A comparison of the resilience of four habitats to fire, and the implications of changes in community composition for conservation: a case study from the Serra de Monchique, Portugal

Background: The occurrence of fire is natural in many ecosystems but recently the number and frequency of fires has increased. Aim: To provide an assessment of the resilience of four habitats in the Serra de Monchique to fire and to assess the implications of changes in community composition for conservation. Methods: Plots were established in heathland, rhododendron scrub, rocky outcrops and woodland and the vegetation recorded pre-fire and two and four years post-fire. A one-off survey of a range of heathland plots with different fire history was also conducted. Results: The rarer habitats (rhododendron scrub, woodland and rocky outcrops) were less resilient to fire than the more abundant heathland habitat. Fire caused an increase in the cover and number of therophyte and hemicryptophyte species, and the more typical dominant species failed to reach their natural cover. In the heathlands Erica australis (an indicator species for the 'dry heathland' habitat of European community interest) increased and Cistus salvifolius and Ulex minor decreased in cover with time since fire. Conclusions: The rarer habitats were least resilient to fire, which is of considerable conservation importance since fire frequency is predicted to increase with climate change. Higher fire frequencies caused a change towards a less valuable heathland type.