Invasion of the tall grass Brachypodium genuense was observed in an area of the central Apennines (Italy) where the population size of Apennine chamois (Rupicapra pyrenaica ornata) was in strong decline. Since this dominant tall grass threatens biodiversity and forage quality, our hypothesis was that B. genuense abundance influenced that of palatable species for the chamois, depending on their functional traits and distribution patterns. Our sampling design used plots of 10 × 10 m and 1 × 1 m to investigate the plant community level and fine-scale interactions. We analyzed data using correlation, generalized linear models, and redundancy analyses. We found that B. genuense can reach high abundance values on the deepest soils. Its high cover value influences plant community composition by competitive exclusion of subordinate species and suppression of functional features because of temporal or spatial niche overlap. This leads to low cover of palatable species at a fine scale, and to poor pasture quality for chamois at a wider scale. Therefore, we postulated that B. genuense invasion, enhanced by long-term grazing cessation, may reduce the availability of palatable plants for Apennine chamois, especially below the potential timberline (1900-2000 m a.s.l.). The high abundance of B. genuense may amplify the effect of other negative factors, such as competition with red deer (Cervus elaphus) and climate change, in restricting the suitable habitat of the Apennine chamois to the higher sectors of the central Apennines. Thus, we suggested that B. genuense spread should be monitored carefully and plans to control its invasion should be implemented.
Keywords: Brachypodium genuense; Forage quality; Grassland management; Grazing cessation; Plant functional trait; Ungulate.