Evaluating the roles of microbial functional breadth and home‐field advantage in leaf litter decomposition
Evaluating the roles of microbial functional breadth and home‐field advantage in leaf litter decomposition
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评估微生物功能广度和主场优势在凋落物分解中的作用
DOI：
10.1111/1365-2435.14026
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发表时间：
2022
影响因子：
5.2
通讯作者：
Strickland, Michael S.
中科院分区：
文献类型：
--
作者：
Osburn, Ernest D.;Hoch, Peter J.;Lucas, Jane M.;McBride, Steven G.;Strickland, Michael S.
土壤生物区系越来越被认为是控制凋落物分解的主要因素，但生物区系影响凋落物分解的确切机制尚未确定。分解者群落可能特别适应当地的垃圾投入，因此以更高的速度分解来自其家园生态系统的垃圾。这种机制被称为主场优势（HFA）假说。或者，凋落物分解率可能仅仅取决于分解者群落中存在的代谢功能的范围。这种机制被称为功能宽度（FB）假说。然而，HFA和FB在凋落物分解中的相对重要性是未知的，HFA和FB的微生物群落驱动因素也是未知的。微生物HFA和FB之间的潜在关系/权衡也是未知的。为了研究HFA和FB在凋落物分解中的作用，我们收集了美国大陆六个不同生态系统的凋落物和土壤，并进行了全因子凋落物×土壤接种物实验。我们测量了150天的凋落物分解（即累积CO2-C呼吸），并使用分析模型计算了每个微生物分解者群落的HFA和FB。我们的结果表明，分解者群落之间存在明显的功能差异，即不同分解者群落对凋落物源的分解不同。这些差异主要是由于不同群落之间FB的差异，而HFA的影响不太明显。我们观察到HFA和干扰敏感细菌门Verruomicrobia之间的正相关关系，表明HFA可能是未受干扰环境中的重要机制。我们还观察到细菌r与K策略者和FB之间的负相关关系，表明微生物生活史策略与凋落物分解功能之间存在重要联系。微生物FB和HFA表现出强烈的单峰关系，在中等FB值下观察到高HFA，而低HFA与低和高FB均相关。这表明分解者对当地植物输入（即高氢氟烷烃）的适应限制了FB，这需要广泛而不是专门的功能。此外，这种关系表明，HFA的影响将不明显，当社区表现出高FB，因此分解所有的凋落物以及FB低，社区分解所有的凋落物差。总的来说，我们的研究为微生物群落影响落叶分解的机制提供了新的见解。
Soil biota are increasingly recognized as a primary control on litter decomposition at both local and regional scales, but the precise mechanisms by which biota influence litter decomposition have yet to be identified.There are multiple hypothesized mechanisms by which biotic communities may influence litter decomposition—for example, decomposer communities may be specially adapted to local litter inputs and therefore decompose litter from their home ecosystem at elevated rates. This mechanism is known as the home‐field advantage (HFA) hypothesis. Alternatively, litter decomposition rates may simply depend upon the range of metabolic functions present within a decomposer community. This mechanism is known as the functional breadth (FB) hypothesis. However, the relative importance of HFA and FB in litter decomposition is unknown, as are the microbial community drivers of HFA and FB. Potential relationships/trade‐offs between microbial HFA and FB are also unknown.To investigate the roles of HFA and FB in litter decomposition, we collected litter and soil from six different ecosystems across the continental US and conducted a full factorial litter × soil inoculum experiment. We measured litter decomposition (i.e. cumulative CO2‐C respired) over 150 days and used an analytical model to calculate the HFA and FB of each microbial decomposer community.Our results indicated clear functional differences among decomposer communities, that is, litter sources were decomposed differently by different decomposer communities. These differences were primarily due to differences in FB between different communities, while HFA effects were less evident.We observed a positive relationship between HFA and the disturbance‐sensitive bacterial phylum Verruomicrobia, suggesting that HFA may be an important mechanism in undisturbed environments. We also observed a negative relationship between bacterial r versus K strategists and FB, suggesting an important link between microbial life‐history strategies and litter decomposition functions.Microbial FB and HFA exhibited a strong unimodal relationship, where high HFA was observed at intermediate FB values, while low HFA was associated with both low and high FB. This suggests that adaptation of decomposers to local plant inputs (i.e. high HFA) constrains FB, which requires broad rather than specialized functionality. Furthermore, this relationship suggests that HFA effects will not be apparent when communities exhibit high FB and therefore decompose all litters well and also when FB is low and communities decompose all litters poorly. Overall, our study provides new insights into the mechanisms by which microbial communities influence the decomposition of leaf litter.Read the free Plain Language Summary for this article on the Journal blog.