Why do Tropical Evergreen forests appear dark inside the forests?

Give a geographical reason for each of the following:

(i) Nilgiri region has variety of vegetation type.

(ii) Sundari trees are used for boat making and construction purposes.

(iii) Littoral forest is also called tidal forest.

Name two areas where Tropical deciduous vegetation is found.

Why are the coniferous trees found in mountain forests in conical shape?