Turtle populations resist fires every 30 years

Turtle populations mora ( Testudo graeca ), a species classified as vulnerable and at risk of extinction, are able to tolerate the passage of flame if it occurs at intervals of three decades or more. However, 'Benjamin' are more sensitive and disappear after each fire. This was revealed by Spanish researchers who have analyzed the impact of fire in the Sierra de la Carrasquilla (Murcia) in 2004 in these reptiles. 

"The tortoises can withstand high temperatures, but that does not mean its shell is a fire-proof frame," Ana Sanz explains to SINC-Aguilar, the study's lead author and currently a postdoctoral fellow at the Center Functional and Evolutionary Ecology in Montpellier (France), who has collaborated with the University Miguel Hernández (UMH) and the Mediterranean Institute for Advanced Studies (IMEDEA-CSIC).


The fire killed 100% of the turtles mora ( Testudo graeca ) under 4 years. Image : Andrés Giménez.
 

One of these fires occurred on August 1, 2004 in the Sierra de la Carrasquilla (Murcia) and scorched an area of ​​250 hectares, in which lived a large population of these reptiles. For a decade, researchers study the behavior of more than 1,000 of them.

The study, published in the journal Biological Conservation , shows that the response of sea-fire was very different depending on age. Thus, the fire killed 100% of animals less than 4 years, and caused an increase in mortality of 62% in sub-adults (between 4 and 8 years) and 12% in adults (8 years).

"For the dynamics of the species is more serious than a fire increase the adult mortality by 12% remove all the young turtles," said Sanz-Aguilar.

According to the study, the viability of populations of these animals depends on the low mortality and longevity of adult individuals. Any factor that increases the mortality of adults, such as increased vulnerability to fire in rocky terrain, "increases the probability of extinction of a population," the authors write.

However, fires every 30 years (a frequency similar to the natural rhythm in Mediterranean landscapes) populations of medium-large turtle dwells not become extinct, according to models developed by researchers. "Exceeded this limit, the probability of extinction increases precipitously", experts warn.

As for the younger turtles, none of them survives the passage of flame in any area by the type of shelters they use, beneath the vegetation and very shallow holes. They also have a lower resistance to high temperatures, not having yet ossified its shell.

The danger increases in spring

Although the fire scorched dozens of animals, live specimens the scientists found themselves in shelters dug into the ground to spend periods of increased heat stress, winter and summer.

In other seasons, their behavior changes and increases their rate of activity. "In spring, the turtles are hidden under a bush so that if at that moment a fire, would destroy all copies," said Sanz-Aguilar.

The turtle dwells spans Europe, Africa and Asia. In the European Union, the largest populations are located in the southeastern Iberian between Murcia and Almeria, occupying an area of 2,600 km 2 . " It's kind typically Mediterranean and the natural landscapes of this area are adapted to particular fire regimes, low Recurrence, "explains the researcher.

The International Union for Conservation of Nature (IUCN) has listed as 'vulnerable', with a risk of extinction in the medium term. In Spain, it is classified as 'endangered' in the Red Book of Spanish Reptiles and Amphibians.

References:

Ana Sanz-Aguilar, Jose Daniel Anadón, Andrés Giménez, Rubén Ballestar, Eva Grace, Daniel Golden, "Coexisting with fire: The case of the terrestrial tortoise Testudo graeca in mediterranean shrublands." Biological Conservation 144: 1040-1049, March 2011 . DOI: 10.1016/j.biocon.2010.12.023.

Source: SINC