Floristic composition in relation to environmental gradients across KwaZulu-Natal, South Africa (original) (raw)
Related papers
Land cover and climate change threats to savanna and grassland habitats in KwaZulu-Natal
2017
Conservation planning in the face of global change is still in its infancy. A suggested approach is to incorporate environmental gradients into conservation planning as they reflect the ecological and evolutionary processes generating and maintaining diversity. Our study provides a framework to identify the dominant environmental gradients determining floristic composition and pattern. Nonmetric multidimensional scaling was used on 2155 sampling plots in savanna and grassland habitat located across the province of KwaZulu-Natal, South Africa (94 697 km), a floristically rich region having steep environmental gradients, to determine the dominant gradients. Hierarchical cluster analysis was used to group similar plots which were then used in a Classification and Regression Tree analysis to determine the environmental delimiters of the identified vegetation clusters. Temperature-related variables were the strongest delimiters of floristic composition across the province, in particular ...
Incorporating ecological and evolutionary processes into continental-scale conservation planning
Ecological Applications, 2009
Systematic conservation planning research has focused on designing systems of conservation areas that efficiently protect a comprehensive and representative set of species and habitats. Recently, there has been an emphasis on improving the adequacy of conservation area design to promote the persistence and future generation of biodiversity. Few studies have explored incorporating ecological and evolutionary processes into conservation planning assessments. Biodiversity in Australia is maintained and generated by numerous ecological and evolutionary processes at various spatial and temporal scales. We accommodated ecological and evolutionary processes in four ways: (1) using sub-catchments as planning units to facilitate the protection of the integrity and function of ecosystem processes occurring on a sub-catchment scale;
The application of systematic conservation planning in the Succulent Karoo biome of South Africa /
Systematic conservation planning is about making spatially explicit decisions regarding the use of land, based on the observed or expected biodiversity present at a site and the potential for that same site to support alternative /and-uses that are not compatible with the persistence of biodiversity. This thesis examines three questions relating to the application of systematic conservation planning: Which biodiversity surrogates should be used in Namaqualand to do systematic conservation plans? How should targets be set for these surrogates? How can this information be integrated and used within a systematic conservation planning framework? Comparing how well different biodiversity surrogates achieved a set of targets illustrated that continuous biodiversity data (i.e. vegetation types and land-classes) perform better as surrogates than point-based species distribution data. Quarter degree square-based species distribution data cannot be used for on-the-ground conservation planning. It was demonstrated that it is possible to set biologically meaningful conservation targets to represent biodiversity pattern in land classes by applying the Species Area Relationship and using plot-based survey data. The method developed here has the potential to revolutionise conservation planning as it provides for the first time a defensible means for setting representation targets for land classes that are grounded on ecological theory and that use real data. The thesis also explores the potential for metapopulation and fragmentation studies to provide useful insights into developing targets for ecological processes by relating the amount of remaining habitat to key thresholds in probability of population persistence. Two examples, at different spatial scales (1:10 000 and 1:100 000), are used to illustrate how different biodiversity information can be integrated and used within a systematic conservation planning framework. At the finer scale biodiversity and land-use data are 2 The Use of Biodiversity Surrogates in Regional ConseNation Plans .
Diversity and Distributions, 2009
Aim To examine whether at a sub-continental scale range-limited species tend to occur close to areas of transition between vegetation boundaries more often than expected by chance. Location South Africa and Lesotho. Methods We examined the relationship between the distance of a grid square to ecological transition areas between vegetation types and both avian and frog rangelimited species richness in the quadrat. We used quadrats at a spatial resolution of quarter degree (15 ′ × 15 ′ ≈ 676 km 2). Spatial congruence between areas representing range-restricted species and those representing ecological transition zones was assessed using a random draw technique. Results Species richness and range size rarity are generally negatively correlated with distance to transition areas between vegetation communities when analysed for the whole region for both groups. Although this relationship becomes weaker after controlling for environmental energy and topographical heterogeneity, the explanatory power of distance to transition areas remains significant, and compared to the different biomes examined, accounts for most of the variation in bird richness (20%), frog richness (18%), range-restricted bird species (17%) and range-restricted frog species (16%) in the savanna biome. The random draw technique indicated that areas representing range-restricted species were situated significantly closer in space to those areas representing transition areas between vegetation communities than expected by chance. Main conclusions We find that at the sub-continental scale, when examined for South Africa, areas of transition between vegetation communities hold concentrations of range-limited species in both birds and frogs. We find that South African endemic/range-limited birds and frogs are located closer to ecological transition zones than endemics and non-endemics combined. This has important implications for ongoing conservation planning in a biogeographical context.
Planning for the Maintenance of Floristic Diversity in the Face of Land Cover and Climate Change
Environmental Management, 2017
Habitat loss and climate change are primary drivers of global biodiversity loss. Species will need to track changing environmental conditions through fragmented and transformed landscapes such as KwaZulu-Natal, South Africa. Landscape connectivity is an important tool for maintaining resilience to global change. We develop a coarse-grained connectivity map between protected areas to aid decision-making for implementing corridors to maintain floristic diversity in the face of global change. The spatial location of corridors was prioritised using a biological underpinning of floristic composition that incorporated high beta diversity regions, important plant areas, climate refugia, and aligned to major climatic gradients driving floristic pattern. We used Linkage Mapper to develop the connectivity network. The resistance layer was based on landcover categories with natural areas discounted according to their contribution towards meeting the biological objectives. Three corridor maps were developed; a conservative option for meeting minimum corridor requirements, an optimal option for meeting a target amount of 50% of the landscape and an option including linkages in highly transformed areas. The importance of various protected areas and critical linkages in maintaining landscape connectivity are discussed, disconnected protected areas and pinch points identified where the loss of small areas could compromise landscape connectivity. This framework is suggested as a way to conserve floristic diversity into the future and is recommended as an approach for other global connectivity initiatives. A lack of implementation of corridors will lead to further habitat loss and fragmentation, resulting in further risk to plant diversity.
Animal Conservation, 2016
In biodiversity-rich landscapes that are developing rapidly, it is generally impossible to delineate land use and prioritize conservation actions in relation to the full variability of species and their responses to anthropogenic activity. Consequently, conservation policy often focuses on protecting habitat used by a few flagship, indicator or umbrella species like tigers Panthera tigris and Asian elephants Elephas maximus, which potentially leaves out species that do not share these habitat preferences. We demonstrate an empirical approach that clustered 14 mammals into surrogate groups that reflect their unique conservation needs. We surveyed a 787 km 2 multiple-use area in the Shencottah Gap of the Western Ghats, India, using foot surveys and camera-trap surveys. Using ecological niche factor analysis, we generated indices of species prevalence (marginality and tolerance) and habitat preferences (factor correlations to marginality axis). We then clustered species by both of the above index types to reveal four clusters based on prevalence and four clusters based on habitat preference. Most clusters contained at least one threatened species. Low-prevalence lion-tailed macaques Macaca silenus and tigers were strongly associated with closed forests and low human disturbance. But elephants, sloth bears Melursus ursinus and gaur Bos gaurus were more tolerant of anthropogenic impact, and sloth bears and gaur preferred open forests and grasslands. Dhole Cuon alpinus and sambar Rusa unicolor were associated with highly anthropogenic habitat (farmland, cash crop and forestry plantations) with high human use. Thus, reliance on flagship species for conservation planning can both underestimate and overestimate the ability of other species to persist in multipleuse landscapes; protecting flagship species would only protect species with similar habitat preferences. For species that avoid human impacts more than the flagship species, core habitat must be protected from human disturbance. For more tolerant species, conservation in anthropogenic habitat may hinge on policies that bolster coexistence with humans.
Biological Conservation, 2010
Riparian zones are important for the many ecosystem services they supply. In settled areas, the vegetation of such zones is shaped by human land-use; this often creates conditions under which alien plant species thrive. Alien plants have been shown to induce large-scale changes in riparian habitats, and they pose a major threat to the continued provision of key ecosystem services. We used direct gradient analysis to assess correlations between land-use and the composition of vegetation along a riparian river corridor in the highly transformed landscape surrounding Stellenbosch in South Africa's Western Cape Province. Vegetation plots were sampled along the entire length of the river from headwaters to estuary (ca. 40 km). Plant community composition was analyzed in relation to land-use data collected in the field, and additional land-use variables computed from digital land-cover data. Patterns of plant community structure were found to be directly related to land-use, with measures of cover, richness, and diversity differing significantly among land-use types. Portions of the riparian zone adjacent to agricultural land had the greatest level of alien plant cover, while areas bordered by urban land maintained the highest alien species richness. Areas adjacent to grazing and natural lands showed intermediate and low levels of invasion, respectively. Several native species were found to persist in areas with high abundance and diversity of invasive alien plants, suggesting that they will be valuable focal species for future restoration attempts. Due to the level of human-mediated change in many areas of the riparian zone, restoration to historic conditions over most of the river is not considered feasible. These areas should be recognized as examples of novel ecosystems, and management efforts should focus on restoring or creating desirable ecosystem functions, rather than on achieving assemblages comprising only native species.
Bothalia, 2008
A temperature and moisture gradient on the equator-facing slope of Jonaskop on the Riviersonderend Mountain. Westem Cape has been selected as an important gradient for monitoring the effects of climate change on fynbos and the Fynbos- Succulent Karoo ecotone. This study provides a description of plant diversity patterns, growth form composition and species turnover across the gradient and the results of four years of climate monitoring at selected points along the altitudinal gradient.The aim o f this study is to provide data for a focused monitoring strategy for the early detection of climate change-related shifts in species’ ranges, as well as gaining a better understanding of the role of climate variability in shaping species growth responses, their distributions, and other ecosystem processes.