A continental-scale validation of ecosystem service models
- Willcock, Simon, Hooftman, Danny A P, Balbi, Stefano, Blanchard, Ryan, Dawson, Terence P, O’Farrell, Patrick J, Hickler, Thomas, Hudson, Malcolm D, Lindeskog, Mats, Martinez-Lopez, Javier, Mulligan, Mark, Reyers, Belinda, Shackleton, Charlie M, Sitas, Nadia, Villa, Ferdinando, Watts, Sophie M, Eigenbrod, Felix, Bullock, James M
- Authors: Willcock, Simon , Hooftman, Danny A P , Balbi, Stefano , Blanchard, Ryan , Dawson, Terence P , O’Farrell, Patrick J , Hickler, Thomas , Hudson, Malcolm D , Lindeskog, Mats , Martinez-Lopez, Javier , Mulligan, Mark , Reyers, Belinda , Shackleton, Charlie M , Sitas, Nadia , Villa, Ferdinando , Watts, Sophie M , Eigenbrod, Felix , Bullock, James M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/177476 , vital:42825 , https://doi.org/10.1007/s10021-019-00380-y
- Description: Faced with environmental degradation, governments worldwide are developing policies to safeguard ecosystem services (ES). Many ES models exist to support these policies, but they are generally poorly validated, especially at large scales, which undermines their credibility. To address this gap, we describe a study of multiple models of five ES, which we validate at an unprecedented scale against 1675 data points across sub-Saharan Africa.
- Full Text:
- Date Issued: 2019
- Authors: Willcock, Simon , Hooftman, Danny A P , Balbi, Stefano , Blanchard, Ryan , Dawson, Terence P , O’Farrell, Patrick J , Hickler, Thomas , Hudson, Malcolm D , Lindeskog, Mats , Martinez-Lopez, Javier , Mulligan, Mark , Reyers, Belinda , Shackleton, Charlie M , Sitas, Nadia , Villa, Ferdinando , Watts, Sophie M , Eigenbrod, Felix , Bullock, James M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/177476 , vital:42825 , https://doi.org/10.1007/s10021-019-00380-y
- Description: Faced with environmental degradation, governments worldwide are developing policies to safeguard ecosystem services (ES). Many ES models exist to support these policies, but they are generally poorly validated, especially at large scales, which undermines their credibility. To address this gap, we describe a study of multiple models of five ES, which we validate at an unprecedented scale against 1675 data points across sub-Saharan Africa.
- Full Text:
- Date Issued: 2019
An evaluation of the current extent and potential spread of Black Bass invasions in South Africa
- Khosa, Dumisani, Marr, Sean M, Wasserman, Ryan J, Zengeya, Tsungai A, Weyl, Olaf L F
- Authors: Khosa, Dumisani , Marr, Sean M , Wasserman, Ryan J , Zengeya, Tsungai A , Weyl, Olaf L F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103867 , vital:32317 , https://doi.org/10.1007/s10530-019-01930-0
- Description: Black Bass, a collective name for members of the centrarchid genus Micropterus, are native to North America, but have been introduced globally to enhance recreational angling. This study assessed the distribution of Micropterus salmoides, M. dolomieu and M. punctulatus in South Africa using both formal (survey-based) and informal (tournament data and social media) information sources. Analysis of the distribution data showed habitat bias between the data sources. Survey data from formal information sources were dominated by locality records in riverine environments while those derived from informal information sources focused more on lacustrine habitats. Presence data were used to develop niche models to identify suitable areas for their establishment. The predicted distribution range of M. salmoides revealed a broad suitability over most of South Africa, however, the Cape Fold Ecoregion and all coastal regions were most suitable for the establishment for both M. dolomieu and M. punctulatus. Flow accumulation and precipitation of coldest quarter were the most important environmental variables associated with the presence of all Black Bass species in South Africa. In addition, anthropogenic disturbance such as agricultural activities were associated with the presence of both Smallmouth Bass and Spotted Bass. An extensive area-based invasion debt was observed for all Micropterus spp. The potential for further spread of Black Bass in South Africa is of ecological concern because of their impact on native biota.
- Full Text:
- Date Issued: 2019
- Authors: Khosa, Dumisani , Marr, Sean M , Wasserman, Ryan J , Zengeya, Tsungai A , Weyl, Olaf L F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103867 , vital:32317 , https://doi.org/10.1007/s10530-019-01930-0
- Description: Black Bass, a collective name for members of the centrarchid genus Micropterus, are native to North America, but have been introduced globally to enhance recreational angling. This study assessed the distribution of Micropterus salmoides, M. dolomieu and M. punctulatus in South Africa using both formal (survey-based) and informal (tournament data and social media) information sources. Analysis of the distribution data showed habitat bias between the data sources. Survey data from formal information sources were dominated by locality records in riverine environments while those derived from informal information sources focused more on lacustrine habitats. Presence data were used to develop niche models to identify suitable areas for their establishment. The predicted distribution range of M. salmoides revealed a broad suitability over most of South Africa, however, the Cape Fold Ecoregion and all coastal regions were most suitable for the establishment for both M. dolomieu and M. punctulatus. Flow accumulation and precipitation of coldest quarter were the most important environmental variables associated with the presence of all Black Bass species in South Africa. In addition, anthropogenic disturbance such as agricultural activities were associated with the presence of both Smallmouth Bass and Spotted Bass. An extensive area-based invasion debt was observed for all Micropterus spp. The potential for further spread of Black Bass in South Africa is of ecological concern because of their impact on native biota.
- Full Text:
- Date Issued: 2019
Applying distributed ledger technology to digital evidence integrity
- Weilbach, William T, Motara, Yusuf, M
- Authors: Weilbach, William T , Motara, Yusuf, M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428960 , vital:72549 , https://ieeexplore.ieee.org/abstract/document/8732798
- Description: This paper examines the way in which blockchain technology can be used to improve the verification of integrity of evidence in digital forensics. Some background into digital forensic practices and blockchain technology are discussed to provide necessary context. A particular scalable method of verifying point-in-time existence of a piece of digital evidence, using the OpenTimestamps (OTS) service, is described, and tests are carried out to independently validate the claims made by the service. The results demonstrate that the OTS service is highly reliable with a zero false positive and false negative error rate for timestamp attestations, but that it is not suitable for timesensitive timestamping due to the variance of the accuracy of timestamps induced by block confirmation times in the Bitcoin blockchain.
- Full Text:
- Date Issued: 2019
- Authors: Weilbach, William T , Motara, Yusuf, M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428960 , vital:72549 , https://ieeexplore.ieee.org/abstract/document/8732798
- Description: This paper examines the way in which blockchain technology can be used to improve the verification of integrity of evidence in digital forensics. Some background into digital forensic practices and blockchain technology are discussed to provide necessary context. A particular scalable method of verifying point-in-time existence of a piece of digital evidence, using the OpenTimestamps (OTS) service, is described, and tests are carried out to independently validate the claims made by the service. The results demonstrate that the OTS service is highly reliable with a zero false positive and false negative error rate for timestamp attestations, but that it is not suitable for timesensitive timestamping due to the variance of the accuracy of timestamps induced by block confirmation times in the Bitcoin blockchain.
- Full Text:
- Date Issued: 2019
Mbeki's African Renaissance Vision as Reflected in isiXhosa Written Poetry: 2005–2011
- Mona, Godfrey V, Kaschula, Russell H
- Authors: Mona, Godfrey V , Kaschula, Russell H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/174705 , vital:42502 , ttps://doi.org/10.1080/18186874.2018.1457616
- Description: IsiXhosa literary critics have not yet interrogated literature that was produced during and after the tenure of Thabo Mvuyelwa Mbeki as deputy president and president of the Republic of South Africa in order to study the impact of his African Renaissance doctrine. This article analyses poetry that was produced from 2005 to 2011. The content of the isiXhosa written poetry is profoundly influenced by the context of former President Mbeki's African Renaissance philosophy, its implementation structures and philosophy of self-confidence and self-reliance. The selected poems analysed and interpreted in this article suggest that Mbeki's legacy of the African Renaissance empowered poets to develop a narrative that advances the building of a regenerated South African nation and the African continent.
- Full Text:
- Date Issued: 2018
- Authors: Mona, Godfrey V , Kaschula, Russell H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/174705 , vital:42502 , ttps://doi.org/10.1080/18186874.2018.1457616
- Description: IsiXhosa literary critics have not yet interrogated literature that was produced during and after the tenure of Thabo Mvuyelwa Mbeki as deputy president and president of the Republic of South Africa in order to study the impact of his African Renaissance doctrine. This article analyses poetry that was produced from 2005 to 2011. The content of the isiXhosa written poetry is profoundly influenced by the context of former President Mbeki's African Renaissance philosophy, its implementation structures and philosophy of self-confidence and self-reliance. The selected poems analysed and interpreted in this article suggest that Mbeki's legacy of the African Renaissance empowered poets to develop a narrative that advances the building of a regenerated South African nation and the African continent.
- Full Text:
- Date Issued: 2018
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