Main criteria for measuring biodiversity are:
1.Species richness which means the no. of species in a given area.It could be the species richness of specific taxa or no.of grasses,bushes,trees etc.
2.Ecological indicators which means these're scientific constructs that use quantitative data to measure aspects of biodiversity  ecological condition.They form a main component of monitoring,assessment & decision-making & are designed to communicate information quickly & easily to policy makers.