关键词: 凋落物分解, N添加, 荒漠生态系统, 分解速率, 养分释放

Abstract: A litterbag decomposition experiment was carried out in southern Gurbantunggut Desert, with four nitrogen treatments: N₀(0 g N·m^-2·a^-1), N₅(5 g N·m^-2·a^-1), N₁₀(10 g N·m^-2·a^-1) and N₂₀(20 g N·m^-2·a^-1). The aims were to examine the effects of exogenous nitrogen addition on decomposition rate and nutrient release of Tamarix ramosissima, Salicornia europaea and their mixture. Results showed that decomposition rates were significantly different among litter types. After 345 days, the decomposition rates of T. ramosissima, S. europaea and their mixture under different treatments were 0.64-0.70, 0.84-0.99 and 0.71-0.81 kg·kg^-1·a^-1, respectively. Both mono- and mixed-litters exhibited nutrient release during decomposition process, with the release rates being 60.6%-67.4%, 56.7%-62.6%, 57.4%-62.3%, 46.8%-63.0% for N, and 51.9%-77.9%, 59.9%-74.7%, 53.0%-79.9%, 52.3%-76.4% for P, respectively for the N₀, N₅, N₁₀ and N₂₀ treatments. Nitrogen addition did not affect litter decomposition rate. The dynamics of N and P during decomposition of different litter types showed different responses to nitrogen addition. Nitrogen addition inhibited N and P releases of S. europaea litter and P release of the mixed litter, but did not affect the nutrient release of T. ramosissima. The results suggested that nitrogen input would not promote litter decomposition in temperate desert ecosystems, but might retard the nutrient returning to soil system.

Key words: litter decomposition, nitrogen addition, desert ecosystem, decomposition rate, nutrient release