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 (<em>i.e.</em>, 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

Ecological functions provided by dung beetles are interlinked across space and time: evidence from 15N isotope tracing

Maintaining multiple ecological functions (multifunctionality) is crucial to sustain viable ecosystems. To date most studies on biodiversity-ecosystem functioning (BEF) have focused on single or few ecological functions and services. However, there is a critical need to evaluate how species and species assemblages affect multiple processes at the same time, and how these functions are interconnected. Dung beetles represent excellent model organisms because they are key contributors to several ecosystem functions. Using a novel method based on the application of 15N-enriched dung in a mesocosm field experiment, we assessed the role of dung beetles in regulating multiple aspects of nutrient cycling in alpine pastures over appropriate spatial (up to a soil depth of 20 cm) and temporal (up to 1 yr after dung application) scales. 15N isotope tracing allowed the evaluation of multiple interrelated ecosystem functions responsible for the cycling of dung-derived nitrogen (DDN) in the soil and vegetation. We also resolved the role of functional group identity and the importance of interactions among co-occurring species for sustaining multiple functions by focusing on two different dung beetle nesting strategies (tunnelers and dwellers). Species interactions were studied by contrasting mixed-species to single-species assemblages, and asking whether the former performed multiple functions better than the latter. Dung beetles influenced at least seven ecological functions by facilitating dung removal, transport of DDN into the soil, microbial ammonification and nitrification processes, uptake of DDN by plants, herbage growth, and changes in botanical composition. Tunnelers and dwellers were found to be similarly efficient for most functions, with differences based on the spatial and temporal scales over which the functions operated. Although mixed-species assemblages seemed to perform better than single-species, this outcome may be dependent on the context. Most importantly though, the different functions were found to be interconnected sequentially as reveled by analyzing 15N content in dung, soil and vegetation. Taken together, our current findings offer strong support for the contention that the link between biodiversity and ecosystem functions should be examined not function by function, but in terms of understanding multiple functions and how they interact with each other