Alder Carr

An alder carr is a particular type of carr, a waterlogged wooded terrain populated with alder trees, found across the United Kingdom and sometimes attracting ash trees as the ground becomes drier. Many alder carrs have developed alongside streams in the New Forest, where alder's capacity to thrive in waterlogged ground lets it dominate these areas, aided by a root-dwelling bacterium, Frankia alni, that extracts nitrogen from the air and compensates for the low nitrogen typical of waterlogged soil.