Can Grazing Moderate Climatic Effects On Herbage Nutritional Quality?

In Mediterranean grasslands, the composition of vegetation and its nutritional quality for animals are strongly affected by the climatic conditions prevailing during winter and spring. Therefore, these seasonal ecosystems provide an opportunity to examine how variability in climatic conditions affects the regeneration and quality of pasture vegetation. The intensity of grazing in this seasonal system can moderate, or alternatively exacerbate, climatic effects on the nutritional quality of the vegetation. Herein, we analyzed the interactive effects of climate variables, grazing intensity, and grazing exclusion on herbage quality parameters using long-term vegetation and climate data collected during 2005-2018 from an extensive experiment in Galilee, Israel. We evaluated the contribution of different climate variables to the prediction of herbage quality parameters. Our results showed that climate variables have a dramatic effect on herbage quality and that this effect interacts with grazing intensity. Herbage quality improved in temperate rainy years compared to warm and dry years. High grazing intensity improved herbage quality under temperate climate conditions, but this effect was moderated or completely disappeared as winter conditions become warmer and drier. The results of the study foresee negative effects of warming and drying on the carrying capacity of natural pastures.