The decomposition of leaf litter constitutes a major pathway of carbon and nutrient cycling in terrestrial ecosystems. Though it is well established that litter decomposition varies among species, most leaf litter decomposes not alone, but in mixture with litter from heterospecifics. The consequences of this mixing, and of the role of multiple dimensions of plant biodiversity, for litter decomposition are ambiguous, with past research suggesting that mixing diverse litter can speed up, slow down, or have no effect on decomposition. Furthermore, different chemical constituents of litter decompose at different rates, and the consequences of diversity for each of these rates are not completely understood. We created litterbags corresponding to 49 different litter mixtures ranging from one to 12 temperate forest species and allowed them to decompose over 2 yr in a common garden in temperate eastern Minnesota, USA. Following collections at 2, 4, 12, and 24 months, we assessed total mass loss and changes in four classes of litter carbon (soluble cell contents, hemicellulose and bound proteins, cellulose, and lignin/acid unhydrolyzable recalcitrants). Species varied in litter decomposition rate (losing from 8% to 41% of total mass) and they lost soluble cell contents (up to 64% of ash‐free mass) and hemicellulose and bound proteins (69%) much more rapidly over 2 yr than they lost cellulose (40%) and acid‐unhydrolyzable residues (12%). A variety of macro‐ and micronutrients supported litter decomposition, with calcium, in particular, promoting it. In mixtures of litter from 2, 5, or 12 species, neither species richness nor phylogenetic diversity was associated with deviations from expected decomposition rates based on monocultures. Yet more functionally diverse litter mixtures lost labile carbon (soluble cell contents and hemicellulose) significantly more slowly than expected. This novel finding of the effect of litter diversity not on total litter decomposition, but on the decomposition of a particular class of litter compounds elucidates potential consequences of biodiversity for cycling of nutrients and energy in forest ecosystems.

中文翻译：

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叶凋落物混合物的功能多样性在两年内减缓了不稳定碳的分解，但不会使难分解的碳分解

凋落物的分解构成了陆地生态系统中碳和养分循环的主要途径。尽管已经确定凋落物分解在物种之间变化，但是大多数叶子凋落物不仅会分解，而且会与异种凋落物混合分解。这种混合的后果以及植物生物多样性的多维作用对于凋落物分解的模棱两可，过去的研究表明，混合不同的凋落物可以加快，减慢速度，或者对分解没有影响。此外，垃圾的不同化学成分以不同的速率分解，并且对于每种速率的多样性后果尚不完全清楚。我们创建了对应于49种不同凋落物混合物的垃圾袋，覆盖范围从1到12个温带森林物种，并允许它们在美国明尼苏达州东部温带的公共花园中分解2年以上。在第2、4、12和24个月收集后，我们评估了总质量损失和四类凋落碳的变化（可溶性细胞含量，半纤维素和结合蛋白，纤维素以及木质素/酸不可水解顽固剂）。物种的凋落物分解速率各不相同（从总质量的8％下降到41％），并且在2年内它们损失了可溶性细胞含量（高达无灰质量的64％）以及半纤维素和结合蛋白（69％）他们损失了纤维素（40％）和酸不可水解的残留物（12％）。大量的微量元素和微量元素支持垃圾分解，尤其是钙的分解。在来自2种，5种或12种物种的枯枝落叶混合物中，物种丰富度和系统发育多样性均与基于单一栽培的预期分解速率的偏离无关。然而，功能更多样化的垃圾混合物损失的不稳定碳（可溶性细胞含量和半纤维素）的损失比预期的要慢得多。凋落物多样性的影响的这一新发现不是对凋落物的总分解，而是对特定类别的凋落物化合物的分解的影响，阐明了生物多样性对森林生态系统养分和能量循环的潜在后果。然而，功能更多样化的垃圾混合物损失的不稳定碳（可溶性细胞含量和半纤维素）的损失比预期的要慢得多。凋落物多样性的影响的这一新发现不是对凋落物的总分解，而是对特定类别的凋落物化合物的分解的影响，阐明了生物多样性对森林生态系统养分和能量循环的潜在后果。然而，功能更多样化的垃圾混合物损失的不稳定碳（可溶性细胞含量和半纤维素）的损失比预期的要慢得多。凋落物多样性的影响的这一新发现不是对凋落物的总分解，而是对特定类别的凋落物化合物的分解的影响，阐明了生物多样性对森林生态系统养分和能量循环的潜在后果。