Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Nocturnal medium-sized bioturbators and their ecosystem services in differently managed rangelands in the Kalahari and Pro-Namib.

Auteur : Rodgers, Michelle

Université de soutenance : Namibia University of Science and Technology

Grade : Master of Natural Resources Management 2019

Résumé
Bioturbating organisms are known for their benefits to landscapes and ecosystems. Studies have to date largely focussed on invertebrates with very little known about the role burrowing mammals play, especially nocturnally active species. They are thought to be vulnerable to land degradation - such as shrub encroachment and livestock overgrazing - leading to increased negative effects on land productivity through the loss of their associated ecosystem services. The abundance and diversity of burrowing medium-sized nocturnal mammals between neighbouring livestock and wildlife land use types were compared in this study in three biomes in Namibia : north Kalahari, south Kalahari, and the Pro-Namib Desert. It postulated that bioturbation by nocturnal mammals is an important feedback mechanism leading to improved soil conditions and therefore improved vegetation productivity. The study used nocturnal road strip counts during the growing (summer) and dry (winter) seasons of 2016, 2017 and 2018 to quantify differences in medium-sized mammal population dynamics. High resolution multispectral unmanned aerial vehicle imagery was used to determine macropore abundance on the northern Kalahari sites, as well as vegetation productivity was estimated for the three study areas and years using Sentinel-2 satellite images. Rangeland productivity was investigated in the field by measuring grass biomass and moisture infiltration around burrow clusters and control sites with no burrows.

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