According to this species-area curve for reptiles and amphibians on a west indian archipelago, a 50% decrease in area will change the number of species living in the remaining area by

According to this species-area curve for reptiles and amphibians on a West Indian archipelago, a 50% decrease in area will change the number of species living in the remaining area by -10%.  A graph depicting the relationship between the size of a region and the biodiversity that it can support is called a Species-area curve.

the national environmental policy act (nepa) is a united states environmental law that promotes the enhancement of the environment and established the president's council on environmental quality (ceq). the law was enacted on january 1, 1970. to date, more than 100 nations around the world have enacted national environmental policies modeled after nepa.

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.