Intrastorm stemflow variability of a xerophytic shrub within a water-limited arid desert ecosystem of northern China

摘要

An increasing number of studies in recent years has elucidated distinguishable effects of stemflow on hydrology and biogeochemistry within a variety of ecosystems. Nonetheless, no known studies have investigated the temporal variability of stemflow volume within discrete rainfall events for xerophytic shrubs. Here, stemflow was monitored at 5-min intervals using a tipping-bucket rain gage during the 2015 growing season for a xerophytic shrub (Caragana korshinskii) within a water-limited arid desert ecosystem of northern China. We characterized the stemflow temporal variability, along with rainfall, and found the temporal heterogeneity of rainfall clearly affected the timing of stemflow inputs into basal soil within discrete rainfall events. The rainfall threshold value for stemflow generation is not a constant value but a range (0.6~2.1 mm, with an average of 1.1 mm) across rainfall events and is closely associated with the antecedent dry period. Time lags existed between the onset of rainfall and the onset of stemflow, and between rainfall peaks and stemflow peaks. Our findings are expected to be helpful for an improved process-based understanding of the temporal stemflow yield of xerophytic shrubs within water-limited arid desert ecosystems.