Shannon Diversity Index, Richness and Shannon Evenness Index are among the most popular diversity indices in ecology. We use those indices to quantify the average farm-level agrobiodiversity in each Nuts 2 region of EU countries.
The Shannon’s Diversity Index, sensitive to rare land cover, measures both the abundance and evenness of agricultural land uses. Richness measures the number of agricultural land-use types present on a farm and therefore reflects the abundance of distinct categories. The Shannon Evenness Index (E) removes the effect of richness and isolates how balanced the distribution of agricultural land-use types is. It ranges from 0 to 1, where 0 indicates strong dominance by a single type and 1 indicates perfectly even land use.
Shannon’s Diversity Index
Shannon’s Diversity Index= 
(abundance and evenness of agricultural land covers) where 
is the ratio of agricultural land cover i (for example the proportion of non-irrigated arable land).
Richness
Richness = Number of agricultural land covers.
Shannon Evenness Index
Shannon Evenness Index=Shannon index/ln(Richness)
