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A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt
Aloe dichotoma populations differ in their rates of recruitment and mortality across the species distribution in South Western Africa. Little is known about how recruitment and mortality rates are affected by local climate and ecological factors. Using repeat photography and a statistical recruitmen...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2015
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| _version_ | 1867613448114798592 |
|---|---|
| access_status_str | Open Access |
| author | van Blerk, Justin |
| author2 | Hoffman, Timm |
| author_browse | Hoffman, Timm van Blerk, Justin |
| author_facet | Hoffman, Timm van Blerk, Justin |
| author_sort | van Blerk, Justin |
| collection | Thesis |
| description | Aloe dichotoma populations differ in their rates of recruitment and mortality across the species distribution in South Western Africa. Little is known about how recruitment and mortality rates are affected by local climate and ecological factors. Using repeat photography and a statistical recruitment model, the recruitment history of an emerging population of over 200 A. dichotoma individuals near Kenhardt was simulated. Historical rainfall data was used in order to assess the possible link between rainfall and recruitment. Recruitment patterns were found to be a combination of episodic events of varying length and magnitude superimposed over a background of low-rate continuous recruitment. The largest, most extended episodic recruitment period peaked in the mid-1970s and led to the establishment of most of the individuals in the Kenhardt population. These trees were generally between 150 and 250 cm in height (2013). Newly discovered juveniles below 100 cm in height were predominantly the result of relatively small and brief episodic recruitment events that occurred in the mid and late 2000s. Between episodic recruitment events, evidence for low-rate continuous recruitment is present, particularly in more recent years. Episodic periods of high-rate recruitment were found to be linked to high rainfall. The largest, most extended recruitment period coincided with the exceptionally high rainfall of the 1970s. The more recent episodic recruitment events also coincided with high rainfall spikes during the 2000s. While correlations between rainfall variables and recruitment were significant, many other factors may affect the strength of this relationship. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/14021 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:36:18.442Z |
| 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:11427/14021 A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt van Blerk, Justin Hoffman, Timm Jack, Sam Biological Sciences Aloe dichotoma populations differ in their rates of recruitment and mortality across the species distribution in South Western Africa. Little is known about how recruitment and mortality rates are affected by local climate and ecological factors. Using repeat photography and a statistical recruitment model, the recruitment history of an emerging population of over 200 A. dichotoma individuals near Kenhardt was simulated. Historical rainfall data was used in order to assess the possible link between rainfall and recruitment. Recruitment patterns were found to be a combination of episodic events of varying length and magnitude superimposed over a background of low-rate continuous recruitment. The largest, most extended episodic recruitment period peaked in the mid-1970s and led to the establishment of most of the individuals in the Kenhardt population. These trees were generally between 150 and 250 cm in height (2013). Newly discovered juveniles below 100 cm in height were predominantly the result of relatively small and brief episodic recruitment events that occurred in the mid and late 2000s. Between episodic recruitment events, evidence for low-rate continuous recruitment is present, particularly in more recent years. Episodic periods of high-rate recruitment were found to be linked to high rainfall. The largest, most extended recruitment period coincided with the exceptionally high rainfall of the 1970s. The more recent episodic recruitment events also coincided with high rainfall spikes during the 2000s. While correlations between rainfall variables and recruitment were significant, many other factors may affect the strength of this relationship. 2015-09-15T10:33:05Z 2015-09-15T10:33:05Z 2013 Bachelor Thesis Honours BSc (Hons) http://hdl.handle.net/11427/14021 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Biological Sciences van Blerk, Justin A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| thesis_degree_str | Bachelor's / Honours |
| title | A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| title_full | A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| title_fullStr | A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| title_full_unstemmed | A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| title_short | A simulated history of Aloe dichotoma recruitment and its link to rainfall : insights from an isolated population near Kenhardt |
| title_sort | simulated history of aloe dichotoma recruitment and its link to rainfall insights from an isolated population near kenhardt |
| topic | Biological Sciences |
| url | http://hdl.handle.net/11427/14021 |
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