Discharge Slope Ecosystem Map Component SA

Accuracy assessment: 7 polygons interpreted as SA on aerial photographs were field checked. 5 remained SA; 1 was revised to SMA; 1 was revised to SCS.

SA is a Discharge Slope map component dominated by a alder, usually thinleaf alder (Alnus incana ssp tenuifolia). SA is uncommon, so far found only near tidewater wetlands, either along the Kenai or Kasilof Rivers; at the upper reaches of a lagoon north of Nikiski, that was a peatland before the 1964 earthquake; or at the base of the bluffs above Homer. SA with thinleaf alder, typically occupies the wettest toeslope positions. Sitka alder indicates chronic natural disturbance, which typically occurs on steep valley sides or bluffs.

SA is more common in complex with the Lutz spruce dominated SL map component. These are named SLA or SAL, depending on whether spruce or alder is dominant, respectively. A uniform spruce forest or woodland (greater than 10% spruce cover) with an alder understory is mapped as an SL unit, and is common in that same landscape position.