Arid ecosystems' response to increasing external pressure

Arid and semi-arid ecosystems, which cover about 40% of the Earth's terrestrial surface, are expected to be among the ecosystems most sensitive to environmental changes. There are growing concerns that climatic changes may lead to increased desertification, impacting approximately 25% of the world's population. I am developing models of the vegetation dynamics in arid ecosystems aiming at better understanding the functioning of arid ecosystems and their response to changes in external conditions, such as grazing pressure or climate change.

 

Indicators of catastrophic shifts

With the current global change, it is becoming increasingly important for us to be able to anticipate shifts in ecological communities. Shifts are often responsible for large, long-lasting changes and can result in dramatic ecological and economic consequences. For terrestrial ecosystems, it has been hypothesized that vegetation patchiness could be used as a signature of imminent transitions in ecosystems. I study how vegetation patchiness changes in arid ecosystems under changing external pressures (e.g. grazing), using both field data and modelling approaches.

 

Positive interactions and their effect on harsh environment dynamics

In harsh environments, individuals can modify their habitat and make it more hospitable for themselves and/or others by relieving the environmental stress. Although evidence on the importance of such positive interactions is accumulating in a wide range of ecosystems, they are largely ignored by current models in ecology. Including positive interactions into ecological theory may be key to understanding population and community processes in physically stressful habitats. Studies already showed that positive interactions in the form of habitat amelioration can have profound effects on the spatial distribution of organisms, on their abundance, and on ecosystem resilience.

 

Positive interactions and food webs

Despite their potential importance for community resilience, little is known about the role of positive interactions embedded in complex networks in stabilizing or destabilizing communities. The aim of my current project is to study the functional role of positive interactions in ecological networks. We investigate, both empirically and theoretically, how positive interactions affect the functioning and stability of ecological communities, as well as the response of these communities to changing external conditions.

 

Is space the key?

Interestingly, when performed by sessile individuals, habitat amelioration occurs most often close to the individual, meaning that these positive effects have a spatial component. In line with this, individuals are often clustered in patches. Such spatial structure of the ecosystem feeds back on both ecological and evolutionary processes. Is the space the key to understanding the functional role of habitat amelioration?

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