|Thursday, 3 March 2005|
Major plan under way to restore Lanka's natural ecosystems
by Dayananda Kariyawasam
Director General of Wildlife Conservation
The tsunami that devastated the coastline of Sri Lanka on December 26th 2004, impacted several protected areas managed by the Department of Wildlife Conservation (DWC), namely Ruhuna National Park Blocks I and II, Yala East National Park, Bundala National Park, Hikkaduwa Marine National Park, Pigeon Island Marine National Park, Kudumbigala Sanctuary, Nimalawa Sanctuary, Lunama-Kalametiya Sanctuary, Proposed Rekawa Sanctuary and Turtle Refuge, and Kokilai Sanctuary.
In view of this, the Director General of DWC appointed a seven member committee under his chairmanship, to assess the impact of the tsunami on these protected areas and to make necessary recommendations for monitoring the recovery of these ecosystems as well as to identify short and long-term restoration activities that need to be undertaken by the DWC to ensure the long-term viability of these protected areas.
The committee comprised of H. D. Ratnayake, Co-chair Person (DWC), S. R. B. Dissanayake (DWC), Dr. Channa Bambaradeniya (IUCN Sri Lanka), Ravi Corea (Sri Lanka Wildlife Conservation Society) Dr. Prithiviraj Fernando (Centre for Conservation and Research) Prof. S. U. K. Ekaratne (University of Colombo), Dr. U. K. G. K. Padmalal (Open University of Sri Lanka) and Dr. Devaka Weerakoon (University of Colombo).
Members of the committee undertook to conduct a rapid assessment of the protected areas impacted by the tsunami and a meeting was held on January 29 to share the findings and to identify short and long-term actions required in view of the findings of the study.
While some of the work such as detailed mapping of the affected areas is still on going, the following were the main findings of the committee.
The protected areas that were significantly impacted by the tsunami were Ruhuna National Park blocks I and II, Yala East National Park, Lunama-Kalametiya Sanctuary, and Proposed Rekawa Sanctuary and Turtle Refuge. The Marine National Parks received little direct impact.
However, they suffered from secondary impacts such as smothering of coral reefs by situation resulting from turbulence created by wave action as well as runoff from land, and damage arising from man-made structures such as fish nets, concrete pillars etc., washed out into the ocean with the receding wave.
The impact on terrestrial ecosystems though considerable, was localized to low-lying areas mostly associated with lagoons and estuaries. In Ruhuna National Park Block 1, the area impacted inclusive of the beach, was 790 hectares. Nine major sites of sea incursion were identified.
These were Palatupana-goda kalapuwa, Kuda Seelawa, Maha Seelawa, Uraniya, Buttuwa, Beeri Kalapuwa, Patanangala, Gona Lahaba and Kallya, all of which are lagoons or bays with direct sea frontage.
In Ruhuna Block II six main areas of impact were identified, namely, Yala wela, Pillinewa, Agara Eliya, Uda Pottana, Gajabawa, and Kumbukkan oya estuary.
In Yala East, the Kumana lagoon was impacted by the tsunami wave. Apart from this, the Lunama-Kalametiya Sanctuary and Proposed Rekawa Sanctuary and Turtle Refuge were considerably damaged.
In all of these areas, the vegetation was impacted much more than large animals or birds. Three types of impacts on vegetation were identified.
The most obvious was the complete or partial uprooting and breaking of trees due to the force of the wave close to surrounding the shore,and along the central region of flooding, leading to death, complete drying and subsequent defoliation of trees.
The other two types of damage were deposition of sand carried inland with the wave, and inundation with seawater, which heavily impacted the understorey vegetation such as grasses and herbs.
A number of freshwater tanks and waterholes in Yala Block I were impacted to some degree by the tsunami. Pattiyawala, Diganwala, Yala Tank, and a number of smaller waterholes were completely inundated, and the Patanangala and Uda Pottana tanks were breached.
A few other waterholes received minor incursions of seawater but were not impacted to any significant degree. While small patches of mangrove vegetation such as was in Maha seelawa were almost completely destroyed, the larger tracts as in Pillinewa, Gajabawa etc. were relatively intact with damage only to areas close to the sea.
The direct impact on animals was less pronounced compared to the vegetation. Very few large animals were found to have perished due to the tsunami.
However, small saline sensitive animals such as land snails and frogs, as well as small mammals and reptiles such as rats, mice, snakes and lizards have been heavily impacted. However due to the patchy nature of the area affected and large population sizes of these groups, the overall impact on these species is likely to be minimal.
Animals have also been indirectly impacted by the damage to vegetation, as these areas can no longer function as optimum habitats for them.
For example, the flooding by seawater of the Buttuwa, Uraniya, Gona Lahaba, Yala Wela, Pillinewa, Agara Eliya and Uda Pottana plains has resulted in a significant loss of grasses and herbs, impacting species such as water buffalo, deer and hare.
However, practically all the species of animals normally observed in these areas were observed already utilizing them.
The loss of fodder is likely to be similar to that caused by failure of rains, hence within the tolerance of these species.
Some animals like birds, small mammals and reptiles appear to have benefited from the damaged vegetation as they were observed to use the tangled masses of vegetation as nesting sites and hiding places.
It was observed that most of the terrestrial ecosystems have already started to recover especially the grasses. While many seedlings of herbs were observed, their recovery may be slower than that of grasses.
Most tree species including mangrove vegetation also appeared to be recovering, unless they were completely uprooted. The detrimental effects of the tsunami on fauna, such as loss of grazing are likely to be transient.
However, the changes in soil salinity and deposition of sand etc. may create conditions more favourable to particular species of plants over others. Therefore, long term monitoring of the vegetation and documentation of any changes in structure and composition of these eco-systems would be important.
Another important finding of this initial assessment was that natural ecosystems have functioned as the first line of defence against the tsunami wave. Especially the sand dunes have withstood the force of the wave very successfully, and if not for them, the Southern and Southeastern coasts would have received a higher level of damage.
For instance the Bundala National Park, which lies on the Southern coast, received very little damage due to protection from sand dunes. Even in the Ruhuna National Park and Yala East National Park, the damage would have been much more severe if not for the sand dunes.
Other coastal and offshore ecosystems such as beach vegetation, mangroves, and coral reefs have also provided protection to the coastline where these ecosystems were preserved in a relatively good condition.
On the other hand in areas where natural ecosystems have been degraded due to over utilization, the damage to the coastal areas has been more extensive.
It has also become apparent that these natural ecosystems can offer a greater resistance against this kind of natural disaster rather than man made structures such as breakwaters and rip rap structures that are in place to prevent erosion.
Furthermore these natural ecosystems in addition to providing protection against erosion and oceanic intrusions provide other services such as functioning as silt traps, breeding grounds for sea fish and selfish, which benefit the small craft fishery.
Based on the findings of this initial study, the committee members have also provided number of recommendations as to what actions are needed to restore the natural ecosystems in the impacted protected areas.
One general recommendation that emerged from all the studies is the need to remove artificial debris from all impacted areas. This action has become critically important in the off shore areas such as Hikkaduwa Marine National Park where the artificial debris that got washed out form the land has become a major threat to the coral reefs.
(To be continued)
Produced by Lake House