Herbarium Digital Library

Sibuyan Island

Category: Critical Plant Sites
Date Posted: 2005-12-27

Sibuyan is a crescent shaped island of Romblon Province. It is bounded on the far north by Marinduque, on the south by Panay Island, on the east by Masbate, and on the west by Tablas and Romblon Islands. It has an area of 445 sq. km. The island has two prominent peaks, Mt. Guiting-Guiting with a height of 2,057m and Mt. Nailog with a height of 789m.

The island has pre-tertiary rock units which consist of schists, marble, altered volcanic rocks, and ultramafic rocks. The climate in the island is classified under Type III characterized as having no very pronounced maximum rain period, with a short dry season lasting only from one to three months. The vegetation of the island consists of different types, namely: mangrove and beach forests, lowland evergreen rainforest, forest over ultrafamic soils, montane forest, summit grassland, and heath forest.

The mangrove vegetation in Sibuyan Island is still extensive, well-developed, and relatively undisturbed in most of its areas. These are found at the mouth of rivers and extensive mudflats at coastal areas. In 1986, it was reported that about 352 hectares of mangrove forest remain.

The summit of all the island's mountain is devoid of tall trees and characterized by a grassland and heath type of vegetation. The dominant plants are grasses such as Poa species and species of Cyperaceae. There are also different species of Rhododendrons, and Vaccinium.

The surveys conducted by the Bureau of Solis Land Resources Evaluation Project of Romblon, the Swedish Space Corporation, Development Alternatives, Inc., and that of the local people, showed that there is still extensive cover of primary forest in Mt. Guiting-guiting, extending to Mt. Nailog to the west and Silum in the north, Taclobo in the south, and Lumbang in the east.

Dr. Elmer Merrill observed that Sibuyan's flora is closely related to the flora of the east coast of Luzon along the Pacific Ocean, especially that from Atimonan and Casiguran Province of Aurora. Its isolation since the last ice age from the other islands of the archipelago enhanced the endemism of the flora and fauna in the island.

Illegal logging, charcoal making, slash-and-burn agriculture and vine gathering are the major threats to the flora and vegetation of the island, particularly Mt. Guiting-Guiting. Some people have started to resort to "carabao-logging", a crude practice of selectively cutting high-grade timber trees with motorized chainsaws, cut into boards or flitches, and dragged by carabaos into the base of the mountain. Gathering of rattans has now extended to the higher part of the mountains since there are no more harvestable rattan poles at the lower altitudes. Slash-and-burn agriculture is also practiced by the local people but this activity is presently confined to the lower fringes of the mountain's lowland primary forest and rarely extended beyond 200m.

Because of its unique flora and fauna, intact diverse vegetation, and interesting geological formation, the island, particularly Mt. Guiting-Guiting, has been proposed as a protected area.

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