Columbia subject headings:
Animal populations--United States.
Biodiversity--United States.
Biotic communities--United States.
Endangered ecosystems--United States.
Endangered species--United States.
Natural resources--United States.
Plant populations--United States.
United States--Environmental conditions.
Harvard subject headings:
Animal populations--United States.
Biodiversity--United States.
Biotic communities--United States.
Endangered ecosystems--United States.
Endangered species--United States
Natural resources--United States
Plant populations--United States.
United States--Environmental conditions.
Princeton subject headings:
Animal populations--United States.
Biodiversity--United States.
Biotic communities--United States.
Natural resources--United States.
Plant populations--United States.
United States--Environmental conditions.