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

Abstract 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 (RCR) of each biotic and abiotic variable to tree-scale F P , B t and stand-scale 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 (RCR = 29.2%) and diameter at breast height (RCR = 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 (RCR = 62.2%) and tree height (RCR = 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.