Litter-decomposing bacterial communities in the detritusphere with and without sexual propagule litter under two related tropical forest environments

The home-field advantage (HFA) is an important aspect in litter decomposition. However, it is not well understood whether HFA is influenced by the presence of sexual propagule litter (SPL), mainly senesced flowers and fruits produced in forests, throughout the litter decomposition process. In this study, two typical forest types, a tropical seasonal rainforest and a rubber plantation with a historical land-use conversion relationship, in Xishuangbanna, Southwestern China, were used as home-field and away-field environments for litter decomposition, respectively. Litter was collected over a period of one year, resulting in a total of 144 sample bags. These samples were used in two decomposition experiments over a 12-month period, with three bags of each litter type (36 bags total) randomly selected each month for analysis. The bacterial communities in both environments were characterized using high-throughput sequencing. Across the four types of litter, the dominant bacterial phyla were Proteobacteria , Actinobacteria , and Bacteroidetes , and the dominant genera were Burkholderia , Bradyrhizobium , and Agrobacterium. SPL exhibited a positive priming effect (PE) on the relative abundances of phyla and genera (PE > 0) and a negative priming effect on the Chao1, Simpson, and Shannon indices (PE < 0). All species-level and diversity indices demonstrated positive values of the effect of HFA (HE, > 0). For both phyla and genera, the field actual superposition effect (FSE) of PE and HA was lower than the theoretical superposition effect (TSE). Specifically, FSE exceeded TSE for the Chao1 and Simpson indices but was lower than TSE for the Shannon index. Environmental factors significantly influenced bacterial community structure, with air temperature and humidity being particularly impactful ( P < 0.05). The detritusphere bacterial community structures of identical litter types were similar in composition, with consistent dominant phyla and genera, across both the home-field Xishuangbanna tropical forest environment and the away-field rubber plantation environment. SPL had a priming effect on litter decomposition with a positive effect on the richness and a negative effect on the diversity index. The presence of HFA was confirmed in this tropical rainforest. SPL and HFA exhibited both antagonistic and synergistic effects on bacterial richness and diversity indices within the detritusphere.