Search

Crimes against wildlife have been in the spotlight in South Africa in the past decade - largely due to the escalation of rhino poaching. As a custodian of iconic species, South Africa is at the heart of the illicit and licit wildlife economy. Since the country's economy relies on wildlife tourism as one of its sources of income, poaching has economic consequences. The negative impact, however, extends into the cultural sphere too. Some fear that extinction will rob future generations of the chance to experience wildlife, thus depriving them of their rightful cultural heritage. This commentary piece suggests that wildlife crime may be a form of cultural victimisation for people who feel that wildlife is part of their identity. It does so while acknowledging that poverty and other structural limitations prevent many South Africans from experiencing wildlife in this way, and that some may feel indifferent or resentful towards conservation initiatives if their basic needs are not met. [ABSTRACT FROM AUTHOR]

Dispersal or recruitment limitation may arrest succession after disturbance. In north-eastern South Africa the Acacia karroo successional pathway is used to facilitate coastal forest recovery after strip-mining. However, although A. karroo establishes naturally, it forms monospecific stands, arresting forest succession for decades. This casts doubt on the efficacy of this restoration pathway. We investigated the causes of arrested succession. The seed and seedling banks of A. karroo stands and of forest at Cape Vidal, and three A. karroo stands (7-27 years old) on rehabilitated strip-mined dunes at nearby Richards Bay were examined. The establishment and growth of seedlings at Cape Vidal were also considered. The seed bank was larger and more diverse in forest, but the seedling bank was larger in Acacia stands. At Richards Bay, the size of the seed bank increased and the seedling bank decreased with Acacia stand age. Excluding mammalian herbivores in Acacia stands at Cape Vidal resulted in greater species richness and survival of naturally established seedlings, as well as two experimentally planted species. Neither seed dispersal nor seedling establishment limited recruitment of tree species in Acacia stands. Herbivory arrested forest succession by causing the differential mortality of seedlings. In contrast, at Richards Bay where there were few mammalian herbivores, the advanced regeneration in A. karroo stands converged on the diversity of nearby forests 29 years after restoration. Controlling herbivore access and seeding Acacia stands with forest species are site-specific options for preventing arrested succession when using the A. karroo successional pathway. [ABSTRACT FROM AUTHOR]

In theory, resprouting enables species with low reproductive output (i.e., few seedlings) to persist. The advantage conferred by seedling sprouts on tree species persistence was evaluated in a subtropical coastal dune forest in South Africa. Species with a higher frequency of seedling sprouts demonstrated greater persistence as evidenced by a larger proportion of seedlings >1 year old and a larger seedling bank than species with few seedling sprouts. Resprouted seedlings had a larger basal diameter than true seedlings. Although resprouting resulted in the maintenance of multiple stems in some seedlings, the proportion of multi-stemmed seedlings was low. Multi-stemming was not a favoured form of seedling growth except in one species that occupied relatively open sites. Despite the apparent difference among species in resprouting ability, we found that seedling resprouting was not phylogenetically constrained. These results demonstrate that seedling sprouts form an important component of seedling banks in coastal dune forest. [ABSTRACT FROM AUTHOR]

Abstract: Indigenous forests are declining throughout southern Africa, partly because of exogenous disturbances such as harvesting of forest resources. We evaluate the influence of colonial logging and present-day harvesting of pole-size trees (2–15cmdbh), used for construction and fuelwood, on the structure and composition of iGxalingenwa forest in KwaZulu-Natal, South Africa. This forest has a distinctive physiognomy, with a thicket-like understorey and an emergent layer of primarily coniferous Podocarpus spp. These emergent trees represent individuals that were too small to be harvested during the colonial period. We argue that the dense angiosperm-dominated understorey arose in gaps created by logging, which allowed greater light levels at the forest floor. The understorey has since been intensively harvested (36% of available stems) for pole-sized stems, including canopy species, effectively suppressing the advanced regeneration as well as the replacement of the senescing canopy and emergent tree populations. The harvesting intensity of pole-sized stems is related to the species, size, and availability of trees. Few straight pole-sized stems are available among the understorey species and typically straight-stemmed canopy species are opportunistically harvested. Examination of community composition further suggests that, without management intervention, this forest will have a reduced stature, a thicket-like physiognomy, and be less diverse and less dominated by conifers. To rescue iGxalingenwa forest from this successional path requires a reduction in harvesting pressure on seedlings and saplings of species that normally dominate the canopy layer, many of which (Podocarpus falcatus, Ptaeroxylon obliquum and Calodendrum capense) appear to have declining populations. The effects of commercial logging a century ago still persist and are being compounded by subsistence harvesting with significant changes to forest physiognomy and composition and the possibility of arrested succession. [Copyright &y& Elsevier]

The distribution of subtropical forests in South Africa is largely a consequence of climatic change during the Quaternary period. We gathered data for 195 canopy tree species from Afrotemperate, scarp, and coastal forests in KwaZulu-Natal, South Africa and assessed patterns in reproductive traits using a comparative phylogenetic approach. The overlap in species composition among the forest types reflected the geographic position and colonisation history of the forests. Despite a high degree of phylogenetic conservatism in reproductive traits, there were differences in their expression among forest types. Afrotemperate forests had a higher incidence of wind pollination, consistent with the steep topography, seasonally dry environment, and limited resource availability in the habitat. Scarp forests had more dry brown fruits with abiotic (explosive and wind) dispersal. Coastal forests had the most species with fleshy fruits, zoochory, and large seeds, all traits that may have facilitated the colonisation or persistence of species in this more recent and dynamic community. Since many suites of traits occur together in diverse phylogenetic lines, they represent adaptive complexes that are influenced by biogeography and environmental conditions. Overall, this study demonstrates that biogeography, environmental factors, and phylogenetic history all influence the distribution of reproductive traits in these forest communities. [ABSTRACT FROM AUTHOR]

In fragmented landscapes, tree recruitment is critical for forest persistence. We examined the effects of disturbance and environmental factors, isolation distance, and forest area on the spatial scale (grain) of regeneration of tree species in Afromontane forest fragments in South Africa. A species’ grain is defined by whether it typically regenerates within its own canopy shadow (fine-grained) or over a larger spatial scale (coarse-grained). Species richness did not differ between small and large forest fragments but there were proportionately more coarse-grained species and fewer fine-grained species in small than in large fragments. While coarse-grained species richness increased with decreasing disturbance and increasing fragment isolation, fine-grained species richness increased with increasing fragment area. Fine-grained species are vulnerable to area-dependent fragmentation pressures. Although they regenerate in their canopy shadow, fine-grained species do not dominate disturbed fragments as expected. While able to survive in small fragments, fine-grained species are potentially dispersal limited and are not good colonisers and depend for their persistence on establishment in large forests. Conversely, because coarse-grained species have effective dispersal mechanisms they can colonise small fragments and are important for the maintenance of tree diversity in fragmented Afromontane forests. Thus, consideration of species grain of regeneration is necessary in conserving Afromontane tree diversity. Fine-grained species are conserved by protecting large forests while coarse-grained species are effectively conserved by maintaining small forest fragments often assumed to be ecologically unviable. [Copyright &y& Elsevier]