连续干旱条件下黄土高原几种人工林存活能力分析

Survival Capability Analysis of Four Kinds of Artificial Forests in Loess Plateau

近年来黄土高原地区的连续干旱气候对该地区的林木生长造成威胁,一些地方出现了树木干梢或成片林死亡的现象。以位于黄土高原典型半干旱丘陵区绥德县辛店沟的油松、侧柏、榆树和柠条人工林为研究对象,测定分析了0～9.9m深土层的土壤含水量,以探求不同树种在连续干旱条件下的存活能力。结果显示,油松存亡的临界土壤湿度在4.5%～5.2%之间,对应的临界相对湿度27.6%～31.9%;榆树存亡的临界土壤湿度在5.2%～5.8%之间,临界相对土壤湿度31.9%～35.6%;侧柏和柠条土壤湿度分别为4.3%和4.2%,相对湿度分别为26.4%和25.8%,但二者还在正常生长。

The continuous dry climate has been threatening the survival of the artificial forests in the Loess plateau in resent years. Some of the branches on the treetops have perished or the whole woods have died of drought. This study has chosen the lands of Pinus tabulaeformis, Platycladus orientalis, Ulmas pumila, Caragana microphylla, grazing and farmland in the loess hilly and gully area of Suide county, Sannxi province, and measured the soil water contents from 0~9.9 m on soil profiles to test the survival ability of different trees. The results showed that the critical survival soil water content for Pinus tabulaeformis and Ulmas pumila are between 4.5%~5.2% and 5.2%~5.8% respectively, and the corresponding relative water moisture are 27.6%~31.9% and 31.9%~35.6% respectively. The soil moisture of Platycladus orientalis and Caragana microphylla are 4.3% and 4.2% respectively, and the corresponding relative water moisture are 26.4% and 25.8%, but both were still alive. 