细菌对五大连池火山森林凋落物早期分解的影响

Effects of bacteria on early⁃stage litter decomposition in Wudalianchi volcanic forest

为了解火山森林生态系统中微生物在凋落物分解和营养循环中的作用,以五大连池火山熔岩台地森林优势树种落叶松、白桦、山杨为研究对象,采用凋落物袋野外原位分解和高通量测序方法,分析细菌群落结构及多样性对凋落物分解的响应。结果表明:经过18个月的分解,3种植物叶片凋落物质量残留率为63.9%~68.1%,白桦叶片凋落物分解最快,分解前后的N含量、C∶N、N∶P存在显著差异。3种植物叶片凋落物的细菌物种数和多样性指数具有显著差异。变形菌门、放线菌门、拟杆菌门为优势菌门,根瘤菌属、鞘氨醇单胞菌属、假单胞菌属为优势菌属,且在3种凋落物间存在显著差异。分解18个月后,凋落物中优势细菌类群与火山熔岩台地土壤趋向一致,火山森林生态系统中凋落物细菌多样性和群落结构受到凋落物中P含量、C∶N和N∶P的影响。

To understand the role of microorganisms in litter decomposition and nutrient cycling in volcanic forest ecosystem,we conducted in⁃situ litterbag decomposition experiment and used Illumina MiSeq high⁃throughput sequencing to analyze the response of bacterial community structure and diversity during the decomposition of litters from Larix gmelinii,Betula platyphylla and Populus davidiana,the dominant tree species in volcanic lava plateau of Wudalianchi.The results showed that mass remaining percentage of litters of three species after 18⁃month decomposition was 63.9%-68.1%.Litter of B.platyphylla decomposed the fastest,with significant difference in N,C:N,and N:P before and after decomposition.The richness of bacterial species and diversity index differed significantly among the three litters.Proteobacteria,Actinomycetes,and Bacteroidetes were the dominant bacterial groups at the phylum level,while Rhizobium,Sphingomonas,and Pseudomonas were the dominant groups at the genus level,with significant difference among the three litters.After 18 months,the dominant bacterial groups in litter tended to be consistent with those in volcanic lava platform soil.In the volcanic forest ecosystem,bacterial diversity and com⁃munity structure were mainly affected by P,C:N,and N:P in the litter.