| 秦岭中段撂荒地植被恢复过程中土壤微生物代谢特征 |
| 摘要点击 1755 全文点击 498 投稿时间：2021-05-28 修订日期：2021-06-18 |
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| 中文关键词 撂荒地 酶化学计量 微生物养分限制 植被恢复 秦岭 |
| 英文关键词 farmland abandonment enzymatic stoichiometry microbial nutrient limitation vegetation restoration Qinling Mountains |
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| 中文摘要 |
| 明确撂荒地植被恢复过程中土壤微生物养分限制特征及其驱动机制对揭示土壤养分循环和维持生态系统稳定具有重要意义.以秦岭中段不同年限撂荒地为研究对象，通过测定土壤理化性质、5种胞外酶活性[β-1，4-葡萄糖苷酶（BG）、纤维二糖水解酶（CBH）、β-1，4-N-乙酰基氨基葡萄糖苷酶（NAG）、亮氨酸氨基肽酶（LAP）和酸性磷酸酶（AP）]，运用胞外酶化学计量学模型，探讨撂荒地植被恢复过程中的土壤微生物养分限制状况及其与土壤性质之间的关系.结果表明，耕地撂荒显著增加了BG、CBH、NAG、LAP和AP的活性；随撂荒年限增加，（BG+CBH）/（NAG+LAP）和（BG+CBH）/AP显著降低，而（NAG+LAP）/AP则相反，相关性分析表明大多数土壤性质与胞外酶活性及其计量比显著相关.酶化学计量向量长度随撂荒年限的增加而减小，表明土壤微生物受碳（C）限制减缓，向量角度均大于45°且呈现降低趋势，表明微生物受到磷（P）限制且逐渐减轻.回归分析表明土壤C和P限制与土壤全量养分、速效养分、养分计量比和物理性质显著相关.偏最小二乘路径模型结果显示，养分计量比是微生物C和P限制的主要驱动因素.综上所述，秦岭植被恢复过程中微生物代谢特征反映了微生物参与下的土壤养分循环机制，为揭示该地区植被恢复过程中群落动态及稳定性，维持区域生态环境安全提供了理论依据. |
| 英文摘要 |
| Clarifying the characteristics of soil microbial nutrient limitation and its driving mechanisms during vegetation restoration after farmland abandonment has important implications for revealing soil nutrient cycling and maintaining ecosystem stability. To determine the limitation of soil microbial nutrients and its relationship with soil properties along a chronosequence of abandoned farmland in the middle of the Qinling Mountains, the soil physicochemical properties and five enzyme activities (β-1,4-glucosidase (BG), cellobiohydrolase (CBH), β-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP)) were measured, and models of extracellular enzymatic activity were applied. The results showed that the activities of BG, CBH, NAG, LAP, and AP were significantly increased following farmland abandonment. With the increasing years of abandonment, the ratios of (BG+CBH)/(NAG+LAP) and (BG+CBH)/AP significantly decreased, whereas the ratio of (NAG+LAP)/AP increased. Correlation analysis showed that most soil physicochemical properties were significantly correlated with extracellular enzyme activities and extracellular enzymatic stoichiometry. The vector length of extracellular enzymatic stoichiometry decreased with the increase in abandonment years, indicating that the limitation of soil microorganisms on carbon (C) was reduced. Moreover, the vector angles (>45°) showed a decreasing trend, indicating that microbial metabolisms were limited by phosphorus (P) and gradually decreased. Regression analysis showed that the C and P limitations were significantly related to total nutrients, available nutrients, nutrient ratio, and soil physical properties. Partial least squares path modeling (PLS-PM) revealed that the C and P limitations were directly regulated by nutrient ratio. PLS-PM further showed that soil total nutrients indirectly affected soil microbial C and P limitations by affecting nutrient ratio, and nutrient ratio affected the soil metabolism limitation via available nutrients and pH. Our study suggests that the characteristics of microbial metabolism during the vegetation restoration process reflect the mechanism of microorganism-mediated soil nutrient cycling, which provides a theoretical basis for revealing the community dynamics and stability during the vegetation restoration process and maintaining the regional ecological environment security in the Qinling Mountains. |
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