Effects of a funnel-shaped canopy on rainfall redistribution and plant water acquisition in a banana (Musa spp.) plantation

Abstract

Most of the world’s tropical landscapes are experiencing changes in land-use and land-cover. In Yunnan Province in southwestern China, land-use changes are widespread throughout the tropics, with large areas of tropical forests being converted to banana (Musa spp.) plantations. In this study, we explored the effects of banana trees’ funnel-shaped leaves on rainfall redistribution and plant water acquisition during the 2017/2018 rainy season. Both the conventional and isotopic (δD and δ18O) methods were used to conduct rainfall partitioning, assess throughfall distribution, and predict plant water sources. We found that the mean contribution of throughfall, stemflow, and interception loss to gross rainfall (rainfall amount: 0.3–33.3 mm) were 71.8 ± 6.8 %, 17.6 ± 3.6 %, and 10.6 ± 3.8 %, respectively. The percentage of stemflow under the banana canopy was noticeably higher than previously reported for other species. The maximum amount of throughfall below the banana canopy was 1.4–4.4 times greater than the gross rainfall (rainfall amount: 14.7–70.5 mm). Soil water content and soil water δD and δ18O showed both horizontal and vertical heterogeneities within the banana plantation. Analysis of δD and δ18O indicated that banana trees absorbed 72.3 % of their water from the shallow soil stratum at 0−30 cm depth. In addition, the acquisition proportion of 0−80 cm soil water ranged from 10.2%–16.3% in the horizontal directions (0−360°). These findings indicated that banana trees’ wide and long leaves considerably altered rainfall redistribution, which in turn affected their water acquisition characteristics. As banana plantations expand in this area, there is an urgent need to further examine environmental consequences such as soil erosion and surface runoff resulting from banana cultivation.