless of the stand density, was accompanied by an increase in tree height and diameter and an increase in the crown competition between the trees, but the number of stems per tree decreased with the increase in age (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In this study, the effect of density on the average biomass of trees was not significant, but with increasing age from 15 to 27 years, we observed an increase in biomass, and after 27 years, we noted a decrease in the average above-ground biomass of mesquite (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eGrowth rates\u003c/h3\u003e\n\u003cp\u003eThe interaction of stand age and density effects on growth rates in height, basal area, crown area and biomass of trees is shown in figure (4). The trend of decreasing growth in height, basal area, collar diameter, biomass, and crown height growth with increasing age is quite evident. Cown area growth lowest in the 27-year-old stand intermediate in the 34-year-old stand and highest in the 15-year-old stand.\u003c/p\u003e \n\u003ch3\u003eSoil quality\u003c/h3\u003e\n\u003cp\u003eAs seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, the surface soil quality index increased with the age and density of the stand, and it was always higher in the higher density portions of the stand. In contrast to trends observed in surface soils, soil quality index decreased with increasing age of the stand in the lower soil layer sampled, but it was still higher in the dense portion of the stand at any given age. The average soil quality index increased from about 0.52 in the 15-year-old low-density plots to about 0.83 in the 34-year-old dense plots.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe correlations between the studied characteristics is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. As can be seen, the soil quality index showed a positive and significant correlation with the total height, crown height, crown diameter, degree of competition, basal area and biomass, but it showed a negative correlation with the number of stems and average annual growth. Basal area had positive and strong correlation with the total height, crown height, degree of competition and crown area. Crown area had a positive and significant correlation with height, collar diameter and degree of competition.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e \u003cb\u003eVegetative characteristics\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe high number of multi-stems in early ages can be attributed to the presence of livestock in afforestation areas and the activation of lateral buds due to grazing and cutting the terminal bud of seedlings (Cooper-Norris et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The change and decrease in the number of tree stems in the following years has disrupted the process of changes in the average basal area and the average above-ground biomass of the stands, so that the biomass in the 27-year-old stand is more than that of the younger and older stands. The average above-ground biomass of 15-year-old and 27-year-old mesquite trees in this study was 98 and 139 kg, respectively, which is higher than the 58 and 111 kg presented by James Ansley et al. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) for \u003cem\u003eProsopis glandulosa\u003c/em\u003e. Stand age is also an important driver for biomass and productivity (Liu et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Michaletz, Cheng, Kerkhoff, \u0026amp; Enquist, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Stand age can affect biomass and productivity through increasing tree size (Pickle et al., 2007; Poorter et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Barry et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Becknell \u0026amp; Powers, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Zhang and Chen, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe higher density of the stand increases soil carbon storage and wood production, due to more complete crown coverage and greater use of light (Forrester et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Morin, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Changes in trunk diameter can increase or decrease productivity due to changes in light distribution between individual trees (Binkley, Stape, Bauerle, \u0026amp; Ryan, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Soares et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhang \u0026amp; Chen, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe basal area at the collar showed a positive and strong correlation with the total height, crown height, degree of competition and crown area, which indicates the presence of space to grow into and reflects the dynamics of stand growth. At low densities, interactions between trees will not occur or will be weak (Forrester \u0026amp; Bauhus, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). As stand density increases, competitive interactions become more intense, trees occupy more growing space and use more resources such as light, water, and nutrients (Boyden, Binkley, \u0026amp; Senock, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Forrester et al. al., 2013). Recent studies based on large forest inventory datasets show that stand density has stronger effects than diversity on forest productivity (Forrester \u0026amp; Bauhus, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Guo \u0026amp; Ren, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Paquette \u0026amp; Messier, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The lack of significance between stand density and many of the independent variables is due, in part, to the relatively low tree densities sampled in this study and lower levels of inter-tree competition for light even in the higher density portions of the stands. Although the results indicate the importance of changes in the stand age compared to that in stand density in these areas, the effect of density on crown height growth (P\u0026thinsp;=\u0026thinsp;0.02) and soil quality index (P\u0026thinsp;=\u0026thinsp;0.000) was significant.\u003c/p\u003e\n\u003ch3\u003eGrowth rates\u003c/h3\u003e\n\u003cp\u003eThe results of this research showed that the average growth in total height, collar diameter, crown height, basal area and biomass of mesquite trees decreased with increasing age. It is obvious that the growth rate of trees changes with their age, due to physiological changes such as reduction in photosynthesis rate, leaf productivity and transfer of carbon sources to different parts of the plant, leaf size and gas exchange rate (Johnson \u0026amp; Abrams, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The decrease in tree growth over time can be attributed to changes in the supply of required resources (light, nutrients, water), changes in the balance between photosynthesis and respiration, increased hydraulic resistance, reduced nutrient supply, or genetic changes with meristem age (Martinez et al., 2007). However, it should be noted that long-term growth patterns vary greatly between and within tree species (Brienen and Zuidema, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Rozendaal and Zuidema, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Ren (2020) reported that the biomass growth of acacia trees in Chinese forest plantations was rapid (from 1.60 to 185.01 tons/ha) during the first 7 years, and then decreased (to 188.69 tons/ha) during the next 27 years.\u003c/p\u003e\n\u003ch3\u003eSoil quality\u003c/h3\u003e\n\u003cp\u003eThe results of this research showed that the average surface soil quality index increased from about 0.52 in the 15-year-old low-density stand to about 0.83 in the 34-year-old dense stand. The increase of surface soil quality index in forest plantations has been reported in many studies. Ren (2020) showed an increase in soil fertility during the first 34 years in \u003cem\u003eAcacia\u003c/em\u003e plantations in China. In fact, soil quality index of the surface soil increases with increasing age and density of forest plantations, due to the increase in vegetation cover and root development that increases the accumulation of organic matter in the surface soil, and hence, the levels of nutrients and chemical elements that improve soil quality (Wang et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2021\u003c/span\u003e and \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Zhao et al., \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Zethof et al., \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The increase in soil fertility can also be related to the increase in nitrogen fixation (Xiong et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Fu et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and Yi et al. (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) reported that during the growth and aging process, soil microorganisms and nematode communities play a key role in improving soil physical and chemical properties.\u003c/p\u003e \u003cp\u003eThe decrease in soil quality index in the lower soil sampled in this study may be due to, the amount of total phosphorus becomes a limiting factor for carbon sequestration as the afforestation stand ages (\u0026Ccedil;omakli and Turgut, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In general, studies have shown that hot and dry climate areas have less potential for the accumulation of soil organic carbon, total nitrogen, and total phosphors below the 20 cm soil depth and therefore the soil quality index is lower compared to soils in humid areas (Colantoni et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Guo et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The negative correlation between soil quality index and the average growth of vegetative characteristics of mesquite trees is related to the increase in the age of the trees and the decrease in the average growth.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWe found that Chojnaki's method for estimating mesquite biomass, which had a lower standard deviation and standard error, performed better than the West method. After 27 years, we observed that height growth rate decreased due to increased competition. The significant increase in collar diameter, basal area, biomass, and surface soil quality index in the 34-year-old stand compared to the 27-year-old stand indicates there may be an opportunity to increase the volume and density of trees in the stand into the future. In general, higher density plantings (250 stems per hectare) of mesquite in afforestation plantings in this dry desert area, improve soil quality and promotes vegetative development and production as stands develop over time, and therefore mesquite is a suitable species for revival of dry and sparsely covered areas.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.H. Conceptualization, Methodology, Data curation, Project administration, Writing \u0026ndash; original draftM.H. Methodology, Formal analysis, Software, Writing \u0026ndash; review \u0026amp; editingA.E. Data curation, Investigation, ResourcesM.B. Validation, Writing \u0026ndash; review \u0026amp; editingD.C.D. Validation, Writing \u0026ndash; review \u0026amp; editing\u003c/p\u003e\u003cp\u003e \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003ewe hereby certify that the manuscript has been approved by all authors and the manuscript has not been published or accepted before and is not under consideration for publication elsewhere. All authors have seen and agreed to the submitted version of the manuscript and doesn\u0026rsquo;t have any conflict of interest.\u003c/span\u003e \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBarry, K. E., Mommer, L., van Ruijven, J., Wirth, C., Wright, A. J., Bai, Y., Milcu, A. (2018). The future of complementarity: Disentangling causes from consequences. 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Competition and facilitation between Eucalyptus and nitrogen-fixing Falcataria in relation to soil fertility. Ecology, 86, 92\u0026ndash;1001. https://doi.org/10.1890/04-0430\u003c/li\u003e\n\u003cli\u003eBrienen RJW, Zuidema PA., 2006. The use of tree rings in tropical forest management: Projecting timber yields of four Bolivian tree species. Forest Ecology and Management, 226(1\u0026ndash;3):256\u0026ndash;67.\u003c/li\u003e\n\u003cli\u003eChen, G., Gu, X., Capinha, C., Lee, S.Y., Cui, B., Yang, F., Lin, Y., Jia, M., Wang, M. and Wang, W., 2023. Large‐scale changes in macrobenthic biodiversity driven by mangrove afforestation. Journal of Applied Ecology.\u003c/li\u003e\n\u003cli\u003eChojnacky DC, Jenkins JC, Heath LS. 2014. Updated generalized biomass equations for North American tree species. \u003cem\u003eForestry\u003c/em\u003e 87:129-151\u003c/li\u003e\n\u003cli\u003eColantoni, A., Ferrara, C., Perini, L. and Salvati, L., 2015. Assessing trends in climate aridity and vulnerability to soil degradation in Italy. \u003cem\u003eEcological indicators\u003c/em\u003e, \u003cem\u003e48\u003c/em\u003e, pp.599-604.\u003c/li\u003e\n\u003cli\u003e\u0026Ccedil;omakli E., Turgut B., 2021. Determining the effects of the forest stand age on the soil quality index in afforested areas: A case study in the Paland\u0026ouml;ken Mountains. Soil and Water Research, 16(4): 237-249.\u003c/li\u003e\n\u003cli\u003eCooper-Norris C.E., Katherine E. Hood, Darrel B. Murray, Tian Zhang, James P. Muir, William E.P., 2023. Mesquites Limit Targeted Grazing Effects on Texas Wintergrass Growth and Reproduction Responses. Rangeland Ecology \u0026amp; Management, 90: 109-120.\u003c/li\u003e\n\u003cli\u003ede-Miguel S., Pukkala T., Assaf N., Shater Z (2014) Intra-specific differences in allometric equations for aboveground biomass of eastern Mediterranean Pinus brutia. Ann. For. 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Ecological Indicators, 125: 107445.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"mesquite, growth, clump age, density, biomass, soil quality","lastPublishedDoi":"10.21203/rs.3.rs-4006840/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4006840/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eEvaluating the degree of success in the growth, effectiveness and durability or replacement of pioneer afforestation in dry areas of the world is one of the important issues of managing these forests. We evaluated the suitability of mesquite for afforesting degraded lands in the dry climate region of Einkhosh, Ilam province, Iran by studying the influence of stand density (180 and 250 trees per ha) and age (15, 27 and 34 years) on tree development, growth and biomass, and soil quality in. We measured tree characteristics (height, crown height, collar diameter and crown area) and calculated above-ground biomass. Soil quality index was determined at two depths (0\u0026ndash;15 and 15\u0026ndash;30 cm) based on the measured physical, chemical and biological soil properties. The results showed that stand age and density and their interaction significantly affected stem number, crown height growth and soil quality index. The average number of stems was the highest (7.8 per hectare) in the 15-year-old stand and the lowest (1.5 per hectare) in the 34-year-old stand. Height, collar diameter, basal area growth, biomass, and competition between trees were significantly affected by stand age and its interaction with stand density (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). The average annual growth of tree collar diameter and height with age was lowest (4.1 mm per year and 17.7 cm per year, respectively) in the 34-year-old stand. In contrast, average annual growth rates of 7.2 mm and 31 cm for collar diameter and height, respectively, in the 15-year-old stand. The surface soil quality index increased with the stand age and density, and it was highest (averaging 0.714) in the dense areas of the 34-year-old stand. In contrast, soil quality index at lower soil depths, decreased with increasing stand age, but it was still highest in the dense areas of the 34-year-old stand. The basal area at the stem collar showed a positive and strong correlation with total height, crown height, degree of competition and crown area. In general, high density mesquite afforestation plantings (250 trees per hectare) in this dry and desert area improved soil quality and increased vegetative and productivity characteristics of mesquite, especially as stands aged. Therefore, mesquite can be a suitable option for revitalization of sites in dry and sparsely vegetated areas.\u003c/p\u003e","manuscriptTitle":"Evaluation of biomass and vegetative characteristics of mesquite (Prosopis juliflora) afforestation in arid area of Iran","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-07 05:08:36","doi":"10.21203/rs.3.rs-4006840/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"31f4fe2a-9ead-4c07-a310-3a80d36d78e7","owner":[],"postedDate":"March 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-05-18T19:08:26+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-07 05:08:36","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4006840","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4006840","identity":"rs-4006840","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}