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5 Hotspots of Biodiversity Thousands of “ecoregions” located in diverse ecological regions comprise the earth’s biodiversity. 6 27 Threats to Biodiversity: Causes These days, biodiversity loss is a global problem. Population explosion and unsustainable utilization of natural resources result in drastic change in environment and habitat loss that ultimately lead to biodiversity loss. 3 • • • • • Development Pressure Exploitation Collection made by scientific/educational institutions Exploitation by local authorities as revenue resources Firewood collection Food gathering and hunting Poaching 28 S.

3 Gamma (γ) Diversity Gamma diversity is the overall diversity at landscape level that includes both α and β diversities. 3 Levels of Biodiversity Theoretically there are three levels of biodiversity. 1 Genetic Diversity Variation of genes within the species is referred as genetic diversity. This constitutes distinct population of the same species or genetic variation within population or varieties within a species. 2 S. Sharma and R. Arya Species Diversity The number of species in a region is known as species diversity.

Among these identified species, only a few have been studied for their medicinal value. Moreover, most of the biodiversity is disappearing very rapidly (as many as 27,000 species are becoming extinct per year). This indicates that 3 species are disappearing every hour while 150 species are disappearing every day. 914 species, finding that about 68 % of evaluated plant species are threatened with extinction. , species richness and evenness. Sometimes the dominance of one vegetation stratum may affect the α diversity of the other strata.