毛竹高速生长期土壤碳氮动态及其微生物特性

Abstract

The soil carbon,nitrogen dynamics and its microbiological ecological characteristic were investigated during bamboo high-speed growth in typical bamboo(Phyllostachys Pubescens) forests.The results showed that the content of total nitrogen(TN) reduced by 13%,22% and 6% respectively in the three testing spots.TN of soil showed a significant positive correlation with alkaline hydrolysis nitrogen,ammonium nitrogen and nitrate nitrogen(R2=0.48*,0.65**,0.70** respectively) during bamboo high-speed growth indicating that the soil nitrogen was absorbed in different forms by bamboo which caused soil total nitrogen reduction.Soil total organic carbon(TOC) and dissolve organic carbon(DOC) including extraction at 20℃(20℃ DOC) and at 80℃(80℃ DOC) were significantly decreased during bamboo growth.The results showed that TOC reduced by 26%,20% and 24% respectively in three testing spots.The content of the 20℃ DOC reduced by 51%,22% and 23% in three testing spot respectively,which was considerably greater(P0.05) than the reduction of 80℃ DOC in the testing spots.The relationship between soil total nitrogen(TN) and total organic carbon(TOC) analysis showed that TN and TOC were strongly inter-correlated(R2=0.89**) indicating that the change of soil carbon was closely related with the content of soil nitrogen during bamboo high-speed growth.Soil microorganisms are important in the cycling of almost all the major plant nutrients including the turnover of organic matter.Environmental conditions and perturbation are likely to affect microbial population structures and their functions in soils which may result in a change of overall soil properties.During high-speed growth,bamboo consumed soil carbon and soil nitrogen which lead to soil nutrient deficiency,effected soil microbial biomass and excessive carbon reduction,it also changed the soil microbial community.The content of soil microbial biomass carbon decreased from 800 mg/kg at the first sampling day to 589 mg/kg at the last sampling day.Soil under different sampling date contained a variety of PLFAs composed of saturated,unsaturated,methyl-branched and cyclopropane fatty acids.Thirty-four PLFAs with chain lengths from C12 to C20 were identified.The PLFA concentration data were subjected to principal components analysis(PCA).The first two principal components(PC1 and PC2) accounted for 62.95% and 17.20% of the variation respectively,which showed soil microbial community was changed significantly during bamboo growth.Specific identified PLFAs including saturated fatty acids(14:0,16:0,18:0,20:0,i15:0,i16:0,i17:0,i18:0,a15:0,a17:0) which represented bacteria were found to be distributed on the right of the load diagram,while unsaturated fatty acids(18:2w6,9c/18:0ANTE) which represented fungi were found to be distributed on the left of the load diagram.Thus,these bacteria indicator PLFAs were more abundant in the later soil sampling,while the fungi indicator PLFAs were more abundant in the early soil sampling,indicating that with the soil nutrient consumption during bamboo high-speed growth,total PLFA and the PLFAs that represent bacteria decreased,While the PLFAs that represent fungi increased.Thus,the change of soil carbon and soil nitrogen can significantly affect soil microbial community structure in the bamboo forest soil.