Many people are surprised to find an oak tree in a tropical setting, but there are a number of species that populate the areas near the equator.  The quercus insignis is one.  It is at risk though, and is listed as “Endangered” by the IUCN. It produces the largest acorns of all the roughly 500 different oak species.

Loss of habitat and harvesting for lumber are the two main reasons that the tropical oak is is decline. The long reproduction cycle, challenges in both acorn germination and replanting all conspire to make conservation efforts for this tree difficult.  

Reproduction
Oak trees are monoecious, which means each tree produces male and female flowers. The male flowers, or catkins, have long, drooping stems with several blooms on each stem. Wind and insects carry the male flowers’ pollen to the female flowers on neighboring oak trees. The female flowers, which appear about one week after the male flowers, are in the upper canopy of each oak and are so small that a magnifying glass is required to identify them.
Not too surprisingly there is not a lot of good data about life-cycle of the insignis. Most oak species don’t even begin to produce acorns until they are at least 20 years old.  The tropical oak only produces those huge acorns every 3-5 years. It is believed that weather and rainfall impact that variation, but no definitive studies have been done to date.
Unlike many other seeds, accords cannot be stored for long periods, since they do not stay viable when dried.  When there are acorns to be had, getting them to germinate is complex and often has a low success rate. A well well executed regime of soaking, monitoring and careful planting is needed for success. Most rainforest species have lateral root structures because there is plentiful water and the deep soil is generally not very rich. Oaks have tap roots, so planting a larger tree is very difficult (the taproot must be vertical  when planted). 
All these challenges combine to make the tropical oak a rarity and makes it difficult to repopulate