Impacts of river regulation and other anthropogenic activities on floodplain vegetation: A case study from Sri Lanka

Abstract

Since the initiation of large-scale development in late 1970s, the Mahaweli River basin in Sri Lanka has experienced significant changes. However, no comprehensive study has been undertaken so far to evaluate the impacts of river regulation on associated ecosystems including floodplains in the downstream. The present study was aimed at identifying the impacts due to both river regulation and other anthropogenic activities on inland floodplain habitats (locally known as villus) located along the final stretch of the River Mahaweli before reaching the Indian Ocean. Four villus, Handapana (HAN), Bendiya (BEN), Karapola (KAR) and Gengala (GEN), were selected for the study. HAN and BEN can be considered as highly influenced (HI) by river regulation while KAR and GEN as less influenced (LI) due to their respective locations. Due to the absence of pre- regulation vegetation data, HI villus were compared with LI villus in order to explore any potential impacts of river regulation. Vegetation was enumerated using belt transect method. To find out other on-going anthropogenic impacts on these villu ecosystems, a survey was conducted using 100 individuals living in two villages located nearby. The results revealed some significant modification in the composition and the diversity of the vegetation, most possibly due to river regulation and other on-going anthropogenic activities. However, the most notable changes were recorded in the herbaceous layer. Some native aquatic herbaceous species have been completely absent over the period of two decades since the developmental activities begun, while some exotic invasive aquatic species (Eichhornia crassipes) dominated the herbaceous layer in HI villus threatening the survival of the remaining native species. Density and richness of lianas too diminished significantly in HI villus perhaps due to changes of micro-habitat conditions as a result of river regulation and also due to over-harvesting for commercial purposes. The results suggest that these ecosystems have been altered over the years due to culmination of factors including altered flow regimes following river regulation and some on-going human influences. The present study highlights the importance of regulating such human influences on villus including fishing and extracting cane and reed in order to protect these vulnerable ecosystems for future generations. The potential of these ecosystems to develop ecotourism has also been emphasized.

Abbreviations

BEN:

Bendiya

GEN:

Gengala

HAN:

Handapana

KAR:

Karapola

MFNP:

Mahaweli Floodplain National Park

References

  1. Ashton, M.S., S. Gunatilleke, N. De Zoysa, M.D. Dassanayake, N. Gunatilleke and S. Wijesundera. 1997. A Field Guide to the Common Trees and Shrubs of Sri Lanka. WHT Publications, Colombo, Sri Lanka.

    Google Scholar 

  2. Bino, G., S.A. Sisson, R.T. Kingsford, R.F. Thomas and S. Bowen. 2015. Developing state and transition models of foodplain vegetation dynamics as a tool for conservation decision-making: a case study of the Macquarie Marshes Ramsar wetland. J. Appl. Ecol. 52:654–664.

    Article  Google Scholar 

  3. Catelotti, K., R.T. Kingsford, G. Bino and P. Bacon. 2015. Inundation requirements for persistence and recovery of river red gums (Eucalyptus camaldulensis) in semi-arid Australia. Biol. Conserv. 184:346–356.

    Article  Google Scholar 

  4. Cater, E. 1993. Ecotourism in the third world: Problems for sustainable tourism development. Tour. Manag. 14:85–90.

    Article  Google Scholar 

  5. CEA 1995. Wetland conservation project, Central Environmental Authority of Sri Lanka. 1995. Wetland site report: Handapan and Bendiya villus, Ministry of transport, environment and women’s affairs.

  6. Dynesius, M. and C. Nilsson. 1994. Fragmentation and flow regulation of river systems in the northern third of the world. Science 266(5186):753–762.

    CAS  Article  Google Scholar 

  7. Fox, J. 2017. Using the R Commander: A Point-and-Click Interface for R. Chapman and Hall/CRC Press, Boca Raton, FL.

    Google Scholar 

  8. Frazier, P. and K. Page. 2006. The effect of river regulation on floodplain wetland inundation, Murrumbidgee River, Australia. Mar. Freshwater Res. 57:133–141.

    Article  Google Scholar 

  9. IUCN-CEA. 2006. Sri Lanka. Central Environmental Authority (CEA); IUCN Sri Lanka; IWMI. 2006. National wetland directory of Sri Lanka. Colombo, Sri Lanka: Central Environmental Authority (CEA);International Union for Conservation of Nature (IUCN); International Water Management Institute (IWMI). 342 p.

  10. Jafari, N. 2010. Ecological and socio-economic utilization of water hyacinth (Eichhornia crassipes Mart Solms). JAEBS 14 (2):43–49.

    Google Scholar 

  11. Kingsford, R.T. 2000. Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia. Austral. Ecol. 25:109–127.

    Article  Google Scholar 

  12. Layer, I. 2002. Vegetation and ecological investigations in the recent floodplain, the Altaue and on the Elbe Auenrand. Dissertationes Botanicae 363:1–193.

    Google Scholar 

  13. Layer, I. 2005. Predicting plant species’ responses to river regulation: the role of water level fluctuations. J. Appl. Ecol. 42:239–250.

    Article  Google Scholar 

  14. Ledo, A. and S.A. Schnitzer. 2014. Disturbance and clonal reproduction determine liana distribution and maintain liana diversity in a tropical forest. Ecology 95:2169–2178.

    Article  Google Scholar 

  15. Lehvävirta, S. and H. Rita. 2002. Natural regeneration of trees in urban woodlands. J. Veg. Sci. 13:57–66.

    Article  Google Scholar 

  16. Mac Nally, R., H. Lada, S.C. Cunningham, J. R. Thomson and E. Fleishman. 2014. Climate-change-driven deterioration of the condition of floodplain forest and the future for the avifauna. Glob. Ecol. Biogeogr. 23:191–202.

    Article  Google Scholar 

  17. Maingi, J.K. and S.E. Marsh. 2002. Quantifying hydrologic impacts following dam construction along the Tana River, Kenya. J. Arid Environ. 50:53–79.

    Article  Google Scholar 

  18. Marks, C. O., K. H. Nislow and F. J. Magilligan. 2014. Quantifying flooding regime in floodplain forests to guide river restoration. Elementa: Science of the Anthropocene 2(1):31.

    Google Scholar 

  19. Murray-Hudson, M. 2009. Floodplain vegetation responses to flood regime in the seasonal Okavango Delta, Botswana. Ph.D. dissertation, University of Florida, USA.

    Google Scholar 

  20. Odland, A. and R. del Moral. 2002. Thirteen years of wetland vegetation succession following a permanent drawdown, Myrkdalen Lake, Norway. Plant Ecol. 162:185–198.

    Article  Google Scholar 

  21. Pascal, J.P. 1988. Wet evergreen forests of the Western Ghats of India: Ecology, structure and Floristic Composition and Succession. Institute Francais De Pondicherry, India.

    Google Scholar 

  22. Pausas, J.G. and M.P. Austin. 2001.Patterns of plant species richness in relation to different environments: An appraisal. J. Veg. Sci. 12:153–166.

    Article  Google Scholar 

  23. Pyrovetsi, M. and G.A. Daoutopoulos. 1989. Conservation-related attitudes of lake fishermen in Greece. Environ. Conserv. 16:245–250.

    Article  Google Scholar 

  24. Roxburgh, S.H., K. Shea and J.B. Wilson. 2004. The intermediate disturbance hypothesis: patch dynamics and mechanisms of species coexistence. Ecology 85:359–371

    Article  Google Scholar 

  25. Scheyvens, R. 1999. Ecotourism and the empowerment of local communities. Tour. Manag. 20(2):245–249.

    Article  Google Scholar 

  26. Schindler, D.W. 2001. The cumulative effects of climate warming and other human stresses on Canadian freshwaters in the new millennium. Can. J. Fish. Aquat. Sci. 58:18–29.

    Article  Google Scholar 

  27. Spackman, S.C. and J.W. Hughes. 1995. Assessment of minimum stream corridor width for Biological Conservation species richness and distribution along mid-order streams in Vermont USA. Biol. Conserv. 71:325–332.

    Article  Google Scholar 

  28. Tolisano, J., P. Abeygunewardene, T. Athukoralala, C. Davis, W. Fleming, I.K. Goonesekara and I.K. Weerewardene. 1993. An environmental evaluation of the Accelerated Mahaweli Development Program: Lessons learned and donor opportunities for improved assistance. Project report. Dai, Bethesda, USA. USAID by Development Alternatives, Inc, 70.

  29. Villamagna, A.M. and B.R. Murphy. 2010. Ecological and socioeconomic impacts of invasive water hyacinth (Eichhornia crassipes): a review. Freshwater Biol. 5:282–298.

    Article  Google Scholar 

  30. Vlas, J. and J. Vlas. 2008. Illustrated Field Guide to the Flowers of Sri Lanka. Mark Booksellers and distributors (Pvt) Ltd, Kandy.

    Google Scholar 

  31. Ward. J., K. Tockner and F. Schiemer. 1999. Biodiversity of floodplain river ecosystems: ecotones and connectivity. River Res. Appl. 15:1–3.

    Google Scholar 

  32. Zefferman, E., J.T. Stevens, G.K. Charles et al. 2015. Plant communities in harsh sites are less invaded: a summary of observations and proposed explanations. AoB Plants 7: plv056.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to S. L. Rajakaruna.

Additional information

The Student Conference on Conservation Science (SCCS) is organized each year in several locations, Tihany at the Lake Balaton in Hungary being one of them. Since 2016, Community Ecology offers a prize at SCCS Tihany for the best presentation in the field of Community Ecology. An independent jury awards the prize that is an invitation to submit a manuscript to the ojurnal. This is the paper of the first SCCST ihany Awardee, Shalini Rajakaruna, back in 2016.

Electronic supplementary material

42974_2017_1802203_MOESM1_ESM.pdf

Table S.1 The detailed list of species recorded during the study in Handapana (HAN-HI), Bendiya( BEN-HI), Karapola (KAR-LI), Gengala (GEN-LI). Presence or absence of the species in study sites are denoted by √ and × respectively. The family that the species belong to, origin of each species (Native= Na, Introduced=IN, Endemic=EN) and their conservation status (CS) according to IUCN categorization (Least concerned= LC, Endangered= En, NT=Nearly threatened, Vulnerable to extinction= VU) is given in the table. Habit of the species are given in brackets (Trees=T, Shrubs=S, Lianas= Li, Herbs= H, Graminoids-Gr).

Rights and permissions

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Rajakaruna, S.L., Ranawana, K.B., Gunarathne, A.M.T.A. et al. Impacts of river regulation and other anthropogenic activities on floodplain vegetation: A case study from Sri Lanka. COMMUNITY ECOLOGY 18, 203–213 (2017). https://doi.org/10.1556/168.2017.18.2.10

Download citation

Keywords

  • Livelihoods
  • River Mahaweli
  • River regulation
  • Tropical wetland
  • Villus