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Multi-taxon and multi-metric responses of insects to habitat disturbance and global change
Thesis (PhDConsEcol)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613735667892224 |
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| access_status_str | Open Access |
| author | Cawood, Rebecca |
| author2 | Pryke, James |
| author_browse | Cawood, Rebecca Pryke, James |
| author_facet | Pryke, James Cawood, Rebecca |
| author_sort | Cawood, Rebecca |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhDConsEcol)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132096 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:40:52.447Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132096 Multi-taxon and multi-metric responses of insects to habitat disturbance and global change Cawood, Rebecca Pryke, James Seymour, Colleen Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. Fynbos ecology -- South Africa -- Western Cape Vegetation dynamics -- South Africa -- Western Cape Insects -- Ecology -- South Africa Wildfires -- Environmental aspects Insects -- Effect of fires on Insect-plant relationships Fynbos -- Effect of fires on UCTD Thesis (PhDConsEcol)--Stellenbosch University, 2025. Cawood, R. 2025. Multi-taxon and multi-metric responses of insects to habitat disturbance and global change. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/02cedbc6-badd-4d99-9521-d99f0552d9ac ENGLISH ABSTRACT: The Cape Floristic Region is one of the six floral kingdoms of the world and a biodiversity hotspot under threat from land transformation, including alien plantations and inappropriate fire regimes. Pine plantations are being cleared in the Table Mountain National Park due to growing concerns about their effects on biodiversity, with fynbos vegetation recovering well when correctly managed, however there is little information on the recovery of insects post pine removal. Frequent fires can decrease plant diversity and perhaps also insect diversity; similarly, when fire is excluded, long intervals between fires can lead to more severe fires and result in the senescence of fynbos vegetation which can also reduce insect diversity. This study had two major objectives: 1) investigate whether how well insect diversity recovers post pine removal and identify environmental variables driving these responses and investigate functional diversity and trait responses of beetles and ants to pine removal and 2) investigate whether insect diversity recovered 15 years postfire relative to areas unburnt over > 15 years. I further investigated the long-term effects of fire on insects and the functional diversity and trait responses of beetles and ants to burning and aspect. Four treatments were surveyed to assess insect recovery after pine removal: pine plantations, fynbos vegetation cleared of pine 10 years previously, fynbos cleared of pine 30 years previously and pristine fynbos. I show that insect species richness, abundance, taxonomic diversity and functional diversity was lowest in pine plantations. Insect recovery varied between groups, with ants showing a linear recovery towards pristine fynbos. However, ants were still taxonomically and functionally different from pristine fynbos 30 years post pine removal. Beetles showed evidence of taxonomic and functional recovery having similar communities in recovering fynbos and pristine fynbos, although this varied between feeding guilds. Wasps recovered quickly in species richness, abundance and diversity, but had different communities at each stage of recovery and pristine fynbos. Polyneopterans showed evidence of recovering in most metrics within 30 years of pine removal. Recovery of insects depends on recovery of fynbos, as insects are driven by plant species richness and structural complexity. To investigate the response of insects to long-term fire intervals I established sites that had burnt 15 years previously and compared them to sites that have not burnt for over 15 years. Four biotopes were surveyed to ascertain the effects of burning and aspect on insects: North facing burnt, North unburnt, West burnt and West unburnt. Some differences in insect assemblage compositions were explained by aspect, but fire had the greater effect on insects. Ants were less abundant, but more diverse in areas that had burnt 15 years previously whereas polyneopterans were more abundant and diverse in sites that had not burnt. Wasps and beetles were not affected by burning or long-term fire intervals. This emphasises the value of a multi-taxon approach including functional traits when monitoring the recovery of insects as each group responds differently. Ants and predatory beetles seem to be the best groups to investigate the recovery of insects to disturbances such as pine clearing and fire. The most important management recommendations include the continued removal of pine plantations, interventions such as alien invasive plant clearing post pine removal and the close monitoring of fire frequency, as fires that are either too frequent or too rare appear to have a negative effect on insects. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2025-05-23T09:01:57Z 2025-05-23T09:01:57Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132096 Stellenbosch University xiii, 151 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fynbos ecology -- South Africa -- Western Cape Vegetation dynamics -- South Africa -- Western Cape Insects -- Ecology -- South Africa Wildfires -- Environmental aspects Insects -- Effect of fires on Insect-plant relationships Fynbos -- Effect of fires on UCTD Cawood, Rebecca Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title | Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title_full | Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title_fullStr | Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title_full_unstemmed | Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title_short | Multi-taxon and multi-metric responses of insects to habitat disturbance and global change |
| title_sort | multi taxon and multi metric responses of insects to habitat disturbance and global change |
| topic | Fynbos ecology -- South Africa -- Western Cape Vegetation dynamics -- South Africa -- Western Cape Insects -- Ecology -- South Africa Wildfires -- Environmental aspects Insects -- Effect of fires on Insect-plant relationships Fynbos -- Effect of fires on UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132096 |
| work_keys_str_mv | AT cawoodrebecca multitaxonandmultimetricresponsesofinsectstohabitatdisturbanceandglobalchange |