Biomass production in experimental grasslands of different species richness during three years of climate warming

Abstract

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3 • C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Complementarity effects, likely mostly through both increased aboveground spatial complementarity and fa-cilitative effects of legumes, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competi-Correspondence to: H. J. De Boeck (hans.deboeck@ua.ac.be) tion for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands , and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

Consequences of elevated temperatures on legume biomass and nitrogen cycling in a field warming and biodiversity experiment in a North American prairie

“…By contrast, a European grassland warming and diversity experiment (De Boeck et al 2008) found that warminginduced decreases in aboveground biomass were higher at higher species diversity. The authors attribute this interaction to increased evapotranspiration and thus increased drought conditions under warming in more diverse communities compared with the drought experienced under warming in less diverse communities.…”

Alien plant species favoured over congeneric natives under experimental climate warming in temperate Belgian climate

“…Under warming, stimulation of growth and primary productivity is possible mainly through altered reaction kinetics (Larcher 2003), acclimation to changing temperatures and water availability (Luo et al 2001;Wythers et al 2005) and improved access to nutrients (Rustad et al 2001). Adverse effects of warming on the productivity of plants can, among others, arise from increased temperature stress (White et al 2000) and from water shortage as a result of increased evapotranspiration (Saleska et al 1999;De Boeck et al 2008). Speciesspecific effects of warming on productivity and competitiveness may lead to changes in plant community composition (Levy et al 2004;Niu et al 2008).…”

Methodological tests of the use of trace elements as tracers to assess root activity

“…abiotic factors such as drought or increased temperature and CO2 levels, (e.g. De Boeck et al 2008;Grime et al 2000;Kahmen et al 2005;Vogel et al 2012), and is of considerable applied relevance in the context of climate change (Reichstein et al 2013). Similarly, there is a lot of research on the effect of species richness in both natural and agricultural ecosystems on ecosystem services, including primary production, nutrient retention, resistance to weed invasion and stability in response to disturbance (Finn et al 2013;Gubsch et al 2011;Hector et al 1999;Kennedy et al 2002;Roscher et al 2011;Tilman et al 2002).…”