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Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography

Repeat photography photosets were used to analyse 20th century changes in populations of Widdringtonia cedarbergensis from four sites in the Cederberg Mountains, South Africa. Systematic evaluation of 115 photosets was combined with field observation and environmental data to determine the age class...

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Main Author: White, Joseph Douglas Mandla
Other Authors: Hoffman, Timm
Format: Thesis
Language:English
Published: Department of Biological Sciences 2015
Subjects:
Biological Sciences
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access_status_str Open Access
author White, Joseph Douglas Mandla
author2 Hoffman, Timm
author_browse Hoffman, Timm
White, Joseph Douglas Mandla
author_facet Hoffman, Timm
White, Joseph Douglas Mandla
author_sort White, Joseph Douglas Mandla
collection Thesis
description Repeat photography photosets were used to analyse 20th century changes in populations of Widdringtonia cedarbergensis from four sites in the Cederberg Mountains, South Africa. Systematic evaluation of 115 photosets was combined with field observation and environmental data to determine the age class and degree of foliage cover, as well as fire frequency, rockiness of habitat, altitude, aspect of slope, annual mean temperature and annual precipitation for each tree viewed in photosets. Mortality and recruitment events were documented in each of the photosets. A total of 1315 trees were recorded in historical photographs (1931- 1982), with 968 of these shown to have died in the repeat photographs (2007-2013), indicating 74% mortality. With only 45 (3.4%) recruits being recorded, the total current living population of W. cedarbergensis in the repeat photographs was 392. There was no significant difference found in mortality or recruitment across the sampled sites. From the historical to repeat photosets there was an 8% increase in the proportion of mature adults and a 13% increase in the proportion of W. cedarbergensis individuals with sparse foliage cover. A generalized linear model was used to determine the effects of environmental factors on W. cedarbergensis mortality in natural populations.
format Thesis
id oai:open.uct.ac.za:11427/14029
institution University of Cape Town (South Africa)
language eng
last_indexed 2026-06-10T12:50:42.369Z
license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2015
publishDateRange 2015
publishDateSort 2015
publisher Department of Biological Sciences
publisherStr Department of Biological Sciences
record_format dspace
source_str UCTD — University of Cape Town Open Access Repository
spelling oai:open.uct.ac.za:11427/14029 Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography White, Joseph Douglas Mandla Hoffman, Timm Jack , Sam February, Edmund C Biological Sciences Repeat photography photosets were used to analyse 20th century changes in populations of Widdringtonia cedarbergensis from four sites in the Cederberg Mountains, South Africa. Systematic evaluation of 115 photosets was combined with field observation and environmental data to determine the age class and degree of foliage cover, as well as fire frequency, rockiness of habitat, altitude, aspect of slope, annual mean temperature and annual precipitation for each tree viewed in photosets. Mortality and recruitment events were documented in each of the photosets. A total of 1315 trees were recorded in historical photographs (1931- 1982), with 968 of these shown to have died in the repeat photographs (2007-2013), indicating 74% mortality. With only 45 (3.4%) recruits being recorded, the total current living population of W. cedarbergensis in the repeat photographs was 392. There was no significant difference found in mortality or recruitment across the sampled sites. From the historical to repeat photosets there was an 8% increase in the proportion of mature adults and a 13% increase in the proportion of W. cedarbergensis individuals with sparse foliage cover. A generalized linear model was used to determine the effects of environmental factors on W. cedarbergensis mortality in natural populations. 2015-09-15T10:33:16Z 2015-09-15T10:33:16Z 2013 Bachelor Thesis Honours BSc (Hons) http://hdl.handle.net/11427/14029 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town
spellingShingle Biological Sciences
White, Joseph Douglas Mandla
Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
thesis_degree_str Bachelor's / Honours
title Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
title_full Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
title_fullStr Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
title_full_unstemmed Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
title_short Analysis of long-term changes in populations of the Clanwiliam Cedar (Widdringtonia cedarbergensis) using repeat photography
title_sort analysis of long term changes in populations of the clanwiliam cedar widdringtonia cedarbergensis using repeat photography
topic Biological Sciences
url http://hdl.handle.net/11427/14029
work_keys_str_mv AT whitejosephdouglasmandla analysisoflongtermchangesinpopulationsoftheclanwiliamcedarwiddringtoniacedarbergensisusingrepeatphotography

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