Data from: Grazing and nitrogen addition restructure the spatial heterogeneity of soil microbial community structure and enzymatic activities

1. In grassland ecosystems, large herbivorous animal grazing
activity and increasing nitrogen deposition strongly
alters microbial community structure and function.
Understanding the effects of grazing and nitrogen
addition on the spatial heterogeneity in soil
microbial community structure, enzymatic activities and the
underlying mechanisms are crucial for making
better predictions of soil organic matter dynamics and
nutrient cycling.  2. We examined the spatial
heterogeneity of soil microbial community
structure and enzymatic activity associated with changes
in soil microclimate, soil characteristics, plant biomass and
soil nutrient responses to grazing and nitrogen
addition using a manipulative experiment with
control (CK), grazing (G), nitrogen addition (N) and
grazing plus nitrogen addition (NG) treatments in a Leymus
chinensis meadow steppe, in northeastern China.  3. The
results demonstrated that soil microbial community structure and enzymatic
activities showed a high level of spatial dependence [C/(C +
C0)≥0.9] in the CK plot. G, N and
NG treatments not only reduced the spatial variability
ofsoil microbial community structure and enzymatic activities, but also
reshaped the spatial links between enzymes
activities and microbial community
structure. Litter biomass, soil temperature and soil
nutrients (soil dissolved inorganic nitrogen or soil
dissolved organic carbon) explained 21-27% of the spatial
variability of soil microbial community structure in the CK
treatment and pH was the strongest
driver for the spatial variability of soil
enzymatic activities. Meanwhile, the homogenization in soil water
content induced by the N addition treatment was
a determinant of the reduction in spatial
heterogeneity of the microbial community structure. The
combination of soil physicochemical properties (bulk density, soil pH and
soil dissolved inorganic nitrogen), soil
temperature and root biomass explained 32-43% of the
spatial variability of the microbial community structure
in the G treatment, and N and G treatments
had additive effects on the spatial heterogeneity of total
PLFAs by homogenizing root biomass. Plant biomass and
microbial community structure were the major drivers for the
spatial heterogeneity of enzymatic activities under G, N and NG.
In NG, the change in spatial variability of enzymatic
activities was dominated by N addition. Regardless of grazing,
N addition facilitated the spatial correlation between
microbial community structure and enzyme activities.  4.
Overall, our results revealed the drivers of soil microbial
community structure and enzymatic
activities spatial pattern shift due to grazing and N
addition, highlighting the
role that spatial variability in soil microbial
community structure and enzymatic
activities has on the L.
chinensis meadow steppe.

1. 在草原生态系统中，大型草食动物的放牧活动与日益增加的氮沉降显著改变微生物群落结构与功能。解析放牧及施氮对土壤微生物群落结构、酶活性空间异质性的影响及其内在机制，对于更精准预测土壤有机质动态与养分循环至关重要。 2. 本研究在中国东北羊草（Leymus chinensis）草甸草原开展控制实验，设置对照（CK）、放牧（G）、施氮（N）及放牧+施氮（NG）处理，探究土壤微生物群落结构与酶活性的空间异质性，及其与土壤微气候、土壤特性、植物生物量及土壤养分对放牧和施氮响应变化的关联。 3. 结果表明，对照（CK）样地中土壤微生物群落结构与酶活性呈现高度空间依赖性[C/(C + C0)≥0.9]。放牧（G）、施氮（N）及放牧+施氮（NG）处理不仅降低了土壤微生物群落结构与酶活性的空间变异，还重塑了酶活性与微生物群落结构间的空间关联。在CK处理中，枯落物生物量、土壤温度及土壤养分（土壤溶解性无机氮或土壤溶解性有机碳）可解释21%-27%的土壤微生物群落结构空间变异，而pH是土壤酶活性空间变异的最强驱动因子。同时，施氮处理导致的土壤含水量均质化是微生物群落结构空间异质性降低的关键因素。在G处理中，土壤理化性质（容重、pH及溶解性无机氮）、土壤温度与根系生物量的组合可解释32%-43%的微生物群落结构空间变异；且N与G处理通过均质化根系生物量，对总磷脂脂肪酸（PLFAs）的空间异质性产生叠加效应。在G、N及NG处理下，植物生物量与微生物群落结构是酶活性空间异质性的主要驱动因子。在NG处理中，酶活性空间变异的变化由施氮主导。无论是否放牧，施氮均促进了微生物群落结构与酶活性间的空间相关性。 4. 综上，本研究揭示了放牧与施氮导致土壤微生物群落结构及酶活性空间格局转变的驱动因子，强调了土壤微生物群落结构与酶活性空间变异在羊草草甸草原中的作用。