喀斯特槽谷典型植物水分利用效率对隧道建设的响应

Response of water use efficiency of typical plants to tunnel construction in karst trough valley

隧道工程建设对喀斯特槽谷地区地下水循环系统的破坏,引起地下水位下降,可能影响周围生态环境。依托重庆中梁山喀斯特槽谷,对旱、雨两季隧道影响区与无隧道影响区不同深度土层(0—20 cm、20—40 cm)土壤含水量以及典型植物(常绿乔木、常绿灌木)瞬时水分利用效率(Instantaneous Water Use Efficiency,WUEinst)进行对比分析,探究植物水分利用效率对隧道建设的响应。结果表明:在不同影响区,主要由蒸发与降水引起土壤含水量在垂直和季节变化上的趋势相似,但隧道影响区土壤含水量在旱、雨两季均显著高于无隧道影响区;不同影响区植物WUEinst存在明显的季节差异,旱季各植物种WUEinst显著高于雨季。而旱、雨两季隧道影响区植物叶片WUEinst显著高于无隧道影响区;此外,植物WUEinst与土壤含水量相关性分析结果表明,不同影响区植物WUEinst与土壤含水量均呈显著负相关关系,但相对于无隧道影响区,隧道影响区植物WUEinst对土壤含水量的变化更加敏感。以上结果表明,隧道建设导致地下水资源漏失,土壤含水量减少,进而改变了植物水分利用特性,使隧道影响区植物种应对一定程度的水分胁迫时采取更保守的水分利用策略。

Tunnel construction undermines groundwater circulation system of karst areas and leads to groundwater level drop,which might exert influence on surrounding ecological environment.Taking karst valley area of Zhongliang Mountains in Chongqing as an example,we conducted a comparative analysis on soil water content at different depths soil layers(0—20 cm and 20—40 cm)and Instantaneous water use efficiency(WUEinst)of typical plants(evergreen arbor and evergreen shrub)in areas affected and unaffected by tunnel in both dry and rainy seasons to explore responses of plants WUEinst to tunneling works.The results showed that evaporation and precipitation mainly led to similarity of soil water content of different depths and in different seasons at both areas.However,soil water content of areas affected by tunnel was significantly higher than that of areas unaffected by tunnel in both dry and rainy seasons.The WUEinst of plants varied greatly with seasons at both areas and the WUEinst of various plants in dry season was significantly higher than that in rainy season.The WUEinst of plants of areas affected by tunnel was significantly higher than that of areas unaffected by tunnel in both dry and rainy seasons.Additionally,the results of correlation analysis between WUEinst of plants and soil water content showed that there was a negative correlation between the WUEinst of plants and soil water content.In comparison with areas unaffected by tunnel,the WUEinst of plants in areas affected by tunnel was more sensitive to changes of soil water content.The above results suggested that the tunneling works led to loss of groundwater resources,decrease of soil water content,and change of WUEinst of plants.Consequently,it is required to take more conservative water use strategies in response to certain water stress on plants in areas affected by tunnel construction.