土壤微生物的资源限制是养分循环和植被发育的关键因素。这在干旱气候中尤为重要。鉴于岩石碎片强烈影响干旱地区的水文和地球化学过程,我们假设微生物资源(C和N)限制将沿岩石碎片含量(RFC)梯度增加。我们在闽江干旱区进行了四个RFC水平(0%,25%,50%,75%,VV-1)和四种植被类型(蒿,紫荆花,SophoraDavidii,和没有植物的土壤)。C(β-1,4-葡萄糖苷酶,BG),N(β-1,4-N-乙酰氨基葡萄糖苷酶,NAG;L-亮氨酸氨基肽酶,LAP),和P(酸性磷酸酶,ACP)采集酶进行了调查,以评估C,N或P.在没有植物的土壤中,C获取酶活性下降了43%,但是,在75%RFC中,氮的获取酶活性比无岩土壤(0%RFC)中增加了72%。增加RFC降低C:N和C:P酶比,以及矢量长度和矢量角度(<45°)。植物增加了土壤中碳和氮获取酶的活性,以及酶C:P,N:P,和向量长度(5.6%-25%),但矢量角度下降(13%-21%)。酶的化学计量取决于生物和非生物因素,例如,土壤含水量,土壤C:N,和磷脂脂肪酸的总含量。增加的RFC使酶的化学计量向较低的C转移,但对微生物的N限制更强。植被增加了微生物的C和N限制,并根据灌木官能团影响酶活性和化学计量。因此,植被的直接影响,养分利用率和微生物生物量含量,土壤特性的间接影响共同增加了沿RFC梯度的微生物资源限制。
Resource limitation for soil microorganisms is the crucial factor in nutrient cycling and vegetation development, which are especially important in arid climate. Given that rock fragments strongly impact hydrologic and geochemical processes in arid areas, we hypothesized that microbial resource (C and N) limitation will increase along the rock fragment content (RFC) gradient. We conducted a field experiment in Minjiang river arid valleys with four RFC content (0 %, 25 %, 50 %, and 75 %, V V-1) and four vegetation types (Artemisia vestita, Bauhinia brachycarpa, Sophora davidii, and the soil without plants). Activities of C (β-1,4-glucosidase, BG), N (β-1,4-N-acetyl-glucosaminidase, NAG; L-leucine aminopeptidase, LAP), and P (acid phosphatase, ACP) acquiring enzymes were investigated to assess the limitations by C, N or P. In unplanted soil, the C acquiring enzyme activity decreased by 43 %, but N acquiring enzyme activity increased by 72 % in 75 % RFC than those in rock-free soils (0 % RFC). Increasing RFC reduced C:N and C:P enzymatic ratios, as well as vector length and vector angle (< 45°). Plants increased the activities of C and N acquiring enzymes in soils, as well as C:P and N:P enzyme activities, as well as vector length (by 5.6 %-25 %), but decreased vector angle (by 13 %-21 %). Enzyme stoichiometry was dependent on biotic and abiotic factors, such as soil water content, soil C:N, and total content of phospholipid fatty acids, reflecting microbial biomass content. Increased RFC shifted enzymatic stoichiometry toward lower C but stronger N limitation for microorganisms. Vegetation increased microbial C and N limitation, and impacted the enzymatic activities and stoichiometry depending on shrub functional groups. Consequently, the direct effects of vegetation, nutrient availability and microbial biomass content, as well as indirect effects of soil properties collectively increased microbial resource limitations along the RFC gradient.