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The impact of invasive riparian trees on stream community structure and ecosystem functioning
Dissertation (MSc (Entomology))--University of Pretoria, 2016.
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| Format: | Thesis |
| Language: | English |
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2026
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| _version_ | 1867613502272700416 |
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| access_status_str | Open Access |
| author2 | Jackson, M.C. |
| author_browse | Jackson, M.C. |
| author_facet | Jackson, M.C. |
| collection | Thesis |
| description | Dissertation (MSc (Entomology))--University of Pretoria, 2016. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110100 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:10.039Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110100 The impact of invasive riparian trees on stream community structure and ecosystem functioning Jackson, M.C. hermina.fourie@zoology.up.ac.za Chimimba, Christian Timothy Fourie, Hermina Elizabeth Subsidies Freshwater ecosystems decomposition rates global warming aquatic invertebrates North West Province South Africa Dissertation (MSc (Entomology))--University of Pretoria, 2016. Although biological invasions are a major threat to biodiversity, they also affect agriculture, forestry and human health. South Africa has various kinds of invasive trees that occupy riparian zones and there are concerns about a decline in native species richness and diversity and the impact that has on freshwater ecosystems. Freshwater ecosystems in particular are vulnerable to global change, including biological invasions, land use and increasing water temperature. Riparian zones form an ecological boundary between terrestrial and aquatic ecosystems, which link adjacent food webs by cross-boundary subsidies. Energy inputs into rivers, such as terrestrial invertebrates and leaf litter, are important for stream consumers. Freshwater ecosystems are impacted by the introduction of non-native allochothonous energy inputs (leaf litter falling into a stream from riparian vegetation). This may have negative influences on stream nutrient dynamics, energy flow, community structure and exchange of materials and organisms between ecosystems. Invasive plant species often dominate riparian ecosystems with negative consequences for native communities. Riverbanks and wetlands in South Africa are vulnerable to invasions because of sufficient water supply that favours the spread of seeds. Native tree species are vulnerable to increasing temperatures and are out-competed by exotic trees which can withstand high temperatures and alter ecosystem structure and functioning. Moreover, increased water temperatures and riparian tree invasions may interact synergistically to alter stream ecosystem structure and functioning. To this end, the present study examines the variation in decomposition rates of native and invasive leaf litter in the Skeerpoort River, North West Province, South Africa. Data revealed that leaf litter quality (percent nitrogen content) noticeably influenced decomposition rates. In addition, the study also investigated the effect of water temperature on decomposition rates by freshwater crabs through a controlled laboratory experiment conducted in a climate room. The results of this experiment revealed the significant impact of water temperature on decomposition rates in streams. Furthermore, the present study also examined the combined impact of multiple riparian plant invasions on stream community species richness and abundances as well as ecosystem functioning across 12 South African streams. The results revealed that decomposition rates for native and invasive leaf species as well as macroinvertebrate abundances and diversity were negatively impacted by human-impacted land use, and that 4 water temperature influenced decomposition rates and the invertebrate richness and abundances. The results in this study have implications for the importance of managing freshwater ecosystems. The study also highlights that both human-impacted land use and climate warming need to be taken into consideration when developing freshwater management policies. Zoology and Entomology MSc (Entomology) 2026-05-15T17:26:18Z 2026-05-15T17:26:18Z 17/02/23 2016 Dissertation http://hdl.handle.net/2263/110100 en application/pdf |
| spellingShingle | Subsidies Freshwater ecosystems decomposition rates global warming aquatic invertebrates North West Province South Africa The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title | The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title_full | The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title_fullStr | The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title_full_unstemmed | The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title_short | The impact of invasive riparian trees on stream community structure and ecosystem functioning |
| title_sort | impact of invasive riparian trees on stream community structure and ecosystem functioning |
| topic | Subsidies Freshwater ecosystems decomposition rates global warming aquatic invertebrates North West Province South Africa |
| url | http://hdl.handle.net/2263/110100 |