Plant species selection by goats foraging on montane semi-natural grasslands and grazable forestlands in the Italian Alps

The interest for goats rearing has increased during last decades on the Italian Alps. However, feeding preferences by grazing goats have not undergone detailed investigation in extensive montane grazing systems. Our study aimed to assess plant species selection by integrating vegetation surveys with animal GPS tracking under two contrasting alpine vegetation communities: a semi-natural grassland (SG) and a grazable forestland (GF). Goats selected a high array of plant species (56 and 47 species in the SG and GF, respectively), but most of their diet was composed by a few species (ten species accounted for 95% and 91% of the total species intake in the SG and GF, respectively). The selection by goats seemed to be more species-dependent rather than functional group-dependent. Goats appeared to be less selective within a homogeneous herbaceous grassland, because they selected plant species proportionally to their abundance (P=0.05). Conversely, in a heterogeneous and stratified grazable forestland they showed a more pronounced preference for most of the browse species, regardless of species abundance. Plant species selection was positively correlated with species height in both vegetation communities (P<0.001). Despite this selective behaviour, animal stocking density played a key role in the selection of many species and this result suggests that animal management (i.e., implementation of different stocking rates and densities) could be an important tool in modifying diet selection, promoting the consumption of particular plant species and thus managing the dynamics of plant communities in alpine environments.