模拟增温对湿地植物凋落物分解及细菌群落的影响

Effects of simulated warming on litter decomposition and bacterial communities of wetland plants

植物凋落物分解是湿地生态系统物质循环的重要组成部分,随着全球气候变化的逐渐加剧,气候变暖对湿地植物凋落物分解的影响已引起人们的广泛关注。本研究通过凋落物袋法对比研究了山东省南四湖湿地中芦苇和香蒲两种典型湿地植物的凋落物分解过程,利用开顶式生长室(Open⁃top Chamber,OTC)模拟了大气增温(2.0±0.5)℃—(4.0±0.5)℃对凋落物分解特征和细菌群落的影响。结果显示,增温显著加速了两种植物凋落物的分解速率,而木质素/氮(Lignin/N)、纤维素/氮(Cellulose/N)是影响凋落物分解速率的重要因子,与分解速率呈显著负相关。增温显著增加了细菌群落的丰度和多样性,碳是厚壁菌门(Firmicutes)等细菌丰度变化的驱动因子,而木质素、木质素/氮是拟杆菌门(Bacteroidota)等细菌丰度变化的驱动因子。细菌群落共现网络显示,在增温条件下,凋落物分解的细菌群落网络主要由共生关系组成。气候变暖提高了细菌之间的相互关系和互惠程度,加快了植物凋落物的分解进程,进而影响了湿地生态系统的碳收支平衡。

Plant litter is an important part of the material cycle in wetland ecosystems.With the gradual intensification of global climate change,the impact of climate warming on the decomposition of plant litter in wetlands has attracted widespread attention.In this study,the decomposition processes of two typical plant litters,Phragmites australis and Typha domingensis,in the wetland of Nansi Lake,Shandong province,were comparatively studied by the litter bag method,and the effects of atmospheric warming(2.0±0.5)℃—(4.0±0.5)℃on the decomposition characteristics of litter and bacterial community structure were simulated by using an Open⁃top chamber(OTC).The results showed that warming significantly accelerated the decomposition rate of the litter of both plants,while Lignin/N and Cellulose/N were important factors affecting the decomposition rate of the litter,and were significantly negatively correlated with the decomposition rate.Warming significantly increased the abundance and diversity of bacterial communities,with carbon being the driver of changes in the abundance of bacteria such as Firmicutes,while Lignin and Lignin/N were the drivers of changes in the abundance of bacteria such as Bacteroidota.The bacterial community co⁃occurrence network showed that the bacterial community network of litter decomposition was mainly composed of symbiotic relationships under warming conditions.Climate warming increased the interrelationships and reciprocity among bacteria,accelerated the decomposition process of plant litter,and thus affected the carbon balance of the wetland ecosystem.