Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka
Construction of dams across rivers is a common practice worldwide. However, obstructing free-flowing rivers could result in many negative impacts on riparian ecosystems, and are highly site-specific. In the present study, we evaluate the potential impacts of river regulation on the riparian vegetati...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Faculty of Science, University of Peradeniya, Sri Lanka
2019-06-01
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| Series: | Ceylon Journal of Science |
| Subjects: | |
| Online Access: | https://cjs.sljol.info/articles/7618 |
| _version_ | 1811325069395230720 |
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| author | S. L. Rajakaruna K.B. Ranawana A. M. T. A. Gunaratne H. M. S. P. Madawala |
| author_facet | S. L. Rajakaruna K.B. Ranawana A. M. T. A. Gunaratne H. M. S. P. Madawala |
| author_sort | S. L. Rajakaruna |
| collection | DOAJ |
| description | Construction of dams across rivers is a common practice worldwide. However, obstructing free-flowing rivers could result in many negative impacts on riparian ecosystems, and are highly site-specific. In the present study, we evaluate the potential impacts of river regulation on the riparian vegetation by enumerating the vegetation at different distances from the dam/reservoir complex from upstream to downstream reaches of a tributary of the river Mahaweli in Sri Lanka. The tree-dominated riparian vegetation has been evaluated using belt transects located in the immediate and 8 km away from the reservoir/dam towards both upstream and the downstream of the tributary (US-0, US-8; DS-0, DS-8, respectively). A total of 150 species belonging to 58 families were identified, of which 43% were tree species. Approximately 77% of species were found exclusively in the upstream while 8% were recorded in the downstream. Both canopy and understory layers showed a significant decline in terms of richness, abundance, diversity and stem density from upstream to downstream. <em>Leuceana</em> <em>leucocephala</em> (Lam.) de Wit, an invasive tree species, showed higher relative abundance in downstream reaches, while riparian species such as <em>Terminalia</em> <em>arjuna</em> (Roxb.) Wight & Arn. and <em>Pongamia</em> <em>pinnata</em> (L.) showed no marked decline from upstream to downstream. The conditions triggered by reduced water discharges and severe river bank erosion may have contributed to these changes. The results indicate that the extreme water management practices in storage reservoirs have incurred negative impacts on the composition of the riparian vegetation. Introduction of well-coordinated flow management practices may help to mitigate some of these negative impacts. |
| first_indexed | 2024-04-13T14:26:32Z |
| format | Article |
| id | doaj.art-9e8214247e644d139da4109ade4782ce |
| institution | Directory Open Access Journal |
| issn | 2513-2814 2513-230X |
| language | English |
| last_indexed | 2024-04-13T14:26:32Z |
| publishDate | 2019-06-01 |
| publisher | Faculty of Science, University of Peradeniya, Sri Lanka |
| record_format | Article |
| series | Ceylon Journal of Science |
| spelling | doaj.art-9e8214247e644d139da4109ade4782ce2022-12-22T02:43:19ZengFaculty of Science, University of Peradeniya, Sri LankaCeylon Journal of Science2513-28142513-230X2019-06-0148214315310.4038/cjs.v48i2.76185756Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri LankaS. L. Rajakaruna0K.B. Ranawana1A. M. T. A. Gunaratne2H. M. S. P. Madawala3University of Peradeniya, PeradeniyaUniversity of Peradeniya, PeradeniyaUniversity of Peradeniya, PeradeniyaUniversity of Peradeniya, PeradeniyaConstruction of dams across rivers is a common practice worldwide. However, obstructing free-flowing rivers could result in many negative impacts on riparian ecosystems, and are highly site-specific. In the present study, we evaluate the potential impacts of river regulation on the riparian vegetation by enumerating the vegetation at different distances from the dam/reservoir complex from upstream to downstream reaches of a tributary of the river Mahaweli in Sri Lanka. The tree-dominated riparian vegetation has been evaluated using belt transects located in the immediate and 8 km away from the reservoir/dam towards both upstream and the downstream of the tributary (US-0, US-8; DS-0, DS-8, respectively). A total of 150 species belonging to 58 families were identified, of which 43% were tree species. Approximately 77% of species were found exclusively in the upstream while 8% were recorded in the downstream. Both canopy and understory layers showed a significant decline in terms of richness, abundance, diversity and stem density from upstream to downstream. <em>Leuceana</em> <em>leucocephala</em> (Lam.) de Wit, an invasive tree species, showed higher relative abundance in downstream reaches, while riparian species such as <em>Terminalia</em> <em>arjuna</em> (Roxb.) Wight & Arn. and <em>Pongamia</em> <em>pinnata</em> (L.) showed no marked decline from upstream to downstream. The conditions triggered by reduced water discharges and severe river bank erosion may have contributed to these changes. The results indicate that the extreme water management practices in storage reservoirs have incurred negative impacts on the composition of the riparian vegetation. Introduction of well-coordinated flow management practices may help to mitigate some of these negative impacts.https://cjs.sljol.info/articles/7618river diversion, riparian vegetation, dam-induced impacts |
| spellingShingle | S. L. Rajakaruna K.B. Ranawana A. M. T. A. Gunaratne H. M. S. P. Madawala Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka Ceylon Journal of Science river diversion, riparian vegetation, dam-induced impacts |
| title | Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka |
| title_full | Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka |
| title_fullStr | Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka |
| title_full_unstemmed | Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka |
| title_short | Change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam: A case study from Sri Lanka |
| title_sort | change of riparian vegetation from upstream to downstream reaches of a tropical river obstructed by a dam a case study from sri lanka |
| topic | river diversion, riparian vegetation, dam-induced impacts |
| url | https://cjs.sljol.info/articles/7618 |
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