黄土丘陵区垂直陡壁表面不同类型生物土壤结皮养分与微生物养分限制特征

生物土壤结皮的发育类型对土壤养分和微生物代谢起着重要作用。为进一步明确在生物结皮发育过程中微生物的限制性养分与影响因素,研究选择黄土丘陵区垂直陡壁表面上的裸土(CK)、浅色藻结皮(LA)、深色藻结皮(DA)、藻藓混合结皮(AM)和藓结皮(M)为研究对象,分析了不同生物土壤结皮类型下碳(C)、氮(N)、磷(P)养分状况与胞外酶活性,并通过胞外酶化学计量来量化微生物的代谢限制。结果表明:LA,DA,AM和M这4种类型生物土壤结皮C,N,P养分含量和微生物生物量C,N,P均显著高于CK(p<0.05),并且SOC,TN,TP和微生物生物量C,N,P随CK,LA,DA,AM和M的顺序逐渐增大,藓结皮微生物量C,N,P分别是CK处理的18.3,27.6,14.1倍。生物土壤结皮的发育显著提高了C,N,P循环酶的活性,冗余分析结果表明土壤养分与酶活性密切相关。此外,通过酶计量的矢量模型结果来看,生物土壤结皮的发育造成微生物相对碳限制的增大与相对磷限制的减小,并受到速效养分含量的影响。偏最小二乘路径模型结果也表明生物土壤结皮的类型会间接影响微生物的代谢限制。总的来说,生物土壤结皮类型的变化会改善土壤养分状况与微生物量等性质,养分资源的供应状况会造成微生物养分代谢的变化。

Characteristics of Nutrient and Microbial Nutrient Limitation of Different Types of Biological Soil Crusts on the Vertical Steep Slopes of Hilly Region in the Loess Plateau

The biological soil crusts play the important roles in soil nutrients and microbial metabolism.To further clarify the constraining nutrients and influencing factors of microbes during the development of biological soil crust.Bare soil(CK),light-colored algal crust(LA),dark algal crust(DA),alga-moss mixed crust(AM)and mossy crust(M)were selected as the research samples,we analyzed the status of carbon(C),nitrogen(N),phosphorus(P)and extracellular enzyme activities of different types of biological soil crusts,and quantified the metabolic limitation of microbes by extracellular enzymatic stoichiometry.The results showed that the contents of C,N,P and the sizes of microbial biomass C,N,P of LA,DA,AM and M were significantly higher than those of CK(p<0.05),and the contents of SOC,TN,TP and the sizes of microbial biomass C,N,P increased gradually in the order:CK