Anthony G. Rebelo

Effectiveness of land classes as surrogates for species in conservation planning for the Cape Floristic Region

Land classes are often used in conservation planning as surrogates for species. The relationship between these surrogates and the distribution of species is usually assumed but rarely tested. Using broad habitat units (BHUs) to represent biodiversity pattern in the Cape Floristic Region, together with point locality data for species (proteas and selected vertebrates), we calculated the effectiveness of BHUs as surrogates for species. Our planning units were grid cells of about 40 km(2), together with boundaries of existing reserves. After assigning conservation targets to BHUs, we derived minimum sets of planning units to meet all targets and calculated irreplaceability values for all units (irreplaceability measures the likelihood of a unit being required to achieve targets). Results showed that BHUs were good surrogates for the majority of protea species, but were not good surrogates for vertebrate species or for a small subset of protea species. These species shared the following characteristics: rarity, limited ranges, Red Data Book status, specialised habitats not defined by BHUs, and distributions driven by historical rather than contemporary ecological factors. We show that targeting land classes and species simultaneously is a viable option and requires only 0.1-0.8% more land (depending on species targets) than targeting land classes alone. We conclude by recommending two different strategies for combining land class and species data in conservation planning, depending on data availability.

Protection of Fynbos vegetation: Ideal and real-world options

Abstract Schemes are set out for the location of noda of nature reserves aimed at protecting the floral diversity of Fynbos vegetation in the Cape Floral Region, in South Africa, using distributional data on the Proteaceae. Species richness is significantly correlated between the Proteaceae and other major families and genera of plants representative of Fynbos, for which data are available. In our ideal scheme, 95% of all vascular plant species could be accommodated in 16% of the area occupied by Fynbos vegetation. However, several of our ideal-world noda are not viable options for Fynbos protection. Hence, we identify additional nodal areas that could be proclaimed as nuclei for nature reserves and incorporated into a real-world option for maximizing the protection of Fynbos floral diversity.

Can Cape Town's unique biodiversity be saved? Balancing conservation imperatives and development needs.

Cape Town is an urban hotspot within the Cape Floristic Region global biodiversity hotspot. This city of 2,460 km2 encompasses four local centers of fynbos plant endemism, 19 national terrestrial vegetation types (six endemic to the city), wetland and coastal ecosystems, and 190 endemic plant species. Biodiversity in the lowlands is under threat of extinction as a result of habitat loss to agriculture, urban development, mining, and degradation by invasive alien plants. Cape Town’s population is 3.7 million, increasing by an estimated 55,000 people/yr, which puts pressure on biodiversity remnants for development. South Africa is a signatory to international instruments to reduce biodiversity loss and has a good legislative and policy framework to conserve biodiversity, yet implementation actions are slow, with limited national and provincial support to conserve Cape Town’s unique and irreplaceable biodiversity. The lack-of-action problem is two-fold: national government is slow to implement the policies developed to realize the international instruments it has signed, with conservation initiatives inadequately funded; and local governments are not yet recognized as important implementation partners. A further problem is created by conflicting policies such as the national housing policy that contributes to urban sprawl and loss of critical biodiversity areas. The City’s Biodiversity Management Branch, with partners, is making some headway at implementation, but stronger political commitment is needed at all levels of government. Our objective is to improve the status and management of biodiversity in existing conservation areas through the statutory proclamation process and management effectiveness monitoring, respectively, and to secure priority areas of the BioNet, Cape Town’s systematic biodiversity plan. The most important tools for the latter are incorporating the BioNet plan into City spatial plans; communication, education, and public awareness; negotiating appropriate management of public land; and conservation stewardship on private land. The timeframe to save Cape Town’s biodiversity is short, and it is unlikely that full success will be achieved without national or international funding and political will at all levels of government.

Commercial exploitation of Brunia albiflora (Bruniaceae) in South Africa

Abstract The effects of commercial exploitation on the mortality and seed production of a serotinous, obligate reseeder, Brunia albiflora, were investigated in fynbos vegetation, South Africa. Plant size, fruit production and plucking intensity were assessed in three exploited and two unexploited populations. Mortality in commercially exploited populations of B. albiflora varied between 8 and 33%, compared with a natural mortality of 1 to 3%. Mortality was much greater (14–33%) in exploited populations on hired land than in a population plucked by the owner, despite a higher intensity of utilization in the latter. Mortality and plucking intensity varied considerably within populations in the Kleinmond Nature Reserve, probably reflecting both population structure and plucking preferences. Fruit production in exploited populations was reduced to one-third that of unexploited populations. Larger plants were selected by pluckers, thus reducing seed production in the populations most productive plants. Plucking increased the proportion of plants which produced epicormic buds at the trunk of the plant. A method for assessing the impacts of exploitation of vegetation is required to ensure that populations of B. albiflora are not exploited beyond their capacity to regenerate. Until data on such impacts become available, it is recommende that all plucking in nature reserves and conservation areas in fynbos should be terminated.

The preservation of plant species in the Cape Floristic Region: problems with the available data bases for the Riversdale Magisterial District

An evaluation of optimal reserve networks requires a data base containing lists of species currently preserved and regional lists for remaining areas. We evaluated two such data bases for the Riversdale Magisterial District: P recis and a catalogue published in 1984. Although the catalogue was more accurate than Precis, having an error of 7 versus 26 per cent of the species listed in the district, neither is adequate for conservation planning purposes. We propose that regional herbaria should be catalogued on data bases intercompatible with a Geographic Information System, that the Catalogue should be updated, computerized and include more detailed distribution and rarity data, and that P recis must be thoroughly verified. Only then can these data bases be of use to planning conservation strategies in the Cape Floristic Region.