Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
PLoS One. 2011;6(8):e23702. doi: 10.1371/journal.pone.0023702. Epub 2011 Aug 16.
Plant litter decomposition is a critical ecosystem process representing a major pathway for carbon flux, but little is known about how it is affected by changes in plant composition and diversity. Single plant functional groups (graminoids, legumes, non-leguminous forbs) were removed from a grassland in northern Canada to examine the impacts of functional group identity on decomposition. Removals were conducted within two different environmental contexts (fertilization and fungicide application) to examine the context-dependency of these identity effects. We examined two different mechanisms by which the loss of plant functional groups may impact decomposition: effects of the living plant community on the decomposition microenvironment, and changes in the species composition of the decomposing litter, as well as the interaction between these mechanisms. We show that the identity of the plant functional group removed affects decomposition through both mechanisms. Removal of both graminoids and forbs slowed decomposition through changes in the decomposition microenvironment. We found non-additive effects of litter mixing, with both the direction and identity of the functional group responsible depending on year; in 2004 graminoids positively influenced decomposition whereas in 2006 forbs negatively influenced decomposition rate. Although these two mechanisms act independently, their effects may be additive if both mechanisms are considered simultaneously. It is essential to understand the variety of mechanisms through which even a single ecosystem property is affected if we are to predict the future consequences of biodiversity loss.
植物凋落物分解是一个关键的生态系统过程，代表了碳通量的主要途径，但对于其如何受到植物组成和多样性变化的影响知之甚少。本研究从加拿大北部的草原中去除了单一的植物功能群（禾本科、豆科、非豆科草本植物），以研究功能群身份对分解的影响。在两种不同的环境背景（施肥和杀菌剂应用）下进行去除实验，以检验这些身份效应的背景依赖性。我们通过两种不同的机制来检验植物功能群损失可能对分解产生影响：活植物群落对分解微环境的影响，以及分解凋落物的物种组成的变化，以及这两种机制之间的相互作用。结果表明，去除的植物功能群身份通过这两种机制影响分解。禾本科和草本植物的去除通过改变分解微环境来减缓分解。我们发现凋落物混合存在非加性效应，其方向和功能群的身份取决于年份；在 2004 年，禾本科植物对分解有积极影响，而在 2006 年，草本植物对分解速率有负面影响。尽管这两种机制独立起作用，但如果同时考虑这两种机制，它们的效应可能是相加的。如果要预测生物多样性丧失的未来后果，了解单一生态系统属性受到影响的多种机制至关重要。
