1/6/12 11:27

When does grazing generate stable vegetation patterns in temperate pastures?

El pastoreo inducido por la heterogeneidad espacial de la vegetación ha sido reconocido recientemente como un componente crucial de los servicios ambientales proporcionados por los pastizales naturales y semi-naturales. Para evaluar cómo el manejo del pastoreo y las características del lugar influyen en la estabilidad de los patrones de vegetación, se requiere de una metodología específica y común. Aplicando esta metodología, los resultados demostraron la influencia dominante de la productividad de la vegetación sobre la estabilidad de los patrones de vegetación en pasturas bajo pastoreo. En consecuencia, las recomendaciones de manejo para adaptar la carga animal deben considerar no sólo la composición florística de las comunidades de pastos, sino también la forma que los herbívoros generan patrones espaciales de vegetación mediante la selección.

Bertrand Dumont, Nicolas Rossignol, Grégory Loucougaray, Pascal Carrere, Joel Chadoeuf, Géraldine Fleurance, Anne Bonis, Anne Farruggia, Stéphanie Gaucherand, Cécile Ginane, Frédérique Louault, Benoit Marion, Francois Mesléard, Nicole Yavercovski

Agriculture, Ecosystems and Environment, 153: 50– 56 (2012)

 

The stability of grazing-induced spatial patterns of vegetation was analyzed at two spatial scales (25 m × 20 m areas and 1.6 m × 0.8 m grids) in pastures of contrasting productivity (maximum standing biomass: 130–800 gDM/m2). At both scales, the mosaic of grazed and ungrazed patches was modeled as a Boolean process, calculating cross-variograms to quantify the temporal stability of grazing patterns and its links with local floristic composition were tested. The scale at which stability of vegetation patterns took place in two successive years depended on pasture productivity. Inter-annual stability of large-scale patterns mainly occurred in extensively used fertile pastures grazed by cattle, and in pastures grazed by horses. Less-fertile grasslands were mainly characterized by a fine-scale stability of grazing patterns. Stable fine-scale patterns were often related to the local abundance of legumes and forbs. Stable large-scale patterns of grazing within lightly grazed productive grasslands could result in divergent local vegetation dynamics, which can be seen as an opportunity for restoring biodiversity in fertile grasslands.