Modelled effects of rising CO2 concentration and climate change on native perennial grass and sown grass-legume pastures

Abstract

Native perennial grass and sown grass-legume pastures are an important agricultural and environmental resource. We investigated the impact of rising carbon dioxide concentration ([CO2]) and projected climate changes on these pasture ecosystems in southeastern Tasmania, Australia, using a biophysical simulation model, EcoMod. The model consists of interdependent modules that describe soil physicochemical and hydrological characteristics, and pasture growth and senescence, with fluxes described by empirical and mechanistic equations. Our simulations showed that in native pastures, projected climate change increased the biomass of C-4 grasses, with limited impact upon C-3 grasses, a trend reversed by rising [CO2]. In sown pastures, projected climate change decreased the biomass of perennial rye grass Lolium perenne and total biomass markedly by 2070, whilst subterranean clover Trifolium subterraneum biomass increased. Subterranean clover biomass changed little with increased [CO2] alone, whereas perennial rye grass biomass increased. Responses across pastures reflected species' tolerances to environmental factors, with projected climate change generally having more of an impact on biomass than rising [CO2]. Changes in both [CO2] and climate led to a reduction in protein content and digestibility. Soil inorganic nutrient concentrations decreased with increasing [CO2] and increased with projected climate change. Further simulations should investigate whether these patterns are robust for different sites and alternative environmental futures. Our results reinforce the need to pursue adaptation strategies in response to environmental change in order to maintain productive pasture ecosystems

Interacting effects of vegetation, soils and management on the sensitivity of Australian savanna rangelands to climate change

“…This reduced the magnitude of increases in forage production under the hotter and wetter scenario, and enhanced reductions in forage production under the hotter and drier scenario. While some land types show considerably amplified responses to the climate change scenarios, the ranges are consistent with the magnitude of responses of native pasture communities elsewhere in Australia (Cullen et al 2009;Perring et al 2010). The directions of the changes in forage production are in agreement with those identified in analyses of climate change impacts on grasslands around the world (Baker et al 1993;Xiao et al 1995;Riedo et al 1997), and field-scale experiments on the effects of elevated CO 2 and rainfall change on C 4 plant growth (Ainsworth and Long 2005;Tubiello et al 2007).…”

Future consequences and challenges for dairy cow production systems arising from climate change in Central Europe – a review

“…As an expression of global warming, the duration and frequency of droughts as well as the overall allocation of rain on regional scales are expected to have deep impacts on grassland and fodder production systems. Changes in grass sward composition and plant growth are expected to influence digestibility for ruminants (Perring et al, 2010), which are themselves also being exposed to the effects of a changing climate.…”

“…As an expression of global warming, the duration and frequency of droughts as well as the overall allocation of rain on regional scales are expected to have deep impacts on grassland and fodder production systems. Changes in grass sward composition and plant growth are expected to influence digestibility for ruminants (Perring et al, 2010), which are themselves also being exposed to the effects of a changing climate.Most of the available publications have separately discussed potential or already measurable effects of climate change on each of the different components of dairy systems. This review brings different aspects, from rumen physiology to the economics of dairy cow production in Central Europe, into focus with a holistic approach to emphasize potential future consequences and challenges arising from climate change.…”

Testing simulations of intra‐ and inter‐annual variation in the plant production response to elevated CO2 against measurements from an 11‐year FACE experiment on grazed pasture

“…Riedo et al ., ; Graux et al ., ) or have made N non‐limiting (e.g. Cullen et al ., ; Perring et al ., ) thus removing the possibility of CO 2 × legume interactions of the kind we have shown here. An exception is the study of Lazzarotto et al .…”

“…We believe this to be the first time such validation tests have been performed which makes our results important as models of this type, and, indeed, models with exactly these parameterizations for their CO 2 responses, are already being used in impact studies (e.g. Cullen et al ., ; Perring et al ., ; Cullen & Eckard, ). Of particular note is the emphasis we have placed on modelling temporal variation in the CO 2 response; such responses are evident in the actual data from the NZ‐FACE experiment (Fig.…”