Numerous CTHB projects aim to improve our understanding regarding the biology and ecology of the microbes and insects associated with woody hosts indigenous to South Africa.
The tree species receiving most attention are Syzygium cordatum, Syzygium guineense, Acacia karroo, Acacia mellifera, Acacia erioloba, Adansonia digitata, Pterocarpus angolensis, Sclerocarya birrea, Rapanea melanophloeos, Colophospermum mopane, Aloe plictilis and species in the Proteaceae, Rutaceae, Rubiaceae and the genera Virgillia and Terminalia.
The specific microbes that are targeted include species in the Botryosphaeriaceae, Cryphonectriaceae and Uredinales (Ravenelia, Puccinia and Uromyces), as well as the genera Armillaria, Ganoderma, Fusarium, Mycosphaerella, Phellinus, Ceratocystis, Gondwanamyces, Coniothyrium (Colletogloeopsis / Phaeophleospora / Kirramyces), Cylindrocladium, Dothistroma, Pantoea, Ophiostoma, Candidatus Liberibacter africanus and Phytophthora.
The insects currently receiving most attention include bark beetles, bruchid beetles, as well as Coryphodema tristis and a number of species that could possibly be used in biocontrol programmes.
Various CTHB projects also consider the ecology and population biology of specific tree species to evaluate the effect that human practices (e.g. timber harvesting, coppicing, bark stripping, etc.) might have on the target plant, ecosystems and the conservation of natural habitats. Many further focus on the possible impacts that soil properties, nutrients, rhizobial symbioses and climatic factors might have on the invasiveness of certain species in diverse landscapes. A small number of projects also aim to investigate the effects that drought, frost and fire might have on the sustainable usage of indigenous woody resources.