华北落叶松与阔叶树种混合凋落叶分解过程中养分和细菌群落变化

采用凋落物分解袋法，研究塞罕坝地区华北落叶松（L）、华北落叶松和白桦（LB）、华北落叶松和蒙古栎（LQ），以及华北落叶松、白桦和蒙古栎（LBQ）的混合凋落叶分解过程中凋落叶养分和细菌群落变化特征。结果表明，在720 d分解过程中，不同混合凋落叶养分变化趋势大致相同，N和P含量呈上升趋势，C和K含量呈下降趋势，pH呈先下降后上升趋势。在分解过程中，混合凋落叶的C和K释放率均高于华北落叶松凋落叶，N和P释放率则相反。华北落叶松凋落叶pH显著低于混合凋落叶。凋落叶分解初期，优势细菌门为变形菌门、蓝细菌门、拟杆菌门和放线菌门；随分解时间延长，变形菌门和蓝细菌门相对丰度逐渐降低，拟杆菌门和放线菌门变化趋势则相反。凋落叶pH和N与细菌多样性指数呈极显著相关。凋落物分解过程中，细菌多样性指数和丰富度呈上升趋势。分解600 d后，华北落叶松凋落叶细菌丰富度低于混合凋落叶。华北落叶松、白桦和蒙古栎凋落叶混合，能够提高部分养分释放率，提高细菌群落多样性。

Changes of nutrient and bacterial communities during decomposition of mixed litters of Larix principis-rupprechtii and broad-leaved species

A field litterbag experiment was conducted to study the changes of nutrients and bacterial community structure during decomposition of different mixed litters in the pure forests of Larix princips-rupprechtii (L) and mixed forests,including L and Betula platyphylla (LB),L and Quercus mongolica (LQ),as well as LBQ,in Saihanba area,Hebei Province,China.The results showed that the nutrient changes of different mixed litters had the same trend,N and P contents increased,C and K contents decreased,whereas pH decreased first and then increased during 720 days decomposition process.Contrast to N and P,nutrient release rate of C and K of leaf litter in mixed forests was significantly higher than that in L forests during decomposition process.The pH value of L litter was significantly lower than that of mixed litter.At the initial stage of leaf litter decomposition,the dominant phyla were Proteobacteria, Cyanobacteria, Bacteroidota and Acidobacteria.During the litter decomposition,the relative abundance of Proteobacteria and Cyanobacteria decreased,while that of Bacteroidetes and Actinobacteria increased.There was a significant correlation between pH,N of litters on bacterial diversity indicators.During the decomposition of litter,the value of bacterial diversity indicators and richness increased.After decomposition for 600 days,the bacterial richness of L litters was lower than that of mixed litters.Accordingly,the leaf litter mixture of L.princips-rupprechtii,B. platyphylla and Q. mongolica leaves could improve some nutrient release rate and bacterial community diversity.