Alpine wetland litter decomposition under wet and dry conditions: A comparative study of native vs. standardized litter

Abstract

Alpine wetlands, critical ecosystems in high-altitude mountain areas, play essential roles in water conservation, biodiversity protection, and carbon (C) sequestration. These ecosystems are particularly sensitive to climate change, with temperature and precipitation variations significantly impacting their structure and functional processes, such as litter decomposition, a key mechanism for C stabilization. This study focused on the Zoige wetland, a representative alpine wetland located on the eastern edge of the Qinghai-Tibet plateau. An incubation experiment was conducted with soil samples under simulated wet and dry moisture conditions to evaluate the environmental impacts on litter decomposition within this ecosystem. In this study, we employed the Tea Bag Index method, utilizing standardized litter, alongside native litter bags to compare the decomposition processes. This comparison between the uniform composition of standardized litter and the chemically diverse native plant litter aims to provide a comprehensive understanding of litter decomposition dynamics in alpine wetland ecosystems. Our finding showed that both standardized and native litter decomposition significantly decreased under dry conditions, in contrast to wetter condition. The components of both standardized and native litter exhibited a decrease over time, with the easily decomposable fractions breaking down swiftly, in contrast to the slower decomposition of the more resistant components. Furthermore, soil exo-enzyme activities varied significantly with environmental conditions. Wet conditions were observed to enhance soil microbial activity, whereas dry conditions resulted in shifts in microbial biomass C and nitrogen, indicative of drought resilience. The correlation analysis revealed that the composition of native litter is the primary factor influencing its decomposition. In contrast, the decomposition of standardized litter was influenced by both its composition and soil microbial activity. Thus, the distinction between the influences on native and standardized litter decomposition highlights the necessity of considering both litter quality and microbial interaction in ecological studies. This approach offers critical insight into the advantages and limitations of each decomposition methodology within alpine wetland ecosystems.

Keywords

• Alpine wetland
• Litter turnover
• Moisture level
• Drought stress
• Carbon stabilization
• Tea Bag Index