Floristic Composition Mediates Change in Forage Nutritive Quality of Atlantic Mountain Grasslands after Experimental Grazing Exclusion

• Published in: Agronomy (Basel) Vol. 11; no. 1; p. 25
• Main Authors: García-Baquero, Gonzalo, Odriozola, Iñaki, Aldezabal, Arantza
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.01.2021
• Subjects: agroecology; agronomy; Animal lactation; Beef cattle; Biodiversity; botanical composition; Calcium; Composition; crude protein; Digestibility; enzymatic reactions; exhibitions; Experiments; Fabaceae; Grasslands; Grazing; Herbivores; Horses; Iberian Peninsula; knowledge; Livestock; mediation analysis; mineral content; mixed modelling; Mountains; neutral detergent fiber; Nutritive value; Phosphorus; phosphorus content; Plant diversity; Precipitation; Proteins; repeated-measures randomized complete block experiment; Sheep; Species composition; Within-subjects design; Iberian Peninsula
• DOI: 10.3390/agronomy11010025
• ISSN: 2073-4395

Simultaneous reduction of biodiversity and forage nutritive value after grazing abandonment represents a critical agroecological problem observed in temperate mountain grasslands. However, how both processes affect each other after the exclusion of large grazers is not well understood. To address this knowledge gap, we used four Atlantic grassland sites in the Aralar masif (northern Iberian Peninsula) to ask whether floristic composition mediates change in forage nutritive quality after grazing exclusion, and, if so, how much of the effect on forage quality is mediated. To examine the effects of grazing exclusion on forage quality and floristic composition a repeated-measures (2005–10) randomized complete block experiment was used. Then, the direct effects of grazing exclusion on forage quality were disentangled from the indirect effects mediated by concurrent change in floristic composition. Grazing exclusion deteriorated forage mineral content, phosphorus content, neutral detergent fiber and, especially, crude protein and enzymatic digestibility. Concurrent floristic change mediated change in crude protein (80%), enzymatic digestibility (55%) and forage content in calcium (31%). Our study shows that plant diversity and forage quality are intimately linked features of Atlantic mountain grasslands and highlights the importance of preserving leguminous and dicotyledonous species to maintain the nutritive value of these grasslands.