Effects of different afforestation measures on fertility of soil in populus szechuanic forest | 不同造林技术措施对藏川杨林地土壤肥力的影响

chinois. 研究拉萨半干旱河谷不同造林技术措施对藏川杨林地土壤化学性质、微生物数量和酶含量的影响，为拉萨半干旱河谷科学造林和退化生态系统的恢复提供依据。于2010-09在拉萨达孜县章多乡半干旱河谷造林地，选择覆石头、覆膜、覆秸秆、覆鸡蛋筐和使用保水剂措施下种植的藏川杨林地为研究对象，以未采用任何措施的造林地为对照，对不同造林措施下土壤的化学性质、微生物数量以及酶含量进行了测定，并进行了主成分分析。不同造林措施下，林地不同土层土壤中的各种养分含量和酶含量均明显高于对照林地，其中增幅最高处理的土壤速效氮、速效磷、速效钾和有机质分别较对照增加24.4%，45.1%，226.3%和181.5%，土壤脲酶、过氧化氢酶、蔗糖酶和磷酸酶分别较对照增加34.4%，194%，1 655%和658.5%，但在不同土层中未表现出相似的规律；不同造林措施下，土壤中的各种微生物数量均明显高于对照林地，增幅最高处理土壤的细菌、真菌和放线菌数量分别较对照增加279.8%，375.3%和111.5%，各处理土壤中的微生物均以细菌数量最多，放线菌次之，真菌最少。采用不同的造林措施进行藏川杨植被恢复，有利于土壤理化性状改善、微生物数量增加及酶含量增强。主成分分析表明，在拉萨半干旱河谷采取覆鸡蛋筐和使用保水剂对土壤的改良效果优于其他措施。

anglais. This study aimed to research the effects of different afforestation measures on physical-chemical properties, microbe quantity and content of enzyme of soil in populus szechuanic forest, and provide a basis for the scientific afforestation and the restoration of degraded ecosystem in Lhasa semi-arid valley. In September 2010, the soil nutrient content, enzyme activity, and soil microorganism of populus szechuanica forests covered with stone, film, straw, egg-tray and with addition of water retaining agent in semi-arid valley region of Lhasa were determined and analyzed. And a principal component analysis was conducted to these variables as well. The soil nutrient content and content of enzyme under different afforestation measures were significantly higher than those of the control test. The highest increase of available nitrogen, available P, available K, and organic matter were 24.4%, 45.1%, 226.3%, and 181.5%, respectively. The urease, catalase, sucrase, and phosphatase increased by 34.4%, 194%, 1 655% and 658.5%, respectively. However, the increase patterns in different soil layers were different. The number of microorganisms in the forest with different afforestation measures were significantly higher than the control group and the highest increase of bacteria, fungi, and actinomycetes were 279.8%, 375.3%, and 111.5% respectively. Bacteria were the most abundant microorganism, followed by actinomycetes and fungi.The different afforestation measures were beneficial to improve soil physical and chemical properties, number of microorganisms, and content of enzyme. The principal component analysis showed that using egg-trays and water retaining agent is superior to other measures in the semi-arid valley region of Lhasa.