A synthesis of recent global change research on pasture and rangeland production: reduced uncertainties and their management implications

• Published in: Agriculture, ecosystems & environment Vol. 82; no. 1; pp. 39 - 55
• Main Authors: Campbell, B.D., Stafford Smith, D.M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2000; Elsevier Science; Elsevier
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; agricultural research; Agronomy. Soil science and plant productions; animal husbandry; Biological and medical sciences; botanical composition; carbon dioxide; Climate change; Climatic models of plant production; Ecology, environment; ecosystems; food security; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities. Techniques. Climatology. Meteorology. Climatic models of plant production; intensive forestry; Life Sciences; livestock; Management; nutritive value; pasture; Pastures; range management; Rangelands; Sensitive regions; simulation models; Synthesis; tropics; Climate change; Synthesis; Management; Rangelands; Sensitive regions; Pastures; Floristic composition; Production quality; Range management; Growth; Carbon dioxide; Fodder; Environmental factor; Review; Vegetation dynamics; Medium enrichment; Pasture; Agricultural production; Rangeland; Fodder crop; Climate modification; AGRONOMIE; REGION SENSIBLE; MODIFICATION DU CLIMAT
• ISSN: 0167-8809; 1873-2305; 0167-8809
• DOI: 10.1016/S0167-8809(00)00215-2

There is significant uncertainty about the effects of global change on the vegetation and animal productivity of pasture and rangeland ecosystems. This paper presents a synthesis of progress made between 1994 and 1999 in the Global Change and Terrestrial Ecosystems (GCTE) Pastures and Rangelands Core Research Project 1 (CRP1) network, a world-wide network of 83 full-time equivalent researchers established in different pasture and rangelands systems to reduce these uncertainties. The network focuses on key processes controlling forage and animal production at a paddock/landscape scale, in order to improve the ability to model animal production. To date, the network has resulted in a considerable reduction in the uncertainties about the effects of elevated CO 2 on growth, and to a lesser extent composition and forage quality, of intensive pastures in cool, wet climatic zones. However, knowledge of other grazed ecosystems and processes is more limited. The greatest confidence is in predicting implications for vegetation production, with lesser confidence in implications for vegetation composition, animal production and adaptation options. Overall, the stimulatory effect of double ambient CO 2 on grassland production averages about +17% in ecosystem-based experiments. This is less than previous estimates. Individual system responses to elevated CO 2 can vary widely and are predicted to be higher in moisture-limited and warm-season grassland systems. Species composition change is likely to be an important mechanism altering grassland production and its value for grazing livestock, especially in drier rangelands with woody shrub invasion. On average, the legume content of productive grass–legume swards is increased by +10% due to CO 2 enrichment. Leaf nitrogen reductions due to elevated CO 2 are often observed but are generally modest compared with effects of other management factors. New data collection efforts should be focused in areas of the world which are most sensitive to food security issues and most subject to global change, in particular humid semi-arid margins and subtropical grasslands. There remains no good basis for extrapolating findings between different pasture and rangeland systems. This synthesis indicates that greater focus is required on the linkages between the biophysical, social and economic factors that will influence future changes in pasture and rangeland ecosystems and their implications for food security.