Grassland science in Europe facing new challenges: biodiversity and global environmental change.

Abstract In Europe, grassland is one of the dominant forms of land use. Within 20 years, the area of permanent grasslands and pastures in Western Europe has declined by 12%. Semi-natural grasslands are often hot spots of biodiversity and are threatened both by intensive farming and by the abandonment of farmland in marginal areas. In this review, we show that biodiversity, climate change, C sequestration and farming systems issues are highly interconnected in grassland ecosystems. In this context, there are new risks (induced by climate change), new opportunities (linked to carbon sequestration and biodiversity conservation for example) and new challenges (concerning farm management and agricultural practices) for managed grasslands. An assessment of the current research perspectives underlines some key questions: (i) How to reduce the sensitivity and increase the resilience of grassland biodiversity to heat waves and droughts in an altered climate? (ii) How to protect soil organic carbon stocks under global warming? (iii) How to preserve the habitat for rare or endangered species, while managing the functional diversity of the vegetation for agricultural purposes? (iv) How to maintain the heterogeneity and diversity of grassland vegetation at the farm and landscape levels? (v) How to design innovative farming systems that integrate the impacts of farm activity on biodiversity, water and air quality, fossil energy use and greenhouse gas effect? (vi) How to produce integrated knowledge taking account of the consistency of the different management practices and their feasibility at farm level according to four criteria (profitability, labour, agricultural and environmental performance)?