Jungle Gym

This is pretty self-explanatory. A group of Dayak kids from the village of Tae in West Kalimantan climbing up the trunk of an illipe nut tree (see Illipe Nut, Illipe Nut II, and Illipe Nut III) in one of the local tembawangs (see Tembawang). [NOTE: The young man on the left in the brown shirt is Susanto, who worked in the camat's office in Batang Tarang and helped a lot with the research in Tae (thx Susanto)]

Illipe Nut III

Gunung Poteng, Raya-Pasi Nature Reserve, West Kalimantan.

Shorea atrinervosa. [NOTE: Metal tag with number on the lower right of the trunk; white plot stake in the foreground.]

Given the obvious supply issues caused by the unpredictable fruiting of illipe nut trees, I was very interested in trying to find an illipe nut tree that fruited every year. Soon after arriving to West Kalimantan in 1989, I went to the Raya-Pasi Nature Reserve north of Pontianak in the Sambas district.  We stopped in Bagak Sawah, a Dayak village near the reserve, to pick up Pak Afong, the park warden. As we were walking to the forest, I casually asked Afong if he knew of any annually fruiting illipe nut trees.  He said he did, and then proceeded to show me several dozen large illipe nut trees that I later determined to be Shorea atrinervosa. The forest floor was carpeted with the seedlings and saplings of S. atrinervosa.  This was surprising because the year before had not been a mast year, and none of the other illipe nut species in West Kalimantan had produced any seed. 

I spent the next three years studying a marked population of Shorea atrinervosa trees in Raya-Pasi to see if Pak Afong was right about the annual fruiting behavior of this illipe nut species.  He was.  A more detailed account of the story can be found here.

Illipe Nut II

Illipe nuts come in a wide variety of sizes and shapes. Irregardless of the size of the seed produced, all species of illipe nut flower and fruit synchronously at unpredictable intervals of from 2 to 10 years. This reproductive behavior, known as "mast fruiting",  is thought to be an evolutionary response to excessive seed predation. What this means from a commercial standpoint, however, is that the availability of seeds from year to year is almost impossible to predict.  Try explaining that to your buyers. [NOTE: Mast fruiting is thought to limit the abundance of frugivores and seed predators in the forest by concentrating their food supply into one brief period every few years when they are swamped by more food than they can posisble eat.]

Illipe Nut

Illipe nuts from various Shorea species.

Dayak children in West Kalimantan with the seeds of S. stenoptera.

Trucks loaded with illipe nuts waiting outside the C.V. Mentawi processing plant in Pontianak, West Kalimantan.

The seeds produced by several species of Shorea in Borneo contain an edible oil whose physical and chemical properties are remarkably similar to cocoa butter.  These seeds are known commercially as "illipe nuts", and large quantities are collected and sold internationally to be used in the manufacture of chocolate, soap, candles, and cosmetics. West Kalimantan exports tens of thousands of tons of illipe nuts. [NOTE: The triglyceride fractions in illipe nut oil occur in similar proportions to those found in cocoa butter, and the oil can be blended with chocolate without altering the texture, gloss, or taste of the original confection.  The higher melting point of illipe nut oil makes it especially useful as a chocolate hardener, i.e. so that it melts in your mouth, not in your hand].