Inter- and intra-event rainfall partitioning dynamics of two typical xerophytic shrubs in the Loess Plateau of China

[摘要] Rainfall is known as the main water replenishment indryland ecosystems, and rainfall partitioning by vegetation reshapes thespatial and temporal distribution patterns of rainwater entry into the soil.The dynamics of rainfall partitioning have been extensively studied at theinter-event scale, yet very few studies have explored its finer intra-eventdynamics and the relating driving factors for shrubs. Here, we conducted aconcurrent in-depth investigation of all rainfall partitioning components at inter- and intra-event scales for two typical xerophytic shrubs ( Caragana korshinskii and Salix psammophila ) inthe Liudaogou catchment of the Loess Plateau, China. The event throughfall(TF), stemflow (SF), and interception loss (IC), and their temporalvariations within the rainfall event, as well as the meteorological factorsand vegetation characteristics, were systematically measured during the2014–2015 rainy seasons. Our results showed that C. korshinskii had significantly higherSF percentage (9.2 %) and lower IC percentage (21.4 %) compared to S. psammophila (3.8 % and 29.5 %, respectively), but their TF percentages were notsignificantly different (69.4 % vs. 66.7 %). At the intra-event scale,TF and SF of S. psammophila were initiated (0.1 vs. 0.3 h and 0.7 vs. 0.8 h) and peaked(1.8 vs. 2.0 h and 2.1 vs. 2.2 h) more quickly, and TF of S. psammophila lasted longer(5.2 vs. 4.8 h) and delivered more intensely (4.3 vs. 3.8 mm h −1 ), whereas SF of C. korshinskii lasted longer (4.6 vs. 4.1 h) and delivered moreintensely (753.8 vs. 471.2 mm h −1 ). For both shrubs,rainfall amount was the most significant factor influencing inter-eventrainfall partitioning, and rainfall intensity and duration controlled theintra-event TF and SF variables. The C. korshinskii with larger branch angle, more smallbranches, and smaller canopy area, has an advantage over S. psammophila to produce SF moreefficiently. The S. psammophila has lower canopy water storage capacity to generateand peak TF and SF earlier, and it has larger abovegroundbiomass and total canopy water storage of individual plants to produce higherIC compared to C. korshinskii . These findings contribute to the finecharacterization of shrub-dominated ecohydrological processes, and improvethe accuracy of water balance estimation in dryland ecosystems.

[学科分类] 妇产科学