Ecological Restoration and Conservation for Forest and Wetland Key Laboratory of Sichuan Province, Sichuan Academy of Forestry Sciences, Chengdu 610081, China.
Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Aca-demy of Forestry, Beijing 100091, China;Miyaluo Research Station of Alpine Forest Ecosystem, Lixian 623100, Sichuan, China.
Ying Yong Sheng Tai Xue Bao. 2023 Nov;34(11):2993-3002. doi: 10.13287/j.1001-9332.202311.003.
Exploring the resource limitation of soil microbial metabolism is essential to understand ecosystem functions and processes. However, the spatially divergent patterns and drivers of soil microbial nutrient limitation cha-racteristics in montane ecosystems at small scales, especially at the slope aspect scale, are still unclear. In this study, we measured soil enzyme activities involved in carbon (C), nitrogen (N) and phosphorus (P) cycle and quantified the microbial nutrient limitations by enzyme stoichiometry in two representative mountain sites in subalpine region of western Sichuan, including the sunny and shady slopes with different vegetation types (shrubland and forest, respectively) in Miyaluo of Lixian County, and with the same vegetation type (shrubland) in Yakexia of Heishui County. The results showed that soil enzyme activities and their stoichiometric ratios were significantly different between slope aspects in Miyaluo, while the differences were not significant in Yakexia. The stoichiometry ratio of C-, N- and P-acquiring enzymes on the sunny slope of Miyaluo was 1:0.96:0.92, approaching the 1:1:1 ratio at the global scale, but deviated from 1:1:1 on the shady slope of Miyaluo (1:1.39:0.75) and the different slopes of Yakexia (1:1.09:1.35). There was no significant difference in vector length between slope aspects at both sites, indicating no significant effect of slope aspect on the microbial C limitation. The vector angle was significantly higher on the sunny slope (43.6°) than that on the shady slope (28.7°) in Miyaluo, suggesting that the microorganisms were mainly N-limited. Partial least squares path model showed that the vector angle was mainly directly influenced by the soil nutrient ratios. The vector angle ranged from 50.3° to 51.4°, and did not differ between slope aspects in Yakexia. Therefore, differences in vegetation types between slope aspects drove variations in soil enzyme activity and microbial nutrient limitation through soil properties. It would provide a scientific basis for predicting the spatial pattern of soil enzyme activity and microbial nutrient limitation.
探究土壤微生物代谢的资源限制对于理解生态系统功能和过程至关重要。然而，在小尺度上，特别是在坡面尺度上，山地生态系统中土壤微生物养分限制特征的空间分异格局和驱动因素仍不清楚。本研究在川西亚高山地区的两个具有代表性的山地站点（分别位于理县米亚罗的阳坡和阴坡，植被类型为灌丛和森林；以及黑水县的牙可夏，植被类型为灌丛），通过测量参与碳（C）、氮（N）和磷（P）循环的土壤酶活性，并通过酶化学计量量化微生物养分限制，来研究小尺度上（特别是坡面尺度上）土壤微生物养分限制特征的空间分异格局和驱动因素。结果表明，米亚罗阳坡和阴坡的土壤酶活性及其化学计量比存在显著差异，而黑水县牙可夏的土壤酶活性及其化学计量比则没有显著差异。米亚罗阳坡的 C、N 和 P 获取酶的化学计量比为 1:0.96:0.92，接近全球尺度上的 1:1:1 比例，但与米亚罗阴坡（1:1.39:0.75）和牙可夏不同坡面（1:1.09:1.35）的 1:1:1 比例存在偏差。两个站点的坡面间向量长度没有显著差异，表明坡面方向对微生物 C 限制没有显著影响。米亚罗阳坡的向量角（43.6°）明显高于阴坡（28.7°），表明微生物主要受 N 限制。偏最小二乘路径模型表明，向量角主要受土壤养分比的直接影响。向量角范围为 50.3°至 51.4°，在牙可夏的坡面间没有差异。因此，坡面间植被类型的差异通过土壤性质驱动土壤酶活性和微生物养分限制的变化。本研究结果可为预测土壤酶活性和微生物养分限制的空间格局提供科学依据。
