Modelling the effects of potential climate change on the dynamics of multi-species mountain pastures: A case study in Gran Paradiso National Park, Italy

Abstract

CONTEXTPasture dynamics of Alpine areas are linked to the complex cryospheric hydrology of Alpine catchment and to the interspecies competition, which are in turn expected to change remarkably under prospective global warming scenarios. OBJECTIVEThis study aimed at assessing the impact of climate change on the productivity of mountain pastures in the Gran Paradiso National Park (Italy). METHODSThe hydrological model Poli-Hydro was used, coupled with the Poli-Pasture model, able to simulate pasture growth, which was further integrated with CoSMo model to consider interspecific competition. Two (competing) species were chosen for low altitude LowAlt areas (below 1800 m asl), Trifolium alpinum and Dactylis glomerata, and two for high altitude HighAlt areas (above 1800 m asl), Festuca rubra and Nardus stricta. Model tuning and evaluation were performed against estimates of leaf area index (LAI), derived from satellite imagery during 2005–2019. Then, climate change impacts were projected until 2100 by considering four IPCC AR6 scenarios and six GCMs. Target variables included a set of agroclimatic indices, LAI and pasture yield. RESULTS AND CONCLUSIONSDue to the projected increase in temperatures during the XXI century, a measurable potential increase in productivity would be expected, especially in the highest areas (up to +97% by 2050, and + 123% by 2100 for the SSP5–8.5 scenario). The relative abundance of pasture species appears to remain mostly stable; at most, the species with higher fodder value even increases slightly. This suggests that a loss in the overall quality of biomass should not occur. These results provide preliminary evidence for the potential development of livestock farming, and thus of a relevant part of the economy in the valleys, at higher altitudes than now. However, to a certain extent pasture performance could be threatened by the projected reduction in summer rainfall, and possibly spreading of pests with increasing temperature. SIGNIFICANCEThe results obtained here could be useful for policy makers, and scientists in the field of pasture/grasslands management, to depict scenarios of future productivity, and to support redefinition of periods, and areas designated for grazing activities in the mountains.