Project Details
Projekt
Impact of recurrent extreme drought events and shrub invasion on Mediterranean cork-oak ecosystem functioning and resilience
Subject Area
Ecology and Biodiversity of Plants and Ecosystems
Term
from 2017 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 322068324
Recurrent extreme climate events such as droughts are projected to increase in many regions worldwide and can strongly affect ecosystem functioning. Concurrently, plant invasion is augmenting, causing the second largest threat to biodiversity. However, there is a lack of knowledge on how these two factors interact and impact ecosystem functioning and resilience. We will use a Mediterranean cork-oak ecosystems of high socio-economic and conservation value as a model system which is currently endangered by the invasion of Cistus ladanifer shrubs due to drought and lack of management. Simultaneously, extreme droughts are predicted to increase over Southwest-Europe, but with strong spatial heterogeneity in terms of duration and severity. Enhanced competition for water with invasive water-spending shrubs may amplify drought effects on cork-oaks and ultimately cause critical drought tolerance thresholds of the key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. However, experimental evidence is lacking. There is an urgent need to better understand and predict thresholds of ecosystem functioning in a changing climate, which require: i) experimental assessment of critical thresholds for species and ecosystem functioning; ii) highly resolved climate information to provide realistic projections of extreme droughts in future decades, and iii) a modelling tool that feeds on the knowledge of ecophysiological adaptation, species interaction, and ecosystem resilience, to quantify changes in the functioning of the invaded ecosystems. The overall aim of this proposal is to gain comprehensive understanding of the mechanisms of coupled extreme drought events and shrub invasion on the functioning and resilience of the model ecosystem and to project areas of vulnerability in a changing climate. We suggest an interdisciplinary approach consisting of a) plant ecophysiology and experimental ecosystem research implementing a multifactorial rain exclusion and shrub removal experiment to identify critical thresholds of ecosystem functioning; b) regionalisation of multi-model climate projections for the provision of representative and highly spatially resolved drought scenarios; c) mechanistic ecosystem modelling of a land surface scheme with realistic representations of the key processes including soil-vegetation, plant-plant and climate-vegetation interactions. Combing these approaches and applying the ecosystem model with future scenarios will enable a more realistic risk assessment of the sustainability of cork-oak woodland as a model system. This will be linked to spatial information on biodiversity, ecosystem services and conservation status of cork-oak woodlands. Moreover, it will permit a better assessment of the interactions between the two main drivers of global change - plant invasion and drought - which are highly relevant for many semi-arid systems.
DFG Programme
Research Grants
International Connection
France, Portugal
Co-Investigators
Dr. Maria Conceição Caldeira, Ph.D.; Dr. Matthias Cuntz
