Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, CCS, Cidade Universitária, Rio de Janeiro, Rio de Janeiro, Brazil.
PLoS One. 2012;7(9):e44925. doi: 10.1371/journal.pone.0044925. Epub 2012 Sep 12.
Tests of the biodiversity and ecosystem functioning (BEF) relationship have focused little attention on the importance of interactions between species diversity and other attributes of ecological communities such as community biomass. Moreover, BEF research has been mainly derived from studies measuring a single ecosystem process that often represents resource consumption within a given habitat. Focus on single processes has prevented us from exploring the characteristics of ecosystem processes that can be critical in helping us to identify how novel pathways throughout BEF mechanisms may operate. Here, we investigated whether and how the effects of biodiversity mediated by non-trophic interactions among benthic bioturbator species vary according to community biomass and ecosystem processes. We hypothesized that (1) bioturbator biomass and species richness interact to affect the rates of benthic nutrient regeneration [dissolved inorganic nitrogen (DIN) and total dissolved phosphorus (TDP)] and consequently bacterioplankton production (BP) and that (2) the complementarity effects of diversity will be stronger on BP than on nutrient regeneration because the former represents a more integrative process that can be mediated by multivariate nutrient complementarity. We show that the effects of bioturbator diversity on nutrient regeneration increased BP via multivariate nutrient complementarity. Consistent with our prediction, the complementarity effects were significantly stronger on BP than on DIN and TDP. The effects of the biomass-species richness interaction on complementarity varied among the individual processes, but the aggregated measures of complementarity over all ecosystem processes were significantly higher at the highest community biomass level. Our results suggest that the complementarity effects of biodiversity can be stronger on more integrative ecosystem processes, which integrate subsidiary "simpler" processes, via multivariate complementarity. In addition, reductions in community biomass may decrease the strength of interspecific interactions so that the enhanced effects of biodiversity on ecosystem processes can disappear well before species become extinct.
生物多样性和生态系统功能（BEF）关系的测试很少关注物种多样性与生态群落的其他属性（如群落生物量）之间相互作用的重要性。此外，BEF 研究主要源自测量单一生态系统过程的研究，而这些过程通常代表特定栖息地内的资源消耗。对单一过程的关注阻止了我们探索能够帮助我们识别贯穿 BEF 机制的新途径可能如何运作的生态系统过程的特征。在这里，我们调查了通过底栖生物搅动者物种之间的非营养相互作用介导的生物多样性的影响是否以及如何根据群落生物量和生态系统过程而变化。我们假设：（1）生物搅动者生物量和物种丰富度相互作用，影响底栖营养物质再生（溶解无机氮（DIN）和总溶解磷（TDP））的速度，进而影响细菌浮游生物的产量（BP）；（2）多样性的互补效应将在 BP 上比在营养物质再生上更强，因为前者代表了更综合的过程，可以通过多元营养互补来介导。我们表明，生物搅动者多样性对营养物质再生的影响通过多元营养互补增加了 BP。与我们的预测一致，互补效应在 BP 上比在 DIN 和 TDP 上要强得多。生物量-物种丰富度相互作用对互补性的影响在各个过程中有所不同，但在最高群落生物量水平下，所有生态系统过程的互补性综合措施显著更高。我们的结果表明，通过多元互补，生物多样性的互补效应在更综合的生态系统过程上可能更强，这些过程综合了附属的“更简单”过程。此外，群落生物量的减少可能会降低种间相互作用的强度，从而使生物多样性对生态系统过程的增强效应在物种灭绝之前就消失了。
