Species Diversity "تنوع الكائنات الحية"

Species Diversity = the number or variety of species in the world or in a particular region
Species richness = the number of species
Evenness or relative abundance = extent to which numbers of individuals of different species are equal or skewed
Speciation generates new species and adds to species richness
Extinction reduces species richness

Immigration  is the inmigration of a species to an area
Emigration is the outmigration of a species from an area
Extirpation is the local extinction of a species

Ecosystem diversity = the number and variety of ecosystems
Also encompasses differing communities and habitats
Rapid vegetation change and varying landscapes within an ecosystem promote higher levels of biodiversity
Ecotones = where different types of habitats intermix