摘要
在张北地区,以杨树为主的防护林出现不同程度的退化现象,水分是干旱区植物生存的主要限制因子,为揭示水分与防护林退化的关系,本文基于稳定氢氧同位素技术,通过对比小叶杨枝条水与潜在水源的同位素值,探究不同退化程度下小叶杨的水分来源及其对各水源的利用比率.结果表明:不同退化程度的杨树林水分来源不同,随退化程度的加深,小叶杨的水分来源从深层逐渐向表层转移.无退化的小叶杨主要利用320~400 cm的土壤水,利用率为25.1%;轻度退化的小叶杨主要利用120~180、180~240和240~320 cm的土壤水,对这3层的利用率总和将近50.0%,而对其他土壤水利用较少;中度退化的小叶杨主要利用20~40、40~60和60~80 cm的土壤水,对这3层土壤水每层利用率在17.5%~20.9%范围,对120 cm及其以下的土壤水利用率均低于10.0%;而重度退化的小叶杨主要利用0~20 cm的表层土壤水分,利用率为30.4%,明显高于其他水源.杨树防护林在衰退过程中的水分来源逐渐变浅,而林地浅层土壤较低的土壤含水量无法满足杨树的正常水分需求,加速了杨树林的退化和死亡.
In Zhangbei County,Hebei Province,poplar-dominated shelterbelts are degraded to different extents. Water availability is the main limiting factor for plant survival in arid areas. The purpose of this study was to reveal the relationship between water availability and poplar degradation. Based on the hydrogen and oxygen stable isotope techniques,we explored the water sources of Populus simonii under different degradation degrees by comparing the isotopic values of P. simonii xylem water with that in potential water source,and calculated the utilization ratio of each water source. The results showed that the water sources of poplar trees varied with degradation degree. The water sources of P. simonii gradually transferred from the deep layer to the surface layer with the increases of degradation. P. simonii with no degradation mainly absorbed soil water in the range of320-400 cm,with the utilization rate being 25.1%. P. simonii with slight degradation mainly used soil water at depth of 120-180,180-240 and 240-320 cm. The total utilization rate of three layers was close to 50. 0%,with less utilization of water from other layers. The moderately degraded P.simonii mainly used soil water at depth of 20-40,40-60 and 60-80 cm. The utilization rate of each layer was 17. 5%-20. 9%,and the contribution rate of soil water under 120 cm was less than10.0%. The severely degraded P. simonii mainly used water from surface soil layer(0-20 cm）,with the utilization rate being 30. 4%,which was significantly higher than that of other water sources. The water sources of poplar shelter forests were gradually shallower during the process of degradation. However,the low soil water content in the shallow layer could not meet the normal water demand of poplar,which would accelerate the degradation and even decline of poplar.
作者
张欢
曹俊
王化冰
宋波
贾国栋
刘自强
余新晓
曾佳
ZHANG Huan, CAO Jun2, WANG Hua-bing2, SONG Bo2, JIA Guo-dong1, LIU Zi- qiang1 , YU Xin-xiao1 , ZENG Jia3(1 College of Water and Soil Conservation, Bering Forestry Uni- versity/Key Laboratory of Soil and Water Conservation and Desertification Combating, Ministry of Education, Beifing 100083, China; 2Miyun Gardening and Greening Bureau, Beijing 101500, China; 3 Qingdao No. 2 Middle School of Shandong Province, Qingdao 266000, Shandong , China)
出处
《应用生态学报》
CAS
CSCD
北大核心
2018年第5期1381-1388,共8页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(41430747
41401013)
林果生态环境功能提升协同创新中心(CEFF-PXM2017_014207_000043)资助~~
关键词
退化程度
小叶杨
氢氧同位素
水分来源
degree of degradation
Populus simonii
hydrogen and oxygen isotopes
water source.
