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Sumatran tropical pine forests

Pine forests are not a vegetation type one would expect to find in a tropical region, but in a small area of mainly northern Sumatra, this is the dominant vegetation. The Sumatran Tropical Pine Forests [IM0304] are not as species-rich as the surround montane forests but do contain similar species as well as those adapted to the vegetation.

  • Scientific Code
    (IM0304)
  • Ecoregion Category
    Indo-Malayan
  • Size
    1,100 square miles
  • Status
    Vulnerable
  • Habitats

Description
Location and General Description
This ecoregion represents the tropical pine forests in northern Sumatra near Lake Toba and along the Barisan Mountain Range. These forests occur within the montane zone of Sumatra. About 150 million years ago Borneo, Sumatra, and western Sulawesi split off from Gondwanaland and drifted north. Around 70 million years ago India slammed into the Asian landmass, forming the Himalayas, and an associated thrust formed Sumatra's Barisan Mountains, which run the length of Sumatra (Whitten et al. 1987).

Based on the Köppen climate zone system, Sumatra falls in the tropical wet climate zone (National Geographic Society 1999). The montane forests of the Barisan Range receive more rainfall on their western slopes than their eastern slopes, which are in a rainshadow. However, most of Sumatra experiences less than three consecutive months of dry weather (less than 100 mm rainfall/month), and rainfall in the montane rain forests averages more than 2,500 mm/year (Whitten et al. 1987). However, the pines exploit the drier areas in the mountain range, mostly on the eastern slopes.

It is in the drier areas that forests are dominated by the Sumatran pine (Pinus merkusii). This species originally was an early pioneer of disturbed land (such as landslides). However, repeated burning of the montane forests by natural and human-made disturbance has caused thick pine forests with a pauce ground layer to become established.

Biodiversity Features
The flora and fauna of the pine forests are not as diverse as those of the surrounding montane or lowland rain forests. There are no endemic or near-endemic mammals in this ecoregion. Only 3 to 4 percent of the bird species found in the surrounding rain forests were also found in pine forests. A large majority of the bird species found in these forests are common to disturbed or secondary forests. Twelve near-endemic bird species are attributed to this ecoregion (table 1).

Table 1. Endemic and Near-Endemic Bird Species.

 

Family Common Name Species
Phasianidae Bronze-tailed peacock-pheasant Polyplectron chalcurum
Campephagidae Sunda minivet Pericrocotus miniatus
Irenidae Blue-masked leafbird Chloropsis venusta
Turdidae Shiny whistling-thrush Myiophonus melanurus
Muscicapidae Rufous-vented niltava Niltava sumatrana
Muscicapidae Sunda robin Cinclidium diana
Pycnonotidae Cream-striped bulbul Pycnonotus leucogrammicus
Pycnonotidae Spot-necked bulbul Pycnonotus tympanistrigus
Pycnonotidae Sunda bulbul Hypsipetes virescens
Zosteropidae Black-capped white-eye Zosterops atricapillus
Timaliidae Sunda laughingthrush Garrulax palliatus
Timaliidae Rusty-breasted wren-babbler Napothera rufipectus

An asterisk signifies that the species' range is limited to this ecoregion.

Current Status
The pine forests are found in montane areas, and large portions of the ecoregion are within two national parks, Kerinci Seblat and Lingga Isaq (table 2). This ecoregion burns frequently from anthropogenic and natural causes.

Table 2. WCMC (1997) Protected Areas That Overlap with the Ecoregion.

Protected Area Area (km2) IUCN Category
Lingga Isaq [IM0159] 230 VI
Kerinci Seblat [IM0159] 760 II
Total 990  

Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of Threats
The pine forests are under much less threat than the lowlands and surrounding montane forests. More than a third of the ecoregion is in protected areas, and the ecoregion lacks high-value dipterocarp tree species. Therefore, these forests are under less threat from logging than the surrounding landscape.

Justification of Ecoregion Delineation
The Pinus merkusii-dominated conifer forests along the Gunung Leuser Range are shown and identified as a distinct ecoregion, the Sumatran Tropical Pine Forests [IM0304]. These forests are the only stands of Pinus found south of the equator (Whitmore 1984). Another tropical pine forest, the Luzon Tropical Pine Forests [IM0302] ecoregion, also occurs in the Philippines, and it developed under similar conditions. MacKinnon's biounit 21 largely corresponds to Udvardy's Sumatra biogeographic province. However, Udvardy did not include the Nicobar Islands. There are eight ecoregions that overlap Udvardy's Sumatra biogeographic province: Sumatran Lowland Rain Forests [IM0158], Sumatran Montane Rain Forests [IM0159], Mentawai Islands Rain Forests [IM0127], Sumatran Peat Swamp Forests [IM0160], Sumatran Freshwater Swamp Forests [IM0157], Sundaland Heath Forests [IM0161], Sumatran Tropical Pine Forests [IM0304], and Sunda Shelf Mangroves [IM1405].

MacKinnon's biounit 21 largely corresponds to Udvardy's Sumatra biogeographic province. However, Udvardy did not include the Nicobar Islands. Eight ecoregions overlap Udvardy's Sumatra biogeographic province: Sumatran Lowland Rain Forests [IM0158], Sumatran Montane Rain Forests [IM0159], Mentawai Islands Rain Forests [IM0127], Sumatran Peat Swamp Forests [IM0160], Sumatran Freshwater Swamp Forests [IM0157], Sundaland Heath Forests [IM0161], Sumatran Tropical Pine Forests [IM0304], and Sunda Shelf Mangroves [IM1405].

References
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List

Prepared by: Colby Loucks and Tony Whitten
Reviewed by:

 

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