On the importance of stemflow to the woody plants in drylands: Individual vs. ecosystem scales

Abstract

Stemflow has long been recognized as an important ecohydrological process in drylands, and may influence dynamics of woody plants by altering rainfall redistribution. However, quantification of the effects of stemflow on woody plants dynamics remains largely unclear. It is also unknown whether the effects of stemflow are consistent for individual plants and ecosystems where woody plants grow. This study developed an ecohydrological model to explore how stemflow affected individual woody plants and ecosystems, and how the effects changed along a rainfall gradient (10–600 mm) in a dryland ecosystem. This study demonstrated the positive effects of stemflow on woody plants in both individual (by a degree of 16–48%) and ecosystem scales (by a degree of 8–45%). Stemflow started to promote woody plant growth in the individual scale even when annual rainfall was very low (<50 mm), whereas stemflow did not exert strong influences for the whole ecosystems until annual precipitation was higher than 130 mm. However, the effects of stemflow in ecosystem scale might surpass the counterpart in individual scale under some ranges of annual rainfall. Namely, the effects of stemflow in individual and ecosystem scales mismatched. The positive feedback between woody cover and stemflow may cause the unequal effects of stemflow for individual plants and ecosystems. Overall, this study quantified how stemflow affected woody plants in individual and ecosystem scales, which may contribute to dryland restorations by assisting vegetation configuration and being integrated into dynamic global vegetation model.