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Universidade do Porto (2018)

Landscape Connectivity and Remote Sensing Applications for Assessing Biodiversity Patterns in Desert Environments

Rodrigues, João

Titre : Landscape Connectivity and Remote Sensing Applications for Assessing Biodiversity Patterns in Desert Environments

Auteur : Rodrigues, João

Université de soutenance : Universidade do Porto

Grade : Doctoral Thesis 2018/

Résumé partiel
Landscape connectivity reduces population isolation and allow dispersal of individuals to areas with favourable climatic conditions. Assessing landscape connectivity patterns in desert environments may constitute a major priority for future conservation planning in those areas. Remote Sensing (RS) has proven to be an effective tool for studies focused in ecology, biodiversity distribution and conservation, given its power in detecting key drivers of biodiversity status/change across the globe. Also, RS provides effective representations of the landscape structure, which constitutes a significant source of information for improving landscape connectivity studies. These techniques are particularly useful for studying biodiversity patterns in extremely remote regions, such as such as deserts and arid regions, where field investigations are difficult to perform. Global biodiversity is currently facing severe losses and many species are on the brink of extinction. Climate change and habitat fragmentation represent two major factors enhancing the catastrophic degradation of biodiversity worldwide. These impacts are normally exacerbated in extreme regions, such as deserts and arid regions. These regions are frequently regarded as naturally poor and homogenous regions, although comprising unique and fragile biodiversity in need of global attention. For instance, the Sahara-Sahel holds many endemics and relict faunal populations with different biogeographical origins, such as the West African crocodile (Crocodylus suchus). Saharan relict populations are subjected to effects of extreme isolation and are deeply exposed to extreme climatic oscillations. Accordingly, the main objective of this thesis is to verify the importance of landscape connectivity for desert organisms and how current assessments of biodiversity patterns in desert environments can profit from the application of RS tools. Concretely, four crucial goals were delineated in order to achieve this principal objective : 1) Evaluate the current state of structural connectivity methods for application in ecology, evolution and conservation ; 2) Attest potential contributions of RS to the assessment of biodiversity distribution patterns in global drylands ; 3) Identify and map in detail important landscape features for the assessment of local biodiversity patterns in the West Sahara-Sahel ; 4) Analyse the distribution and the effects of climatic oscillations on population structure and connectivity of West African crocodiles in the West Sahara-Sahel.For achieving the first goal, it was developed a review encompassing basal theoretical concepts and listing major advantages and disadvantages of structural connectivity methods. This review is focused on insufficiently reviewed methods and on the most recent methodological developments for measuring structural connectivity. Additionally, insights concerning the applicability of these methods in ecology, evolution and conservation are provided, and future directions for improving landscape connectivity studies are also discussed. Future landscape connectivity studies should focus on the development of integrative frameworks. This may be accomplished by incorporating complementary methods/outputs that will improve our understanding of specieslandscape relationships at structural and functional levels. Increased efforts on the development of computational resources and on data collection (e.g., genetic and movement data) will allow the employment of sophisticated methods to evaluate population connectivity and the preservation of landscape connectivity patterns

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Page publiée le 29 octobre 2018