Advances in modelling animal - vegetation interactions and their use in guiding grazing management.

Grazing managers and scientists are faced with new social concerns, such as those relating to the environmental ‘value’ of grazinglands, which are no longer viewed as ‘natural forages’ only. Scientists need to design new models that include a set of decision rules about how to graze animals under multiple objectives. To study how an animal perceives and moves through its environment, grazing has to be considered as an ecological process. Hence, it is crucial to re-scale grazing mechanisms within spatial and temporal levels. Our paper then presents recent advances in the knowledge of animal social behaviour and spatial memory, which help to understand how herds and flocks exploit heterogeneous environments. An analysis of three recent and still developing grazing models finally enables us to discuss how this knowledge can be incorporated into research models. We refute the classic ‘carrying capacity’ paradigm that ignores one of the major aspects of herbivore at pasture : mobility. We encourage farmers to become ‘designers’ of grazing areas, using appropriate paddocking or shepherding rules to impact the animals’ spatial distribution and change their expectations about the relative value of feeding sites, in order to graze them in less preferred areas. Hopefully, recent advances in the knowledge of the cognitive abilities of herbivores open the way to a new generation of models that help to better understand how grazing managers can cope with pasture heterogeneity and variability.