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Horton Plains

More than 50 per cent of the flora species are affected due to the forest die-back phenomenon at the Horton Plains National Park, says Sri Lanka’s leading herpetologist Anslem de Silva.

In fact, earlier this year he completed an extensive study on the park. He was well supported by Botanical Gardens Director Dr. D. S. A. Wijesundara, who studied the flowering plants in the park.

Anslem says that his study clearly indicates that a staggering number of fauna species, especially reptiles, are killed due to road accidents. This trend is increasing day by day and it is high time action is taken to prevent further killings.

He also says that there is evidence that there had been large scale gemming in the last century.

His recent study on Horton Plains is included in his latest book The Diversity of Horton Plains National Park that will be on bookshelves today (31).

Last year Anslem successfully published a large monograph on the Dumbara mountains.

The Island received the first copy of The Diversity of Horton Plains National Park from the publisher Vijitha Yapa.

This very well produced book with nine informative chapters covers perhaps all what one wants to know about this unique ecosystem where one finds forest grassland and marsh land. Horton Plains, along with the Dumbara mountains, is in the process of being upgraded to World Heritage Site status.

The comprehensiveness of the book is enhanced with the addition of a bibliography on published literature on Horton Plains. This would be useful for all researchers and managers of this ecosystem. Furthermore the chapter on flowering plants of the Horton Plains National Park by Dr. D. S. A. Wijesundara, Director, Botanical Gardens, Peradeniya is a bonus. There are 143 colour plates, most of them photographed by Anslem. It also has excellent photographs by Gehan de Silva Wijeratne, Siril Wijesundara, Rathnasiri Premathilake and Gehan Chandrawansa

Anslem carried out his research project at Horton Plains in 1997, 1998 and from January to December 2000 as the team leader of the National Zoological Survey of Sri Lanka, funded by the National Science Foundation, Colombo.

Anslem as the current Chair of the Declining Amphibian Populations Task Force of the SSC/IUCN working group, Sri Lanka, has identified in the Saddle tree-frog (Polypedates eques, Mukalan Pahimbu Gasmadiya in Sinhalese) an endemic frog a new species of Cestode.

Work is in progress at present to identify the species and its life cycle.

Anslem also produced and directed a documentary on Horton Plains titled “Mahaeliya: Horton Plains”. This video won a special award during the Tokyo International Video Contest in the year 2000.

Horton Plains was earlier known as Mahaeliya (big light) possibly due to the vast open grasslands. It was first declared a Nature Reserve under the Fauna and Flora Protection Ordinance in December 1969, and on March 16, 1988. Horton Plains was upgraded to a National Park by Gazette No. 497/10. At present it is known as the Horton Plains National Park.

The Horton Plains is the highest tableland in Sri Lanka, situated 2,100 to 2,300 metres above the mean sea level. Horton Plains was formed during the Archaean (5000-2500 million years ago) and uplifted in Post-Jurassic times (150-136 million years ago). It is an important wetland site (Ramsar Convention) in the country.

The water from constant rain and mist is drained by streams which in turn form tributaries that feed some major rivers, Mahaweli, Walawe and Kelani. Horton Plains also feeds Belihuloya, Agra Oya, Kiriketi Oya, Uma Oya and Bogawantalawa Oya.

Several species of arthropods and insects can be observed in this ecosystem. Several species of butterflies and a number of moths can also be observed at Horton Plains. This includes some rare endemic butterflies as well.

There are also appreciable populations of the rare relict shrimp Mahaeliya Lanka shrimp (Lancaris singhalensis).

For the field ornithologist, Horton Plains National Park offers good opportunities to see 17 of the 23 endemic birds in Sri Lanka. In fact Horton Plains is regarded as one of the best birding sites in the country.

Mammals

The park is the home to nearly 20 species of mammals. The presence of elephants was recorded at Horton Plains National Park over a century ago. At present, the largest and most commonly seen mammal is the sambhur (Cervus unicolor).

This stag can weigh up to 300 to 350 kg. According to Anslem, the sambhur was the main game species that was hunted with rifle and hound by sportsmen during British rule. Present day visitors to Horton Plains could observe small herds of sambhur grazing in the grasslands in the evenings.

During the day they were observed resting inside the forest. At presentthe leopard (Panthera pardus kotiya) is the largest carnivore in the park and the main predator of sambhur.

Other animals

Possibly about 15 species of amphibians inhabit Horton Plains. Most frogs lay their eggs in the humus under leaf-litter in a cavity made by the females or are leaf-nesting species.

“These frogs are known as direct developers as they do not pass the well known aquatic tadpole stage and metamorphose into frog-lets,” Anslem said.

During their studies at the Park Anslem and his team observed and identified only six endemic species of reptiles, comprising three agamid lizards, one skink and two species of snakes.

Threats

Studies indicate that the first human impact on the fauna, flora and landscape at the park such as hunting and deforestation for Mesolithic pre-farming commenced with the onset of warmer and wetter climatic conditions at Horton Plains 18,500 years ago.

In the past three centuries, including the British period (1815-1948), the park was a popular hunting ground for sambhur deer and the Ceylon jungle fowl (Gallus lafayetti) by early European sportsmen.

The forest die-back phenomenon had first been observed in Totupola kanda in late 1970s Anslem said. While a study in 1978 described the loss of two dominant tree species: Kina (Calphyllum sp) and Damba (Syzygium sp), now it appears that over 50 per cent of the species is affected.

The Diversity of Horton Plains National Park with 275 pages and 143 colour plates is priced at Rs. 1500 and is available at all Vijitha Yapa outlets.

by Ifham Nizam
Pictures courtesy Gehan de Silva Wijeratne and Anslem de Silva
The Island - March 31, 2007

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