Riparian forests provide abundant plant litter – mostly in the form of dead leaves (hereafter litter) – for both forest soils and adjacent stream ecosystems, supporting terrestrial and aquatic detritus-based food webs. Although the fate of litter is predominantly dependent on its chemical and physical traits, there is limited availability of data on those traits over large spatial scales or empirical comparisons of traits across tropical biomes. We filled this gap by exploring the differences and similarities of nine litter traits and their dependence on phylogenetics for 68 plant species from riparian forests across three continental-scale, South American biomes: Amazon, Atlantic Forest and Cerrado. All three biomes produced litter with similar percentages of carbon (C) and phosphorus (P), C:P mass ratios, specific leaf area and toughness. However, litter from the driest biome (Cerrado) was better defended chemically (higher phenolic content) and had lower nutritional quality (higher C:nitrogen [N] mass ratio) but showed lower nutritional limitation (lower N:P mass ratio) than litter from more humid biomes. We found no phylogenetic signal for traits after constructing a phylogenetic tree across all biomes, suggesting that trait differences across biomes were environmentally determined. However, a strong phylogenetic signal was observed for P in the Atlantic Forest, which indicates that closely related species have similar %P in that biome. Our findings suggest that litter from more humid biomes was higher in nitrogen, although more phosphorus-limited, than litter produced in drier climates such as that of the Cerrado biome.

中文翻译：

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热带湿润和干燥生物群落之间河岸植物物种的不同凋落物特征

河岸森林为森林土壤和邻近的溪流生态系统提供丰富的植物凋落物——主要是枯叶（以下简称凋落物），支持陆地和水生基于碎屑的食物网。尽管垃圾的命运主要取决于其化学和物理特性，但关于这些特性的大空间尺度数据或跨热带生物群落特性的经验比较的可用性有限。我们通过探索来自三个大陆规模的南美生物群落：亚马逊、大西洋森林和塞拉多河岸森林的 68 种植物物种的九个凋落物性状的异同及其对系统发育的依赖性来填补这一空白。所有三个生物群落产生的垃圾具有相似的碳 (C) 和磷 (P) 百分比、C:P 质量比、比叶面积和韧性。然而，来自最干燥生物群落（Cerrado）的垃圾在化学上得到了更好的保护（酚类含量较高）并且营养质量较低（较高的 C：氮 [N] 质量比）但显示出比垃圾更低的营养限制（较低的 N：P 质量比）来自更潮湿的生物群系。在构建所有生物群落的系统发育树后，我们没有发现性状的系统发育信号，这表明生物群落之间的性状差异是由环境决定的。然而，在大西洋森林中观察到 P 的强烈系统发育信号，这表明密切相关的物种在该生物群落中具有相似的 %P。我们的研究结果表明，与干燥气候（如塞拉多生物群落）中产生的垃圾相比，来自更潮湿生物群落的垃圾含氮量更高，尽管磷含量有限。来自最干燥生物群落（Cerrado）的垃圾在化学上得到更好的保护（酚类含量较高）并且营养质量较低（较高的 C：氮 [N] 质量比）但显示出较低的营养限制（较低的 N：P 质量比）潮湿的生物群落。在构建所有生物群落的系统发育树后，我们没有发现性状的系统发育信号，这表明生物群落之间的性状差异是由环境决定的。然而，在大西洋森林中观察到 P 的强烈系统发育信号，这表明密切相关的物种在该生物群落中具有相似的 %P。我们的研究结果表明，与干燥气候（如塞拉多生物群落）中产生的垃圾相比，来自更潮湿生物群落的垃圾含氮量更高，尽管磷含量有限。来自最干燥生物群落（Cerrado）的垃圾在化学上得到更好的保护（酚类含量较高）并且营养质量较低（较高的 C：氮 [N] 质量比）但显示出较低的营养限制（较低的 N：P 质量比）潮湿的生物群落。在构建所有生物群落的系统发育树后，我们没有发现性状的系统发育信号，这表明生物群落之间的性状差异是由环境决定的。然而，在大西洋森林中观察到 P 的强烈系统发育信号，这表明密切相关的物种在该生物群落中具有相似的 %P。我们的研究结果表明，与干燥气候（如塞拉多生物群落）中产生的垃圾相比，来自更潮湿生物群落的垃圾含氮量更高，尽管磷含量有限。