Interspecific variation in tree- and stand-scale stemflow funneling ratios in a subtropical deciduous forest in eastern China

摘要

Stemflow is an important water flux in forested ecosystems, which is influenced by both biotic and abiotic factors. The stemflow funneling ratio, F_P, is a straightforward parameter to express the funneling efficiency of individual trees,F_(P,B_t) , or at the stand-scale, F_(P,B_s). Nevertheless, no known studies have compared the F_P and its influencing factors between tree- and stand-scales in a subtropical deciduous forest. In this study, F_P values from Q. acutissima and B. papyrifera trees were computed for a subtropical area of eastern China, and examined in relation to five biotic variables and ten abiotic variables. The relative contribution ratio (R_(CR)) of each biotic and abiotic variable to F_(P,B_t) and F_(P,B_s) were evaluated by relative importance analysis. The median F_(P,B_s) of B. papyrifera (104.2) was significantly higher than that of Q. acutissima (62.2), with the median F_(P,B_t) of Q. acutissima and B. papyrifera both varying greatly among individual trees. Projected crown area (R_(CR) = 29.2) and diameter at breast height (R_(CR) = 21.4) were the two most important biotic factors governing F_(P,B_t) of Q. acutissima, while the two critical biotic factors affecting F_(P,B_t) of B. papyrifera were trunk lean (R_(CR) = 62.2) and tree height (R_(CR) = 15.1), respectively. At the stand scale, gross precipitation (GP), rainfall duration (DE) and vapor pressure deficit (D) were the three most critical factors affecting F_(P,B_s) of Q. acutissima and B. papyrifera. GP and DE exerted positive effects but D a negative effect on stemflow generation. These findings provide new insights into the F_P at both tree- and stand-scales within subtropical ecosystems.