关键词: 高寒灌丛, 模拟增温, 土壤呼吸组分, 土壤碳循环

Abstract: An in situ opentop chamber (OTC) experiment was conducted to investigate the effects of climate warming on soil respiration in the growing season ofSibiraea angustata alpine scrubland on the eastern Qinghai-Tibet Plateau. The results showed that the simulated warming increased the average temperature of air and soil by 0.6 ℃ and 1.2 ℃, respectively, and decreased soil moisture by 2.7 percents. Simulated warming significantly increased the rates of total soil respiration and all its components. The rates of total soil respiration, heterotrophic respiration, rhizosphere respiration, fine root respiration and rhizomicrobial respiration were increased by 54.3%-99.2%, 60.8%-80.3%, 30.0%-165.0%, 37.6%-110.1% and 96.7%-215.3%, respectively. Soil enzyme activities, soil temperature and soil pH were the main contributors to the changes of the rates of soil respiration components, which explained more than 49.2% variations of soil respiration rates. There was no significant effect of soil microbial biomass, soil inorganic nitrogen content and soil moisture on the rates of soil respiration components. The rates of rhizosphere respiration and fine root respiration were positively correlated with fine root biomass. These results indicated that global climate warming could promote soil respiration of alpine scrub ecosystem on the eastern Qinghai-Tibet Plateau by changing biotic and abiotic factors, and thus accelerate soil carbon cycling.

Key words: alpine scrub, simulated warming, soil respiration component, soil carbon cycling.