Fire & Tortoises


Humans have altered Mediterranean landscapes and ecosystems for more than 8000 years, and despite human influences the region is considered a biodiversity hotspots. In the last few decades fire suppression policies have modified the ecosystems’ functioning, but prescribed burning has been considered a management tool to prevent extensive wildfires and restore the dynamics of fire-maintained ecosystems. Anna Sanz-Aquilar and colleagues (2011) assessed the impact of fire on survival rates, reproduction and movement of the Mediterranean Spur High Tortoise, Testudo graeca ibera, at the Cumbres de la Galera Biological Reserve, in the Sierra de la Carrasquilla, Spain. They found fire impacted survival of mostly of young individuals, with dramatic mortality of juveniles with the burned areas during the first and the second year after the fire. The reduction in vegetation cover after a fire could increase the visibility of young and vulnerable individuals to predators interfere with thermoregulatory behavior, or effect food availability. They found no differences in fecundity and movement patterns of tortoises between burned and unburned areas. Their, population models showed areas with fire frequencies of less than one fire every 20–30 years the tortoise populations seemed to cope with the effects of fires with little damage to the populations. But, when this fire frequency was surpassed, the probability of population extinctions exploded for all populations, except for those with the largest numbers of individuals. Thus, tortoise populations may be able to deal with naturally occurring fire frequencies, but the effects of more frequent fires may severely threaten the species. 

Citation
Sanz-Aguilar, A., J. D. Anadón, A. Giménez, R. Ballestar, E. Graciá and D. Oro. 2011. Coexisting with fire: The case of the terrestrial tortoise Testudo graeca in mediterranean shrublands. Biological Conservation, In Press. doi:10.1016/j.biocon.2010.12.023 

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