Showing papers by "Barend F.N. Erasmus published in 2010"

Getting the most out of atlas data

Abstract: Aim To review some of the applications in ecology and conservation biogeography of datasets derived from atlas projects We discuss data applications and data quality issues and suggest ways in which atlas data could be improved Location Southern Africa and worldwide Methods Atlas projects are broadly defined as collections or syntheses of original, spatially explicit data on species occurrences We review uses of atlas datasets and discuss data quality issues using examples from atlas projects in southern Africa and worldwide Results Atlas projects must cope with tradeoffs between data quality and quantity, standardization of sampling methods, quantification of sampling effort, and mismatches in skills and expectations between data collectors and data users The most useful atlases have a good measure of sampling effort; include data collected at a fine enough resolution to link to habitat variables of potential interest; have a sufficiently large sample size to work with in a multivariate context; and offer clear, quantitative indications of the quality of each record to allow for the needs of users who have specific demands for high-quality data Main conclusions Atlases have an important role to play in biodiversity conservation and ideally should aim to offer reliable, high quality data that can withstand public, scientific and legal scrutiny

Land-cover change in the Kruger to Canyons Biosphere Reserve (1993-2006): a first step towards creating a conservation plan for the subregion.

Abstract: This paper is a first step towards a conservation plan for the Kruger to Canyons Biosphere Reserve (K2C) on the South African Central Lowveld, quantifying the historical land-cover trends (1993–2006). During the analysis period, 36% of the biosphere reserve (BR) underwent land-cover change. Settlement areas increased by 39.7%, mainly in rural areas, becoming denser, particularly along roadways. Human-Impacted Vegetation increased by 6.8% and Intact Vegetation declined by 7.3%, predominantly around settlement areas, which is testament to the interdependency between rural communities and the local environment. However, settlement expansion exceeded the rate of rangeland growth; in the long term, this may raise questions for sustainable resource extraction. Similarly, the block losses of intact vegetation are of concern; issues of fragmentation arise, with knock-on effects for ecosystem functioning. In the economic sector, agriculture increased by 51.9%, while forestry and mining declined by 7.1% and 6.3%, respectively. The future of these three sectors may also have significant repercussions for land-cover change in the BR. The identification of historical drivers, along with the chance that existing trends may continue, will have important implications for biodiversity protection in this landscape. Applied within a conservation-planning framework, these land-cover data, together with economic and biodiversity data, will help reconcile the spatial requirements of socio-economic development with those of conservation.

Land-cover change in the Kruger to Canyons Biosphere Reserve (1993-2006) : a first step towards creating a conservation plan for the subregion : research article

Abstract: This paper is a first step towards a conservation plan for the Kruger to Canyons Biosphere Reserve (K2C) on the South African Central Lowveld, quantifying the historical land-cover trends (1993-2006). During the analysis period, 36% of the biosphere reserve (BR) underwent land-cover change. Settlement areas increased by 39.7%, mainly in rural areas, becoming denser, particularly along roadways. Human-Impacted Vegetation increased by 6.8% and Intact Vegetation declined by 7.3%, predominantly around settlement areas, which is testament to the interdependency between rural communities and the local environment. However, settlement expansion exceeded the rate of rangeland growth; in the long term, this may raise questions for sustainable resource extraction. Similarly, the block losses of intact vegetation are of concern; issues of fragmentation arise, with knock-on effects for ecosystem functioning. In the economic sector, agriculture increased by 51.9%, while forestry and mining declined by 7.1% and 6.3%, respectively. The future of these three sectors may also have significant repercussions for land-cover change in the BR. The identification of historical drivers, along with the chance that existing trends may continue, will have important implications for biodiversity protection in this landscape. Applied within a conservation-planning framework, these land-cover data, together with economic and biodiversity data, will help reconcile the spatial requirements of socio-economic development with those of conservation.

Extracting strctural land cover components using small-footprint waveform lidar data

Abstract: Previous work has shown the ability of waveform LiDAR sensors to accurately describe various land cover types [1] and biomass estimates made in the field [2]. What is lacking, however, is a way to describe the different structural components that are embedded in the digitized backscattered energy from the LiDAR pulse. This study aims to extract structural components from waveform LiDAR data in terms of woody, herbaceous, and bare ground components from data collected over a savanna environment in and around Kruger National Park (KNP), South Africa. These components are comprised of metrics extracted from the waveforms and validated using biomass measurements made in field plots. Different size windows around plot centers, 3×3 pixels and 9×9 pixels (resulting in 1.5m and 4.5 m footprint, respectively), were used to examine scale effects of larger footprints. It was found that composite waveforms resembling plot sizes (9×9) most often are able to describe more than 80% of the woody biomass variability across the entire study site, and individually for two of the three land uses within the area. However, the herbaceous component of the waveform did not correlate well with the field measurements, while the bare ground component was verified visually in a side-by-side comparison with optical imagery.

REVIEW Getting the most out of atlas data

Abstract: Aim To review some of the applications in ecology and conservation biogeography of datasets derived from atlas projects. We discuss data applications and data quality issues and suggest ways in which atlas data could be improved. Location Southern Africa and worldwide. Methods Atlas projects are broadly defined as collections or syntheses of original, spatially explicit data on species occurrences. We review uses of atlas datasets and discuss data quality issues using examples from atlas projects in southern Africa and worldwide. Results Atlas projects must cope with tradeoffs between data quality and quantity, standardization of sampling methods, quantification of sampling effort, and mismatches in skills and expectations between data collectors and data users. The most useful atlases have a good measure of sampling effort; include data collected at a fine enough resolution to link to habitat variables of potential interest; have a sufficiently large sample size to work with in a multivariate context; and offer clear, quantitative indications of the quality of each record to allow for the needs of users who have specific demands for high-quality data.