Biodiversity is the greatest treasure we have... Its diminishment is to be prevented at all cost. - Thomas Eisner

The Convention on Biological Diversity defines biodiversity as:"the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species, and of ecosystems."

Biological diversity is fundamental for all systems, natural and human-made, because living organisms play a central role in the major elements (carbon and nitrogen) and water cycles. That's why biodiversity can measure how healthy and how resistant it is to changes. 


In order to measure biodiversity there are different methods, and the most common are: 

• Simpson's diversity index (D) is a simple mathematical measure that characterizes species diversity in a community. The proportion of species i relative to the total number of species (p_i) is calculated and squared. The squared proportions for all the species are summed, and the reciprocal is taken:
  
  
  

Where D is Simpson's Diversity Index, S is total amount of species in the comunity, p_i is the proportion of S made up of the ith species and  E_D is the equitability.


It measures the probability that two individuals randomly selected from a sample will belong to the same species. The higher the value obtained the more diverse an ecosystem is.

• Shannon's Diversity Index: Is another diversity index used for characterize diversity in a community. It accounts for both abundance and evenness of the species present. The formula for applying this index is:

• Berger-Parker diversity index: measure the number of individuals in the dominant taxon, relative to n.