Effects of climate change in the biomass of montado agro-sylvo-pastoral system

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia - UL

The present dissertation aims at understanding how the future climate change scenarios may affect the production of grassland biomass in the montado agro-sylvo-pastoral system, by studying the effects of precipitation, aridity and topography (slope) in both the field, in different sites along a climatic gradient in Alentejo, and in greenhouse trials, using the seedbank collected at those sites. The impact of these three factors was studied independently, in order to understand the importance of each of them for biomass productivity and, consequently, determine the main driving factors. The results showed a stronger effect of precipitation during the growing season on biomass productivity, in both field and greenhouse trials, thus highlighting this factor, among the three studied, as the major driver of biomass response and consequently of future changes in the landscape of montado agro-sylvo-pastoral system in Alentejo. The comparison of field and greenhouse trial was also intended to study the seedbank ability to retain information regarding the past climate history of its site of origin – ‘memory’. Results showed that in greenhouse, regardless of the locations from where the soil samples were taken, the seed bank responded similarly in terms of biomass production, vegetation cover, species richness and flowering onset when subjected to similar favorable conditions in the greenhouse – regular and abundant watering.

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