Answer:
D (3)
Explanation:
Species richness is the number of different species within an ecological community, area, ecosystem or sample etc. It is the numerical characteristics of an ecosystem. Species richness is a measure of the variety of species and it is done by counting the number of different species in that given region. Species richness does not take into consideration the abundance of the different species or how widely distributed they are.
In this case, a tree community is involved. The community consists of three different tree species: Maple, Oak, and Alder. Hence, the species richness is simply the number of different species in the tree community, which is three(3).
