Affiliation:
1. School of Climate Studies and Department of Botany and Zoology Stellenbosch University Matieland South Africa
2. Council for Scientific and Industrial Research (CSIR) Pretoria South Africa
3. Environmental Change Institute, School of Geography and the Environment University of Oxford Oxford UK
Abstract
AbstractWoody plant encroachment (WPE) has been found to alter ecosystem functioning and services in savannas. In rain‐limited savannas, increasing woody cover can reduce streamflow and groundwater by altering evapotranspiration rates and rainfall partitioning, but the ecological relevance of this impact is not well known. This study quantified the altered partitioning of rainfall by two woody plant structural types (fine‐ and broad‐leaved trees) across a gradient of encroachment in a semi‐arid savanna in South Africa. Averaged across both plant functional types, loss of rainfall through canopy interception and subsequent evaporation roughly doubled (from 20.5% to 43.6% of total rainfall) with a roughly 13‐fold increase in woody cover (from 2.4 to 31.4 m2/ha tree basal cover). Spatial partitioning changes comprised fourfold increases in stemflow (from 0.8% to 3.9% of total rainfall) and a decline in throughfall proportion of about two‐fifths (from 80.2% to 47.3% of total rainfall). Changes in partitioning were dependent on plant functional type; rainfall interception by the fine‐leaved multi‐stemmed shrub Dichrostachys cinerea was almost double that of the broad‐leaved tree Terminalia sericea at the highest levels of woody encroachment (i.e., 49.7% vs. 29.1% of total rainfall intercepted at tree basal area of 31.4 m2/ha). Partitioning was also dependent on rainfall characteristics, with the proportion of rainfall intercepted inversely related to rainfall event size and intensity. Therefore, increasing tree cover in African grassy ecosystems reduces the amount of canopy throughfall, especially beneath canopies of fine‐leaved species in smaller rainfall events. Rainfall interception traits may thus confer a selective advantage, especially for fine‐leaved woody plant species in semi‐arid savannas.
Funder
Department of Science and Innovation, South Africa
Subject
Nature and Landscape Conservation,Ecology,Ecology, Evolution, Behavior and Systematics
Cited by
3 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献