State indicators provide a firsthand description of both the state and the development of biodiversity. For this reason, Z indicators—particularly the three core indicators «Species Diversity at National and Regional Level ( Z3), in Landscapes (Z7) and in Habitats (Z9)»—make up the essence of biodiversity monitoring.

There are three levels of diversity differentiated in BDM:

Genetic diversity: diversity within species is already of major importance in relation to the primary objective of preserving biodiversity. Diversity can be lost before a species becomes extinct if, say, populations become regionally extinct. For budget reasons, BDM is confined to surveying livestock breeds and crop plant varieties (Z1 and Z2).

Diversity of biotic communities: the diversity of biotic communities is highly complex, difficult to record and experts disagree about its significance. As a result, BDM is restricted to one quantitative and one qualitative indicator each for monitoring particularly valuable habitats (Z10 and Z11).

Species diversity: species diversity is easy to describe and its value can readily be understood. Species are normally easy to distinguish. The three core indicators Z9, Z7 and Z3 register the diversity in habitats, landscapes, and biogeographical regions i.e. the country as a whole. For the purpose of gathering Z7 and Z9 data, BDM has established two new surveying networks. These also generate the data required to monitor the population development of roughly 1,500 common or widespread species (resulting in Z8).

Overview of Z indicators
Z1	Number of livestock breeds and plant varieties
Z2	Proportion of livestock breeds and plant varieties
Z3	Species diversity at national and regional level
Z4	Number of species in Switzerland facing global extinction
Z5	Change in the endangerment status of species
Z6	Population size of endangered species
Z7	Species diversity in landscapes
Z8	Population size of common species
Z9	Species diversity in habitats
Z10	Size of valuable habitats
Z11	Quality of valuable habitats
Z12	Diversity of Species Communities