Revealing rainfall partitioning characteristics of shrubs in semi-arid sandy land: Based on in-situ measurement data

• Rainfall was partitioned into T (83.1%), SF (4.8%), and CI (12.1%). • Rainfall amount and duration primarily control T, SF, and CI. • TF and SF were sensitive to moderate and low-intensity rainfall. Rainfall is partitioned by the vegetation canopy into three components: throughfall, stemflow, and canopy interception, which profoundly influence key hydrological processes, including vegetation growth, groundwater recharge, water cycling, and regional water balance. However, research comparing the applicability of throughfall measurement methods in semi-arid shrub communities remains scarce, and quantitative analyses of rainfall partitioning processes based on in-situ observations are still inadequate. This study focuses on the sand-fixing pioneer vegetation of semi-arid sandy land, Caragana microphylla , and conducts simultaneous throughfall measurements using the rain gauge method and the trough method to compare the differences between the two approaches. Based on the trough method data, the characteristics of rainfall partitioning and its driver factors were analyzed. Our findings revealed that throughfall (TF), stemflow (SF), and canopy interception (CI) in Caragana microphylla shrublands accounted for 83.14 %, 4.81 %, and 12.05 % of the total rainfall, respectively. The throughfall rate measured using the rain gauge method (65.46 %) was slightly lower than that measured using the trough method (69.75 %). Rainfall amount and rainfall duration were extremely significantly positively correlated with TF, SF, and CI ( P < 0.001, R 2 > 0.5),whereas the correlation between temperature, vapor pressure deficit, wind speed, and the three components was relatively weak ( R 2 ≈ 0.2). The throughfall rate is influenced by the combined effects of canopy structural characteristics, including crown width, base diameter, plant height, and branch number, with plant height being the most important influencing factor. The findings of this study will highlight the impact of observation methods on the accuracy of throughfall measurements and provide quantitative evidence for the rainfall utilization of sand-fixing vegetation in arid regions, thus offering scientific support for desertification control and the efficient use of water resources.