Determining the agricultural potential of semi-natural Irish grasslands

With increasing world population it is a necessity to increase agricultural production. However, generally a loss of biodiversity is associated with agricultural intensification. It has been suggested that certain ecosystems may be amenable to maintain high levels of productivity without significant loss of biodiversity. European grasslands, having coevolved with agricultural management, may represent such an ecosystem. However, currently they are either managed with high inputs of fertilizer or they are being abandoned. Such management does not use the ecological potential of grasslands to support production (the agricultural value) and has negative impacts on their biodiversity. In order to increase awareness of the agricultural value of grasslands, an index (analogous to an index of biodiversity) was developed. The index takes into account the plants’ potential for productivity and nutritional value, as well as their potential to withstand environmental stress. It is based on extensive databases for plant traits and nutritional value (e.g. BioFlor, CLIMB project). Using this index and vegetation data (over 1,700 releves) from the 1960s and 1970s (before fertilizer was applied in large quantities), the agricultural value of semi-natural grasslands of Ireland was determined. The results describe the variation in agricultural potential between grassland types, with some of these grasslands managed with little or no fertilizer approaching the agricultural value of grasslands with high fertilizer input. This approach only takes into consideration plant traits related to agricultural potential and needs to be used in conjunction with other environmental information like soils and climate. However, it can contribute to better target agri-environmental measures to the specific characteristics of the ecosystems managed. For all grassland types in Ireland, realizing their full productive potential without external inputs of fertilizer would benefit both the diversity as well as the sustainability of these agricultural systems.