Guide to Alaskan Black Spruce Wetland Bryophytes: Species Specific to Delineation for Interior and South Central Regions

摘要

Currently, there is an effort underway to update and revise the U.S. Army Corps of Engineers (Corps) wetland delineation manual (Wakeley 2002) in support of Section 404 of the Clean Water Act (CWA) (33U.S.C.1344). As part of this updating, the United States has been divided into ten subregions. The new subregion boundaries follow an ecosystem-based region classification that has also been used in the development of national hydric soil indicators (NRCS 2006). As part of this effort, the State of Alaska has been designated as one of these 10 subregions. During development of the Alaskan wetland supplement (U.S. Army Corps of Engineers 2007), the Vegetation Working Group, composed of advanced delineators who assisted in revising the new wetland supplement, decided to develop a cryptogam indicator for the black spruce vegetation type. This vegetation type was selected because it is usually considered to be hydrophytic but frequently extends beyond the wetland boundary. The occurrence of hydrophytic black spruce vegetation outside of wetlands is problematic and confusing for field delineators in Alaska who are trying to locate the wetland boundary using the three-factor approach of hydrophytic vegetation, hydric soils, and hydrology. The purpose of the cryptogam indicator is to assist in establishing a hydrophytic vegetation boundary within the black-spruce- dominated vegetation that aligns closer to the hydric soil and hydrology indicators. To develop the cryptogam indicator, a study was undertaken to select high-fidelity cryptogam species that could reliably locate that part of the black spruce community that closely aligns itself with hydric soils and hydrology indicators. To develop and test this cryptogam indicator, a series of studies were undertaken during 2004 and 2005 in several black spruce community types in the Anchorage (South Central Alaska) and Fairbanks (Interior Alaska) areas.