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喀斯特地区土壤生态化学计量特征在不同岩性和恢复方式下的差异

Effects of different restoration methods and lithology on ecological stoichiometry of karst soil

  • 摘要: 以不同恢复方式(人工林、次生林)和岩性(白云岩、石灰岩)土壤为研究对象,采用相关性分析和冗余分析方法探讨了不同岩性和恢复方式下土壤碳(C)、氮(N)、磷(P)、钾(K)等的含量和化学计量特征及其影响因素。结果显示:(1)白云岩和石灰岩次生林土壤C、P养分含量显著高于人工林,而白云岩人工林和次生林N、K差异并不显著;(2)石灰岩土壤C∶P和N∶P显著低于白云岩,C∶N差异并不显著,研究区土壤的C∶N、C∶P、N∶P的均值介于9.05~11.50、8.68~27.75和0.86~3.11,远低于全国均值(12.01、61和5.2),而石灰岩人工林C∶N、C∶P、N∶P最小,土壤中N元素更为缺乏;此外,白云岩土壤C∶K、N∶K、K∶P显著低于石灰岩,且白云岩次生林N∶K>2.1和K∶P<3.4,植物的生长更容易受K限制;(3)白云岩植被恢复主要受Ca含量、田间持水量(WHC)和年均降水量(MAP)的影响,而石灰岩主要受WHC、MAP和土壤酸碱度(pH值)的影响。研究结果说明,相较于次生林,人工林土壤表现出C、N、P的缺乏,进行白云岩次生林植被恢复,建议添加钾肥缓解养分限制,而石灰岩人工林应考虑N的限制。

     

    Abstract: This study investigated the elemental composition and stoichiometric patterns of soil carbon (C), nitrogen (N), phosphorus (P), and potassium (K) under different lithological backgrounds and vegetation restoration strategies in a karst landscape. Using correlation and redundancy analyses, soils from artificial and secondary forests established on dolomite and limestone were compared to identify key drivers shaping nutrient dynamics, with the goal of informing lithology-specific restoration practices. Results showed that: (1) Secondary forests on both dolomite and limestone exhibited significantly higher concentrations of soil C and P than corresponding plantations, while N and K contents did not differ significantly between dolomite forest types. (2) Stoichiometric ratios of C∶P and N∶P were significantly lower in limestone soils than in dolomite, whereas C∶N ratios showed no significant differences. Across all samples, mean C∶N, C∶P, and N∶P values ranged from 9.05–11.50, 8.68–27.75, and 0.86–3.11, respectively, substantially below national benchmarks (12.01, 61, and 5.2), indicating widespread nutrient limitations. Notably, limestone plantations exhibited the lowest C∶N, C∶P, and N∶P, reflecting pronounced N deficiency. In contrast, dolomite soils exhibited significantly lower C∶K, N∶K, and K∶P ratios compared to limestone, with N∶K>2.1 and K∶P<3.4 in dolomite secondary forests, indicating that plant growth was more susceptible to K limitation. (3) Multivariate analyses identified Ca content, soil water-holding capacity (WHC), and mean annual precipitation (MAP) as primary drivers of nutrient dynamics in dolomite systems, whereas WHC, MAP, and soil pH were most influential in limestone soils. Overall, plantation soils exhibited greater depletion of C, N, and P relative to secondary forests, highlighting the need to prioritize vegetation restoration on dolomite substrates. Furthermore, K supplementation should be implemented in secondary forests to alleviate nutrient limitations, while N deficiency must be addressed in artificial restoration efforts on limestone soils.

     

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