Soil matters: measured soil variables explain significant variation of tree beta-diversity in permanent forest plots (Lienhuachih, Taiwan)

Li-Wan CHANG1, David ZELENÝ2, Ching-Feng LI2, Shau-Ting CHIU3 & Chang-Fu HSIEH1
1 Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan
2 Department of Botany and Zoology, Masaryk University, Brno, Czech Republic
3 Department of Botany, Taiwan National Museum of Natural Science, Taichung, Taiwan

Recently, several studies used forest permanent plots, established within the framework of Center for Tropical Forest Science, to investigate the beta-diversity pattern of forest vegetation in tropical, subtropical and temperate zones. Topographical variables, which are available for all permanent plots, are usually the only environmental factors used in these studies, although it is acknowledged that topography influences the vegetation mostly indirectly via soil properties. This issue becomes important especially in studies focusing on variance partitioning of betadiversity among environmental and spatial components and comparison of their proportions, aimed to disentangle the importance of niche and neutral assembly in plant communities where we expect that available environmental factors are sufficient for describing the environmental control of species composition. We focused on two questions: 1) how does the variation in species composition explained by environment increase when soil variables are included into analysis along to topographical variables, and 2) which topographical and soil variables, respectively, are redundant (i.e. highly correlated with others) and which are not. We used the data from the 25 ha forest permanent plot in Lienhuachih, located in central Taiwan, where we measured 4 topographical and 16 soil parameters from soil samples collected in each of 625 grid cells. As a result, we found that including soil data as explanatory variables along to topographical factors is more than twice the variation explained by environment. The most important soil variable in Lienhuachih is C/N ratio, and the most important topographical variable is convexity. We conclude that soil variables, although partly correlated to topography, play an important role in explaining variation in species composition.

© 2012 Organizing Committee