Canopy Trimming Experiment (CTE) Microbial diversity DNA data

Hurricanes are common disturbances in the Caribbean region that affect tree distribution, species diversity and biomass in forests. Little is known of how microbial communities in soil and litter are affected by natural or anthropogenic disturbances. The objective of our study was to determine the relative abundance and diversity of microorganisms in leaf litter at different stages of decomposition, and the effect of canopy opening and debris addition or removal. Results: Leaf mass loss was slowest in the treatment with canopy trimming and debris removal. Canopy opening was associated with lower litter moisture, lower fungal connectivity between litter layers and slower mass loss after three months. Addition of green leaves increased moisture, and frequently accelerated mass loss of the senesced leaves below them at 17, 28 and 40.5, but not 53 weeks. After 28 weeks, mass loss showed a significant treatment interaction, and was concordant with fungal connectivity between litter cohorts. TRFLP profiles of the 16S rDNA digested with MnlI and fungal ITS digested with HaeIII shows that the microbial communities at 17, 28 and 53 weeks were highly divergent among treatments (Sorensen index of similarity). In comparisons of green versus senesced leaves within treatments, bacterial communities’ differed somewhat, fungal communities differed strongly, but mass loss did not differ. Conclusions: Microbial community changes through time can be related to microclimate and the availability of labile compounds. Fungi appeared to control the succession of microorganisms in decomposing leaves.飓风是加勒比地区常见的自然扰动事件，可对森林内的树木分布、物种多样性及生物量造成影响。目前学界对自然或人为扰动如何影响土壤与枯落物中的微生物群落仍知之甚少。本研究旨在明确不同分解阶段的叶片枯落物中微生物的相对丰度与多样性，以及林冠开度、枯落物添加或移除对其产生的影响。 结果显示：在修枝并移除枯落物的实验处理组中，叶片质量损失速率最慢。林冠开度增大与枯落物含水率降低、枯落物层间真菌连通性下降以及实验进行3个月后的质量损失减缓相关。添加新鲜绿叶会提升枯落物含水率，且在第17、28及40.5周时，通常会加速其下方衰老叶片的质量损失，但在第53周时未观察到此效应。实验进行28周后，叶片质量损失呈现出显著的实验处理交互效应，且与枯落物组间的真菌连通性相一致。对经限制性内切酶MnlI酶切的16S核糖体DNA（16S rDNA）以及经限制性内切酶HaeIII酶切的真菌内转录间隔区（ITS, Internal Transcribed Spacer）进行末端限制性片段长度多态性（TRFLP, Terminal Restriction Fragment Length Polymorphism）分析的结果显示，在第17、28和53周时，各实验处理组的微生物群落组成差异显著（基于索伦森相似性指数）。在同一实验处理组内比较新鲜绿叶与衰老叶片时，细菌群落仅存在小幅差异，而真菌群落差异显著，但两组的叶片质量损失并无不同。 结论：微生物群落随时间的变化可与微气候以及易分解化合物的可获得性相关联。真菌似乎主导了分解叶片中微生物的群落演替过程。