Diversity varies from local to global scales, and can be
defined in many ways. Due to the difficulty of studying
unseen organisms in the soil matrix, many measures of diversity
aboveground, especially abundance, cannot be easily
used belowground. While both species richness (the number
of species) and diversity (the number and abundance of
species) are easily measured aboveground, until very recently
only species richness was estimable belowground for most
organisms. Here, when diversity is discussed as a concept it
will include measures of both species richness and diversity.
Patterns of plant and insect diversity vary along latitudinal
gradients.