Action versus result-oriented schemes : a dynamic modelling approach linking grazing and bird populations in a grassland agro-ecosystem
Résumé
In Europe, most agri-environment schemes are action-oriented. However recent assessment indicates mixed benefi ts for biodiversity. It has been suggested that the development of result-oriented measures could improve their effi ciency. The objective of this study was to assess whether result-based measures could be more effi cient in conciliating production and conservation outcomes. We focused on a grazed grassland agro-ecosystem which is the breeding habitat of two wader species. A dynamic model of grass and bird populations was developed to predict grazing strategies ensuring bird conservation. Viable control approach was used to identify out of the whole set of possible grazing strategies, those respecting constraints at any time. To compare both agri-environment schemes, the model was run with constraints either defi ned to represent action-oriented (threshold on maximal stocking rates) or result-oriented measures (threshold on minimal bird population size at horizon). Model simulations show that result-oriented measures were more effi cient in conciliating production and conservation because they made it possible to alternate grazing intensity between years. This strategy was not feasible with action-oriented measures. These results could contribute to defi ne alternative agri-environment schemes with better profi t for both production and conservation goals in agricultural grasslands.
Domaines
Environnement et Société
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