Shifts in plant functional community composition under hydrological stress strongly decelerate litter decomposition
Shifts in plant functional community composition under hydrological stress strongly decelerate litter decomposition
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DOI：
10.1002/ece3.6310
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发表时间：
2020-04
影响因子：
2.6
通讯作者：
J. Walter;C. M. Buchmann;F. Schurr
中科院分区：
文献类型：
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作者：
J. Walter;C. M. Buchmann;F. Schurr
凋落物分解是陆地生态系统养分和碳循环的关键过程。在持续的气候变化下，分解过程可能会改变，既通过对分解者活动的直接影响，也通过凋落物质量变化引起的间接影响。我们研究了水文变化如何通过植物物种相对丰度（群落加权平均（CWM）性状和功能多样性）变化引起的植物功能群落重组间接影响分解。我们进一步评估了这些间接的窝质量影响与直接影响的比较。我们建立了一个围隔生态系统实验，其中人工草地群落和天然草坪片受到不同的水文条件（干旱和洪涝）的两个生长季节。从性状数据库中获得物种水平的平均性状，并与物种的相对丰度相结合，以评估功能性群落重建。我们研究了这些社区的混合凋落物在一个共同的“凋落物床”的分解。这些间接影响进行了比较，不同的水文条件对土壤呼吸和标准凋落物分解（直接影响）的影响。干旱减少生物量生产播种社区和天然草坪片，而涝渍只减少生物量播种社区。水文胁迫导致物种丰度发生深刻变化，从而导致植物功能群落组成发生深刻变化。水文胁迫群落的CMW叶干物质含量较高，CMW叶氮含量较低，功能多样性较低。较低的水煤浆叶片氮含量和功能多样性与分解缓慢密切相关。这些间接影响与直接影响不同，但更大，更持久。物种平均性状数据库，因此有相当大的预测能力分解。我们的研究结果表明，在未来可能会更频繁地发生的压力土壤水分条件，迅速改变物种的丰度。由此产生的功能群落重组将减缓水文压力下的分解。
Abstract Litter decomposition is a key process of nutrient and carbon cycling in terrestrial ecosystems. The decomposition process will likely be altered under ongoing climate change, both through direct effects on decomposer activity and through indirect effects caused by changes in litter quality. We studied how hydrological change indirectly affects decomposition via plant functional community restructuring caused by changes in plant species’ relative abundances (community‐weighted mean (CWM) traits and functional diversity). We further assessed how those indirect litter quality effects compare to direct effects. We set up a mesocosm experiment, in which sown grassland communities and natural turf pieces were subjected to different hydrological conditions (dryness and waterlogging) for two growing seasons. Species‐level mean traits were obtained from trait databases and combined with species’ relative abundances to assess functional community restructuring. We studied decomposition of mixed litter from these communities in a common “litterbed.” These indirect effects were compared to effects of different hydrological conditions on soil respiration and on decomposition of standard litter (direct effects). Dryness reduced biomass production in sown communities and natural turf pieces, while waterlogging only reduced biomass in sown communities. Hydrological stress caused profound shifts in species’ abundances and consequently in plant functional community composition. Hydrologically stressed communities had higher CMW leaf dry matter content, lower CMW leaf nitrogen content, and lower functional diversity. Lower CWM leaf N content and functional diversity were strongly related to slower decomposition. These indirect effects paralleled direct effects, but were larger and longer‐lasting. Species mean traits from trait databases had therefore considerable predictive power for decomposition. Our results show that stressful soil moisture conditions, that are likely to occur more frequently in the future, quickly shift species’ abundances. The resulting functional community restructuring will decelerate decomposition under hydrological stress.