Privett S.D.J.,Fynbos Ecoscapes |
Krug R.M.,University Paris - Sud |
Krug R.M.,Stellenbosch University |
Forbes G.,CapeNature |
Gaertner M.,Stellenbosch University
South African Journal of Botany | Year: 2014
We present a simple method for assessing the medium-term sustainability of different flower harvesting intensities (i.e. percentage of number of stems harvested per individual) for two re-seeders and re-sprouters of fynbos plants on the Agulhas Plain in the Cape Floristic Region, South Africa. We interpret our results from an ecological point of view, looking at impacts of harvesting on vegetative re-growth and survival of frequently harvested fynbos species, and an economic point of view, determining the cumulative number of stems harvested per year.We analysed the impact of different harvesting intensities on two obligate re-seeding (Erica corifolia (L.) and Erica imbricata (L.)) and two strongly re-sprouting species (Brunia laevis (Thunb.) and Staavia radiata (L. Dahl)) on different flower farms. Seventy-five randomly selected plants of each species were experimentally harvested in the same way as is done by flower harvesters. Fifteen plants of each species were left as controls (un-harvested) and 15 each were harvested (cut 15-20. cm below the inflorescence) such that 25%, 50%, 75%, and 100% of the inflorescences were removed. Harvested stems were labelled and the number of new shoots counted. Additionally we recorded plant height and mortality.100% harvesting resulted in high mortality rates for both re-seeders (for both species 100% of the individuals were dead at the end of the experiment) and resprouters (for one species all 15 individuals were dead at the end of the experiment and for the other species 4 of 15). Re-seeders in particular were highly susceptible to harvesting below the first branching node, which generally also resulted in plant death. Both guilds can survive up to 75% harvesting (resprouters experienced no mortality for one species, while in the other 4 out of 15 died; of the re-seeders, 9 out of 15 died in the one species, while only 1 out of 15 in the other) and are still able to grow in height. For both seeders and resprouters we recommend that flower harvesters do not harvest in young veld. To ensure sufficient seed set and to avoid seed bank depletion we recommend to preferably only harvest between 25 and 50% of stems per individual. © 2014 South African Association of Botanists.
Durant J.M.,University of Oslo |
Crawford R.J.M.,Oceans and Coasts |
Crawford R.J.M.,University of Cape Town |
Wolfaardt A.C.,University of Cape Town |
And 5 more authors.
Marine Ecology Progress Series | Year: 2010
Off the coast of South Africa, the 2 most important prey items for African penguins Spheniscus demersus are sardine Sardinops sagax and anchovy Engraulis encrasicolus, species heavily exploited by commercial fisheries. At Dassen Island, the proportion of burrows occupied for breeding by African penguins from 1995 to 2008 was affected positively by the interaction between the overall biomass of sardine and anchovy. However, sardine had a positive effect while anchovy had a negative one. This unexpected negative relationship may result from a reduced local availability of anchovy linked to the fishing effort that continued to be focussed in the vicinity of Dassen Island, while the growing anchovy stock experienced an eastward shift away from Dassen Island in recent years, creating a spatial mismatch between penguin and available anchovy. A decrease of the Southern Oscillation Index tended to advance the onset of penguins' breeding, as did an increase in sea surface temperature (SST) at the sardine and anchovy spawning grounds. An increase in SST at the nursery and spawning areas tended to decrease the penguin per capita growth rate. Earlier breeding resulted in decreased chick production, possibly because it created a temporal mismatch between chick rearing and winter availability of young-of-the-year anchovy and sardine along South Africa's west coast. The local abundance of prey is more important for breeding African penguins than overall fish abundance. Consequently, management of the purse-seine fishery should be adjusted spatially in order to ensure adequate local food supplies for breeding African penguins. © Inter-Research 2010.
Veldtman R.,Stellenbosch University |
Veldtman R.,South African National Biodiversity Institute |
Lado T.F.,Stellenbosch University |
Lado T.F.,South African National Biodiversity Institute |
And 6 more authors.
Diversity and Distributions | Year: 2011
Aim The use of host-specific biological control agents is widely considered an effective option for the management of invasive alien plant species. However, the formation of novel associations between released biological control agents and indigenous species poses risks. Here, we investigate whether native food webs associated with two galling biological control agents on Acacia longifolia and A. saligna are similar to those found in their introduced range. Location Gall inhabitants recorded from South Africa and Australia. Methods Non-targeted insects were collected from galls in introduced ranges for comparisons to that of the agents' native ranges. Results We find that two host plant-specific galling biological control agents accumulate food web links with higher trophic levels in their introduced range that are similar in number, taxonomic/phylogenetic pattern and guild composition to those in their native range. Bray-Curtis percentage similarity between native (Australia) and novel (South Africa) food webs was 30-50% and 50-75% at the family and superfamily taxonomic level, respectively, and 45-50% if considering shared phylogenetic diversity. Main conclusions Trichilogaster acaciaelongifoliae and Uromycladium tepperianum accumulated food webs in South Africa that are strikingly similar in complexity and structure to those that occur in their native ranges. This indicates that the structure of food webs in the introduced range could be predicted by studying food webs in the native range of a biological control agent, potentially paving the way for more effective risk assessment of weed biological control. © 2011 Blackwell Publishing Ltd.
Weyl O.L.F.,South African Institute For Aquatic Biodiversity |
Impson N.D.,CapeNature |
Woodford D.J.,South African Institute For Aquatic Biodiversity |
Steinkjer J.,Norwegian Directorate for Nature Management
Fisheries | Year: 2014
Nonnative fishes threaten native fish communities in many rivers of the world. In South Africa's Cape Floristic Region, predation by nonnative fishes has severely impacted native fish populations and more than half of the 17 endemic fish species are endangered. To preserve the unique endemic fish fauna, removal of nonnative fish from conservation areas is a priority in this region. In February 2012, South Africa's first nonnative fish eradication using rotenone took place in the Rondegat River, a small headwater stream that had been invaded by Smallmouth Bass (Micropterus dolomieu). The successful treatment culminated from a decade-long process that was facilitated through collaboration among a South African nature conservation authority (CapeNature), the South African Institute for Aquatic Biodiversity, and the American Fisheries Society Fish Management Chemicals Subcommittee. The successful removal of alien fish and almost instantaneous increase in biodiversity is anticipated to encourage more endemic fish restorations in South Africa. © 2014 American Fisheries Society.
Mcconnachie M.M.,Stellenbosch University |
van Wilgen B.W.,Stellenbosch University |
Richardson D.M.,Stellenbosch University |
Ferraro P.J.,Georgia State University |
Journal of Applied Ecology | Year: 2015
Protected areas (PAs) are a key intervention for conserving biodiversity and ecosystem services. A major challenge for PAs is the control of invasive non-native plants that spread into PAs from surrounding sources such as forestry plantations. The links between invasions and different source populations are poorly understood, making it difficult to apportion responsibilities for control costs. We estimated the effect of plantations of invasive pines (Pinus species) on the spread of these trees into PAs in South Africa's Cape Floristic Region (CFR). We assessed the effect of (i) distance from plantation, (ii) plantation and PA orientation in relation to the prevailing wind and (iii) the proportionate size of the surrounding plantation on the abundance of invasions in PAs. We also estimated the historic and potential future costs of controlling invasions in the PAs. PA management units within 3 km of a plantation had over double the pine cover of control units >6 km from plantations (6·12% vs. 2·39%). We attributed 51% of the pine invasions in PAs to plantations. Neither the proportional size of the plantations nor their orientation relative to prevailing winds had a detectable effect on the cover of invasive pines. Costs of controlling invasive pines in the study area totalled 98 million Rand (10 Rand = c. 1 US$ in 2013) between 2001 and 2012. It could cost between 273 and 916 million Rand (all future costs expressed in 2013 Rand), and take between 34 and 113 years, to clear the remaining invasive pines in the study area, depending on rates of spread and the cost-effectiveness of control. Policy implications. Estimating the contribution of an invasion source, in this case forestry plantations, requires estimating an unobservable counterfactual outcome: the invasions that would have occurred in the absence of the plantations. We have made a first step towards doing this by using empirical approaches that vary in the strictness of their assumptions, along with robustness tests to that assess the plausibility of these assumptions. Our study provides the starting point for estimating the contribution of plantation forestry to protected area invasions in the Cape Floristic Region of South Africa. Estimating the contribution of an invasion source, in this case forestry plantations, requires estimating an unobservable counterfactual outcome: the invasions that would have occurred in the absence of the plantations. We have made a first step towards doing this by using empirical approaches that vary in the strictness of their assumptions, along with robustness tests to that assess the plausibility of these assumptions. Our study provides the starting point for estimating the contribution of plantation forestry to protected area invasions in the Cape Floristic Region of South Africa. © 2014 British Ecological Society.
Nel J.L.,South African Council for Scientific and Industrial Research |
Reyers B.,South African Council for Scientific and Industrial Research |
Roux D.J.,Water Research Node |
Dean Impson N.,CapeNature |
Cowling R.M.,Nelson Mandela Metropolitan University
Freshwater Biology | Year: 2011
1. The progression of approaches in systematic conservation planning from representation to representation and persistence has greatly enhanced its potential applicability to freshwaters. However, conceptual frameworks that consolidate principles for incorporating persistence into freshwater conservation planning are still lacking.2. We present four key principles to consider when planning for the persistence of freshwater biodiversity: selecting ecosystems of high ecological integrity; incorporating connectivity; incorporating areas important to population persistence; and identifying additional natural processes that can be mapped.3. The practicalities of gathering data and conducting the conservation plan to address these principles are explored here using a case study in the Olifants/Doorn Water Management Area, South Africa. Spatial layers are developed for depicting ecological integrity, sub-catchment boundaries, riparian zones and wetlands, high water-yield areas and patterns of groundwater discharge and recharge.4. These data are used to develop a conservation area network that supports both representation and persistence of freshwater biodiversity. Although the planning region is relatively data rich by global standards, several data deficiencies were identified. We suggest ways of using environmental surrogates to address data deficiencies, improving confidence in these surrogates by combining them wherever possible with existing field data and expert knowledge.5. We also recommend methods to achieve spatial efficiency by simultaneously designing for representation and persistence of freshwater biodiversity. Spatial efficiency can be achieved in different ways when using a conservation planning algorithm and a multiple-use zoning strategy.6. The allocation of multiple-use zones aligns closely with the objectives of integrated water resources management and land use planning. Given the practicalities at local levels of planning, we recommend using multiple-use zones in the design phase, rather than merely at the end once the design is complete. © 2010 Blackwell Publishing Ltd.
Crawford R.J.M.,Branch Oceans and Coasts |
Crawford R.J.M.,University of Cape Town |
Makhado A.B.,Branch Oceans and Coasts |
Makhado A.B.,University of Cape Town |
And 2 more authors.
Ostrich | Year: 2014
There were recent changes in the distributions of the main prey of four seabirds off South Africa, with sardine Sardinops sagax and anchovy Engraulis encrasicolus shifting from South Africa's north-west coast towards the south-east. This contributed to numbers of African Penguins Spheniscus demersus and Cape Cormorants Phalacrocorax capensis breeding in South Africa decreasing by more than 50%. By contrast, numbers of Cape Gannets Morus capensis and Swift (Crested) Terns Thalasseus bergii increased. The success of the gannet and the tern in the face of recent change is attributable to a rapid increase in South Africa's eastern colony of gannets, aided by high survival of adult birds and perhaps by immigration of first-time breeders from decreasing western colonies, and a probable high production of Swift Terns. The gannet has an extensive foraging range and the tern is nomadic between breeding localities, which gives these species greater flexibility than the other two to adapt to large changes in the distributions of their prey. Additionally, the gannet is able to supplement its diet with fishery discards. A lesser mobility of the African Penguin and the Cape Cormorant rendered them susceptible to a reduced local availability of prey and both species suffered high adult mortality in the last decade. © 2014, Copyright © NISC (Pty) Ltd.
Selinske M.J.,Imperial College London |
Coetzee J.,Rhodes University |
Purnell K.,CapeNature |
Knight A.T.,Imperial College London |
And 2 more authors.
Conservation Letters | Year: 2015
Private land conservation is an increasingly popular approach to protect critical biodiversity. In the Western Cape Province of South Africa private land conservation is the focal strategy for CapeNature, the provincial conservation agency. Despite its importance, little is known about the drivers of landowner participation in the CapeNature program and how these varied motivations influence participant satisfaction and retention. Our psychometric survey of 75 enrolled landowners found that the highest ranked motivations to participate were Conservation and Place Attachment but Social Learning had a stronger influence on program satisfaction. Landowners participate to fulfill a motivation or set of motivations but their satisfaction and commitment may hinge on other unforeseen motivations or factors. Understanding the relationship between motivations, satisfaction, and commitment is necessary for a successful retention strategy in any conservation program, especially on private lands where success depends on landowner commitment. This research was incorporated into improving CapeNature's program delivery. © 2014 The Authors.
Marr S.M.,University of Cape Town |
Impson N.D.,CapeNature |
Tweddle D.,South African Institute For Aquatic Biodiversity
African Journal of Aquatic Science | Year: 2012
Non-native fish are considered the most important threat to the survival of the indigenous freshwater fishes in the Cape Floristic Region (CFR). A pilot project to evaluate the use of the piscicide rotenone to eradicate non-native fish from selected reaches in four rivers has been proposed by CapeNature, the conservation authority of the Western Cape province, South Africa. Each river has unique characteristics and challenges to achieving the eradication of non-native fish and the restoration of its indigenous fish assemblage. The proposal is described and the management methods available for reducing the impact of non-native fish on indigenous species are discussed. An environmental impact assessment (EIA) concluded that the project was justified and necessary, the choice of rivers sound, and supported the use of piscicides. The need for the project, the selection of sites and the findings of the EIA are discussed. It is expected that the project will be successful while having minimal impact on other aquatic fauna. The successful completion of the pilot project could help establish methods to eradicate non-native fish from critical biodiversity areas in South Africa. Such projects must, however, be part of a comprehensive conservation management plan to be implemented by conservation agencies in the CFR. © 2012 Copyright NISC (Pty) Ltd.
Sherley R.B.,University of Cape Town |
Waller L.J.,University of Cape Town |
Strauss V.,Southern African Foundation for the Conservation of Coastal Birds |
Geldenhuys D.,CapeNature |
And 2 more authors.
PLoS ONE | Year: 2014
The African penguin Spheniscus demersus has an 'Endangered' conservation status and a decreasing population. Following abandonment, 841 African penguin chicks in 2006 and 481 in 2007 were admitted to SANCCOB (Southern African Foundation for the Conservation of Coastal Birds) for hand-rearing from colonies in the Western Cape, South Africa, after large numbers of breeding adults commenced moult with chicks still in the nest. Of those admitted, 91% and 73% respectively were released into the wild. There were veterinary concerns about avian malaria, airsacculitis and pneumonia, feather-loss and pododermatitis (bumblefoot). Post-release juvenile (0.32, s.e. = 0.08) and adult (0.76, s.e. = 0.10) survival rates were similar to African penguin chicks reared after oil spills and to recent survival rates recorded for naturally-reared birds. By December 2012, 12 birds had bred, six at their colony of origin, and the apparent recruitment rate was 0.11 (s.e. =0.03). Hand-rearing of abandoned penguin chicks is recommended as a conservation tool to limit mortality and to bolster the population at specific colonies. The feasibility of conservation translocations for the creation of new colonies for this species using hand-reared chicks warrants investigation. Any such programme would be predicated on adequate disease surveillance programmes established to minimise the risk of disease introduction to wild birds. Copyright: © 2014 Sherley et al.