Effects of long-term vegetation restoration on soil nutrients and stoichiometric characteristics in degraded savanna across various altitudes in dry-hot valleys

ZHANG Han, ZHENG Bo-qin, WEN Guo-jing, ZHANG Jie, MA Ji-ling, FENG De-feng, YANG Chao-lei, ZHANG Ming-da, Tian Bo, SUN Yong-yu, SONG Qing-hai, JIN Yan-qiang   

  1. Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences 666303,
    , University of Chinese Academy of Sciences 100049,
    Yunnan Key Laboratory of Forest Ecosystem Stability and Global Change, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences 666303,
    Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences 653300,
    College of Soil and Water Conservation, Southwest Forestry University 650224,
    , Yunnan Provincial Observation and Research Station for Soil and Water Resources and Carbon Sequestration in the Alpine Gorge Area of Jinsha River 651400,
    , Kunming General Survey of Natural Resources Center, China Geological Survey 650100,
    , Yunnan Climate Center 650034,
    Institute of Highland Forest Science, Chinese Academy of Forestry 650224,
  • Received:2025-03-24 Revised:2025-11-03
  • Contact: JIN, Yan-qiang
  • Supported by:
    the Yunnan Fundamental Research Projects(202401AT070219); the Yunnan Province Key Research and Development Plan Project(202403AC100028); the ‘Light of West China Program’ of CAS, and the ‘Yunnan Revitalization Talent Support Program’ in Yunnan Province of China(XDYC-QNRC-2022-0047); the 14th Five-Year Plans of Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences(XTBG-1450202)

Abstract: Aims The ecological protection and restoration in the fragile dry-hot valleys have consistently garnered attention. However, how soil nutrients and stoichiometric characteristics respond to both artificial and natural restoration treatments across different altitude gradients in the dry-hot valleys remain unclear, especially regarding long-term effects. Methods The changes in soil environment (pH, moisture), soil nutrients (carbon, nitrogen, and phosphorus) and stoichiometric ratio (C:N:P) of degraded savanna in the dry-hot valleys of Yuanmou, Yunnan Province following 10 years of different vegetation restoration treatments have been examined across various altitude gradients. Important findings Soil moisture and nutrients under different restoration treatments changed significantly with the seasons. Compared to degraded forest, both artificial and natural restoration treatments significantly enhanced soil moisture and nutrients. However, the two restoration treatments promoted different nitrogen forms: artificial restoration increased NO3--N, while natural restoration promoted NH4+-N. The two artificial restoration treatments exhibited altitude-dependent. The Acacia confusa forest at mid altitude was more conducive to soil nutrients accumulation, whereas the Leucaena leucocephala forest at high altitude proved to be more beneficial. Soil stoichiometric ratios further demonstrated this interaction between restoration method and altitude. At mid altitude, the C:N of Leucaena leucocephala forest was significantly lower (9.96 in dry and 9.85 in rainy season, P < 0.05) than other treatments. At high altitude, the natural restoration showed significantly higher C:N (17.95) and N:P (13.08) during the dry season (P < 0.05). In general, natural restoration was more effective in soil nutrients accumulation than artificial restoration. It is recommended that natural restoration be adopted as the primary strategy, artificial restoration must adhere to altitude-specific tree species selection . These findings offer practical guidance for vegetation restoration and subsequent sustainable forest management in degraded ecosystems in dry-hot valleys.

Key words: stoichiometric ratio, altitude gradients, ecological restoration, long-term effects, dry-hot valley

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