Human disturbance and environmental factors as drivers of long‐term post‐fire regeneration patterns in Mediterranean forests

Abstract

Question: What are the main forces driving natural regeneration in burned mature Mediterranean forests in the medium‐long term and what are the likely successional trajectories of unmanaged vegetation? Location: Valencia Region, eastern Spain. Methods: A wildfire burned 33 000 ha of Pinus halepensis and P. pinaster forest in 1979, and subsequent smaller wildfires took place between 1984 and 1996. The study was designed to sample the range of environmental and disturbance (fire recurrence and land use) conditions. The territory was classified into 17 different geomorphological and fire‐recurrence units. Vegetation cover and floristic composition were measured on a total of 113 plots (1000 m2 each) randomly selected within these units. Results: The results show that 23 years after the fire the regenerated vegetation consists of successional shrublands, and that forest ecosystem resilience can be very low. The vegetation presents a strong correlation with most of the environmental variables, but fire (one or two fires), soil type and land use (in that order) are the main drivers of vegetation composition. Quercus coccifera shrublands persist on limestone soils while diverse types of other shrublands (dominated by seeder species) are found on marl soils. Conclusions: The results of this study indicate that disturbance factors strongly coupled to human activities, such as land use and fire, play a critical role in the current state of vegetation. Fire creates vegetation patches in different successional states while land use and soil type define the different types of shrubland in terms of their specific composition.

Old-field secondary succession in SE Spain: can fire divert it?

“…Our results agree with the conceptual model proposed by Baeza et al (2007), which suggested that stable communities composed of C. albidus and U. parviflorus would become established in old-fields of SE Spain when the fire intervals were less than 10 years. Hence, our work evidences that old-field successions could behave like other Mediterranean ecosystems; where fire recurrence is high the dominance of small-size shrubs and herbs is promoted (Zedler et al 1983;Haidinger and Keeley 1993;Baeza et al 2007).…”

“…In fire-prone ecosystems, deviations from the expected successional pathways have been proposed especially where there is a high fire recurrence over relatively short time periods (Noble and Slatyer 1980;Trabaud 1991;Eugenio and Lloret 2004;Donato et al 2009). As a consequence vegetation can be diverted to communities composed mainly of small-sized species with high proportion of fine fuels, which can provide a positive feedback on the likelihood of fire recurrence (Zedler et al 1983;Haidinger and Keeley 1993;Baeza et al 2007).…”

Impacts of Global Change on Mediterranean Forests and Their Services

“…Desertification in the north is driven by intensive irrigation and by past and current over-exploitation of the vegetation, e.g., by livestock pressure, all driven by markets and regional agricultural policies, whereas desertification in Africa is driven more by the increased encroachment of rangeland by cultivation or livestock production in recent decades due to the exponential growth in population [193]. Moreover, community succession and soil processes after fires and/or increasing droughts in Mediterranean plant communities have created patchy vegetation and accelerated soil degradation [194], reducing water infiltration [195], all of which lead to desertification. Several Mediterranean areas of European countries have been subjected to land-use change in recent decades [196][197][198], whereby unproductive areas were forested, abandoned or overexploited [198].…”

Implementation of a distributed sediment model in different data availability scenarios.

“…This phenomenon was already described in literature, e.g. by Cerdà [1998c], Rey Benayas et al [2007] and Baeza et al [2007].…”

“…This dynamic is typical of many Mediterranean catchments, which suffered strong land abandonment during the 1960s, inducing accelerated land degradation and the development of a shrub cover, as is the case of the Rambla del Poyo catchment. This behaviour was mentioned in various studies, such as Cerdà [1998], Rey Benayas et al [2007] and Baeza et al [2007].…”