Factors influencing the assembly of understory woody communities in Pinus massoniana plantations in Guangxi, China

The study of community assembly, or the non-random process of species coming together, can reveal mechanisms that allow species to coexist and maintain their diversity. To investigate the community-building mechanisms behind the assembly of woody plant communities in Pinus massoniana plantations, we found plantations existing in three different climates (northern tropic, central subtropic, and southern subtropic) and at three different successional stages (young, middle-aged, and old-growth) in Guangxi, China. Using field community surveys and sampling, we collected, named, and analyzed a variety of woody plant species, and measured their functional using leaf thickness (LT), tissue density (LTD), area (LA), specific area (SLA), dry matter content (LDMC), nitrogen content per unit mass (LNC mass ), potassium content per unit mass (LKC mass ), and several other indicators. Using these communities’ functional traits and computer models that generated their likely phylogeny, we were able to elucidate what forces may have driven the development of community-building mechanisms communities in their various climates and successional stages. We found: 1) The functional traits LT, LTD, SLA, LDMC, LNC mass , and LKC mass were likely phylogenetically conserved, while the other traits we measured likely were not. 2) When we based communities’ structures on their functional traits, they were generally consistent their phylogenetic structure in southern and central subtropical plantations, middle-aged plantations in northern tropics and central subtropics, and old-growth plantations in northern tropics. In these communities, their assembly was driven by habitat filtering. 3) Communities in middle-aged and old-growth plantations in southern subtropical Guangxi had functional traits inconsistent with their phylogeny: while their functional traits indicated a tendency to aggregate, their phylogeny indicated a shift from aggregation to dispersion. In these communities, their assembly was driven by habitat filtering and similarity limitation. This information can then be used to enhance the function of ecosystem services and protect biodiversity of communities in Pinus massoniana plantations through tropic and subtropic China.