Tree mortality and regeneration of Euphrates poplar riparian forests along the Tarim River,Northwest China  

作　　者：Ayjamal Keram Umut Halik Tayierjiang Aishan Maierdang Keyimu Kadeliya Jiapaer Guolei Li 

机构地区：[1]College of Resources and Environmental Science,Key Laboratory for Oasis Ecology of Ministry of Education,Xinjiang University,Ürümqi 830046,China [2]College of Forestry,Key Laboratory for Silviculture and Conservation of Ministry of Education,Beijing Forestry University,Beijing 100083,China [3]State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China

出　　处：《Forest Ecosystems》2021年第4期659-671,共13页森林生态系统（英文版）

基　　金：funded by the National Natural Science Foundation of China(31860134,U1703102,31700386).

摘　　要：Background:Tree mortality and regeneration(seedling and sapling recruitment)are essential components of forest dynamics in arid regions,especially where subjected to serious eco-hydrological problems.In recent decades,the mortality of the Euphrates poplar(Populus euphratica)along the Tarim River in Northwest China has increased.However,few studies have quantified the causes of mortality and regeneration in this azonal riparian forest type.Methods:The present study describes the annual hydrological response of tree mortality and regeneration in forest gaps.A total of 60 canopy gaps were investigated in six replicate grid plots(50m×50 m)and the annual runoff and water consumption data during the period of 1955–2016 were collected from hydrological stations in the middle reaches of the Tarim River.We compared the regeneration density of seedlings and saplings within the canopy gap areas(CGAs),undercanopy areas(UCAs),and uncovered riverbank areas(RBAs)through detailed field investigation.Results:Our study found that the mortality of young and middle-aged gap makers has increased remarkably over recent decades,particularly since the year 1996.The main results indicated that regional water scarcity was the primary limiting factor for long-term changes in tree mortality,as shown by a significant correlation between the diameter at breast height(DBH)of dead trees and the annual surface water.The average density(or regeneration rate)of seedlings and saplings was highest in the RBAs,intermediate in the CGAs,and lowest in the UCAs.Compared with the UCAs,the CGAs promote tree regeneration to some extent by providing favorable conditions for the survival and growth of seedlings and saplings,which would otherwise be suppressed in the understory.Furthermore,although the density of seedlings and saplings in the CGAs was not as high as in the RBAs,the survival rate was higher in the CGAs than in the RBAs.Conclusion:Forest canopy gaps in floodplain areas can play a decisive role in the long-term germination and regeneration of

关 键 词：Tree mortality Regeneration strategy Seedling and sapling recruitment Gap makers Riparian forest Tarim River 

分 类 号：S718.4[农业科学—林学]