Glossary of Alaska Natural History Terms:
References listed at the bottom

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A

Active layer. A seasonally thawed surface layer of soil in arctic or alpine regions that lies above permanently frozen ground and is between a few centimeters and about 3 meters thick.

Afforestation. The establishment of forest by natural succession or by the planting of trees on land where they did not grow formerly. Afforestation. The establishment of forest by natural succession or by the planting of trees on land where they did not grow formerly.

Alcids. Any of the Alcidae family (Order Charadriiformes) of marine birds having a stout bill, short wings and tail, webbed feet, a large head and heavy body, and thick, compact plumage. Confined to the northern parts of the Northern Hemisphere, alcids include auks, guillemots, murres, and puffins. Any of the Alcidae family (Order Charadriiformes) of marine birds having a stout bill, short wings and tail, webbed feet, a large head and heavy body, and thick, compact plumage. Confined to the northern parts of the Northern Hemisphere, alcids include auks, guillemots, murres, and puffins.

Alevin. A young fish, particularly a young salmon that is still attached to the yolk sac. A young fish, particularly a young salmon that is still attached to the yolk sac.