氮添加对银杏幼林土壤有机碳化学组成及土壤微生物群落的影响(英文)

Effects of Nitrogen Addition on Chemical Composition of Soil Organic Carbon and Soil Microbial Community in a Young Ginkgo biloba Plantation

采用磷脂脂肪酸法通过田间试验研究氮添加对银杏人工幼龄林土壤有机碳化学组分、微生物生物量与群落结构的影响,施氮水平设置为0 kg·hm-2a-1N(对照),50 kg·hm-2a-1N(低氮),100 kg·hm-2a-1N(中氮)及150kg·hm-2a-1N(高氮),试验周期为1年。结果表明:高氮处理显著降低土壤有机碳含量及氧烷基碳组分但增加烷基碳与氧烷基碳比值。不同施氮水平对土壤微生物量及群落结构的影响不同,总体上中、高氮处理显著影响土壤微生物量与群落结构组成。中、高氮处理显著降低土壤微生物生物量碳含量但增加土壤微生物生物量氮含量,同时显著降低土壤总微生物量、真菌生物量及细菌生物量;而且中、高氮处理显著降低革兰氏阳性菌的相对丰度,但增加真菌细菌比和放线菌的相对丰度。另外,高氮处理显著降低土壤pH及土壤呼吸。

To determine the effects of nitrogen deposition on chemical composition of soil organic carbon （ SOC ） and microbial community characteristics in a young subtropical plantation,a field N addition experiment was established in a young plantation of Ginkgo biloba in China. The experiment was conducted from May 2012 to May 2013 by bimonthly application of ammonia nitrate solution with four treatments： Control （ 0 kg·hm -2 a -1 N ） ,Low-N （ 50 kg·hm -2 a -1 N ） , Medium-N （100 kg·hm -2 a -1 N） and High-N （150 kg·hm -2 a -1 N） . High-N treatment significantly decreased soil organic carbon （SOC） concentration and the proportion of O-alkyl but increased Alkyl∶ O-alkyl ratio. Moreover,N addition significantly affected soil microbial biomass and altered differentially soil microbial community composition with the amount of N loaded. Medium-N and High-N treatments significantly decreased microbial biomass carbon （ C） concentration but increased microbial biomass nitrogen （ N ） concentration. Besides, Medium-N and High-N treatments significantly decreased soil total microbial biomass,fungal biomass,and bacterial biomass. Additionally,Medium-N and High-N treatments significantly decreased the relative abundance of Gram-positive bacterial PLFAs and increased fungal： bacterial ratio as well as the relative abundance of actinomycetes PLFAs. Furthermore,High-N treatment significantly decreased soil pH,and soil respiration. Our results suggest that increased nitrogen deposition could significantly affect soil microbial biomass and community composition with the alterations of some soil chemical properties in the studied young plantation of G. biloba. This study could provide important scientific reference for the mechanism of soil microbial response to nitrogen deposition in young G. biloba plantations of subtropical China.