Name: Vale CG

Biodeserts supervisor: Brito JC

Co-supervisor: Stuart Pimm, Duke University, USA

Title: Biodiversity conservation in arid environments under climate change

Institution: University of Porto

Status: Completed

 

Abstract

The synergetic effects of human activities and climate change come in the current biodiversity crisis. The major aim of Biodiversity Conservation is to halt biodiversity loss by defining priority areas for conservation that maximize species representation and enable persistence. The overlooked arid environments are important areas for conservation where the goals of representativeness and persistence can be achieved while promoting sustainable resource use. This thesis contributes to biodiversity conservation by suggesting good practices to accurate identify suitable areas and by improving current knowledge on biodiversity patterns in arid environments, particularly the Sahara-Sahel.

The main objective of the thesis is to address biodiversity conservation in arid environments, focusing on the Sahara-Sahel, a region where biodiversity is under strong climatic control and is vulnerable to climate change. Four specific goals were defined: 1) compare the performance of ecological niche models built at different scales to predict species distribution at range margins and the distribution of ecologically plastic species; 2) evaluate the conservation status of mountain restricted species; 3) identify local hotspots of biodiversity; and 4) identify functional groups vulnerable to future climate change.

The implications of the study area extent, resolution and threshold selection in the performance of ecological niche models to predict species distributions at range margins were analysed. Additionally, scale-related effects were assessed for ecologically plastic species. For local conservation planning under present conditions, fine-resolution regional models should be used, as they were more accurate in predicting current species distributions at range margins located in abrupt transition zones, and in defining suitable areas for the occurrence of ecologically plastic species. Conservative thresholds applied to regional models improve the definition of suitable areas to effectively design protected areas at the edge of species distributions.

Ecological niche models were applied to predict environmental factors related with species distributions and identify suitable areas for Sahara-Sahel endemic species (Felovia vae and Agama boulengeri), to ultimately evaluate their conservation status. Predicted suitable areas were used to calculate the number of subpopulations, the extent of occurrence and area of occupancy. Both species were mostly related with rock-pools, rocky deserts and bare areas, and associated to Mauritanian mountains, being deemed as Least Concern. These studies contributed to increase knowledge about Sahara-Sahel endemics and to emphasize the biological value of Mauritanian mountains as island-like mountains.

To explore the importance of gueltas as local hotspots of biodiversity, the number of vertebrates and endemics present in 69 mountain rock-pools (locally known as gueltas) were quantified and compared with species present in a surrounding area and recorded in Mauritania. Taking into account the percentage of endemics and threats, gueltas were ranked by their priority for conservation. Gueltas were considered local hotspots of biodiversity, as they are tiny places holding high number of species, including endemics, and are vulnerable to droughts and human activities. They could provide future refugia under climate change scenarios, so they are crucial for long-term conservation of Sahara-Sahel biodiversity and also for local communities, whose economy is based on water exploitation and surrounding productive habitats of gueltas.

The functional strategy of the Sahara-Sahel endemics was summarised into functional groups and their exposure to the magnitude and velocity of climate change was accessed to identify the functional groups more vulnerable by climate change. Seven functional groups with different levels of vulnerability to velocity and magnitude of climate change were identified according to their current range. Functional groups constituted by arid-adapted species combining sensitivity and low adaptive capacity, and living in flat areas, were the most threatened groups to climate change. The study provides indications on functional vulnerability to climate change in other warm deserts of the world.

Altogether, this work combined distinct methodologies applied to different biodiversity components to increase knowledge on biodiversity distribution patterns and vulnerabilities in arid environments, which ultimately can be used for designing systematic conservation programs.