Year: 2014
Type: dissertation
Abstract: Introduction: Factors modulating resilience to fire in Mediterranean woodlandscovary.For example, due to plant-soil feedback, resistance and resilience of above-and below-ground ecosystems are expected to be interrelated (Seybold et al. 1999;Herrick 2000;Certini 2005), although testing of this assumption is scarce.However, it is important to emphasize that different ecosystem components and processes may vary largely in their sensitivity to disturbances and in their capacity for recovery (Lavorel 1999).For example, the recovery of vegetation cover after fire can be relatively fast, while the species relative abundance may need more time to return to pre-fire values.This dissertation primarily uses the engineering concept of stability, assuming that resistance is the ability to withstand the fire effect and resilience as the ability of an ecosystem or community to return to pre-fire conditions.Therefore, resistance is measured as the amount of immediate fire-driven change in the properties of interest, and resilience as the amount of change in these properties towards recovery of pre-fire values, measured at a given time after fire.However, the concept of ecological resilience is also present throughout the dissertation when potential for ecosystem shifts into alternative states are considered. Factors affecting ecosystem resistance and resilience to fireResistance and resilience of an ecosystem to fire results from a combination of biotic and abiotic factors that are related to (1) the fire regime (fire severity and frequency); (2) post-fire climatic conditions; and (3) factors inherent to the physical and biological structure of the vegetation community and to the site conditions.These factors interact between themselves and act at different scales.Fire potentially may affect all levels of biological organizations, and therefore plays an important role in the structuring and functioning of populations, communities, and ecosystems.The magnitude of the effect of fire on vegetation and soil (resistance) depends essentially on fire severity, which actually can be considered as the reverse property of resistance (see below), together with other plants and soil characteristics that relate to their sensitivity and degree of protection; while the recovery capacity (resilience) of vegetation and soils after fire depends on fire severity, the regenerative ability of the resident species, and the post-fire conditions. Fire frequencyThe impact of fire frequency on ecosystems is a function of interval-dependent processes related to the availability of time for plant establishment, maturation, seed production and longevity (in dormancy) of seeder species, as well as for the recovery of the storage of non-structural carbohydrates of resprouter species (Zedler 1995;Clarke et al. 2013).Fire-dependent obligate seeder species can face the risk of either immaturity or senescence for short and long intervals between fires, respectively (Zedler 1995).Short intervals may negatively affect density and growth rates of tree and shrub populations (e.g.Pinus sp) (Ne'eman et al. 1999; Eugenio et al. 2006a).Seeder shrub species (e.g., Rosmarinus offıcinalis, Cistus albidus) seem to achieve maximum Apart from plant fire-persistence traits, other plant individual and community characteristics can be relevant in determining post-fire vegetation recovery.The plant size of resprouter individuals seems to be the most important factor determining the number and biomass of resprouts (Canadell et al. 1991).Stand age, which relates to fire frequency may be also crucial in post-fire regeneration, particularly for seeder species, as it affects the capacity for producing seeds as well as for seed storage and canopy banks (Kazanis and Arianotsou 2004; Eugenio et al. 2006a).Species diversity may also be relevant.For example, long standing forests with a high number of species, and thus more diverse functional traits, will ensure forest recovery after fire and high
Author: Rosario López Poma
Language: English
Topic: Fire effects on ecosystems
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W1559897068