Due to the fact that Tengkawang or rather its seeds or fruits, a kind of nuts, are not available every year, it might be not on top of one’s agenda regarding non-timber forest products. Nonetheless Tengkawang is worthwhile to mention and to describe, not least, because Tengkawang is a tree that belongs to the Dipterocarpaceae family, which is dominating the rainforest in South-East Asia. Even if not available every year, Tengkawang nuts play also a role as a source of income. As a Non Timber Forest product it can indeed help diversify forest production and provide an economically attractive alternative to exclusive use of tropical rainforest for timber production. Planting and sustainable cultivating of high value Tengkawang trees are a contribution to conserve biodiversity and to increase community’s income at the same time. As for today, communities are aware and motivated for preserving the Tengkawang trees. They are already used for a long time and usually not cut down. The trees are also often planted close to villages, especially in wet areas or close to rivers. Big tengkawang trees are a common sight and in some areas with durian the biggest trees still standing. Customary laws protect the trees but sometimes it is hard to proof since the wood is hard to distinguish from other Meranti species.
Flowering and Fruiting
Tengkawang trees belong to the Shorea genus and are, as mentioned, part of the Dipterocarpaceae family.
The name Dipterocarpaceae describes the seeds produced by most of the species and is taken from the Greek: di = two, ptero = wing and carp = seed – “Two wing seed”. Some species produce seeds with more than two wings, while others produce seeds with one wing only or even no wing, though.
There are many remarkable facts known about Dipterocarpaceae forest. One of the most amazing one is the general flowering or mass flowering which occurs at irregular intervals of 3-10 years. During that time almost all Dipterocarpaceae species and many other plants flower over a period of roughly 3 months[i], starting approximately in August and ending in October. This general flowering seems to be followed almost always by a massive fruit set, survival of seeds and seedlings and successful pollinations. It is suggested that general flowering is a kind of “survival” strategy and serves either to satiate seed predators or to facilitate pollination or both.
While this provides a good explanation for general flowering, it does not explain how general flowing is triggered. There is a quite interesting hypothesis, which suggests that droughts associated with the El Niño southern oscillation (ENSO) are plausible triggers for this phenomenon, where the largest events occur after several years of little or small flowering[ii]. Droughts happen during transition periods from the La Niña to El Niño, or at the beginning of an El Niño period. Apparently this also applies to Tengkawang. In February and March 2010 there was a rich harvest of Tengkawang nuts in Kapuas Hulu, which followed after a very long and hot dry season in 2009. Interestingly there was an El Niño event across the tropical pacific, which has started June 2009[iii]!
The Tengkawang tree starts to bear fruits at the age of 8-9 years, flowers from August to October and fruit ripen and fall is from January to March the following year – see above.
Local and an international use of Tengkawang nuts
Tengkawang seed is produced mainly from Borneo and South Sumatra. The seed or nut contains about 14% oil, which resembles butter in its physical and chemical properties. Local people use Tengkawang oil for frying and medicines.
On the industrial scale, Tengkawang oil or butter is primarily used as substitute of cocoa butter in chocolate. Furthermore it is used for wax, cosmetics, pharmaceuticals, soap, margarine and grease making Indonesia is the main producer and exporter of Tengkawang nuts. Almost all production is exported, mainly to west Europe (the United Kingdom, Netherlands, France, and Denmark), Japan, Singapore and Hong Kong.[iv]
Processing the nuts and trade
Tengkawang trees produce up to 600 kg seeds (unprocessed) per hectare. The quality of nuts is dependent on the levels of moisture and free fatty acids (FFA). Fallen fruits are collected by the villagers and the processing must start immediately, in order to keep the FFA content below 10%. Though, sometimes there are too many fruits to be colleded and processed in time.
At first the wings have to be removed from the fruits then they are dried/smoked (using dry wood as fuel) for up to three days in order to crack the pericarps. After this the extracted nuts will be sundried in order to make them more durable. Then they are packed into sacks and are ready for sale.
The Price affected by market fluctuations and started in 2010 at 6000 IDR (0.5 Euro) per kilo of processed nuts. However the price for one kilo may vary from harvest season to harvest season
[i] Sakai, Shoko; K Momose, T Yumoto, T Nagamitsu, H Nagamasu, A A. Hamid and T Nakashizuka (1999). “Plant reproductive phenology over four years including an episode of general flowering in a lowland dipterocarp forest,Sarawak, Malaysia“. American Journal of Botany 86: 1414–36.
[ii] Shoko Sakai, Rhett D. Harrison, Kuniyasu Momose, Koichiro Kuraji, Hidetoshi Nagamasu, Tetsuzo Yasunari, Lucy Chong and Tohru Nakashizuka “Irregular droughts trigger mass flowering in aseasonal tropical forests in asia” American Journal of Botany. 2006;93:1134-1139.
[iii] World Meteorological Organization El Niño/ La Niña Update 1st December 2009
[iv] Food and Agriculture Organisation of the United Nations (FAO): Non-wood forest products In 15 countries of Tropical Asia.