14 - Is fire an agent favouring plant invasions?

Summary

By its frequent recurrence in the past and the present, fire is an important ecological force influencing the dynamics of plant communities in all regions of mediterranean climate. Fire more or less regularly interrupts the natural cycle of vegetation succession and its advent allows some stands to be rejuvenated. By disturbing the natural vegetation does fire permit introduced species to establish in burned areas? By disturbing vegetation (i.e. by opening gaps for potentially invasive species), does fire create areas where non-indigenous species may be able to establish? What are the types of invasive species: do they come from outside the communities but belong to local floras, or do they come from afar, from other countries? Do such species persist or are they only transitory? In short, is fire a factor in plant invasion or are local species so strongly adapted to fire that they do not permit any changes in the floristic composition of burned communities? Plant species display such a wide range of reproductive means that they are able to colonise a large variety of environments in such a manner that at least one species always has the potential to invade a burned area.

This research theme is an exciting and promising one for the understanding of vegetation dynamics and the past, present and future floristic composition and stucture of communities. Yet, unfortunately, only a few studies deal with plant invasion after fire in mediterranean-type ecosystems.