Trade-Offs and Synergies between Plant Species Diversity and Water Retention Capacity of Pinus massoniana Plantation Community in Danjiangkou Reservoir Area

In order to quantify the plant species diversity characteristics of Pinus massoniana plantations with different stand densities in Danjiangkou reservoir area Hubei Province and relationship their trade-offs synergies water retention capacity give full play forest ecosystem services improve level sustainable management plantations, we used typical plot method, selected 35-year-old low density (925–1000 plants·ha), medium (1425–1625 high (2375–2525 its community structure, composition, understory were studied, respectively, between two calculated. We found that: (1) According survey statistics, there 69 plants shrub herb layers under including 32 shrubs 37 herbs, belonging 33 families 62 genera. (2) The richness layer increased increase density, which was opposite layer. Shannon–Wiener index Simpson dominance showed regularity > while decreased gradually density. Pielou evenness highest high-density medium-density stands, respectively. (3) Trunk flow, soil storage conditions, litter low-medium conditions synergistic relationships layer, everything else trade-off relationships. As far as is concerned, low-density have higher more stable a diversity.