The resilience ability of vegetation after different fire recurrences in Provence

Abstract

Literature on relationships between wildfires and vegetation in Mediterranean areas indicates high resilience ability for most ecosystems on calcareous soils, but data are scarce for acidic soils. The resilience ability of a "fire-driven" ecosystem is expected to depend both on the characteristics of the ecosystem and on the fire recurrence.We investigated the vegetation according to fire recurrence in a site with ecological and patrimonial stakes (the Maures massif, Provence, South Eastern France), in order to determine which ecosystems are more resilient and why. We sampled different modalities of fire recurrence (frequency of fires and interval of time between fires), and we investigated vegetation resilience to fire through different components such as composition, richness, diversity and structure. The sites corresponded to five modalities of increasing fire recurrence since 1959: control plots which had not burned since 1959, plots burned by a major and intense wildfire in 1990 (= reference fire), other plots burned twice or thrice before the 1990 fire and plots burned several times then and in 2003.The results confirmed that our Mediterranean ecosystems on acidic soils are mainly auto-successional, as vegetation composition remained rather constant after fire. Significant differences of composition existed between the control plots and the plots lastly affected by the 2003 fire. In contrast, significant differences of functional diversity (i.e. plant traits) existed among the five modalities, in particular an increase of ruderal species and a decrease of competitive taxa with increasing fire recurrence. Moreover, some types of vegetation were identified according to fire recurrence modalities. A variation partitioning procedure (partial CCA) indicated that the environmental data set explained better the plant distribution than the fire recurrence data set.The final objective of the study is to improve the understanding of the interrelationships between fires and the dynamics of vegetation, for a sustainable management of these Mediterranean ecosystems.

Fire recurrence effects on the abundance of plants grouped by traits in Quercus suber L. woodlands and maquis

“…Indeed, the time since the last fire was more influential than the time since the previous last fire, as previously found by Schaffhauser et al (2008). However, both TSF and fire frequency had different effects on different PTs, as hypothesized (see Fig.…”

“…These findings indicate that a fire interval of 10-15 years is the resilience threshold for the studied communities. However, a large pool of species was common to most plots (Ouelmouhoub and Benhouhou, 2007;Schaffhauser et al, 2008), suggesting that a long fire history has played a strong selective role in these ecosystems (Bergaglio et al, 2006), and has sometimes been more influential than land use history (Arianoutsou et al, 2002;. We also found that E. arborea cover had a highly detrimental impact on functional diversity.…”

Resprouter fraction in Cape Restionaceae assemblages varies with climate and soil type

“…). Furthermore, variation in long‐term fire frequency can also impact local assemblage composition (Schaffhauser, Curt & Tatoni ; Vila‐Cabrera, Saura‐Mas & Lloret ). One example in which these aspects of biodiversity are affected by fire is in the Cape Floristic Region (CFR; e.g.…”

“…Differential fire intensity among localities can impact dominance patterns (Bond, Smythe & Balfour 2001) and increase phylogenetic clustering (Verdu & Pausas 2007;Ojeda et al 2010). Furthermore, variation in long-term fire frequency can also impact local assemblage composition (Schaffhauser, Curt & Tatoni 2008;Vila-Cabrera, Saura-Mas & Lloret 2008). One example in which these aspects of biodiversity are affected by fire is in the Cape Floristic Region (CFR; e.g.…”

Resilience of Mediterranean communities to fire depends on burn severity and type of ecosystem

“…Resilience can be measured by analyzing the recovery of vegetation variables such as the fraction of vegetation cover or species composition with respect to pre-disturbance situations (Halpern 1988;Wittenberg et al 2007;Schaffhauser et al 2008;Coop et al 2016). The study of post-fire resilience is a highly relevant issue in the Mediterranean Basin, since it offers an approximation of the recovery of ecosystem services that are of value to society, and whose provisioning could be threatened as a consequence of current fire regimes and global change (Puerta-Piñero et al 2012;Seidl et al 2016).…”