Soil enzyme activity and stoichiometry along a gradient of vegetation restoration at the Karst Critical Zone Observatory in Southwest China
Soil enzyme activity and stoichiometry along a gradient of vegetation restoration at the Karst Critical Zone Observatory in Southwest China
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DOI：
10.1002/ldr.3389
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发表时间：
2019-07
影响因子：
4.7
通讯作者：
Zhiming Guo;Xinyu Zhang;S. Green;J. Dungait;X. Wen;T. Quine
中科院分区：
文献类型：
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作者：
Zhiming Guo;Xinyu Zhang;S. Green;J. Dungait;X. Wen;T. Quine
“退耕还绿色计划”于20世纪90年代实施，旨在解决覆盖中国三分之一土地的喀斯特地貌极度退化的问题，这主要是由于数十年来管理不善的集约农业造成的。土壤功能的恢复是废弃农田生态系统再生成功的关键，其中碳（C）和养分循环已被耕作严重干扰。然而，生态“临界点”超过土壤功能是不可恢复的，在可管理的时间尺度可能已经通过脆弱的亚热带喀斯特生态系统。本研究的目的是利用土壤中碳、氮（N）和磷（P）获取关键酶的活性作为农业废弃后植被恢复的生物响应的代表，在严重退化的喀斯特流域中进行研究。贵州省喀斯特关键区观测站。2016年，采用空间换时间的方法建立了植被恢复的时间序列：坡耕地<最近废弃的坡耕地<灌木林<次生（再生）林<原生（天然）林。在每个恢复阶段，从地表到基岩（深度达80 cm）对土壤进行取样。弃耕后表层0 ~ 30 cm土壤中所有酶的活性均增加，且与土壤养分和水分含量呈正相关。废弃农田和灌木丛中C-相对于N-水解酶活性的比率降低以及N-相对于P-水解酶活性的比率增加表明氮素缺乏。与原始森林相比，灌丛和次生林土壤中N-相对于P-水解酶活性和C-相对于P-水解酶活性的比率降低，表明磷缺乏。我们的研究结果表明，随着植被的自然恢复，接近自然的生物土壤功能是可恢复的，并表明在废弃后的早期阶段，通过管理营养物质的补充，恢复速度可能会加快。这一新信息可能有助于为营养贫乏的亚热带环境中退化农田的管理再生提供信息。
The “Grain for Green Programme” was implemented in the 1990s as a solution to the extreme degradation of karst landscapes that cover one‐third of China, largely caused by decades of poorly managed intensive agriculture. The recovery of soil functions is key to the success of ecosystem regeneration of abandoned croplands where the carbon (C) and nutrient cycles have been severely perturbed by cultivation. However, an ecological ‘tipping point’ beyond which soil functions are unrecoverable in manageable timescales may have been passed in the fragile, subtropical karst ecosystem. The aim of this study was to use the activity of key enzymes for C, nitrogen (N), and phosphorus (P) acquisition in the soil as a proxy for the biological response to vegetation restoration after agricultural abandonment in a severely degraded karst catchment at the Karst Critical Zone Observatory in Guizhou Province. In 2016, a space‐for‐time approach was used to establish a chronosequence of vegetation recovery: sloping cropland < recently abandoned sloping cropland < shrubland < secondary (regenerated) forest < primary (natural) forest. Soils were sampled from the surface to the bedrock (up to 80‐cm depth) in each recovery phase. The activity of all enzymes in the top 0 to 30‐cm depth increased after abandonment and was positively correlated with soil nutrient and water contents. Nitrogen deficiencies were indicated by the reduced ratios of C‐ relative to N‐hydrolase activity and the increased ratios of N‐ relative to P‐hydrolase activity in the abandoned croplands and shrublands. Phosphorus deficiencies were indicated by the reduced ratios of N‐ relative to P‐hydrolase activity and C‐ relative to P‐hydrolase activity in the soils of the shrubland and secondary forest compared with the primary forest. Our results revealed that near‐to‐natural biological soil function was recoverable as vegetation naturally restored and suggested that the rate of recovery may be accelerated by managed nutrient amendments during the early stages after abandonment. This new information may help to inform the managed regeneration of degraded agricultural land in nutrient‐poor, subtropical environments.