Assessment of Vegetation at Selected Grazing Sites Central Sudan, and Animal Dietary Composition using Animal Manure Pollen Analysis.

This study primarily sought to assess vegetation composition, diversity, and distribution across six significant grazing sites in Khartoum State, Central Sudan. This study also aimed to elucidate the diet of small ruminants and camels through the analysis of plant pollen found in their manure. A random sampling procedure was employed to conduct various vegetation measurements. Animal manure underwent chemical treatment with 10% KOH and was analyzed using the standard acetolysis method to quantify and identify pollen grains from the manure. Paleontological Statistics (PAST) version 4.13 was utilized to perform various statistical analyses on vegetation and pollen to address research inquiries. The study sites demonstrated significant variability in vegetation composition as well as alpha and beta diversity. The eastern Nile sites were distinctly different from the Northwestern sites. The Abuseweid site exhibited the greatest herbaceous diversity and richness, whereas the Buhat site demonstrated the highest dominance of species. Acacia species exhibited extensive distribution across sites. Buhat exhibited the highest percentage of woody cover, whereas the sand dune site demonstrated the lowest percentage. Grass pollen comprised most of the pollen in animal feces samples, with Indigofera pollen prevalent in Al-Salama samples and Amaranthus pollen prevalent in Buhat samples. The diets of goats and camels predominantly comprised grasses, followed by forbs and Acacia, whereas sheep favored Indigofera, followed by Acacia and Tribulus. The correlation between plant species relative density and pollen percentage of Al-Haf, Al-Salama and Buhat was significant and positive. This study offers valuable insights into the assessment of vegetation in grazing areas and the prediction of grazing animals’ diets based on fecal pollen data. This information is crucial for designing effective rangeland management. Assessment of Vegetation at Selected Grazing Sites Central Sudan, and Animal Dietary Composition using Animal Manure Pollen Analysis. Abdelrahim A. Elbalola* Biology Department, Faculty of Science, Tabuk University, Tabuk, KSA Tabuk 71491-P.O. Box 741 [email protected] 00966509212489. Author contribution: Conceptualization – Ideas; formulation or evolution of overarching research goals and aims. Data curation – Management activities to annotate (produce metadata), scrub data and maintain research data (including software code, where it is necessary for interpreting the data itself) for initial use and later re-use. Formal analysis – Application of statistical, mathematical, computational, or other formal techniques to analyze or synthesize study data. Funding acquisition – Acquisition of the financial support for the project leading to this publication. Investigation – Conducting a research and investigation process, specifically performing the experiments, or data/evidence collection. Methodology – Development or design of methodology; creation of models. Project administration – Management and coordination responsibility for r the research activity planning and execution. Resources – Provision of study materials, reagents, materials, patients, laboratory samples, animals, instrumentation, computing resources, or other analysis tools. Software – Programming, software development; designing computer programs; implementation of the computer code and supporting algorithms; testing of existing code components. Supervision – Oversight and leadership responsibility for the research activity planning and execution, including mentorship external to the core team. Validation – Verification, whether as a part of the activity or separate, of the overall replication/reproducibility of results/experiments and other research outputs. Visualization – Preparation, creation and/or presentation of the published work, specifically visualization/data presentation. Writing – original draft – Preparation, creation and/or presentation of the published work, specifically writing the initial draft (including substantive translation). Writing – review & editing – Preparation, creation and/or presentation of the published work by those from the original research group, specifically critical review, commentary or revision – including pre- or post-publication stages. Author Affiliation: Biology Department, Faculty of Science, Tabuk University, Tabuk, KSA Tabuk 71491-P.O. Box 741 [email protected] 00966509212489. Email address of corresponding author: Funding information: None. Conflict of interest statement: The author whose name is mentioned immediately below certify that he has NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Author name : Abdelrahim Adam Elbalola. Data availability statement: The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

This study primarily sought to assess vegetation composition, diversity, and distribution across six significant grazing sites in Khartoum State, Central Sudan. This study also aimed to elucidate the diet of small ruminants and camels through the analysis of plant pollen found in their manure. A random sampling procedure was employed to conduct various vegetation measurements. Animal manure underwent chemical treatment with 10% KOH and was analyzed using the standard acetolysis method to quantify and identify pollen grains from the manure. Paleontological Statistics (PAST) version 4.13 was utilized to perform various statistical analyses on vegetation and pollen to address research inquiries. The study sites demonstrated significant variability in vegetation composition as well as alpha and beta diversity. The eastern Nile sites were distinctly different from the Northwestern sites. The Abuseweid site exhibited the greatest herbaceous diversity and richness, whereas the Buhat site demonstrated the highest dominance of species. Acacia species exhibited extensive distribution across sites. Buhat exhibited the highest percentage of woody cover, whereas the sand dune site demonstrated the lowest percentage. Grass pollen comprised most of the pollen in animal feces samples, with Indigofera pollen prevalent in Al-Salama samples and Amaranthus pollen prevalent in Buhat samples. The diets of goats and camels predominantly comprised grasses, followed by forbs and Acacia, whereas sheep favored Indigofera, followed by Acacia and Tribulus. The correlation between plant species relative density and pollen percentage of Al-Haf, Al-Salama and Buhat was significant and positive. This study offers valuable insights into the assessment of vegetation in grazing areas and the prediction of grazing animals’ diets based on fecal pollen data. This information is crucial for designing effective rangeland management.

rangeland, vegetation composition, diversity, animal diet, fecal pollen, semi-arid, Sudan.

. Numerous authors have proposed definitions for rangelands (Holecheck et al. (1989); Maxwell (1990); Stoddart et al. (1975); Harington et al. (1984). Rangelands consist of regions that are not conducive to agricultural practices or timber harvesting because of their rocky, steep, saline, or intermittently wet characteristics. Saline savannas and deserts represent the primary categories of rangeland ecosystems, while wetlands, forests, alpine regions, grasslands, and tundra constitute the remaining types (Friedel et al., 2000). Sudan’s semi-desert belt has a southern boundary at 14° N (Abdel Magid et al., 2005). Harrison and Jackson classified Sudan’s semi-desert habitat in 1958 by identifying natural vegetation types. Mohamed et al. (2016) found a 13.2% decrease in five floristic composition, precipitation, and soil type zones. The area decreased from 417.297 to 250.196 km2. Natural vegetation in eastern semi-arid Sudan decreased from 26.1% in 1979 to 12.6% in 1999 and 9.4% in 2007 (Sulieman et al., 2013). The desert class from the north to the central Sudan replaced the lost region. Over the past 50 years, rain-fed agriculture has destroyed forest cover, shrubs, rangeland, ecosystems, and wildlife habitats (UNEP, 2007). Human activities like agricultural clearing, energy production, overgrazing, and brush fires affect this region’s vegetation cover, which is essential for meeting population needs and supporting livestock (Sulieman, 2008). The region also harvests grass for thatching and shrubs for construction and firewood (Halwagy, 1961). Overgrazing includes both the number of animals and the duration of grazing, especially before seed dispersal. This practice harms the plant community (Elnour, 2008) and changes species composition (Noy, 1979). Stunted plants result from photosynthesis tissue removal. Heavy grazing pressure is the main cause of rangeland degradation, according to Abusuwar and Darrag (2004). Recurrent grass and shrub burning alters the annual litter deposition cycle (Heady, 1975), replaces perennials with annuals (Skerman, 1962), affects soil microbiota (Meiklejohn, 1955), and changes species composition and plant characteristics. Ecological zone reduction and modification, whether natural or anthropogenic, are expected to reduce plant species diversity. A region within an ecological zone with a specific soil classification type and rainfall pattern can support a defined species assemblage with relative abundances. Each species assembles component cycles, interacts with ecosystem components, and meets its needs. This species structure is the result of competition. The reduction and forced alteration of land areas that sustain any species assemblage will result in competitive displacement, extinction, decline, and invasion, creating new transitional or permanent assemblages. Natural rangelands are able to meet the dietary requirements of livestock for a predetermined amount of time in arid savannah and semi-desert regions. This time is contingent on the amount of rainfall that occurs during the wet season as well as the length of time that it lasts. Broccoli and shrubs are essential components in livestock productivity in arid and semi-arid regions because they mitigate protein deficiencies during the prolonged dry summer season. Although they serve as effective safeguards against seasonal feed shortages, they are also essential elements in the production of livestock in these regions. In the process of formulating range management strategies, the parameters of animal diet botanical composition and pasture species composition play a significant role. These strategies include the selection of species for reseeding degraded ranges and the identification of essential species that will serve as the foundation for range management. There are many different animal species, and it is expected that their eating habits will vary. (Abusuwar et al., (2010); Hoffman, 1973). The Bite-Count Method, which was developed by van Dayne, is currently being utilized quite frequently for the purpose of determining the botanical composition of animal diets. Previous studies of dietary and grazing behaviors relied on the analysis of macro remains found in stomach contents or feces, in addition to fecal counts (Punsvik et al., 1979; Staaland et al., 1979; Staaland et al., 1984; Staaland et al., 1986). These studies were conducted in order to determine those behaviors. When it comes to pollen extraction, the KOH/acetolysis method (Faegri et al., 1964; Erdtman, 1969) is utilized quite frequently. The KOH/acetolysis technique that is commonly used was modified by Brad Witt et al. (2006), who published their findings. After the digestive process, pollen is easily identifiable, and there are well-established methods for both preparing it and identifying it. In addition, feces are easily collected and can be sampled without causing any harm to the animals, while also causing only a minimal amount of disturbance to them (Bjune, 2000). The percentage species composition as a measure and an indicator of range status is a useful and easy method for obtaining such information. The knowledge of the botanical composition of grazing animals’ diets is crucial for the effective distribution of forage among various herbivore types, the selection of grazing animals that are compatible with forage resources, the identification of species necessary for reseeding degraded ranges, the prediction of overgrazing consequences by different animals, the identification of key species for management purposes, and the assessment of the appropriateness of exotic animals for specific range types. The dietary botanical composition of livestock directly mirrors the species composition of natural rangelands, although it varies somewhat based on the livestock’s preferences for selecting these species (Abusuwar et al., 2010).

and Methods. The study sites. The examined region is classified as Acacia Desert Scrub (Andrew, 1948; Smith, 1949) or Acacia tortilis-Maerua crassifolia Desert Scrub (Harrison and Jackson, 1958). The Comprehensive Agricultural Census of 2009 estimated that the area of Khartoum state occupied by natural rangelands and forests was 2.1 million hectares. The state is home to over 1,384,000 livestock, comprising 24,000 cattle (17%), 7,000 camels (1%), 513,000 sheep (37%), and 624,000 goats (45%). Three sites in the eastern section of the study area, Wadi Al-Haf, Al-Salam, and Wadi Abu Seweid, and three in the Northwestern section, Wadi Medaisees, Wadi Buhat, and a sand dunes to the west, were chosen for the study. The research locations were examined in 2022 during the rainy season. The coordinates of Wadi Al-Haf are 15° 42.330ʹ N, 033° 06.278ʹ E. The coordinates for Al-Salama were 15° 42.289ʹ N, 033° 06.283ʹ E, and location 15° 37.133ʹ N, 032° 55.005ʹ E, was for Wadi Abuseweid in the eastern part of the study area. Wadi Medaisees is in the Northwestern corner of Khartoum State. Location: 16° 12.223’ N, 31° 41.392’ E. Buhat, 108 km Northwestern Omdurman city at 16° 20.395’ N, 31° 48.686’ E, it is a part of Wadi El Mugaddam at Buhat village. The area had many sand dunes of various sizes. The initial segment of Qoz Abu Dolou’a sand dunes selected for this study was at (16° 11.234’ N, 31° 49.258’ E). Vegetation sampling. This study utilized a combination of systematic, non-random, and random sampling procedures (Greig-Smith, 1983). Sampling sites were selected non-randomly, informed by local knowledge regarding grazing areas and the flow directions of the studied lowlands (wadies), where both cultivation and grazing activities occur during the rainy season. A metal quadrate measuring 1m x 1m was utilized for herbaceous sampling. Five quadrates were determined to adequately encompass all herbaceous species at each site. 20 x 20 plots were used for woody vegetation. Quadrates were randomly positioned along a line transect established parallel to the lowland (wadi) direction. Vegetation density and cover . The density of herbaceous species was assessed within a 1 m x 1 m quadrat. Individuals of each species were counted, with all individuals rooted within the quadrat considered. The species present in each quadrat were recorded along with their respective individual counts. Species identification was conducted by specialists from the Department of Botany at the Faculty of Science, Khartoum University, and the Administration of Rangeland and Fodder of Khartoum State, utilizing references such as the Flora of Tropical East Africa (FTEA). The data sheets included a list of species and their respective counts within each quadrate, which facilitated the determination of the presence or absence of each herbaceous species in the quadrate. Relative densities were computed in accordance with Curtis (1959). Woody cover was assessed utilizing the methodology outlined by Husch et al. (1982). This method involved measuring the crown diameter of each tree within the (20 m x 20 m) plot by extending a measuring tape on the ground, with the start and end points of the measurements aligned to the outermost edges of the crown, ensuring the tape was tangent to the tree stem. The crown diameter was subsequently measured again in a manner perpendicular to the initial measurement. The measurements were documented as diameter one (D1) and diameter two (D2). The crown cover for each tree was subsequently calculated using the equation provided below: \(Crown\ area\ (CA)=\frac{D1+D2\ }{4}\ \times\pi\) 2 The total crown coverage of all trees of each species within the plot was aggregated, and the percentage of the plot area occupied by the tree crowns of that species was computed as follows: \begin{equation} \%\ species\ \ cover=\frac{\text{total\ crown\ covers\ of\ that\ species}}{\text{plot\ area}}\ x\ 100\%\nonumber \\ \end{equation} Woody cover at each site was determined as a percentage of the total area of four plots (20 m x 20 m) based on the cover generated by trees of all species. Pollen analysis, quantification, and identification. Significant quantities of recent manure of camels, sheep, and goats were collected from each study site and stored in labeled paper bags. Sheep and goat manure were combined in composite samples due to the challenges in distinguishing between them. Manure samples were subsequently transported to the laboratory for pollen analysis. The botanical composition of animal diets was assessed through quantitative and qualitative analysis of pollen found in manure, serving as an indicator of the plant species ingested by the animals. The pollen of each species or group of species within the same taxonomic group exhibits distinct characteristics. Pollen is readily recognizable, identifiable, and countable. Fresh animal manure was washed with water to eliminate any potential pollen present on the outer surface. Subsequently, samples underwent chemical treatment with 10% KOH and were analyzed following the standard acetolysis method for contemporary pollen grains (Faegri & Iverson, 1975). Pollen samples were stained with Basic Fuchsin pigment and subsequently stored in stick vials. Pollen grains were enumerated across 10 slides, each prepared with a single drop sample, mounted in glycerin, covered with a cover slip, and examined under a light microscope. Pollen types and species were counted individually in transects by sliding the specimen from left to right and vice versa. The process persisted until the entire slide was covered, at which point the quantity of pollen per slide was documented. Subsequently, the contribution of each species to the animal diet was computed as a percentage. Photographs of various pollen species were captured using a 14-megapixel Sony-Cyber Shot digital camera through the microscope’s eyepiece. Statistical analysis. A colored stacked chart depicting the distribution and abundance of plant species at the study sites was created. A Bray-Curtis similarity test was performed on the species abundance data from the sites, resulting in a similarity matrix. A diversity test was performed, yielding multiple species diversity indices. Pollen distribution and abundance were depicted in colored, stacked charts. A Bray-Curtis correlation test (p < 0.05) was performed to assess the relationship between species relative density and percentage manure pollen, resulting in a corresponding plot. All statistical analyses were conducted utilizing Paleontological Statistics (PAST) version 4.13.

. Herbaceous species composition, diversity, and distribution . Figure 1 illustrates the distribution and abundance of plant species across the study sites. The sites exhibited significant variation in their vegetation composition and abundance. The Eastern Nile sites (the three left columns) exhibited distinct vegetation structures compared to the Northwestern sites. Al-Haf site was predominantly characterized by the grass species Aristida mutabilis, while Medaisees site was primarily dominated by Amaranthus gracizans, which entirely supplanted Buhat site. Zaleya pentandra exhibited dominance at the sand dune location. It was also noted that the vegetation of Al-Salama and Abuseweid comprised multiple species. The Bray-Curtis similarity matrix presented in Table 1 corroborated these findings, revealing that Medaisees and Buhat (Northwestern sites) demonstrated the highest similarity (0.620896), succeeded by Abuseweid and Al-Salama (0.557482). This outcome validated that the locations exhibited significant variation in their species composition. Table 2 presents various species diversity indices for the study locations. Abuseweid demonstrated the highest Shannon and Taxa-S diversity indices, followed by Medaisees, whereas Buhat exhibited the greatest species dominance, followed by Al-Haf site. The species composition turnover between sites that was measured by Whittaker beta diversity scored 1.7826. Figure 1: A stacked chart (color scheme) showing the distribution and abundance of plant species in the study sites. Table 1: Bray-Curtis similarity matrix between the study sites based on herbaceous species occurrence and density. | Al-Salama | 0.284747 | |||| | Abuseweid | 0.398813 | 0.557482 | ||| | Medaisees | 0.099885 | 0.114257 | 0.113957 | || | Buhat | 0.0006 | 0.006698 | 0.013758 | 0.620896 | | | Sand dune | 0.293627 | 0.198637 | 0.247585 | 0.075818 | 0 | Table 2: Plant species diversity indices of the study sites. | Taxa_S | 11 | 9 | 20 | 17 | 6 | 6 | | Dominance_D | 0.5609 | 0.2613 | 0.2783 | 0.4415 | 0.9724 | 0.3519 | | Simpson_1-D | 0.4391 | 0.7387 | 0.7217 | 0.5585 | 0.02762 | 0.6481 | | Shannon_H | 0.8764 | 1.513 | 1.69 | 1.231 | 0.1137 | 1.209 | | Evenness_e^H/S | 0.2184 | 0.5042 | 0.2709 | 0.2015 | 0.1867 | 0.5582 | | Equitability_J | 0.3655 | 0.6884 | 0.5641 | 0.4346 | 0.06346 | 0.6746 | | Global beta diversity (Whittaker) | 1.7826 | Woody cover . The percentage of woody cover per species and the total woody cover at each study site are presented in Table 3. Wadi Buhat exhibited the highest percentage of woody cover relative to the other sites, whereas Sand Dune demonstrated the lowest value. Wadi Al-Haf and Wadi Abuseweid exhibited similar levels of vegetative cover. At Wadi Al-Haf, Acacia ehrenbergiana comprised the predominant woody cover, accounting for 37.95%. At Al-Salama, Acacia tortilis subsp. spirocarpa comprised the predominant woody cover (13.5%); at Wadi Abu Seweid, the primary woody cover was represented by Acacia seyal (38.04%), whereas at Wadi Medaisees, Acacia nubica constituted the principal woody cover (10.67%) relative to other species. At Wadi Buhat, Acacia tortilis subsp. Radiana and Leptadenia pyrotechnica comprised the majority of the woody cover, accounting for 41.44% and 40.90%, respectively. At the sand dune location, Maerua crassifolia comprised 3.76% and 4.55%, respectively. Table 3: Percentage cover per woody species and the overall woody cover at each of the study sites. | Acacia ehrenbergiana | 37.95% | 3.67% | - | - | - | - | | Acacia seyal | 3.26% | - | 38.04% | - | - | - | | Acacia radiana | 2.59% | 1.57% | 10.87% | - | 41.44% | - | | Acacia nubica | 0.11% | - | 10.98% | 10.67% | - | - | | Acacia spirocarpa | - | 13.05% | - | - | - | - | | Ziziphus spina-christi | 0.32% | 1.19% | 8.71% | 0.96% | - | - | | Balanites aegyptiaca | 3.38% | - | - | - | - | - | | Maerua crassifolia | - | - | - | 0.62% | - | 3.76% | | Leptadenia pyrotechnica | - | - | - | 4.93% | 40.90% | - | | Salvadora persica | - | - | - | 0.74% | 0.61% | - | | Bascia senegalensis | - | - | - | - | 6.46% | - | | % woody cover | 49.61% | 19.48% | 48.60% | 17.92% | 89.41% | 3.76% | Pollen distribution and abundance in animal manure. The distribution and quantities of various pollen species in the manure of grazing small ruminants and camels from different locations are presented as percentages in Table 4 and as color-coded stacked charts in Figures 2a and 2b. Photos of pollen species detected in the investigated manure samples were shown in figure 3. The result highlighted that the diets of grazing animals were made up of mixtures of grasses, forbs, and browse species in varying percentages. Grass pollen constituted the predominant percentage of pollen identified in the manure of both small ruminants (sheep and goats) and camels, except for small ruminants’ manure in Al-Salama, where Indigofera pollen was most prevalent, and in Buhat, where Amaranthus pollen was most abundant. Various pollen types exhibited differing quantities in animal manure from different locations. Acacia pollen was not present in the sand dune samples, whereas Portulaca pollen was exclusively identified within them. The correlation between plant species relative density and pollen percentage pollen in animal feces shown in figure 4, was positive significant (p< 0.05) for Al-Haf, Al-Salama and Buhat, and positive for Abuseweid and Medaisees. Table 4: Distribution and abundance of pollen types (%) between different animals’ manure samples. | Al-Haf | Al Salama | Abuseweid | Medaisees | Buhat | Sand dune | ||||||| | SR | C | SR | C | SR | C | SR | C | SR | C | SR | C | | | Grass spp. | 94.77% | 82.71% | 31.49% | 75.29% | 92.64% | 97.53% | 97.53% | 97.40% | 16.67% | 60.50% | 94.38% | 96.72% | | Tribulus spp. | - | 5.26% | - | 14.04% | 6.69% | 2.34% | 0.33% | 2.01% | - | 12.5% | 1.12% | 3.28% | | Acacia spp. | 0.65% | 12.03% | - | 10.67% | 0.13% | 0.13% | 0.33% | 0.10% | 32.50% | 14% | - | - | | Indigofera spp. | 4.58% | - | 68.51% | - | - | - | 2.01% | 0.13% | - | - | 0.37% | - | | Amaranthus spp. | - | - | - | - | - | - | - | 0.13% | 50.73% | 13% | - | - | | Portulaca spp. | - | - | - | - | - | - | - | - | - | - | 4.12% | - | Figure 2a: Distribution and abundance of different pollen types between sheep and goats’ feces at different sites Figure 2b: Distribution and abundance of different pollen types between camels’ feces at different sites Figure 3: representative photos of pollen types detected in animal feces samples. Figure 4: Bray-Curtis correlation plot between plant species relative density (RD) and pollen species percentage of the studied sites.

. The study sites exhibited considerable variation in plant species composition, diversity, and dominance. Numerous prior studies have examined the distinct variability in vegetation attributes across local, regional, and global scales, attributing this phenomenon to various factors, including soil property heterogeneity (Denslow, 1987); dispersal mechanisms, biotic interactions, gap dynamics, and edaphic or topographic variations (Jones et al., 2007); ecological processes, evolutionary history, and environmental influences (Pausas and Austin, 2001; Slik et al., 2009; Ding et al., 2012); as well as habitat heterogeneity and nutrient balance (Liu et al., 2020). At regional or local scales, climate, soil type, and topography are more significant determinants of diversity distributions than other environmental factors (Ding et al., 2012; Toledo et al., 2012; Shi et al., 2018). The relative advantage of Abuseweid over other sites is attributed to its representation of the ’Butana’ plain, recognized by local pastoralists and farmers for its superior vegetation cover (Sulieman et al., 2013). The soil is classified as vertisols, characterized by dark, cracking clays commonly known as black cotton soil, predominantly alluvial in origin from materials deposited by the Blue and White Nile. This soil is defined by clay content exceeding 60%, an alkaline pH, the presence of gypsum and calcium carbonate, and its vegetation is influenced more by edaphic than climatic factors (Zaroug, 2000). Buhat exhibited the highest dominance value due to the near-total dominance of a single taxon (Amaranthus graecizans) at this site, which also recorded a high number of individuals, second only to Abuseweid, alongside the lowest Shannon index. Equitability, which assesses the uniformity of individual distribution among the existing taxa (Harper, 1999), was maximized at the sand dune, coinciding with the minimal number of taxa and individuals. Global beta diversity refers to the variation in species composition and abundance among study sites, as well as the differences in species richness from one site to another (Whittaker, 1956 & 1960). It also delineates species turnover (Whittaker, 1972). Tuomisto (2010) defined it as the effective number of distinct compositional units (sites). This knowledge on the percentage species composition serves as an effective measure and indicator of range status, providing a straightforward method for acquiring this information. Of the plant species naturally growing across the grazing sites investigated, the grazing animal feces contained mixtures of six plant categories/species, indicating the animals’ choices for their diets. Parsons et al. (1994); Hester et al. (1999); and Rutter et al. (2004) reported that grazing ruminants provided with free choice exhibit a mixed diet, demonstrating partial preferences for specific forages. The findings indicated that the diet of goats and camels primarily consisted of grass, followed by forbs and rowsing. Sheep exhibited a preference for Indigofera, a forb species, over grasses and browse, and favored Acacia, a browse, over Tribulus, another forb species. This outcome contradicts the findings of Abusuwar et al. (2010), who asserted that goats exhibit a preference for browsing in all seasons, while sheep tend to favor grasses during the wet season. The preference of sheep for Indigofera, recognized for its high protein content over grasses, aligns with findings that forage rich in crude protein is highly palatable to both cattle and sheep (Hardison et al., 1954; Cook, 1959; Blaser et al., 1960; Arnold, 1960a). This suggests that the preference hierarchy (grasses, followed by forbs, then browse) proposed by Abusuwar et al. (2010) and Coppock et al. (1986) is not universally applicable across all sites. The preference for grass over forbs, or vice versa, is contingent upon the specific plant species composition of each site, indicating that within grasses or forbs, certain species are favored over others. Additionally, some grasses are preferred over specific forbs and vice versa, as well as certain browse being favored over particular forbs and vice versa. This corroborates the assertion of Leigh (1961) that livestock preferentially consumed grass cultivars with elevated phosphorus and potassium levels over those with lower mineral content. This aligns with the assertions made by Rutagwenda et al. (1990), who indicated that browsers (camels and goats) and, to a lesser degree, intermediate feeders (sheep) can select high-quality forage. The correlation between plant species dominance and animal diet composition, as indicated by pollen analysis, demonstrates that species presence and abundance significantly influenced animal diet. This conclusion is drawn from the observation that species prevalent in the Al-Salama, Buhat, and Abuseweid sites were extensively grazed by animals. The absence of other forb species in the detected pollen in animal feces does not imply that these plants are not consumed by the animals; they may be ingested prior to flowering, or their inflorescences may be unpalatable to the animals. These divergent results may be attributed to variations in the methodologies employed to ascertain the animal diet botanical composition. This variation in animal behavior in feeding would show the importance of having a mixed herd under an open grazing system to fully utilize the different vegetation compositions available in the range. The understanding of the botanical composition of grazing animals’ diets is essential for the effective allocation of forage among diverse herbivore categories, the selection of grazing animals that align with forage resources, the identification of species required for reseeding degraded ranges, the prediction of overgrazing impacts by various animals, the identification of critical species for management objectives, and the evaluation of the suitability of exotic animals for particular range types. The dietary botanical composition of livestock reflects the species composition of natural rangelands, albeit with variations influenced by the livestock’s species selection preferences (Abusuwar et al., 2010).

. The grazing sites investigated are highly variable in terms of vegetation structure, species composition, dominance and diversity. This variation is attributed to soil property heterogeneity dispersal mechanisms, biotic interactions, gap dynamics, topographic variations, and environmental influences. Grass species significantly contributed to animal diets, except at three sites where a shift in species dominance occurred. The correlation between plant species distribution and dominance and animal diet composition, as indicated by pollen analysis, demonstrates that species presence and abundance significantly influenced animal diet. This conclusion is drawn from the observation that species prevalent in the Al-Salama, Buhat, and Medaisees sites were extensively grazed by animals.

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Authors Metrics & Citations Metrics Article Usage 216views 177downloads Citations Download citation Abdelrahim Elbalola. Assessment of Vegetation at Selected Grazing Sites Central Sudan, and Animal Dietary Composition using Animal Manure Pollen Analysis.. Authorea. 27 January 2025. DOI: https://doi.org/10.22541/au.173796000.08904283/v1 DOI: https://doi.org/10.22541/au.173796000.08904283/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.