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

Accueil du site → Doctorat → Afrique du Sud → 2019 → Exploring ecosystem functioning, service provision and management options on grazed semi-arid rangelands and climate change

University of Limpopo (2019)

Exploring ecosystem functioning, service provision and management options on grazed semi-arid rangelands and climate change

Mudongo, Edwin I.

Titre : Exploring ecosystem functioning, service provision and management options on grazed semi-arid rangelands and climate change

Auteur : Mudongo, Edwin I.

Université de soutenance : University of Limpopo

Grade : DOCTOR OF PHILOSOPHY (PHD) IN AGRICULTURE (ANIMAL PRODUCTION – RANGELAND ECOLOGY) 2019

Résumé partiel
Global environmental change is increasingly recognised as a concern particularly in dry rangelands where livelihoods rely heavily on ecosystem services from climate sensitive agriculture. Current models predict rising temperatures and decreasing precipitation with high variability, and increasing frequencies of droughts in these ecosystems. For African rangelands, livestock numbers are also expected to increase in response to increasing human population. These changes, in combination, are expected to impact negatively on ecosystem function and service provision with devastating effects particularly in Africa due to the high rural populations that have a low adaptive capacity. Thus it is critical to advance ecological understanding of these systems’ response and resistance to the effects of drought and grazing. Motivated by both the current condition and predicted changes in local rangelands, the overall aim of this study was to explore ecosystem function and service provision in grazed semi-arid rangelands and ultimately suggest viable management options and adaptation strategies. Four questions were asked in this regard ; 1) Do existing drought and grazing literature adequately address predicted future climate change scenarios particularly in the context of southern African rangelands ? 2) How can the knowledge gaps in drought and grazing (combined) studies be overcome in these ecosystems ? 3) How does ranch-scale grazing management influence herbaceous and woody vegetation dynamics ? and 4) How does herbivore impact and recovery periods influence rangeland dynamics in climatically variable semi-arid ecosystems ? In order to answer the above questions, this study carried out a critical review of drought and grazing literature to evaluate the relevance of conventional grazing research in the wake of global environmental change. The study also established a large-scale experiment that combines precipitation manipulations with cattle grazing and possible management options in the rangelands of Limpopo Province – South Africa to complement plot-scale clipping and ranch-scale grazing case studies conducted in semi arid rangelands of southwestern Botswana. The review revealed that grazing-related research is well documented in Africa, although it lacks certain levels of realism in terms of scales (temporal and spatial), study designs (e.g. common garden vs in situ manipulations) and the nature of treatments (i.e. clipping vs grazing), whereas relevant drought (and / or grazing) research is lacking. Furthermore, from the review, it was demonstrated that dry rangelands are complex ecosystems that require multifactorial standardized experimental approaches to study individual and interactive effects of several ecosystem drivers simultaneously.

Présentation

Version intégrale (12,6 Mb)

Page publiée le 1er avril 2020