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Cattle Grazing Fails to Control Shrub Encroachment in Mediterranean Landscapes

Calleja, Juan Antonio, Escolà, Marta, Carvalho, João, Forcadell, Josep Maria, Serrano, Emmanuel, Bartolomé, Jordi
Rangeland ecology & management 2019 v.72 no.5 pp. 803-811
Common Agricultural Policy, Erica multiflora, Olea europaea, Quercus ilex, Rosmarinus officinalis, beef cattle, cattle feeds, diet, ecological succession, ecosystems, fire hazard, forests, grasslands, grazing intensity, herbaceous plants, herds, issues and policy, land cover, landscapes, risk, shrubs, stocking rate, temporal variation, vegetation structure, wildfires, woody plants, Europe
The Common Agricultural Policy supports the use of free-ranging cattle herds to control woody encroachment and fire hazards in Europe. There is, however, little empirical evidence about the effectiveness of extensive grazing to preserve open landscapes in the Mediterranean Basin. In this work, we evaluated the effects of extensive beef cattle grazing on the vegetation structure in a Mediterranean ecosystem using a twofold framework: 1) analyzing temporal changes in the forest, shrub, and grassland cover in areas under different grazing pressures for 16 yr (1993−2009) and 2) studying diet selection to assess the impact of cattle on the local Mediterranean vegetation. Our landscape structure analyses revealed a remarkable change in land cover over the study period. However, woody community dynamics seemed to be more related to natural vegetation succession than to cattle effects. Extensive grazing seemed to preserve grasslands but only at high stocking rates. On the other hand, the diet analyses supported the lack of a role for cattle in encroachment control. Beef cattle diets were based on herbaceous plants (59%) with lower contribution of woody ones (41%). Cattle only showed a significant preference (P < 0.05) for few woody species (Erica multiflora, Olea europaea, Quercus ilex, and Rosmarinus officinalis), mostly at high-density stocking rates. Hence, our results support the idea that extensive cattle grazing alone exerts a negligible effect on shrub encroachment and thus on the risk of fire in the studied Mediterranean area. We urge a redesign of current research to truly integrate extensive cattle grazing as High Nature Value farming in European policies to successfully meet its putative goals, such as shrub encroachment control and wildfire risk prevention.