拉萨半干旱河谷人工杨树纯林生态增益研究

目的]根据配置模式对拉萨半干旱河谷地带人工杨树纯林进行改造。方法]研究了其改造前后林分生长状况的变化、土壤养分含量和含水量的变化、土壤容重与孔隙度的变化、不同配置模式对土壤容重和孔隙度的影响、不同配置模式中植物根系分布特征、不同配置模式的筛选。结果]纯林经过改造成混交林后,林分生物量分布格局要比纯林更为合理和均匀,具有更高的生产力;纯林改造后,对土壤有机质含量和含水率都有显著提高;改造后的纯林内增加了土壤表面的枯枝落叶层,从而使得其内的土壤容重小,土壤孔隙度变大;不论在任何时间段,群状配置林下土壤的平均容重小于行状配置,而孔隙度则与之相反,三角形配置的土壤容重和土壤孔隙度则具二者之间;在不同时间段,同一配置模式下林地间的土壤容重与孔隙度也有一定差异;配置模式中的土壤容重为群状配置〈三角形配置〈行状配置,孔隙度为群状配置〉三角形配置〉行状配置,有机质含量为群状配置〉三角形配置〉行状配置。经过改造后的纯林群落结构更趋稳定、合理。结论]该研究结果可为拉萨半干旱河谷地带退化生态系统的恢复与植被重建提供一定的理论依据和指导。

Study on the Ecological Gain of Artificial Pure Poplar Forest in Semi-arid Valley Region of Lasa

Objective] According to allocation model,the artificial pure forests of poplar of Semi-arid valley in Lasa were modified.Method] The characteristics were studied,such as the changes in stand growth conditions,soil nutrient and water content changes,changes of soil bulk density and soil porosity,different configuration mode on the soil bulk density and porosity,root system distribution on different configuration mode,screening of different configuration modes and so on.Result] Many characteristics changed...