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Contribution of fungal and invertebrate communities to wood decay in tropical terrestrial and aquatic habitats
Ecology ( IF 4.8 ) Pub Date : 2020-08-19 , DOI: 10.1002/ecy.3097
Astrid Ferrer 1 , Katy D Heath 1 , Thomas Canam 2 , Hector D Flores 2 , James W Dalling 1, 3
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Wood is a major carbon input into aquatic ecosystems and is thought to decay slowly, yet surprisingly little terrestrial carbon accumulates in marine sediments. A better mechanistic understanding of how habitat conditions and decomposer communities influence wood decay processes along the river-estuary-ocean continuum can address this seeming paradox. We measured mass loss, wood element, and polymer concentrations, quantified invertebrate-induced decay, and sequenced fungal communities associated with replicate sections of Guazuma branch wood submerged in freshwater, estuarine, and near-shore marine habitats and placed on the soil surface in nearby terrestrial habitats in three watersheds in the tropical eastern Pacific. Over 15 months we found that wood decayed at similar rates in estuarine, marine and terrestrial sites, reflecting the combined activity of invertebrate and microbial decomposers. In contrast, in the absence of shipworms (Teredinidae), which accounted for ~ 40% of wood mass loss in the estuarine habitats, decay proceeded more slowly in freshwater. Over the experiment wood element chemistry diverged among freshwater, estuarine and marine habitats, due to differences in both nutrient losses (e.g., potassium and phosphorus) and gains (e.g., calcium and aluminum) through decay. Similarly, we observed changes in wood polymer content, with the highest losses of cellulose, hemicellulose, and lignin moieties in the marine habitat. Aquatic fungal communities were strongly dominated by ascomycetes (88-99% of taxa), compared to terrestrial communities (55% ascomycetes). Large differences in fungal diversity were also observed across habitats with three-fold higher richness in terrestrial than freshwater habitats and two-fold higher diversity in freshwater than estuarine/marine habitats. Divergent decay trajectories across habitats were associated with widespread order-level differences in fungal composition, with distinct communities found in freshwater, estuarine and marine habitats. However, few individual taxa that were significantly associated with mass loss were broadly distributed, suggesting a high level of functional redundancy. The rapid processing of wood entering tropical rivers by microbes and invertebrates, comparable to that on land, indicates that estuaries and coastal oceans are hotspots not just for the processing of particulate and dissolved organic carbon, but also for woody debris and for the breakdown of lignin, the most recalcitrant polymer in plant tissue.

中文翻译:

真菌和无脊椎动物群落对热带陆地和水生栖息地木材腐烂的贡献

木材是水生生态系统的主要碳输入,被认为衰减缓慢,但令人惊讶的是,海洋沉积物中积聚的陆地碳很少。更好地了解栖息地条件和分解者群落如何影响河流 - 河口 - 海洋连续体的木材腐烂过程,可以解决这个看似矛盾的问题。我们测量了质量损失、木材元素和聚合物浓度,量化了无脊椎动物引起的腐烂,并对与淹没在淡水、河口和近岸海洋栖息地中并放置在附近土壤表面的 Guazuma 树枝木的复制部分相关的真菌群落进行了测序。热带东太平洋三个流域的陆地栖息地。在 15 个月的时间里,我们发现木材在河口、海洋和陆地上以相似的速度腐烂,反映了无脊椎动物和微生物分解者的综合活动。相比之下,在没有占河口栖息地木材质量损失约 40% 的船虫 (Teredinidae) 的情况下,淡水中的腐烂进行得更慢。在实验中,由于营养损失(例如钾和磷)和腐烂获得(例如钙和铝)的差异,木材元素化学在淡水、河口和海洋栖息地之间存在差异。同样,我们观察到木材聚合物含量的变化,海洋栖息地中纤维素、半纤维素和木质素部分的损失最大。与陆生真菌群落(子囊菌群 55%)相比,水生真菌群落以子囊菌群(88-99% 的分类群)为主。在不同栖息地也观察到真菌多样性的巨大差异,陆地栖息地的丰富度是淡水栖息地的三倍,淡水的多样性是河口/海洋栖息地的两倍。不同栖息地的不同衰变轨迹与真菌组成的广泛阶级差异有关,在淡水、河口和海洋栖息地中发现了不同的群落。然而,与质量损失显着相关的个体分类群很少分布广泛,这表明功能冗余度很高。微生物和无脊椎动物对进入热带河流的木材进行的快速加工,与陆地上的相似,表明河口和沿海海洋不仅是加工颗粒和溶解有机碳的热点,
更新日期:2020-08-19
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