The aim of this thesis work was the assessment of the potential effects of climate change upon the productivity of pasture in Italian Alps, focusing on Valtellina valley and the Gran Paradiso National Park in Valle d’Aosta region. To do so, some agro-climatic indices, related to climate and water availability, were introduced to summarize the effects. A pasture model Poli-Pasture was developed here as module of the existing hydrological model Poli-Hydro, and it was used for the simulation of plants growth. Two different configurations in pasture modelling were used for the two case studies. Poli-Pasture was corrected for the case study of Gran Paradiso National Park with a module, based on CoSMo model, for the simulation of inter-specific competition. Starting from the information of collected samples in the study areas in fulfilment of the IPCC MOUPA project, some species were chosen, among the most abundant in Italian pastures, as reference for the simulation of pasture productivity. In particular, Trisetum flavescens and Nardus stricta were considered as index species in Valtellina valley, in a low altitude belt and in a high altitude one respectively, while Trifolium alpinum, Dactylis glomerata, Nardus stricta and Festuca rubra were considered representative of the pasture community in Gran Paradiso National Park, in the same altitude belts (here two species for altitude belt). After the calibration of the model and the simulation for the present period, the model was used, for both cases, to project pasture productivity until the end of the XXI century, using the scenarios of the Fifth and Sixth Assessment Reports of IPCC, and considering a large number of global circulation models, specifically 3 for AR5 and 6 for AR6. In response to the increase of temperature, the model projected a potential increase of pasture productivity, with some exceptions in low altitudes, in particular in Valtellina valley (until -31% for AR5 under 1100 m asl in the period 2041-2050). In Valtellina valley under AR5 the increase of total productivity is projected between +38% and +173% respectively for RCP 2.6 at the middle of the century (2041-2050) and RCP 8.5 at the end of the century (2091-2100), while under AR6 the increase ranges between +62% and +210% for SSPs 2.6 and 8.5 at the end of the century. In the area of Gran Paradiso National Park under AR6 the increase of annual productivity ranges between +81% and +116% for SSP 7.0 at the middle of the century and SSP 8.5 at the end of the century. Here in low altitude belt the variation is contained, while in high altitude belt it is considerable. A large percentage increase does not correspond to a large increase in absolute value, considering an average fresh biomass productivity of 6.5 t/ha (12.9 t/ha in low altitude belt and 1.9 in high altitude belt) in Valtellina valley and of 3.6 t/ha (6.5 t/ha in low altitude belt and 3.5 t/ha in high altitude belt) in Gran Paradiso area during the present period. The large expected evapotranspiration demand in future was satisfied in practice in Valtellina, notwithstanding the decrease of precipitation, thanks to a better use of water availability. Differently, in Gran Paradiso area the lack of water availability from precipitation and snow melt could be a limitation to growth. The result of the inter-specific competition simulation shows a larger presence of Trifolium alpinum (55%-59%) in low altitude belt and of Nardus stricta (71%-74%) in high altitude belt. In the future this condition will be exacerbated thanks to the better resistance of these species to high temperatures and drought conditions. Each species has a different nutritional value, so the general increase of biomass productivity is not related to an improvement of the value for pasture of bovines. The results provide preliminary evidence of altitudinal shift of pasture lands and of potential livestock, and thereby economic development, in the valley at higher altitudes than now.
L’obiettivo di questo lavoro di tesi è l’analisi degli effetti potenziali dei cambiamenti climatici sulla produttività dei pascoli nelle Alpi italiane, in particolare in Valtellina e nel Parco Nazionale del Gran Paradiso, nella zona valdostana. Sono stati quindi introdotti alcuni indici agro-climatici, relativi alle condizioni climatiche e alla disponibilità idrica, per riassumere gli effetti. È stato utilizzato un modello con due diverse configurazioni nei due casi di studio. Per la simulazione della crescita vegetazionale, è stato sviluppato il modello Poli-Pasture, associandolo al modello idrologico già esistente Poli-Hydro. La modellazione pascoliva è stata eseguita con diverse configurazioni nei due casi di studio. Poli-Pasture è stato corretto nel caso studio del Gran Paradiso, con un modulo per la simulazione della competizione interspecifica, basandosi sul modello CoSMo. Basandosi sulle informazioni raccolte dai campionamenti effettuati nell’ambito del progetto IPCC MOUPA, sono state scelte alcune specie, tra le più abbondanti nei pascoli italiani, come rappresentative per la comunità per la simulazione della produttività pascoliva. In particolare in Valtellina sono state utilizzate Trisetum flavescens e Nardus stricta rispettivamente per una fascia a bassa quota e una ad alta quota, mentre nel parco del Gran Paradiso sono state considerate Trifolium alpinum e Dactylis glomerata a bassa quota e Nardus stricta e Festuca rubra ad alta quota. Dopo la calibrazione del modello e la simulazione nel periodo presente, il modello è stato utilizzato in entrambi i casi di studio per le proiezioni della produttività pascoliva fino alla fine del XXI secolo, utilizzando gli scenari del quinto e sesto rapporto di valutazione dell’IPCC e combinandoli con un considerevole numero di modelli di circolazione globale, in particolare 3 per l’AR5 e 6 per l’AR6. In risposta all’aumento di temperatura le simulazioni mostrano un potenziale aumento della produttività, con alcune eccezioni a bassa quota in Valtellina (fino al -31% sotto i 1100 m slm per l’AR5 nel periodo 2041-2050). In Valtellina, per l’AR5, l’aumento potenziale di produttività totale varia tra +38% per il RCP 2.6 a metà secolo (2041-2050) e +173% per il RCP 8.5 a fine secolo (2091-2100), mentre per l’AR6 l’aumento va da +62% a +210% rispettivamente per gli SSPs 2.6 e 8.5 alla fine del secolo. Nell’area del parco del Gran Paradiso per l’AR6 l’aumento di produttività annuale varia tra +81% e +116% per il SSP 7.0 a metà secolo e il SSP 8.5 a fine secolo. Qui l’aumento a bassa quota è limitato, mentre è considerevole ad alta quota. L’aumento significativo in percentuale non corrisponde però ad un grande aumento in valore assoluto, considerando la produttività media nel periodo di controllo di 6.5 t/ha (12.9 t/ha a bassa quota e 1.9 t/ha ad alta quota) in Valtellina e di 3.6 t/ha (6.5 t/ha a bassa quota e 3.5 t/ha ad alta quota) nel parco del Gran Paradiso. La grande richiesta evapotraspirativa in futuro viene in pratica soddisfatta in Valtellina, nonostante la riduzione delle precipitazioni, anche grazie ad un utilizzo più efficiente dell’acqua disponibile. Diversamente nell’area del Gran Paradiso talvolta la mancanza di disponibilità d’acqua risulta limitante per la crescita. I risultati della simulazione della competizione inter-specifica mostrano una maggiore presenza di Trifolium alpinum (55%-59%) a bassa quota e di Nardus stricta (71%-74%) ad alta quota. In futuro queste specie saranno ancora più abbondanti grazie alla loro migliore resistenza a temperature elevate e a condizioni di siccità. Ogni specie ha però un diverso valore nutrizionale, quindi l’aumento complessivo di produttività non è collegato a un miglioramento del valore per il pascolamento dei bovini. I risultati forniscono un’evidenza preliminare in futuro dell’innalzamento in quota delle aree pascolive, e uno sviluppo dell’allevamento a quote più elevate rispetto ad ora.
Impacts of climate change on hydrologically driven pasture dynamics in mountain catchments
Casale, Francesca
2022/2023
Abstract
The aim of this thesis work was the assessment of the potential effects of climate change upon the productivity of pasture in Italian Alps, focusing on Valtellina valley and the Gran Paradiso National Park in Valle d’Aosta region. To do so, some agro-climatic indices, related to climate and water availability, were introduced to summarize the effects. A pasture model Poli-Pasture was developed here as module of the existing hydrological model Poli-Hydro, and it was used for the simulation of plants growth. Two different configurations in pasture modelling were used for the two case studies. Poli-Pasture was corrected for the case study of Gran Paradiso National Park with a module, based on CoSMo model, for the simulation of inter-specific competition. Starting from the information of collected samples in the study areas in fulfilment of the IPCC MOUPA project, some species were chosen, among the most abundant in Italian pastures, as reference for the simulation of pasture productivity. In particular, Trisetum flavescens and Nardus stricta were considered as index species in Valtellina valley, in a low altitude belt and in a high altitude one respectively, while Trifolium alpinum, Dactylis glomerata, Nardus stricta and Festuca rubra were considered representative of the pasture community in Gran Paradiso National Park, in the same altitude belts (here two species for altitude belt). After the calibration of the model and the simulation for the present period, the model was used, for both cases, to project pasture productivity until the end of the XXI century, using the scenarios of the Fifth and Sixth Assessment Reports of IPCC, and considering a large number of global circulation models, specifically 3 for AR5 and 6 for AR6. In response to the increase of temperature, the model projected a potential increase of pasture productivity, with some exceptions in low altitudes, in particular in Valtellina valley (until -31% for AR5 under 1100 m asl in the period 2041-2050). In Valtellina valley under AR5 the increase of total productivity is projected between +38% and +173% respectively for RCP 2.6 at the middle of the century (2041-2050) and RCP 8.5 at the end of the century (2091-2100), while under AR6 the increase ranges between +62% and +210% for SSPs 2.6 and 8.5 at the end of the century. In the area of Gran Paradiso National Park under AR6 the increase of annual productivity ranges between +81% and +116% for SSP 7.0 at the middle of the century and SSP 8.5 at the end of the century. Here in low altitude belt the variation is contained, while in high altitude belt it is considerable. A large percentage increase does not correspond to a large increase in absolute value, considering an average fresh biomass productivity of 6.5 t/ha (12.9 t/ha in low altitude belt and 1.9 in high altitude belt) in Valtellina valley and of 3.6 t/ha (6.5 t/ha in low altitude belt and 3.5 t/ha in high altitude belt) in Gran Paradiso area during the present period. The large expected evapotranspiration demand in future was satisfied in practice in Valtellina, notwithstanding the decrease of precipitation, thanks to a better use of water availability. Differently, in Gran Paradiso area the lack of water availability from precipitation and snow melt could be a limitation to growth. The result of the inter-specific competition simulation shows a larger presence of Trifolium alpinum (55%-59%) in low altitude belt and of Nardus stricta (71%-74%) in high altitude belt. In the future this condition will be exacerbated thanks to the better resistance of these species to high temperatures and drought conditions. Each species has a different nutritional value, so the general increase of biomass productivity is not related to an improvement of the value for pasture of bovines. The results provide preliminary evidence of altitudinal shift of pasture lands and of potential livestock, and thereby economic development, in the valley at higher altitudes than now.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/197296