关键词: 氮沉降, 养分释放, 慈竹林, 凋落物, 华西雨屏区

Abstract:

An in situ experiment was conducted in a Neosinocalamus affinis plantation in rainy area of western China to study nutrient release of leaf litter in response to simulated nitrogen deposition. Four treatments were set, i.e., null N level (CK, 0 kg·hm^-2a^-1), low N level (LN, 50 kg·hm^-2a^-1), moderate N level (MN, 150 kg·hm^-2a^-1) and high N level (HN, 300 kg·hm^-2a^-1). The results showed as follows: Different elements showed different trends in the whole process: The concentrations of C, P and Mg decreased with N increasing; the N initially decreased, then increased, and finally decreased; the K showed a curve which first increased, then decreased, and increased again at the end; the Ca increased at the beginning and then decreased. The characteristics of nutrient release patterns were as the following: K accumulated at early stage and released later; C, P, Ca and Mg released all through the process; N showed a curve of leaching-accumulation-releasing in CK treatment while it was directly releasing in LN, MN, HN. N deposition exerted a positive effect on the release of C, N, P, K, Ca, Mg with the highest release rate in MN. It suggests that it might take 2.019-2.853 years to decompose 95% of N element. During the process of leaf litter decomposing under N deposition, the C/N ratios showed a up-down trend. On the whole, C/N ratios decreased at the first 2 months, and then increased.

Key words: nitrogen deposition, nutrient release, Neosinocalamus affinis, leaf litter, rainy area of western China