Region
Adriatic Sea
1
Afghanistan
80
Africa
22
Africa, Central
1
Africa, East
6
Africa, Southern
2
Africa, Sub-Saharan
13
Africa, West
4
Alaska
33
Albania
2
Alberta
1
Algeria
6
Alsea River Watershed
1
Amazon River Region
5
Amazon River Valley
1
Amazon River Watershed
2
Amazonas
1
Amazonas (Venezuela)
1
America
7
American Samoa
2
Andaman and Nicobar Islands
1
Andes
3
Andorra
3
Angola
1
Anguilla
1
Anne Arundel County
2
Antarctica
6
Antigua and Barbuda
4
Apache-Sitgreaves National Forest
4
Apache-Sitgreaves National Forest (Ariz.)
3
Appalachian Region, Southern
1
Aral Sea (Uzbekistan and Kazakhstan)
1
Arapaho National Forest
1
Arctic regions
2
Argentina
16
Arizona
16
Armenia (Republic)
3
Ascension
5
Ashley National Forest (Utah and Wyo.)
1
Asia
18
Asia, Central
2
Atlantic Coast
1
Atlantic Coast (North America)
2
Atlantic Coast (U.S.)
7
Atlantic Ocean
2
Australia
25
Australia, Northern
1
Austria
2
Ayalán Cemetery Site
1
Ayalán Cemetery Site (Ecuador)
1
more ...