Shade tolerance in young trees varies between species, and may determine the pattern of forest succession.

Historically this has been due to human activity, and more recently primarily from natural forest succession.

Liriodendron tulipifera is generally considered to be a shade-intolerant species that is most commonly associated with the first century of forest succession.

Today, saplings sown by large remnant Douglas-fir trees are distributed widely over the mountain in an example of forest succession.

Interaction with the habitat is also unclear regarding monsoonal forest succession into grasslands.

This begins the first stage of forest succession called "stand initiation".

They are the most shade-tolerant species of tree to establish in the process of forest succession.

Today, seedlings sown by second growth Douglas-fir forest can be seen advancing up into the preserve's grasslands in an example of forest succession.

Habitat degradation due to later stages of forest succession has also been attributed to the decline of this species.

(See figure 7.1 for a schematic representation of the forest successions.)