A data synthesis and comparative review of rainfall partitioning: Drivers and management implications in fruit crops

Abstract

Rainfall partitioning, the redistribution of gross rainfall into canopy interception (Ic), throughfall (TF), and stemflow (SF), is a critical ecohydrological indicator governing water acquisition, soil water availability, and yield in fruit crops. Although studies in various climates have quantified rainfall partitioning across different fruit crops, a concerted effort to quantitatively synthesize such data is still lacking. To address this gap, data from previously published studies on 13 fruit crop species across 13 experimental sites were compiled and analyzed to better understand how these indicators respond to environmental drivers, plant morphological attributes, and artificial management practices. A boosted regression tree (BRT) model was employed to quantify the relative importance of rainfall event characteristics and meteorological factors in driving Ic, TF, and SF. The results indicated that the mean per-event Ic, TF, and SF were 2.2 mm, 12.7 mm, and 0.6 mm, respectively, corresponding to average event-based partitioning ratios of 25.4%, 73.0%, and 4.3%. TF was the primary rainfall partitioning pathway, characterized by the strongest positive linear dependence on gross rainfall (R 2 = 0.96, p < 0.01) and minimal sensitivity to variations in leaf area index. The BRT model revealed that, among environmental drivers, rainfall amount and wind speed predominantly governed TF flux, Ic flux, and the Ic ratio, collectively accounting for 94.5%, 83.5%, and 92.6% of the relative importance, respectively. Notably, despite incorporating data from various fruit crops, these findings may be biased toward the data-dominant species (apple). Plant morphological attributes and management practices significantly altered these components: evergreen fruit crops exhibited a much higher mean Ic ratio (38.0%) than deciduous crops (20.6%) due to perennial leaf coverage. Tree-type crops showed distinctly lower TF and SF ratios compared to bush- or vine-type crops. In tree-type crops, increased planting density enhanced the Ic and SF ratios; conversely, bush- and vine-type crops were more susceptible to competition-driven inhibition at high densities, which weakened their canopy interception function. These findings provide a basis for the hypothesis that hydrological complementarity could be harnessed through layered mixed-cultivation systems combining evergreen and deciduous species. Because tree-type crops constitute a large proportion of fruit crops, optimizing their planting density is of vital importance. Future research could verify the practical effectiveness of two specific strategies: applying medium planting densities in high-rainfall areas to reduce evaporation losses, and adopting high planting densities in low-rainfall areas to enhance localized soil-water storage.