Wang Bao Rong, Yang Jia Jia, An Shao Shan, Zhang Hai Xing, Bai Xue Juan
College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, Shaanxi, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jan;29(1):247-259. doi: 10.13287/j.1001-9332.201801.039.
The objectives of this study were to explore the effects of vegetation type, topographic features and their combined effects on soil microbial biomass stoichiometry, so as to better understand the interaction of soil, soil microbes and nutrient cycling under different vegetation types in the hilly-gully region of the Loess Plateau. Soils from three vegetation zones (forest zone, forest-steppe and steppe) and five slope positions (south/north backslope, south/north shoulder and summit) were chosen and the effects of vegetation types and topography features on soil and C:N:P ratios in soil microbial biomass were investigated in this study. The results showed that, among the five slope positions, the highest concentrations of soil and soil microbial biomass C, N, P were found at the backslope position and the north-facing slope. The effects of vegetation types on soil and soil microbial biomass C, N and P in the two soil layers were significantly different, whereas the effects of slope aspect and positions were only numerically different. As for different soil layers, the topsoil (0-10 cm) was more affected by slope aspect, while the subsoil (10-20 cm) was more influenced by slop position. While the effects of vegetation type on soil C:N, C:P and N:P and soil microbial biomass C:N, C:P were significant, slope aspect and slope position only influenced soil C:P and N:P. Consequently, on the Loess Plateau, the effects of vegetation type on soil and soil microbial biomass C, N, P were stronger than those of the topographic features. The standardized major axis tests showed that C:N:P stoichiometry in soil microbes was well-constrained, especially in the steppe zone. The soil microbial biomass N:P might be used as a useful tool to assess nutrient limitation of ecosystem processes in terrestrial ecosystems. If combined with plant leaf N:P, they could provide more accurate information to estimate the nutrient limitation of fragile ecosystem in hilly-gully region of the Loess Plateau.
本研究的目的是探讨植被类型、地形特征及其综合作用对土壤微生物生物量化学计量的影响，以便更好地理解黄土高原丘陵沟壑区不同植被类型下土壤、土壤微生物与养分循环之间的相互作用。本研究选取了三个植被带（林区、林草交错区和草原区）和五个坡位（南/北坡背坡、南/北坡肩和山顶）的土壤，研究了植被类型和地形特征对土壤及土壤微生物生物量碳氮磷比的影响。结果表明，在五个坡位中，土壤及土壤微生物生物量碳、氮、磷的最高浓度出现在背坡位置和北向坡。植被类型对两层土壤中土壤及土壤微生物生物量碳、氮、磷的影响存在显著差异，而坡向和坡位的影响仅在数值上有所不同。对于不同土层，表层土壤（0 - 10厘米）受坡向影响更大，而底层土壤（10 - 20厘米）受坡位影响更大。虽然植被类型对土壤碳氮比、碳磷比和氮磷比以及土壤微生物生物量碳氮比、碳磷比有显著影响，但坡向和坡位仅影响土壤碳磷比和氮磷比。因此，在黄土高原，植被类型对土壤及土壤微生物生物量碳、氮、磷的影响强于地形特征。标准化主轴检验表明，土壤微生物中的碳氮磷化学计量受到良好限制，尤其是在草原区。土壤微生物生物量氮磷比可能是评估陆地生态系统中生态系统过程养分限制的有用工具。如果与植物叶片氮磷比相结合，它们可以提供更准确的信息来估计黄土高原丘陵沟壑区脆弱生态系统的养分限制。
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