Dynamics of multi-specie pasturelands under potential climate changes. The Gran Paradiso Park of Italy.

Climate change’s effects are remarkable on water systems, especially for alpine mountain regions. This study aims to assess the impact of climate change upon productivity of mountain pastures in the Gran Paradiso National Park (GPNP), Italy. For this purpose, some agro-climatic indices were introduced. GPNP dynamics 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. The hydrological Poli-Hydro model was used to simulate the cryospheric processes affecting the hydrology of high altitude catchments of the area. The Poli-Pasture model was developed for the simulation of pasture vegetation growth, and completed with adaptation of the CoSMo model, to consider interspecific competition. Two species were chosen for low altitude (elevation lower than 1800 m a.s.l.), e.g. Trifolium Alpinum and Dactylis Glomerata, and two species, Festuca Rubra and Nardus Stricta, for high altitude (elevation greater than 1800 m a.s.l.).

Model calibration and validation were performed against LAI (Leaf Index Area) during 2005-2019, using observed values available from satellite imagery.

Through four scenarios from the Sixth Assessment Report of IPCC (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) applied to six GCM models (CESM2, CMCC, EC-EARTH3, HADGEM3 and MPI-ESM), meteorological data up to the year 2100 were derived. Using such climate projections, future agro-climatic indices, leaf area index and pasture yield were estimated.

According to IPCC projections, during growing season, temperature will noticeably increase at the end of the century, especially in high altitude areas, where mountain areas will experience highest temperature eve, with few heat wave days.

Due to increasing temperatures, a potential increase in productivity has been found in higher areas (up to 96% more by 2050 and 123% in by 2100, according to SSP5 8.5 scenario) and a lower change in lower elevation areas. The results provide preliminary evidence of potential livestock, and thereby economic development in the valley at higher altitudes than now. Under reduction of precipitation in summer, decrease in water consumption is expected, with possible lack of available water.