Massimiliano Probo

Pastoral Practices to Reverse Shrub Encroachment of Sub-Alpine Grasslands: Dung Beetles (Coleoptera, Scarabaeoidea) Respond More Quickly Than Vegetation

In recent decades, pastoral abandonment has produced profound ecological changes in the Alps. In particular, the reduction in grazing has led to extensive shrub encroachment of semi-natural grasslands, which may represent a threat to open habitat biodiversity. To reverse shrub encroachment, we assessed short-term effects of two different pastoral practices on vegetation and dung beetles (Coleoptera, Scarabaeoidea). Strategic placement of mineral mix supplements (MMS) and arrangement of temporary night camp areas (TNCA) for cattle were carried out during summer 2011 in the Val Troncea Natural Park, north-western Italian Alps. In 2012, one year after treatment, a reduction in shrub cover and an increase in bare ground cover around MMS sites was detected. A more intense effect was detected within TNCA through increases in forage pastoral value, and in the cover and height of the herbaceous layer. Immediately after treatment, changes in dung beetle diversity (total abundance, species richness, Shannon diversity, taxonomic and functional diversity) showed a limited disturbance effect caused by high cattle density. In contrast, dung beetle diversity significantly increased one year later both at MMS and TNCA sites, with a stronger effect within TNCA. Multivariate Regression Trees and associated Indicator Value analyses showed that some ecologically relevant dung beetle species preferred areas deprived of shrub vegetation. Our main conclusions are: i) TNCA are more effective than MMS in terms of changes to vegetation and dung beetles, ii) dung beetles respond more quickly than vegetation to pastoral practices, and iii) the main driver of the rapid response by dung beetles is the removal of shrubs. The resulting increase in dung beetle abundance and diversity, which are largely responsible for grassland ecosystem functioning, may have a positive effect on meso-eutrophic grassland restoration. Shrub encroachment in the Alps may therefore be reversed, and restoration of grassland enhanced, by using appropriate pastoral practices.

Use of mineral mix supplements to modify the grazing patterns by cattle for the restoration of sub-alpine and alpine shrub-encroached grasslands

Throughout the last decades, agricultural abandonment in European mountain areas has caused changes in traditional livestock management with consequences for semi-natural grassland use and vegetation. In the Western Italian Alps, continuous extensive grazing has become the simplest and the most common system for managing large cattle herds. As a result, limited grazing in many rugged locations has led to an extensive shrub-encroachment of semi-natural grasslands in the sub-alpine and alpine belts. A study was conducted to assess if the provision of mineral mix supplements (MMS): (1) increases the use of steep and shrub-encroached locations by beef cows, and (2) helps restore meso-eutrophic grassland vegetation around supplement-deployment sites. During the summer grazing season, MMS were placed within 10 steep and shrub-encroached areas in two adjacent pastures (364 and 366 ha), and 12 cows were tracked with GPS collars. For each supplement site, a paired control site was identified, and vegetation surveys were performed in the surrounding areas of both sites. Placement of MMS increased the use of areas within 12 m of supplement locations compared with corresponding control areas. Cattle use of areas within 100 m of the MMS sites was also greater than expected by chance. The use by cattle, associated with trampling, grazing and faecal deposition, reduced the cover of shrubs and oligotrophic herbaceous species and increased the average nutrient N-value and forage pastoral value of the new vegetation types established around MMS sites 2 years after their use by cattle. Strategic placement of MMS appears to be a sustainable practice to restore sub-alpine and alpine shrub-encroached grasslands. Nevertheless these results must be considered preliminary as a longer period is needed to evaluate the long-term effectiveness of this practice for the restoration of semi-natural grasslands.

Implementation of a rotational grazing system with large paddocks changes the distribution of grazing cattle in the south-western Italian Alps

Continuous grazing systems (CGS) are still widely used for managing cattle herds in the south-western Alps. Recently, Pastoral Plans have been used as a policy tool to improve grazing management. Rotational grazing systems (RGS) with large paddocks (i.e. ~100 ha on average) and stocking rate adjustments based on recommended levels calculated from vegetation surveys have been implemented through Pastoral Plans to improve the uniformity of grazing. A case study was conducted to compare grazing distribution patterns of beef cows during the summer under CGS and RGS on sub-alpine and alpine pastures within Val Troncea Natural Park in the south-western Alps of Italy. Cows were tracked with global positioning system collars at 15-min intervals under both CGS and RGS. Cattle distribution patterns were aggregated in both grazing systems, but in the RGS concentration of grazing was less clustered and the selection of vegetation communities was more homogeneous than in CGS. Under CGS, cows were attracted (P   0.05) high pastoral value, and they avoided areas farther from water (P < 0.05). Similar to CGS, cows under RGS were attracted (P < 0.05) to salt and avoided (P < 0.05) steep slopes. In the RGS, cows used steeper slopes and areas farther from salt and water in the second half of the grazing period within a paddock compared with the first half, which likely explains the improvement in uniformity of grazing with RGS. Our findings indicate that Pastoral Plans that combine appropriate stocking levels and RGS are valid policy and management tools that have the potential to improve grazing distribution on rough sub-alpine and alpine pastures in the south-western Alps.

Relationships between botanical and chemical composition of forages: a multivariate approach to grasslands in the Western Italian Alps

BACKGROUND Plant composition of species-rich mountain grasslands can affect the sensorial and chemical attributes of dairy and meat products, with implications for human health. A multivariate approach was used to analyse the complex relationships between vegetation characteristics (botanical composition and plant community variables) and chemical composition (proximate constituents and fatty acid profile) in mesophilic and dry vegetation ecological groups, comprising six different semi-natural grassland types in the Western Italian Alps. RESULTS Mesophilic and dry grasslands were comparable in terms of phenology, biodiversity indices and proportion of botanical families. The content of total fatty acids and that of the most abundant fatty acids (alpha-linolenic, linoleic and palmitic acids) were mainly associated to nutrient-rich plant species, belonging to the mesophilic grassland ecological group. Mesophilic grasslands showed also higher values of crude protein, lower values of fibre content and they were related to higher pastoral values of vegetation compared to dry grasslands. The proximate composition and fatty acid profile appeared mainly single species dependent rather than botanical family dependent. CONCLUSION These findings highlight that forage from mesophilic grasslands can provide higher nutritive value for ruminants and may be associated to ruminant-derived food products with a healthier fatty acid profile.

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.

Species-rich Nardus stricta grasslands host a higher vascular plant diversity on calcareous than on siliceous bedrock

Background: Species-rich Nardus stricta grasslands are a priority habitat for conservation in Europe. They typically occur on siliceous substrates and less frequently are found on calcareous bedrock. Aims: The present paper aimed to identify the environmental factors (i.e. bedrock type, topographic, and climatic factors) that are related with community diversity and to assess if differences in plant diversity between N. stricta communities on calcareous and siliceous bedrock occur. We hypothesised that Nardus grasslands on calcareous bedrock hosted a higher vascular plant diversity than those on siliceous bedrock. Methods: Based on 579 vegetation surveys carried out in the south-western Alps, we assessed vascular plant diversity (species richness, Shannon diversity, and Pielou’s equitability index) of species-rich Nardus grasslands and compared it between N. stricta communities on calcareous and siliceous bedrock. Results: Elevation was identified as the main factor related to species composition, while species diversity was mostly related to mean annual precipitation and bedrock type. Species richness, Shannon diversity, and Pielou’s equitability index were higher within the communities on calcareous rather than on siliceous bedrock and a total of 89 and 34 indicator species were detected, respectively. Conclusions: Based on our results, we suggest to protect primarily, as a habitat of priority interest, N. stricta grasslands on calcareous substrates for the higher vascular plant diversity hosted.