关键词: 滇东南脆弱区, 森林类型, 养分限制, 碳氮磷含量, 生态化学计量

Abstract: Understanding the carbon:nitrogen:phosphorus (C∶N∶P) stoichiometry and coupling in karst rocky-desertified and dry-hot valley forests is essential for nutrient management and ecological restoration. We quantified C, N, and P concentrations in foliage, freshly senesced litter and surface soils across five typical forest types in Mile and Shiping counties, southeastern Yunnan. The results were as follows. (1) Mean foliar C, N, and P concentrations were 426.69, 13.36, and 1.61 g·kg^-1 in Mile and 433.60, 12.19, and 1.26 g·kg^-1 in Shiping, respectively. Across all ecosystem compartments, Mile exhibited consistently lower C but higher N and P concentrations than Shiping. (2) Relative growth rates were below the global mean and followed the order of Mile>Shiping. Higher litter C∶N and C∶P ratios indicated slower decomposition in Shiping, mirroring its lower growth rates. (3) The resorption efficiency of N and P in Shiping was 52.7% and 69.5%, respectively, indicating a strong nutrient resorption effect. This suggests that plants adopt adaptive strategies such as altering root structures to enhance nutrient retention capacity under conditions of nutrient deficiency. (4) Foliar N∶P ratios (<14) revealed pervasive N limitation. However, the nutrient limitations varied among different forest types. Soil C∶P ratios suggested considerable P mineralization potential. We recommend enhancing soil nitrogen availability through N fertilization or replanting nitrogenfixing tree species in the understory. Our results can provide scientific basis for a better understanding of C, N and P biogeochemical cycles, as well as for the conservation and restoration of forest ecosystems in ecologically fragile areas.

Key words: fragile zone of southeast Yunnan, forest type, nutrient limitation, C, N and P content, ecological stoichiometry