华北落叶松与阔叶树种混合凋落叶分解过程中养分释放和酶活性变化

Changes of nutrient release and enzyme activity during the decomposition of mixed leaf litter of Larix principis-rupprechtii and broadleaved tree species

森林凋落物是森林土壤的重要组成部分,凋落物分解在调控森林生态系统养分循环中发挥了关键作用。采用凋落物分解袋法,研究河北塞罕坝地区华北落叶松与白桦,华北落叶松与蒙古栎,华北落叶松、白桦和蒙古栎混合凋落叶及纯华北落叶松凋落叶分解过程中分解速率、养分释放和酶活性的变化。结果表明:经过近2年的分解,混合凋落叶分解速率均显著高于纯华北落叶松凋落物叶;在所有处理中,华北落叶松与白桦混合凋落叶分解速率最高。在凋落叶分解过程中,不同处理养分含量变化一致,凋落叶N、P含量呈上升趋势,C、K含量和C/N呈下降趋势;相对纯华北落叶松凋落叶,各混合凋落叶分解可以促进凋落叶C、K的释放,但对N、P的释放有一定的抑制作用。在凋落叶分解过程中,不同处理凋落叶过氧化氢酶、脲酶、酸性磷酸酶活性呈上升趋势,蔗糖酶活性呈下降趋势;凋落叶分解速率与凋落叶过氧化氢酶、脲酶、酸性磷酸酶活性呈正相关,与蔗糖酶活性呈负相关。总体来看,华北落叶松和白桦、蒙古栎凋落叶混合可以促进华北落叶松凋落叶的分解,且凋落叶中酶活性动态变化与凋落叶的分解密切相关。

Litter is an important contribution to forest soil. Litter decomposition plays an important role in nutrient cycling of forest ecosystem. A field litterbag experiment was conducted to examine the dynamics of decomposition rate, nutrient release and enzyme activity during litter decomposition in the pure forests of Larix principis-rupprechtii(L) and mixed forests, including L and Betula platyphylla(B), L and Quercus mongolica(Q), as well as LBQ, in Saihanba area, Hebei Pro-vince, China. The results showed that the decomposition rate of leaf litter in L forest was significantly lower than that in mixed forests during the 720 d decomposition. The LB had the highest decomposition rate of L leaf litter. All treatments had the same change trend of nutrient contents, with the contents of N and P being increased and that of C, K and C/N being decreased. Contrast to pure leaf litter of L, leaf litter in mixed forests could promote the release of C and K, and inhibit litter N and P release. During the litter decomposition, the activities of catalase, urease and acid phosphatase increased, while that of sucrase decreased in all leaf litter of forests. The decomposition rate of leaf litter was positively correlated with the activities of catalase, urease and acid phosphatase, negatively correlated with that of sucrase. Our results showed that leaf litter mixture of L. principis-rupprechtii, B. platyphylla and Q. mongolica could enhance the litter decomposition of L. principis-rupprechtii, and that enzyme activities were closely related to litter decomposition.