Name: Chergui B

Biodeserts supervisor: Santos X

Co-supervisor: Fahd S

Provisional title: Analysis of the resilience to fire of the reptile community and the forest in the western Rif Mountains (northern Morocco)

Institution: University Abdelmalek Essaâdi, Morocco

Status: Completed

Abstract

Wildfires have played a determining role in shaping the evolution and functioning of many ecosystems around the world. Over the past three centuries, human population density and distribution have increased exponentially which intensified the human influence on fire number and impact. In recent decades global warming, land abandonment and changes in traditional agricultural activities are driving changes in the frequency and extent of fires. As in Mediterranean countries, forested areas in Morocco are exposed to recurrent fire risk favoured by the extreme flammability of tree species during summer, especially in the northern part of the country has the highest fire frequency.
The first chapter of this thesis aims to comparing the fire regime between southern European and North African countries, and thus our hypothesis is that this difference generates contrasting fire regimes between the two regions. To test our hypothesis, we compared fire statistics from the western Rif (northern Morocco, during 1988 – 2015) and from Valencia (eastern Spain, during 1880 – 2014). The result suggests that western Rif of Morocco has a typical Mediterranean fire regime with fires occurring in the hot, dry summer season. However, fires are very small and the annual proportion of burnt area is very low, compared to the current regime in Valencia (post-1970s). The current Rif fire size class distribution matches the fire regime in Valencia prior to the 1970s before the collapse of the rural population and when fires were fuel-limited.
In the African rim of the Western Mediterranean Basin, cork oak forest and pine plantation are the most frequently burnt woodlands. The second chapter of this thesis aims to analyze the hypothesis that pine plantations are less resilient in habitat structure (canopy, understory, diversity of vegetation) than cork oak forest. Generalized linear mixed models (GLMM) showed that cork oak forest was more resilient to fire than was pine plantation in habitat structure. On the other hand, both forest types were resilient to fire in the composition of the plant communities, i.e., plant composition prior to fire did not change afterwards.
The third chapter of this thesis assesses whether forest type influences the responses to fire of reptile communities. To this aim we studied 13 burnt sites in 2015 and 2016 in the African rim of the Western Mediterranean. We analyzed relative abundance and species richness data using generalized linear mixed models to examine the influence of fire, forest type (cork oak and pine), habitat structure. We further used distance sampling models to estimate the density of the five commonest reptile species. A total of 2249 individuals of 15 species of reptile from 9 families were observed across the six-sampling visit. The response of reptiles to fire varied between the two forest types: reptile abundance did not change with fire in cork oak forest, and increased with fire in pine plantation. Species richness was higher in cork oak forests, and increased from unburnt to burnt areas. Two out of five commonest lizards in the region, Acanthodactylus erythrurus and Podarcis vaucheri, responded positively to fire in pine plantation and remained similar in cork oak forest. The knowledge of species response to wildfires and to post fire salvage logging is essential to conduct a sustainable management.
The aims of the fourth chapter of this thesis were to studied the functional responses that reptiles show to fire in two contrasting forest types, cork oak forest and pine plantation. To this aim we compiled seven functional traits for the reptile species present in the study region, and quantified functional diversity at each sampled transect. The functional richness did not change with fire in cork oak forest plots, but increased with fire in the pine plantation ones. According to the redundancy analysis, unburnt forests mostly the community was formed functionally by small Mediterranean ground- and rock-dwelling lizards. In burnt cork oak and pine plantation plots, however, the presence of geckos and phytophagous terrestrial tortoises indicate the availability of other resources that can be exploited by reptiles with different functional traits.
The spur-thighed tortoise is currently one of the most reptiles affected by fires. In the fifth chapter, we investigated that examines the responses of spur-thighed tortoise Testudo graeca to fire in native forests cork oak and pine plantations forest at different altitudes. To this aim we studied 8 burnt sites of natural cork oak forest and pine plantation with 8 replicates per site from 2015 to 2017. Tortoise densities were estimated with line transect distance sampling. The detection probability of tortoises was higher in burnt than unburnt transects. The density of tortoises was negatively associated with altitude and declined with fire around a 50% in both forest types.