For dipterocarps to grow tall enough to reach the canopy, they need light.
Remember, when a canopy gap opens up, usually from the death of another tree, those dipterocarps that have the most adaptable genome respond fastest, that is, they make the most reiterations.
Bright lights, big city and the plutocrats
The biggest, tallest dipterocarps, the ones that thrive in the light, also have the most resource needs.
Ironically, these same trees also tend to be relatively short-lived. It’s not hard to see why. It gets hot under the bright lights. Sometimes, so hot that the tree is not able to accumulate enough carbon to offset its respiration costs.
For example, they need the most water, and thus have the highest hydraulic conductivity, to pump water all the way from the roots to the canopy. But they are also the most wasteful of that water.
They need the most nutrition to feed their girth, and so they thrive in fertile soils. But they are so good at getting what they need for themselves, they don’t leave anything for any other tree. So, counterintuitively, fertile soils are often the least bio-diverse. Only the biggest and the brightest can survive there.
By contrast, the smaller, slow-growing dipterocarps in the forest understorey have better water-use efficiency. As a result, they are also less susceptible to drought.
And less fertile soils also also support a greater variety of dipterocarps. There’s not enough in there to feed one superstar, but there sure is enough to feed a multitude of regular folk.