Higher effect of plant species diversity on productivity in natural than artificial ecosystems

Abstract

Current and expected changes in biodiversity have motivated major experiments, which reported a positive relationship between plant species diversity and primary production. As a first step in addressing this relationship, these manipulative experiments controlled as many potential confounding covariables as possible and assembled artificial ecosystems for the purpose of the experiments. As a new step in this endeavor, we asked how plant species richness relates to productivity in a natural ecosystem. Here, we report on an experiment conducted in a natural ecosystem in the Patagonian steppe, in which we assessed the biodiversity effect on primary production. Using a plant species diversity gradient generated by removing species while maintaining constant biomass, we found that aboveground net primary production increased with the number of plant species. We also found that the biodiversity effect was larger in natural than in artificial ecosystems. This result supports previous findings and also suggests that the effect of biodiversity in natural ecosystems may be much larger than currently thought.biodiversity ͉ carbon cycle ͉ ecosystem functioning ͉ Patagonian steppe ͉ resource partitioning H uman activities largely impact the natural rate of change in biodiversity by influencing species invasion, displacement, and extinction rates (1, 2). For this reason, it is crucial to understand the effects of biodiversity change on the functioning of ecosystems and their capacity for providing goods and services (1, 3). The first logical attempt to address the question of the effects of biodiversity on ecosystem functioning with an experimental approach was to create gradients of plant species richness by sowing different numbers of species into homogenized soils (4-6). These experiments with artificial ecosystems showed a positive relationship between plant species richness and productivity (4-8). A further step in our endeavor to assess the effects of biodiversity change on ecosystem functioning requires tackling this issue in natural ecosystems. Observations in natural ecosystems showed inconclusive evidence of the effect of plant species richness on productivity (4, 9-11). Manipulative experiments performed in naturally assembled communities can complement results from synthetic assemblages, which represent early successional stages (12). Here, we report an experiment designed to assess the magnitude of the plant species richness effect on aboveground net primary production (ANPP) in a natural ecosystem in the Patagonian steppe.Our hypotheses were that increased plant species diversity would result in increased ANPP (5,13,14) and that the effect of biodiversity on primary production would be higher in natural than in artificial ecosystems (15). Natural ecosystems should show higher niche partitioning and stronger positive biological interactions among organisms, because species coexisted for longer periods of time and because natural ecosystems have lower frequencies of disturbance (15). Niche partitioning is the use...

Nitrogen response efficiency of a managed and phytodiverse temperate grassland

“…This may be due to the larger species richness in permanent grassland compared to many studies where diversity effects were largest at species richness levels smaller than five species . Although Flombaum and Sala (2008) reported a larger effect of plant biodiversity on productivity in a natural grassland ecosystem compared to artificial ecosystems, their study only included a biodiversity gradient of one to six species, which is still considerably lower than managed, temperate grasslands with 10 to 60 plant species . So far no studies on the impact of management practices, sward composition and their interactions on NRE in agriculturally-managed, permanent grassland have been published.…”

Community Structure and Productivity in Western Mongolian Steppe

“…Species diversity, however, was higher than at sites 1 and 6. Plant species diversity is thought to be positively related to productivity in natural ecosystems (Flombaum & Sala, 2008), and buffers changes in biomass when a species is added or removed (Hughes & Roughgarden, 2000). Maintain high species diversity is therefore, important in supporting the ability of an ecosystem to adapt to environmental change.…”

The relationship between species richness and ecosystem multifunctionality in the Pinus yunnanensis natural secondary forest

“…单一生态系统功能的影响 (Hector & Bagchi, 2007), 比如生物多样性对陆地和水生生态系统的初级生 产力、氮积累的影响等 (Hector et al, 1999;Flombaum & Sala, 2008;Cardinale, 2011 …”