Protecting biodiversity in grassland ecosystems
The GLOBEPURE (Global drivers of loss of biodiversity with eutrophication and their potential use for restoration ecology) project investigated which factors affect grassland biodiversity and stability. The aim was to find solutions to redress human-driven imbalances in this type of ecosystem. Researchers examined how environmental changes resulting from human activities, including the use of fertilisers, carbon dioxide, fire, grazing and water, influence the functioning and biodiversity of the ecosystem. Data was analysed from a global experimental Nutrient Network covering more than 70 grassland sites on 5 continents and from 12 multi-year experiments conducted at a single site in Minnesota, the United States. Although ecologists are aware that drivers of global change affect many aspects of ecosystem functioning, including ecosystem productivity, stability and biodiversity, their effect on stability of productivity in natural grasslands was unknown. GLOBEPURE scientists found that a major global change, the fertilisation of grasslands, caused biodiversity loss. This was because of increased competition for light, resulting in lower rates of germination due to increased leaf litter and soil acidification. Researchers found that global change impact on grassland stability was through changes in plant diversity. A decrease in diversity leads to a decrease in stability regardless of which driver caused the loss of diversity. A loss of biodiversity also results in destabilisation of diverse species' responses to environmental fluctuations. In a non-fertilised, species-rich environment, reduced biomass of some species may be compensated for by increased biomass of others, resulting in minimal total biomass change. Fertilising grassland, whether intentionally or by run-off, upsets this balance, resulting in greater biomass fluctuations over time and weakened stability of the entire grassland ecosystem. The study suggested that conservation policies should encourage management procedures that restore or maintain natural levels of biodiversity or minimise the negative impacts of anthropogenic global environmental changes on biodiversity loss. This will help to ensure the stable provision of ecosystem services. GLOBEPURE work will therefore contribute to mitigating the impacts of human-driven changes in environmental biodiversity by aiding conservation efforts geared towards restoring grassland ecosystem balance.
Keywords
Biodiversity, grassland, ecosystems, eutrophication, fertilisation
