Traditionally, ecologists have used individual lattice data to simulate species distribution at the individual species or community levels. In that method, trees are always counted as individuals regardless of scale and life stage effects.
Dr. CAO Min and his team of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study in a 20-ha tropical forest dynamics plot (21°37′08″N, 101°35′ 07″E) in Xishuangbanna, Southwest China. They modeled lattice count data and basal area data at the individual species level and at the community level while simultaneously considering scale and life stage effects.
They hypothesized that basal area data are more closely related to environmental variables and predicted that the R-squared value of the fitted model based on basal area data would be higher than that based on count data because of strong environmental filtering effects. They also predicted that the variation explained by environmental variables would be higher for basal area data than for individual count data, also owing to strong environmental filtering effects.
Their study demonstrated that both lattice count data and basal area data can be reliably used to simulate the spatial distribution of tree species. Their results showed that environmental variables do contribute to the tree species distributions to some extent, but both simultaneous autoregressive and variation partitioning analyses demonstrated that neutral spatial effects are dominant in determining species distributions in the 20-ha plot.
The study entitled “Strong Neutral Spatial Effects Shape Tree Species Distributions across Life Stages at Multiple Scales” has been published in PLoS ONE 7(5): e38247. doi:10.1371/journal.pone.0038247