Sungai Tiagau (Extension) Forest Reserve

Sungai Tiagau Ext. is a Class I Protection Forest. The forest reserve (FR) is located about 70 km northwest of Tawau town and situated in between Kalabakan FR (Class II) and the larger fragment of Sungai Tiagau FR (Class I). The reserve is accessible via the Kalabakan-Tawau road and continues with the Kalabakan-Tongod road.

Latitude/Longitude:    4° 41.264’N-  4° 35.704’N, 117° 19.060’E-117° 26.551’E

The Kalabakan-Tongod road is transverse at the southern boundary of the reserve. Part of the Luasong Field Centre compound is within the Class I reserve. On the western part of the reserve, an abandoned sawmill used to be the Ganda Deras Sawmill.

Creations – Sungai Tiagau (Extension) was gazetted in 2014, and the reserve was formerly part of the Kalabakan FR (Class II).

Management responsibility – Kalabakan District Forestry Office

Boundary matters – The boundary is yet to be demarcated.

Management plan – None.

Current Use – Protection.

Settlements and other buildings approximately 2 km from the boundary:

Settlement:

• Kg. Makandot
• Luasong

Other buildings

• Abandoned sawmill

The surrounding land-uses are mostly joint venture private company oil palm estates with Sabah Foundation and Sabah Softwood Sdn Bhd. On the northwest border of the reserve bordering tree plantation by Yayasan Sabah.

Topography 

Figure 1: Topography and drainage map of Sungai Tiagau (Extension) FR

Hydrology 

Major river: Luasong river

Soils

Brantian, Bang, Crocker, Kalabakan, Lokan and Mawing soil association.

Meteorological data

See Sapulut and Kalabakan rainfall data.

The lowland mixed dipterocarp forest covered a large area of the FR. The upland mixed dipterocarp forest is found in the northern part of the reserve, and a fraction of lowland mixed dipterocarp and kerangas forest is located in the southern part of the reserve.

Flora

A total of 572 plant taxa were recorded from the reserve. The ten most speciose families in decreasing order are the Dipterocarpaceae (56), Rubiaceae (38), Lauraceae (33), Phyllanthaceae (29), Euphorbiaceae (26), Annonaceae (24), Malvaceae (20), Meliaceae (19), Fabaceae (18) and Myrtaceae (18). There are 158 taxa endemics to Borneo, including 19 endemics to Sabah. 

Threatened species under IUCN Red List:

• • 40 Species

Taxa under Wildlife Conservation Enactment 1997: –

Schedule 1, part II – (i) Tetrastigma

Schedule 2, part II – (i) 7 Ginger (ii) 2 Agarwood (iii) Palm (iv) Ramin

Species listed under Appendix II CITES: 

• • 3 Species

Prohibited Species Under Sabah Forest Enactment 1968: 

• • 53 species (mostly of fruits trees and threatened tree species)

Two high conservation value plant species, namely Shorea symingtonii and A. beccariana are selected as part of the key conservation targets for monitoring biodiversity integrity in Sungai Tiagau (ext.) FR. Adequate knowledge of plant diversity is vital for the formulation of Sungai Tiagau (ext.) FR Forest Management Plan.

Avian

Ninety-four species from 44 families were recorded from this FR. The four most specious families are Bucerotidae (8), Cuculidae (7), Phasianidae (5), Nectariniidae (5), Megalaimidae (4), Pellorneidae (4), Muscicapidae (4), and Accipitridae (4).

Threatened species under IUCN Red List recorded from this FR include the Helmeted Hornbill (CR), Wrinkled Hornbill (EN), White-crowned Hornbill (EN), Wreathed Hornbill (VU), Wallace’s Hawk-eagle (VU), Rhinoceros Hornbill (VU), Chestnut-necklaced Partridge (VU), and Black Hornbill (VU).

Insect

About 66 nocturnal species are recorded from the FR. At least six Bornean endemics were recorded from the 2019 survey. The endemics include one beetle species and five moth species. Summary of insects sighting are as follows: 

• • Butterfly –  18 species; Interesting species: Trogonoptera brookiana (Rajah Brooke) & Troides amphrysus (Golden Birdwing)
  • Moth –  20 species; Endemics: Amata prepuncta, Barsine lucibilis, Eugoa tesselata, Plutodes cyclaria and Eupanacra psaltria.
  • Beetle –  7 species; Endemic: Calomera crespignyi
  • Dragonfly & damselfly – 8 species
  • Other insects – At least 13 species; Interesting species: Exploding Ants (Colobopsi saundersis)

Mammals

A total of 21 mammal species from 13 families were recorded from this FR.

• • Urva brachyurus (NT)**
  • Martes flavigula (LC)**
  • Viverra tangalunga (LC)**
  • Hemigalus derbyanus (NT)**
  • Paradoxurus hermaphroditus (LC)**
  • Arctictis binturong (VU)**
  • Mydaus javanensis (LC)**
  • Sus barbatus (VU)***
  • Tragulus napu (LC)***
  • Rusa unicolor (VU)***
  • Tragulus kanchil (LC)***
  • Muntiacus atherodes (LC)***
  • Bos javanicus (EN)*
  • Elephas maximus borneensis (EN)*
  • Macaca nemestrina (VU)**
  • Hylobates muelleri (EN)**
  • Manis javanica (CR)*
  • Callosciurus prevostii (LC)
  • Ratufa affinis (NT)**
  • Callosciurus notatus (LC)
  • Hystrix brachyura (LC)***

Wildlife Conservation Enactment 1997: Schedule 1*; Schedule 2**; Schedule 3***

• Sabah Forestry Department conducted multidisciplinary studies during the Heart of Borneo Expedition (HoB) in 2019.

Forest fire – The reserve is susceptible to a forest fire as the area comprises secondary vegetation of various successional stages. 

Encroachment – Due to the easy access to the forest reserve, encroachment could be a potential threat.

The reserve’s forested area is a critical water source for Luasong Forestry Centre.