Browsing by Author "Durrheim, Graham"
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- ItemMonitoring consumptive resource use in South African national parks(AOSIS, 2019-01-30) Vermeulen, Wessel; Van Wilgen, Niclola; Smith, Kyle; Dopolo, Mbulelo; Swemmer, Louise; Annecke, Wendy; Bezuidenhout, Hugo; Durrheim, Graham; Hanekom, Nick; Hendricks, Howard; McGeoch, Melodie; Ngubeni, Ntombizodwa; Symonds, AlexisMonitoring is an essential component of measuring the performance of protected areas. This requirement led to the development of a biodiversity monitoring system for South African National Parks (SANParks). The system comprises of ten major programmes, each focusing on a core area of conservation biodiversity monitoring, with resource use being one of the focal areas. With the growing appreciation of the importance of natural resources for the socioeconomic well-being of communities and other stakeholders, sustainable resource use is an important component of the management of natural areas and national parks. To gauge sustainability, a sound monitoring and research programme that fits within the context of the SANParks’ adaptive management approach towards social-ecological system management is required. The purpose of this article was to define the context and scope in which consumptive resource use takes place within SANParks and to outline the criteria necessary for developing a sound monitoring programme to assess the sustainability of such use. The monitoring programme is structured in view of the fact that sustainable resource use is achievable only where all dimensions of sustainability (social, economic and ecological) are considered simultaneously. In terms of the social and economic dimensions of sustainability, the programme provides for assessing stakeholder needs, trends in resource use and the social and economic impacts of resource use. Monitoring that relates to the ecological dimension of sustainability of biological resource use deals with the rate of turnover and population dynamics of target species, as well as harvest impact. In terms of abiotic (non-renewable) resources, monitoring deals with sound management practices to minimise impact on the environment, and to optimise benefits through responsible use. Conservation implications: The resource use monitoring programme is intended to ensure that monitoring relating to the harvesting of natural resources from national parks is scientifically sound and conducted in a structured way, towards meeting the objective of sustainable use and compliance with national legislation. The article illustrates how SANParks meets its obligation to monitor biodiversity conservation while at the same time meeting the needs for the consumptive use of resources.
- ItemQuantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity(SpringerOpen, 2018) Hui, Cang; Vermeulen, Wessel; Durrheim, GrahamBackground: Species turnover is typically measured by partitioning diversity components into alpha and pairwise beta diversity. However, alpha and beta components cannot express the full spectrum of multiple-site compositional turnover. To this end, zeta diversity has been proposed as an extended framework to allow complete biodiversity partitioning and to measure multiple-site species turnover. We use a zeta-diversity framework to explore the turnover and potential community assembly processes of an African Montane Forest. Methods: Using a 20 m grid, we explore the species turnover in a 4.55 ha forest plot located in the Garden Route National Park of South Africa, with 47 and 27 canopy and sub-canopy tree species in the regional pool. We first calculate how zeta diversity declines and how the probability of retention of species with particular occupancies changes with increasing zeta orders (i.e. the number of sites [grid cells] involved in the calculation). Using null models with row sums and column sums constrained respectively, we explore whether species turnover is driven by mechanisms of ecological differences (species-specific occupancies) or habitat heterogeneity (site-specific alpha diversity and thus environmental filters). Results: The decline of zeta diversity with zeta order followed a power law; that is, the probability of retention increased with species occupancies, suggesting common species being more likely to be discovered in extra sites. The null model retaining row sums (species’ occupancy) of the species-by-site matrix recreated perfectly the decline of zeta diversity, while the null model of habitat heterogeneity (retaining column sums) was rejected. This suggests that mechanisms driving species-specific occupancies (i.e. ecological differences between species) dictate the multi-site species turnover in the community. The spatial patterns of zeta diversity revealed little spatial structuring forces, supporting a fine-grain structure in these southern Cape forests. Conclusions: The framework of zeta diversity revealed mechanisms driving the large discrepancies in the occupancy among species that are behind the species turnover in the African Montane forest plot. Future studies could further link species turnover to spatial distance decay. Environmental filters and temporal turnover from landscape demography could bring a cohesive understanding of community assembly in these unique forest ecosystems.