{"title":"Does damming streams alter the water use strategies of riparian trees? A case study in a subtropic climate","authors":"Pei Zhao, Wim Cornelis, Xiangyu Tang, Peng Zhao, Jialiang Tang","doi":"10.1002/ldr.3500","DOIUrl":null,"url":null,"abstract":"<p>Understand the mechanism governing degradation of riparian forests in response to damming streams is needed for a comprehensive impact assessment of dams in relation to protection of river ecosystems. However, the ascription of riparian forest degradation to the hydrological changes induced by dams lacks of direct proof and the hypothesis that dam construction alters the water use strategy of riparian trees is yet to be tested. In this study, the water sources of riparian trees grown upstream and downstream of dams at SW China, were investigated by dual isotopes and a Bayesian model. We observed that xylem water in downstream <i>Populus adenopoda</i> had significantly lower line-conditioned excess values than upstream trees. The water source of upstream trees was barely subjected to evaporation. Upstream mature and young <i>P. adenopoda</i> trees both acquired more streamwater (47.2 ± 9.8% and 44.8 ± 7.9%) than groundwater (28.2 ± 4.4% and 29.2 ± 3.5%) or soil water (24.5 ± 5.6% and 26.0 ± 4.9%). Downstream mature and young <i>P. adenopoda</i> trees both largely used soil water (49.0 ± 11.6% and 53.0 ± 6.2%) as main water source. In contrast, <i>Pterocarya stenoptera</i> highly depended on streamwater, regardless of size and location, implying that damming had little effect on this species. Damming streams may increase water competition among downstream riparian trees, which could explain declines in growth rate, canopy dieback, tree death, and eventually downstream land degradation. We believe that this study is of significant value for research into riparian forest degradation resulting from hydrological changes, and in particular to apprehend the impact of small dams, which has barely been studied.</p>","PeriodicalId":203,"journal":{"name":"Land Degradation & Development","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2019-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ldr.3500","citationCount":"4","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Land Degradation & Development","FirstCategoryId":"97","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ldr.3500","RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 4
Abstract
Understand the mechanism governing degradation of riparian forests in response to damming streams is needed for a comprehensive impact assessment of dams in relation to protection of river ecosystems. However, the ascription of riparian forest degradation to the hydrological changes induced by dams lacks of direct proof and the hypothesis that dam construction alters the water use strategy of riparian trees is yet to be tested. In this study, the water sources of riparian trees grown upstream and downstream of dams at SW China, were investigated by dual isotopes and a Bayesian model. We observed that xylem water in downstream Populus adenopoda had significantly lower line-conditioned excess values than upstream trees. The water source of upstream trees was barely subjected to evaporation. Upstream mature and young P. adenopoda trees both acquired more streamwater (47.2 ± 9.8% and 44.8 ± 7.9%) than groundwater (28.2 ± 4.4% and 29.2 ± 3.5%) or soil water (24.5 ± 5.6% and 26.0 ± 4.9%). Downstream mature and young P. adenopoda trees both largely used soil water (49.0 ± 11.6% and 53.0 ± 6.2%) as main water source. In contrast, Pterocarya stenoptera highly depended on streamwater, regardless of size and location, implying that damming had little effect on this species. Damming streams may increase water competition among downstream riparian trees, which could explain declines in growth rate, canopy dieback, tree death, and eventually downstream land degradation. We believe that this study is of significant value for research into riparian forest degradation resulting from hydrological changes, and in particular to apprehend the impact of small dams, which has barely been studied.
期刊介绍:
Land Degradation & Development is an international journal which seeks to promote rational study of the recognition, monitoring, control and rehabilitation of degradation in terrestrial environments. The journal focuses on:
- what land degradation is;
- what causes land degradation;
- the impacts of land degradation
- the scale of land degradation;
- the history, current status or future trends of land degradation;
- avoidance, mitigation and control of land degradation;
- remedial actions to rehabilitate or restore degraded land;
- sustainable land management.