Feyissa Adugna, Gurmesa Geshere Abdisa, Yang Fan, Long Chunyan, Zhang Qian, Cheng Xiaoli
Key Laboratory of Soil Ecology and Health in Universities of Yunnan Province, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China; College of Agriculture and Veterinary Sciences, Ambo University, Ambo, Ethiopia.
Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
Sci Total Environ. 2022 Jun 15;825:154019. doi: 10.1016/j.scitotenv.2022.154019. Epub 2022 Feb 19.
Soil extracellular enzymes plays key roles in ecosystem carbon (C), nitrogen (N), and phosphorus (P) cycling, and are very sensitive to climatic, plant, and edaphic factors. However, the interactive effects of these factors on soil enzyme activities at large spatial scales remain unclear. Here, we investigated the spatial pattern of the activities of five soil hydrolyzing enzymes [β-D-cellobiohydrolase (CB), β-1,4-glucosidase (BG), β-1,4-N-acetyl-glucosaminidase (NAG), L-leucine aminopeptidase (LAP), and acid phosphatase (AP)], and their C:N:P acquisition ratios in relation to plant inputs and edaphic properties across a 600-km climatic gradient in secondary grasslands of subtropical China. The activities of CB, BG, and NAG decreased while that of LAP increased with the increasing mean annual temperature (MAT). The activities of all enzymes did not significantly vary with the mean annual precipitation (MAP). We found that the activities of BG, NAG, and AP were predominately dependent on plant N contents, while the soil LAP activity was tightly related to soil recalcitrant C and N contents. In contrast, the ecoenzymatic C:nutrient (N and P) acquisition ratios increased with increasing MAP and decreasing MAT, primarily due to the increase in plant input at warmer and wetter sites. In addition to climates, plant C inputs, C use efficiency, soil pH, soil organic C, soil C:P, and N:P ratios explained 79% and 72% of the overall variation in ecoenzymatic C:nutrient and P:N acquisition ratios, respectively. The pattern of ecoenzymatic C:N:P acquisition ratios also revealed unexpected N limitation in subtropical grasslands. Overall, our study highlighted the importance of climate in controlling soil biological C, N, and P acquisition activities through its direct and indirect effects on plant inputs and soil edaphic factors, thereby providing useful information for better understanding and predictions of soil C and nutrient cycling in grassland ecosystems at regional scales.
土壤胞外酶在生态系统碳（C）、氮（N）和磷（P）循环中发挥着关键作用，并且对气候、植物和土壤因子非常敏感。然而，在大空间尺度上，这些因子对土壤酶活性的交互作用仍不清楚。在此，我们研究了中国亚热带次生草原600公里气候梯度上五种土壤水解酶[β-D-纤维二糖水解酶（CB）、β-1,4-葡萄糖苷酶（BG）、β-1,4-N-乙酰氨基葡萄糖苷酶（NAG）、L-亮氨酸氨肽酶（LAP）和酸性磷酸酶（AP）]的活性空间格局，以及它们与植物输入和土壤性质相关的C:N:P获取比率。随着年平均温度（MAT）升高，CB、BG和NAG的活性降低，而LAP的活性增加。所有酶的活性均未随年平均降水量（MAP）发生显著变化。我们发现，BG、NAG和AP的活性主要依赖于植物N含量，而土壤LAP活性与土壤难降解C和N含量密切相关。相反，生态酶C:养分（N和P）获取比率随MAP升高和MAT降低而增加，这主要是由于温暖湿润地区植物输入增加所致。除气候外，植物C输入、C利用效率、土壤pH值、土壤有机C、土壤C:P和N:P比率分别解释了生态酶C:养分和P:N获取比率总体变异的79%和72%。生态酶C:N:P获取比率格局还揭示了亚热带草原存在意外的N限制。总体而言，我们的研究强调了气候通过对植物输入和土壤性质的直接和间接影响来控制土壤生物C、N和P获取活动的重要性，从而为更好地理解和预测区域尺度草地生态系统土壤C和养分循环提供了有用信息。
