施氮对不同有机碳水平桉树林土壤微生物群落结构和功能的影响  

Effects of nitrogen application on soil microbial community composition and function in Eucalyptus plantations with different soil organic carbon levels

作　　者：苏丹[1] 张凯[1] 陈法霖[1] 李睿达 郑华[1] 

机构地区：[1]中国科学院生态环境研究中心城市与区域生态国家重点实验室,北京100085

出　　处：《生态环境学报》2014年第3期423-429,共7页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(31170425);中国科学院知识创新工程重要方向项目(KZCX2-EW-QN406)

摘　　要：碳、氮是影响土壤微生物群落结构和功能的2种重要生源要素,但研究施氮对人工林土壤微生物群落影响时很少考虑土壤有机碳水平。本研究以我国南方桉树Eucalyptus人工林为对象,研究施氮水平(对照:0 kg·hm-2,常规施氮水平166.8kg·hm-2,施二倍氮素水平333.7 kg·hm-2)对不同有机碳水平桉树林土壤微生物群落结构(磷脂脂肪酸构成)和功能(土壤酶活性及可溶性土壤有机碳含量)的影响,结果表明:施氮显著降低土壤微生物群落磷脂脂肪酸总量以及细菌、真菌、放线菌磷脂脂肪酸量和真菌/细菌比值(P<0.05);区分不同处理的土壤微生物磷脂脂肪酸主要是:真菌特征脂肪酸16:1ω5c、18:1ω9c、18:2ω9c及细菌特征脂肪酸16:1ω7c、i17:0和放线菌特征脂肪酸10Me18:0;施氮显著增加了土壤纤维素酶、酚氧化酶活性及土壤可溶性有机碳含量(P<0.05);尽管高土壤有机碳水平样地的土壤微生物磷脂脂肪酸量、土壤酶活性以及可溶性有机碳含量显著高于低土壤有机碳水平样地,但低、高土壤有机碳水平样地的土壤微生物群落结构和功能对施氮的响应不一致,土壤细菌、真菌、放线菌磷脂脂肪酸量以及酚氧化酶活性和土壤可溶性有机碳含量在低土壤有机碳水平样地中对施氮的响应更敏感,而这些指标在高土壤有机碳水平样地中只有在施二倍氮素处理中才显著降低或不变化。该研究结果表明不同土壤有机碳水平中的土壤微生物群落对施氮的响应不一致,强调了在全面认识氮肥施用对土壤微生物群落的影响时,需要充分考虑土壤有机碳水平。Nitrogen and carbon are two important elements influencing soil microbial community composition and function. The impacts of nitrogen application on soil microbial communities are widely studied in plantations, however, their soil organic carbon levels are poorly considered. To explore coupled impacts of carbon and nitrogen on soil microbial communities, soil microbial community composition （indexed by Phospholipid Fatty-acid Analysis, PLFA） and function （indexed by soil extracellular enzyme activities and soil dissolved organic carbon （DOC） content） were analyzed in Eucalyptus plantations with significantly different soil organic contents and three nitrogen application levels （control： 0 kg·hm-2, normal nitrogen level NN： 166.8 kg·hm-2, the double nitrogen level HN：333.7 kg·hm-2）. The total PLFAs, the PLFAs of bacteria, fungi, actinomycetes, and the ratios of fungi/bacteria decreased with the increase of nitrogen application. Fatty-acid 16：1ω5c, 18：1ω9c, 18：2ω9c, 16：1ω7c, i17：0 and 10Me18：0 distinguished the soil microbial communities under different nitrogen application treatments. Cellulase and phenol oxidase activities, and soil organic DOC significantly increased with nitrogen application. Soil microbial PLFA, soil extracellular enzyme activity and soil DOC are significantly higher in the sites with high soil organic carbon content than those in the sites with low soil organic carbon content. However, the responses of soil microbial community composition and function to nitrogen application are different in the two sites with different soil organic carbon contents, which are more sensitive in low soil organic carbon sites. While soil microbial community composition and function only changed in the sites with high soil organic carbon content and HN treatment. We conclude that soil organic carbon content can’t be neglected when the effects of nitrogen fertilization on soil microbial communities are analyzed.

关 键 词：施氮 有机碳水平 微生物群落 真菌 细菌 土壤酶 

分 类 号：S718.5[农业科学—林学]