Shorea guiso, commonly known as guijo (also red balan or red balau), is a species of tree in the family Dipterocarpaceae. It is native to lowland rainforests across Southeast Asia, including Cambodia, Laos, Vietnam, Thailand, Peninsular Malaysia, Sumatra, Borneo, and the Philippines.
Taxonomy and Nomenclature
The species was originally described as Mocanera guiso by Blanco, and later reclassified under the genus Shorea by Blume. The common name guijo is a Philippine Spanish word derived from the Tagalog gihò. Other local names include yamban-yamban in Zambales and taralai in Tarlac. Synonyms include Anisoptera guiso, Dipterocarpus guiso, Shorea longipetala, Shorea pierrei, and Shorea vidaliana, among others.
Description
Shorea guiso is a large emergent canopy tree that can grow up to 30–40 meters (98–131 feet) in height, with a trunk diameter reaching up to 1.80 meters (5.9 feet) or more. The bark is light reddish brown when freshly exposed, with light grayish brown thin sapwood that is clearly distinguishable from the heartwood, which ranges from light ashy brown to brown, occasionally with a reddish tint. The leaves are lanceolate or ovate lanceolate to oblong, with an acute to acuminate apex and a rounded base, and have at least 15 pairs of nerves. The branchlets are characteristically dark in color.
Distribution and Habitat
The species has a native range extending from southern Indochina to western and central Malesia. It is found in Cambodia, Laos, Vietnam, Thailand, Peninsular Malaysia, Sumatra, Borneo, and the Philippines. It typically inhabits low-altitude forests, often on ridges.
Uses and Economic Importance
The wood of Shorea guiso is moderately heavy to hard, and splitting it is difficult. It is used for construction, furniture making, ship and boat building, and other applications requiring hard wood with an aesthetically pleasing grain. It is also used as a decking product due to its resistance to rot and insects (though not termites). However, the wood is not long-lasting when exposed to weather or in ground contact, so it is used where extreme durability is not required. The resin of the tree is used as an ingredient in varnishes and paints.
In the Philippines, the price of guijo lumber was regulated in 1947 by President Manuel Roxas through Executive Order No. 66, which set a ceiling price for guijo and other types of lumber.
Conservation Status
Shorea guiso is listed as Vulnerable on the IUCN Red List of Threatened Species (2017 assessment). The population has undergone more than a 30% reduction over the past three generations, with decline continuing due to logging and slash-and-burn agriculture (kaingin). In the Philippines, some sources (such as the BINHI greening program) have listed the species as critically endangered. Historically, in 1921, guijo was abundant in the Philippines, estimated to cover about 5% of forest volume across numerous provinces and islands.
