A.M. Zobolo

Impacts of cattle on ecological restoration of coastal forests in KwaZulu-Natal, South Africa

Livestock from communities bordered by dune mining, urban areas and commercial forestry in northern KwaZulu-Natal spend substantial time foraging in the coastal forest that the mining company is obliged to restore. A survey of livestock owners and an experimental study of impacts of cattle on restoration processes were conducted to develop better knowledge of the perceptions of livestock owners neighbouring the mine, and the impacts of their cattle on rehabilitating coastal dune forest. Shortages of grazing and livestock diseases were perceived to be the major constraints on livestock operations. Mitigation included grazing cattle in the rehabilitating forest and treating livestock diseases with available medicinal plant species. An exclosure experiment in one of the older stands undergoing restoration showed that cattle grazing reduced grass biomass and Acacia kosiensis seedling recruitment. A study of seeds collected from cattle dung showed that Psidium guajava, an important invasive alien woody species, was dispersed by cattle into the rehabilitating forest, but passage through cattle did not enhance germination of the invasive species. The study concluded that: (1) the proximity of livestock owners to large-scale commercial land uses influenced their perceptions and their resources, and (2) grazing and trampling by cattle in the rehabilitating dune forest may hinder the ecological restoration process.

Genetic diversity in Cucurbita pepo landraces from northern KwaZulu-Natal, South Africa, revealed by random amplified polymorphic DNA (RAPD) markers

Genetic variation in seven selfed and unselfed Cucurbita pepo landraces from districts in KwaZulu- Natal Province was investigated using the random amplified polymorphic DNA (RAPD). Out of 36 primers screened nine were selected, which gave 100 clear and bright fragments, out of which 94 (94%) fragments were considered polymorphic. The sizes of bands ranged from 75 to 1800 bp. The number of bands per primer ranged between nine and 14. The genetic differentiation coefficient between populations (G ST ) varied between 0.0022 and 0.0100, while the gene flow ranged between 49.4545 and 223.7226. The effective number of alleles, Nei’s gene diversity index and Shannon’s information index were the highest in the selfed population from Zululand (yellow) district (ZS) population (Ne= 1.2046; H=0.1677; I=0.3060) and the lowest in unselfed population from uThungulu (yellow) (TNS) population (Ne=1.1512; H=0.1301; I=0.2518). The production of specific RAPD markers by different primers indicated gene diversity between: Selfed and unselfed populations from the same geographic origin; populations with yellow/orange mature fruit from a population with green mature fruit; and also among different populations in general. The selfed population from uThungulu (yellow) (TS) and TNS populations, both from uThungulu district, were the highest in genetic identity (I N = 0.9996) and the closest in the genetic distance (D = 0.0004). The unselfed population from Umkhanyakude (green) (CPSP) and unselfed population from Umkhanyakude (yellow (MNS) populations as well as CPSP and TNS populations were the lowest in genetic identity (I N = 0.9985) and the furthest in genetic distance (D = 0.0015). The dendrogram mainly grouped the populations according to their mature fruit colour, and then according to their geographical origin. All genetic parameters indicated that there was plentiful genetic diversity in C. pepo landraces of northern KwaZulu-Natal, South Africa. Key words: Cucurbita pepo landraces, genetic variation, self-pollination, random amplified polymorphic DNA (RAPD) markers, northern KwaZulu-Natal.