Responses of Ecological Stoichiometry of Plants and Soils to Degradation Levels in Alpine Wetlands of the Qinghai-Tibet Plateau.

Abstract

Alpine wetlands on the Qinghai-Tibet Plateau play a crucial role in biodiversity conservation and global carbon cycling. However, degradation has altered plant-soil stoichiometric relationships, impacting ecosystem function. This study examined the effects of wetland degradation on the carbon (C), nitrogen (N), and phosphorus (P) dynamics in plant leaves and soil. We selected wetlands in Maqu County, China, and categorized them into four degradation levels: no degradation (ND), light degradation (LD), moderate degradation (MD), and heavy degradation (HD). Field sampling and laboratory analysis quantified plant and soil C, N, and P contents and stoichiometric ratios. Results showed that: (1) Increasing degradation reduced plant height, coverage, and biomass, while soil pH, bulk density, and electrical conductivity increased, and water content declined; (2) Leaf organic carbon and total phosphorus decreased with degradation, while total nitrogen followed the trend ND > HD > LD > MD; (3) Soil organic carbon, total nitrogen, total phosphorus, C:P, and N:P ratios declined, whereas soil C:N increased; (4) Leaf C:N and C:P were highly sensitive to degradation, while leaf N:P remained stable; (5) Soil bulk density and water content were primary drivers of plant-soil nutrient shifts. These findings highlight the role of soil physical properties in mediating degradation effects and provide insights for targeted wetland restoration strategies.