A Review of the Impacts and Opportunities for African Urban Dragonflies

Urban settlements range from small villages in rural areas to large metropoles with densely packed infrastructures. Urbanization presents many challenges to the maintenance of freshwater quality and conservation of freshwater biota, especially in Africa. There are many opportunities as well, particularly by fostering contributions from citizen scientists. We review the relationships between dragonflies and urbanization in southern Africa. Shifts in dragonfly assemblages indicate environmental change, as different species are variously sensitive to abiotic and biotic water and bank conditions. They are also conservation umbrellas for many other co-occurring species. Major threats to southern African dragonflies include increasing infrastructure densification, frequent droughts, habitat loss, pollution, and invasive alien vegetation. Mitigation measures include implementation of conservation corridors, maintenance of healthy permanent ponds, pollution reduction, and removal of invasive alien trees. Citizen science is now an important approach for supplementing and supporting professional scientific research.

Hottentot Buttonquail Turnix hottentottus: Endangered or just overlooked?

SummaryThere is remarkably little documented information in the scientific literature on any of the 18 species of buttonquail as they are very difficult to observe in the wild. This lack of information has hampered informed conservation decision making. We undertook the first biome-wide survey for the fynbos endemic Hottentot Buttonquail Turnix hottentottus, using flush transect surveys covering 275 km. We used location data for sightings as well as from records reported by the bird-watching community and modelled distribution using MaxEnt. Encounters were restricted to the fynbos biome, and the top contributors to our prediction of suitable habitat were habitat transformation, slope and time since fire. We obtained a density estimate of 0.032 individuals per hectare which, across an estimated median range of 27,855 km2, provides a population estimate of 89,136 individuals. Given the extent of the range and the population estimate we suggest the IUCN Red List status could be ‘Vulnerable’, rather than ‘Endangered’. Agricultural and alien-vegetation encroachment means that the future of the species is certainly under threat and further studies are needed to inform conservation management.

Accelerating Computer-Based Recognition of Fynbos Leaves Using a Graphics Processing Unit

The Cape Floristic Kingdom (CFK) is the most diverse floristic kingdom in the world and has been declared an international heritage site. However, it is under threat from wild fires and invasive species. Much of the work of managing this natural resource, such as removing alien vegetation or fighting wild fires, is done by volunteers and casual workers. Many fynbos species, for which the Table Mountain National Park is known, are difficult to identify, particularly by non-expert volunteers. Accurate and fast identification of plant species would be beneficial in these contexts. The Fynbos Leaf Optical Recognition Application (FLORA) was thus developed to assist in the recognition of plants of the CFK. The first version of FLORA was developed as a rapid prototype in MATLAB; it utilized sequential algorithms to identify plant leaves, and much of this code was interpreted M files. The initial implementation suffered from slow performance, though, and could not run as a lightweight standalone executable, making it cumbersome. FLORA was thus re-developed as a standalone C++ version that was subsequently enhanced further by accelerating critical routines, by running them on a graphics processing unit (GPU). This paper presents the design and testing of both the C++ version and the GPU-accelerated version of FLORA. Comparative testing was done on all three versions of FLORA, viz., the original MATLAB prototype, the C++ non-accelerated version, and the C++ GPU-accelerated version to show the performance and accuracy of the different versions. The accuracy of the predictions remained consistent across versions. The C++ version was noticeable faster than the original prototype, achieving an average speed-up of 8.7 for high-resolution 3456x2304 pixel images. The GPU-accelerated version was even faster, saving 51.85 ms on average for high-resolution images. Such a time saving would be perceptible for batch processing, such as rebuilding feature descriptors for all the leaves in the leaf database. Further work on this project involves testing the system with a wider variety of leaves and trying different machine learning algorithms for the leaf prediction routines.

Land transformation and its implication for biodiversity integrity and hydrological functioning from 1944 to 1999, Karkloof catchment, South Africa

Background and objectives: Land transformation of the Karkloof catchment is described for the period 1944–1999, together with implications for biodiversity integrity and hydrological functioning.Method: Maps of land categories were generated by using aerial photographs and a geographical information system. Property ownership and extent were mapped based on title deed searches and analysis of property grants. Implications of land transformation on biodiversity integrity and hydrological functioning were determined according to an expert approach using the analytic hierarchy process.Results: More than half (54%) of the natural grassland area has been transformed to commercial timber plantations (427% increase) and commercial agricultural cropping (311% increase). Loss of grassland in the Karkloof catchment is considered to be representative of the general trend in the moist eastern portion of the Grassland Biome of South Africa. Both combined forest and woodland and areas of dense alien vegetation increased (26% and 397%, respectively), whereas the area under subsistence cultivation decreased (98%). Land ownership has changed from private individuals to private business entities (31%) and corporate forestry (26%). Biodiversity integrity of the catchment is estimated to have decreased by 326% and hydrological functioning for the support of aquatic biodiversity by 166%.Conclusion: Continued pressure to change patterns of ownership and land use is expected. This is likely to occur within the global context of climate change, population growth and shortages of land and its products. Immense pressure on the land areas, and specifically water services and biodiversity, is likely to occur, with associated environmental impacts.

The role and value of water in natural capital restoration on the Agulhas Plain

The Agulhas Plain is a low-lying coastal area within the Cape Floristic Region. It is heavily invaded by alien vegetation that infringes upon the sustainable supply of ecosystem goods and services provided by the native fynbos vegetation. Alien clearing and natural capital restoration is expected to recover these ecosystem goods and services and in particular to increase water availability. The study conducts cost-benefit analyses to assess whether alien clearing and natural capital restoration would add value to the Agulhas Plain through sufficiently increasing the supply of marketable ecosystem goods and services. The results indicate that the costs of alien clearing and restoration cannot be justified in the absence of water as a valued commodity. Other ecosystem goods and services included have a negligible impact on justifying costs.

Application of the contingent valuation method to estimate the willingness-to-pay for restoring indigenous vegetation in Underberg, Kwazulu-Natal, South Africa

This study estimates the willingness-to-pay (WTP) for a project (i.e. the Working for Water Programme) aimed at removing alien vegetation and restoring indigenous vegetation in Underberg, KwaZulu-Natal, South Africa. The WTP estimate reflects the benefit of preference for indigenous vegetation over alien vegetation. In a survey, a questionnaire was administered to 260 households in the Underberg region during September 2005. It was deduced that the mean WTP for the project was R21.12 in 2005 (R26.40 in 2008), the total WTP was R25 344.00 (R31 680.00 in 2008) and the WTP per hectare was R21.87 (R27.34 in 2008). A valuation function to predict WTP responses was also estimated. The function showed that knowledge of the local Working for Water Programme and income were important determinants of WTP.