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Impact of recurrent extreme drought events and shrub invasion on Mediterranean cork-oak ecosystem functioning and resilience


The overall aim of this proposal is to gain a comprehensive understanding of the mechanisms of the cumulative effects of extreme drought events and shrub invasion on the functioning and resilience of water-limited Mediterranean cork-oak ecosystems, as a model system, and to project areas of vulnerability under future climate change.


Fig.1 | Mediterranean cork-oak stand invaded by a dense Cistus ladanifer understory, Vila Viçosa, Portugal.


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.


Fig. 2 | Relative precipitation anomalies during winter 2011/2012 over Europe (December 2011 to February 2012) relative to long-term mean (1950-2013).


The project is based on 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.


Figure 5. Conceptual figure of ecosystem response to synergistic effects of invasion and extreme

drought coupled with the forecasted increasing dryness. Caldeira et al. 2015.


Partners: Christiane Werner, Maria Caldeira, Raquel Lobo de Vale  (ISA, Lisbon), Joaquim Pinto (KIT, Karlsruhe), Matthias Cuntz (INRA, Nancy), Maren Dubbert (Freiburg), Miguel Bugalho (CEABN Inbio, ISA, Lisbon)


Caldeira M, Lecomte X, David T, Pinto JG, Bugalho MM, Werner C (2015) Synergistic effects of plant invasion and extreme drought reduce ecosystem functioning and resilience. Sci Reports 5: 15110