It has been suggested that wildfires, naturally occurring or of anthropogenic causes, have been an integral part of eastern Mediterranean ecosystems for millennia. Consequently, wildfires, being disturbance agents, have an important role in dictating the dynamics and structure of these ecosystems. Ecosystem response to such intense and frequent disturbances is not dictated by a single wildfire event, but rather by the long-term fire regime. The repeated removal and destruction of the canopy and litter cover may result in non-random regeneration of specific species, complex plant-soil interactions, and ultimately in shifting vegetation community structures and vegetation composition.
To assess the ensuing fire-induced changes in eastern Mediterranean ecosystems, we studied in a series of experiments and field-studies the vegetation dynamics and soil properties in areas affected by repeated fire in Mt. Carmel, Israel (1980-2015).
Following wildfires which took place during 2005 and 2010 we established small scale vegetation and soil plots (10 m^2) to monitor small scale responses under various fire regimes. We complemented this effort by conducting large spatio-temporal scale vegetation surveys and analyzing a sequence of satellite images, to determine to what extent vegetation community structures may have changed. We further assessed small-scale hydro-geomorphic dynamics, following the wildfire events.
Results/Conclusions
The culminated results of our studies highlight the differential recovery and response of the Mt. Carmel ecosystems, in relation to varied fire history. As we have previously presented, vegetation recovery rates, at small scales, slower in areas repeatedly burned. These patterns are associated with prolonged elevated runoff and soil loss values. At larger spatial scales we demonstrate the inhibited regeneration of woody species, in areas burned a consecutive number of times. Additionally, four years after the 2010 wildfire event, Pinus halepensis, exhibits inhibited regeneration at the population level.
Stemming from these results and from data published in the literature, we present a conceptual model describing possible vegetation communities’ recovery trajectories, in response to various fire regimes. Specifically, we illustrate shifts from tree dominated communities to domination of herbaceous vegetation, in response to multiple fires, and short fire intervals.