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

Accueil du site → Doctorat → Afrique du Sud → 2021 → Mistletoes as drivers of plant community structure and resource heterogeneity in semi-arid savanna ecosystems, Zimbabwe

University of the Witwatersrand (2021)

Mistletoes as drivers of plant community structure and resource heterogeneity in semi-arid savanna ecosystems, Zimbabwe

Maponga, Tsitsi Sithandiwe

Titre : Mistletoes as drivers of plant community structure and resource heterogeneity in semi-arid savanna ecosystems, Zimbabwe

Auteur : Maponga, Tsitsi Sithandiwe

Université de soutenance : University of the Witwatersrand

Grade : Doctor of Philosophy (PhD ) 2021

Résumé partiel
The role of mistletoes in influencing resource heterogeneity has been shown in many environments. Studies have shown that by providing additional litter and weakening their hosts’, mistletoes can change plant community structure by providing sub-ordinate subcanopy species a competitive edge thereby increasing species richness and diversity. These studies have mainly focused on differences between mistletoe-infected and uninfected trees, yet it is possible that different mistletoe-infection degrees’ influence species composition within and beyond their canopies. Therefore, this thesis investigated the effects of mistletoe-infection degrees on Vachellia karroo (Hayne) Banfi and Glasso on plant community structure in a semi-arid savanna in South-West, Zimbabwe. Firstly, this thesis investigated how high- and low mistletoe-infection degrees on V. karroo trees influence abiotic and biotic conditions within and beyond the canopy patches. Further, it examined whether there were variations in species composition, species and functional diversity, and size measurements of understory plants within high- and low mistletoe-infection canopy patches and intercanopy spaces. Thirdly, it explored whether different mistletoe-infection degrees reduced the reproductive and regeneration capacities of their host trees and the recruitment of host juveniles (seedlings and saplings). Lastly, although studies have investigated how uninfected mature trees influence the spatial distribution of other surrounding woody species of different stage classes, little is known on how mistletoe-infected trees influence the spatial patterns of surrounding woody plants. Therefore, the fourth aim investigated how mistletoe-infected V. karroo trees influence the spatial patterns of their surrounding conspecific and heterospecific woody plants of different stage classes within three 50m × 50m plots with > 30 mistletoe-infected V. karroo trees. The results show that intercanopy spaces had between 18% to 34%, and 18% higher herbaceous biomass and maximum grass height, respectively, compared to canopy patches. Herbaceous biomass and maximum grass height were 8% to 23%, and 13%, respectively, higher in low- compared to high mistletoe-infection microhabitats.

Présentation

Version intégrale (9,6 Mb)

Page publiée le 15 avril 2022