Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1088/1748-9326/ab71a1 |
When savannas recover from overgrazing, ecohydrological connectivity collapses | |
Basant, Shishir1; Wilcox, Bradford P.1; Leite, Pedro M.1; Morgan, Cristine L.2,3 | |
2020-05-01 | |
发表期刊 | ENVIRONMENTAL RESEARCH LETTERS |
ISSN | 1748-9326 |
出版年 | 2020 |
卷号 | 15期号:5 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | Grasslands and savannas across the globe have undergone a dramatic transition over the past century. Historical overgrazing has set in motion a cascade of events ranging from desertification in arid climates to woody plant encroachment (WPE) in semiarid and subhumid climates. In recent decades, grazing pressure on many of these landscapes has declined significantly, and where rainfall is sufficient (as in most semiarid and subhumid settings), herbaceous vegetation in intercanopy areas will recover. An important question is, how has this transition altered ecohydrological connectivity (overland flow and runoff-runon dynamics)? A woody-plant-encroached, subhumid savanna site in South Texas with a history of heavy grazing (but ungrazed since 1981) was used as a model landscape to address this question. Overland flow, soil moisture, and field saturated hydraulic conductivity (K-fs) were measured along a catena extending from the upland savanna-parkland areas to the downslope, more densely wooded areas. For comparison, K-fs and infiltrability were also measured at a moderately grazed upland site 14 km east of our study site, selected as a surrogate for past conditions at our site. In contrast to the prevailing hypothesis that the downslope areas ('drainage-woodlands') at our study site have continued to be supported by runoff generated from the upland areas, our measurements yielded no evidence for the redistribution of water from the uplands to the drainage areas under the current ungrazed conditions. Further, K-fs at the ungrazed study site was two orders of magnitude higher than that at the grazed site and infiltrability was twice as high at the ungrazed site than the grazed site. These findings, coupled with historical information from the site, strongly suggest that historical overgrazing amplified the runoff-runon process, resulting in significant subsidies of water from the uplands to the drainage areas. Then, with the relaxation of grazing pressure and subsequent landscape recovery, redistribution of water via surface runoff was relatively rare. We believe that our results are generalizable for savannas that have recovered from overgrazing. When these savannas are heavily grazed, ecohydrological connectivity is greatly increased; but if grazing pressure relaxes, ecohydrological connectivity will collapse. These changes in ecohydrological connectivity have important, but not always well understood, ecological consequences. |
英文关键词 | ecohydrology drylands savanna connectivity hydrology woody plant encroachment grazing |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000529889300001 |
WOS关键词 | WOODY-PLANT ENCROACHMENT ; SEMIARID WOODLANDS ; INFILTRATION RATES ; SOUTHERN TEXAS ; SOIL TEXTURE ; RUNOFF ; VEGETATION ; GRASSLAND ; PATTERNS ; PRODUCTIVITY |
WOS类目 | Environmental Sciences ; Meteorology & Atmospheric Sciences |
WOS研究方向 | Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/279322 |
专题 | 气候变化 |
作者单位 | 1.Texas A&M Univ, Dept Ecosyst Sci & Management, College Stn, TX 77843 USA; 2.Texas A&M Univ, Dept Soil & Crop Sci, College Stn, TX 77843 USA; 3.Soil Hlth Inst, Morrisville, NC USA |
推荐引用方式 GB/T 7714 | Basant, Shishir,Wilcox, Bradford P.,Leite, Pedro M.,et al. When savannas recover from overgrazing, ecohydrological connectivity collapses[J]. ENVIRONMENTAL RESEARCH LETTERS,2020,15(5). |
APA | Basant, Shishir,Wilcox, Bradford P.,Leite, Pedro M.,&Morgan, Cristine L..(2020).When savannas recover from overgrazing, ecohydrological connectivity collapses.ENVIRONMENTAL RESEARCH LETTERS,15(5). |
MLA | Basant, Shishir,et al."When savannas recover from overgrazing, ecohydrological connectivity collapses".ENVIRONMENTAL RESEARCH LETTERS 15.5(2020). |
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