Effects of topographical and edaphic factors on the distribution of plant communities in two subtropical karst forests, southwestern China

Relationships between topography, soil properties and the distribution of plant communities on two different rocky hillsides are examined in two subtropical karst forests in the Maolan National Natural Reserve, southwestern China. Surveys of two 1-ha permanent plots at each forest, and measurements of four topographic and thirteen edaphic factors on the slopes were performed. Twoway Indicator Species Analysis (TWINSPAN) and Detrended Canonical Correspondence Analysis (DCCA) were used for the classification of plant communities and for vegetation ordination with environmental variables. One hundred 10 mx10 m quadrats in each plot were classified into four plant community types. A clear altitudinal gradient suggested that elevation was important in community differentiation. The topography and soil explained 51.06% and 54.69% of the variability of the distribution of plant species in the two forest plots, respectively, indicating both topographic factors (eg. elevation, slope and rock-bareness rate) and edaphic factors (e.g. total P, K and exchangeable Ca) were the important drivers of the distribution of woody plant species in subtropical karst forest. However, our results suggested that topographical factors were more important than edaphic ones in affecting local plant distribution on steep slopes with extensive rock outcrops, while edaphic factors were more influential on gentle slope and relatively thick soil over rock in subtropical karst forest. Understanding relationships between vegetation and environmental factors in karst forest ecosystems would enable us to apply these findings in vegetation management strategies and restoration of forest communities.