Rainfall partitioning in Amazon Forest: Implications of reduced impact logging for hydrological processes

Abstract

Sustainability is related to the exploitation of a resource without depleting it. To reduce environmental damage, sustainable forest management practices through low-impact exploration have been encouraged. However, studies that provide information for understanding the rainfall partitioning are incipient. This study aimed to evaluate the effects of Sustainable Forest Management on rainfall partitioning and the maintenance of forest hydrology processes in the Jamari National Forest - southwest Brazilian Amazon. We examined the throughfall, stemflow, net precipitation and interception loss variability over 13 months in both an unlogged and logged (1625 and 1450 ind ha−1, respectively) Amazon Forest. Despite the higher tree density in the unlogged forest, the dendrometric attributes did not show significant differences between stands. Results indicate that throughfall exceeded rainfall on 54% and 42% of months in unlogged and logged forest, respectively. In the unlogged forest, net precipitation indicated that more water than that from rainfall reached the forest floor (105.6% = 102% throughfall + 3.6% stemflow). The logged forest showed a lower amount of rainfall, with 91.0% reaching the soil floor by net precipitation (89.8% throughfall + 1.7% stemflow). Especially in the dry season, net precipitation was 175% higher in unlogged forest. The amount of stemflow highlighted that the unlogged forest has more stemflow than the forest subjected to reduced-logging practices, i.e., the logged forest lost 4261 L m−2 BA−1 y−1 by stemflow, which is a reduction of 65%. For both stands, the total basal area-scale stemflow yield was higher on D<30 trees. The results reinforce that we need a better understanding of the impact of sustainable forest management on the ecohydrology processes in the Amazon Forest, as well as their implications for rainfall partitioning, especially in the context of climate changes at the local scale.