Mycorrhizal and saprotrophic fungal guilds compete for the same organic substrates but affect decomposition differently
Mycorrhizal and saprotrophic fungal guilds compete for the same organic substrates but affect decomposition differently
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DOI：
10.1111/1365-2435.12677
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发表时间：
2016-12-01
影响因子：
5.2
通讯作者：
Clemmensen, Karina E.
中科院分区：
文献类型：
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作者：
Bodeker, Inga T. M.;Lindahl, Bjorn D.;Clemmensen, Karina E.
1.凋落物腐殖和根相关真菌的社区垂直分离内北方森林土壤剖面。目前还不清楚这种深度分区是否完全由基质介导的生态位分区（即不同的基本生态位），或通过空间和资源的竞争（即不同的实现生态位）。提高对这些真菌团的空间划分机制的理解是至关重要的，因为它们以不同的方式调节碳和养分循环。在现场设置下，我们测试了基质质量和当地的真菌物种池在不同深度的影响，以确定潜在的腐殖和菌根真菌的殖民和利用有机质。天然基板的三个质量新鲜或部分分解的凋落物或腐殖土-孵育在相应的有机层的北方森林土壤剖面中的完全析因设计。经过一个和两个生长季后，采用454-焦磷酸测序法测定基质中真菌群落组成，并分析基质的分解情况.在实验过程中的真菌群落的发展被确定为类似程度的垂直位置的基板（24%的解释的变化）和基板质量（20%），表明干扰竞争是一个强大的额外的驱动程序的基板依赖的深度分区系统中的真菌公会。在第一个生长季节，凋落物基质分解缓慢时，根相关的社区殖民化比殖民化的群落凋落物腐殖生物，而腐殖质只有轻微分解的真菌公会。在第二个赛季，某些担子菌从两个公会是特别有效的本地化和利用其原生有机基质，虽然在垂直剖面位移。这验证了真菌群落组成，而不是小气候因素，负责观察到的深度相关的差异分解活动在第一个赛季。总之，我们的研究结果表明，腐殖和根相关的真菌公会有重叠的基本生态位相对于不同质量的基板的殖民化，并在土壤中的外生菌根为主的生态系统的基板依赖的深度分区的干扰竞争得到加强。通过竞争性相互作用，菌根真菌可以通过抑制更有效的枯落物腐解生物的活动来间接调节枯落物的分解速率。
1. Communities of litter saprotrophic and root-associated fungi are vertically separated within boreal forest soil profiles. It is unclear whether this depth partitioning is maintained exclusively by substrate-mediated niche partitioning (i.e. distinct fundamental niches), or by competition for space and resources (i.e. distinct realized niches). Improved understanding of the mechanisms driving spatial partitioning of these fungal guilds is critical, as they modulate carbon and nutrient cycling in different ways.2. Under field settings, we tested the effects of substrate quality and the local fungal species pool at various depths in determining the potential of saprotrophic and mycorrhizal fungi to colonize and exploit organic matter. Natural substrates of three qualities-fresh or partly decomposed litter or humus -were incubated in the corresponding organic layers of a boreal forest soil profile in a fully factorial design. After one and two growing seasons, fungal community composition in the substrates was determined by 454-pyrosequencing and decomposition was analyzed.3. Fungal community development during the course of the experiment was determined to similar degrees by vertical location of the substrates (24% of explained variation) and by substrate quality (20%), indicating that interference competition is a strong additional driver of the substrate-dependent depth partitioning of fungal guilds in the system. During the first growing season, litter substrates decomposed slower when colonized by root-associated communities than when colonized by communities of litter saprotrophs, whereas humus was only slightly decomposed by both fungal guilds. During the second season, certain basidiomycetes from both guilds were particularly efficient in localizing and exploiting their native organic substrates although displaced in the vertical profile. This validates that fungal community composition, rather than microclimatic factors, were responsible for observed depth-related differences in decomposer activities during the first season.4. In conclusion, our results suggest that saprotrophic and root-associated fungal guilds have overlapping fundamental niches with respect to colonization of substrates of different qualities, and that their substrate-dependent depth partitioning in soils of ectomycorrhiza-dominated ecosystems is reinforced by interference competition. Through competitive interactions, mycorrhizal fungi can thus indirectly regulate litter decomposition rates by restraining activities of more efficient litter saprotrophs.