Grazing abandonment negatively affects forage quality in Iberian Atlantic grasslands

Abstract

Forage quality in mountain grasslands is an important factor for maintaining or improving animal performance. Previous studies identified plant traits beneficial for animal nutrition; however, little is known regarding their maintenance in plant communities. Our main hypothesis was that grazing favors plants with high regrowth capacity and low resource utilization efficiency, promoting the production of high-quality forage. To test the hypothesis, we conducted a grazer exclusion experiment in an Iberian Atlantic grassland combined with a response-effect framework based on various plant traits and an appropriate statistical methodology to measure the relative contribution of species turnover and intraspecific trait variability (ITV) after grazing abandonment. Our results showed that forage quality declined after short-term grazing abandonment, via strong ITV effects and weak species turnover effects. Strong species turnover effects might appear after longer period of abandonment if, as expected, tall grasses with low tissue quality outcompete species with high tissue quality.