Tim G. O'Connor - Academia.edu (original) (raw)
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Papers by Tim G. O'Connor
Integrated Environmental Assessment and Management
Integrated Environmental assessment and Management, 2019
Environmental information is acquired and assessed during the environmental impact assessment pro... more Environmental information is acquired and assessed during the environmental impact assessment process for surface-strip coal mine approval. However, integrating these data and quantifying rehabilitation risk using a holistic multidisciplinary approach is seldom undertaken. We present a rehabilitation risk assessment integrated network (R2AINTM) framework that can be applied using Bayesian networks (BNs) to integrate and quantify such rehabilitation risks. Our framework has 7 steps, including key integration of rehabilitation risk sources and the quantification of undesired rehabilitation risk events to the final application of mitigation. We demonstrate the framework using a soil compaction BN case study in the Witbank Coalfield, South Africa and the Bowen Basin, Australia. Our approach allows for a probabilistic assessment of rehabilitation risk associated with multidisciplines to be integrated and quantified. Using this method, a site’s rehabilitation risk profile can be determined before mining activities commence and the effects of manipulating management actions during later mine phases to reduce risk can be gauged, to aid decision making. Integr Environ Assess Manag 2019;15:190–208. C 2019 SETAC
African Journal of Range & Forage Science, 2015
Austral Ecology, 2014
Conservation planning in the face of global change is still in its infancy. A suggested approach ... more 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 2 ), 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 mean annual temperature. Frost duration was the primary variable in the Classification and Regression Tree analysis with important implications for savanna/grassland dynamics. Soil properties (base, pH status) and moisture variables accounted for most of the variation for the second and third axes of floristic variation. Given that climatic and edaphic variables were well correlated with floristic composition, it is anticipated that a changing climate will have a marked influence on floristic composition. We predict warmer temperatures may facilitate the spread of frost sensitive savanna species into previously cooler, grassland areas. Species associated with specific soil types will not easily be able to move up the altitudinal gradient to cooler climes because geology is aligned in an approximately north-south direction compared with increasing altitude from east-west. Future conservation planning should take cognisance of these gradients which are surrogates for ecological and evolutionary processes promoting persistence.
Biological Conservation, 2007
An hypothesis predicting which woody species selected by elephant are at risk of local extirpatio... more An hypothesis predicting which woody species selected by elephant are at risk of local extirpation is based on an understanding of elephant digestive physiology, foraging ecology, attributes of individual plants and populations, and historical changes in ecosystems.
African Journal of Range & Forage Science, 2014
ABSTRACT Fire is rare in semi-arid eastern Karoo dwarf shrublands, South Africa, and responses to... more ABSTRACT Fire is rare in semi-arid eastern Karoo dwarf shrublands, South Africa, and responses to fire are largely unknown. Recent increased grassiness, and hence fuel loads, at Grootfontein in the Eastern Cape allowed an accidental fire (24.3 ha) to carry, and afforded the opportunity to examine compositional and structural effects of fire on a grassy dwarf shrubland. Sampling seven months after the fire, 108 species (102 perennial) were encountered, of which 74 were resprouters, six were fire sensitive (non-sprouters), and the remainder (rare, non-perennial or herbaceous) had an unknown response. The dominant pre-fire shrub, Eriocephalus ericoides, was extirpated by the fire, as was the unpalatable and sometimes invasive Ruschia intricata. All grass species resprouted, and grass became the dominant life-form after the fire, indicating a possible conferred competitive advantage. Resprouting shrubs grew to only a small fraction of their pre-burn size. The unpalatable, aromatic shrub Stachys rugosa was the dominant post-burn shrub. Extirpated species will need to regenerate from seeds, but no seedlings were found in the gaps where shrubs had stood. The widespread ability to resprout confers resilience on this vegetation, but fire does induce changes in structure, in the dominance of life forms, and it decreases canopy cover.
African Journal of Range & Forage Science, 2014
Rangeland Ecology & Management, 2011
Commercial livestock production offers one of the main opportunities for mainstreaming of biodive... more Commercial livestock production offers one of the main opportunities for mainstreaming of biodiversity conservation in the grassland biome of South Africa. Grazing management is expected to influence success. With the uses of three long-term grazing trials, effects of stocking rate and ...
Weyer, V.D., Granger, J.E., Hill, T.R. & O’Connor, T.G., 2015, ‘Land transformation and its implication for biodiversity integrity and hydrological functioning from 1944 to 1999, Karkloof catchment, South Africa’, Bothalia 45(1), Art. #1907, 13 pages. http:// dx.doi.org/10.4102/abc. v45i1.1907, 2015
Background and objectives: Land transformation of the Karkloof catchment is described for the per... more 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.
Integrated Environmental Assessment and Management
Integrated Environmental assessment and Management, 2019
Environmental information is acquired and assessed during the environmental impact assessment pro... more Environmental information is acquired and assessed during the environmental impact assessment process for surface-strip coal mine approval. However, integrating these data and quantifying rehabilitation risk using a holistic multidisciplinary approach is seldom undertaken. We present a rehabilitation risk assessment integrated network (R2AINTM) framework that can be applied using Bayesian networks (BNs) to integrate and quantify such rehabilitation risks. Our framework has 7 steps, including key integration of rehabilitation risk sources and the quantification of undesired rehabilitation risk events to the final application of mitigation. We demonstrate the framework using a soil compaction BN case study in the Witbank Coalfield, South Africa and the Bowen Basin, Australia. Our approach allows for a probabilistic assessment of rehabilitation risk associated with multidisciplines to be integrated and quantified. Using this method, a site’s rehabilitation risk profile can be determined before mining activities commence and the effects of manipulating management actions during later mine phases to reduce risk can be gauged, to aid decision making. Integr Environ Assess Manag 2019;15:190–208. C 2019 SETAC
African Journal of Range & Forage Science, 2015
Austral Ecology, 2014
Conservation planning in the face of global change is still in its infancy. A suggested approach ... more 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 2 ), 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 mean annual temperature. Frost duration was the primary variable in the Classification and Regression Tree analysis with important implications for savanna/grassland dynamics. Soil properties (base, pH status) and moisture variables accounted for most of the variation for the second and third axes of floristic variation. Given that climatic and edaphic variables were well correlated with floristic composition, it is anticipated that a changing climate will have a marked influence on floristic composition. We predict warmer temperatures may facilitate the spread of frost sensitive savanna species into previously cooler, grassland areas. Species associated with specific soil types will not easily be able to move up the altitudinal gradient to cooler climes because geology is aligned in an approximately north-south direction compared with increasing altitude from east-west. Future conservation planning should take cognisance of these gradients which are surrogates for ecological and evolutionary processes promoting persistence.
Biological Conservation, 2007
An hypothesis predicting which woody species selected by elephant are at risk of local extirpatio... more An hypothesis predicting which woody species selected by elephant are at risk of local extirpation is based on an understanding of elephant digestive physiology, foraging ecology, attributes of individual plants and populations, and historical changes in ecosystems.
African Journal of Range & Forage Science, 2014
ABSTRACT Fire is rare in semi-arid eastern Karoo dwarf shrublands, South Africa, and responses to... more ABSTRACT Fire is rare in semi-arid eastern Karoo dwarf shrublands, South Africa, and responses to fire are largely unknown. Recent increased grassiness, and hence fuel loads, at Grootfontein in the Eastern Cape allowed an accidental fire (24.3 ha) to carry, and afforded the opportunity to examine compositional and structural effects of fire on a grassy dwarf shrubland. Sampling seven months after the fire, 108 species (102 perennial) were encountered, of which 74 were resprouters, six were fire sensitive (non-sprouters), and the remainder (rare, non-perennial or herbaceous) had an unknown response. The dominant pre-fire shrub, Eriocephalus ericoides, was extirpated by the fire, as was the unpalatable and sometimes invasive Ruschia intricata. All grass species resprouted, and grass became the dominant life-form after the fire, indicating a possible conferred competitive advantage. Resprouting shrubs grew to only a small fraction of their pre-burn size. The unpalatable, aromatic shrub Stachys rugosa was the dominant post-burn shrub. Extirpated species will need to regenerate from seeds, but no seedlings were found in the gaps where shrubs had stood. The widespread ability to resprout confers resilience on this vegetation, but fire does induce changes in structure, in the dominance of life forms, and it decreases canopy cover.
African Journal of Range & Forage Science, 2014
Rangeland Ecology & Management, 2011
Commercial livestock production offers one of the main opportunities for mainstreaming of biodive... more Commercial livestock production offers one of the main opportunities for mainstreaming of biodiversity conservation in the grassland biome of South Africa. Grazing management is expected to influence success. With the uses of three long-term grazing trials, effects of stocking rate and ...
Weyer, V.D., Granger, J.E., Hill, T.R. & O’Connor, T.G., 2015, ‘Land transformation and its implication for biodiversity integrity and hydrological functioning from 1944 to 1999, Karkloof catchment, South Africa’, Bothalia 45(1), Art. #1907, 13 pages. http:// dx.doi.org/10.4102/abc. v45i1.1907, 2015
Background and objectives: Land transformation of the Karkloof catchment is described for the per... more 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.