Habitat Functions

We identified wetland habitat functions based on GIS analyses, interviews with experts, and the scientific literature .  Descriptions of these functions were added to the map as different fields.  The field named CohoHF indicates the type of Coho habitat (see below); CraneHF indicates whether or not the wetland is "Probable Sandhill crane nesting habitat"; and the CaribouHF field indicates whether or not the wetland is "Caribou Summer and Calving Habitat".  An additional field named "HFunction" combines the values for CohoHF, CraneHF and CaribouHF.  See below for more details on how these functions were derived.

Silver Salmon (Coho, Oncorhynchus kisutch Walbaum) Habitat Analysis

Silver salmon use the widest variety of wetland habitat of any anadromous fish on the Kenai Peninsula.  The Alaska Department of Fish and Game has mapped anadromous fish occurrence, including coho presence, in its Anadromous Waters Catalog, but realizes that not all streams are completely mapped.  The Wetland Map described here includes a complete map of small streams and open water wetland habitat for the Western Kenai Lowlands.  In order to identify streams and wetlands likely to support coho, we used the Anadromous Waters Catalogue along with the Wetland Map to determine where coho are likely to be found.

Definitions

Streams already mapped in the Anadromous Waters Catalogue as supporting coho are termed "Coho Catalogue Streams".  We classified both streams and wetlands that are not included in the Anadromous Waters Catalogue into two categories, likely and possible, according to their likelihood to support coho.    Riparian wetlands (excluding "AMT" and "Rib"- terraces and bars) that flow directly into Catalogue Streams were named "likely coho streams."

Wetlands directly adjacent to streams supporting coho maintain stream qualities important for coho life cycles.  These wetlands filter water and buffer flood flows.  Any non-open water wetland directly adjacent to a Coho Catalogue Stream was named "coho support habitat".

Sandhill Crane (Grus canadensis) Habitat Analysis

Sandhill cranes nest in large wetlands, especially where open water or emergent vegetation and small islands are intermixed (Safina, 1993).  Baker, et. al. (1995) wondered at what spatial scale were cranes selecting nest sites.  Did they just include habitat immediately adjacent to nests, or did they select sites based n the character of the habitat further away?  How far?  They analyzed crane nest habitat selection across spatial scales in the Seney National Wildlife Refuge, Michigan.  They found that habitat adjacent to nests was different from habitat adjacent to random points up to about 200 meters from nests.  They thought that larger areas could possibly differ from random points, however, the small area of the wildlife refuge (28,384 acres; about 1000 meter radius) caused larger areas surrounding nests to converge with areas surrounding random points making difference detection difficult.  Cranes did appear to select nest sites by including the quality of the habitat at least 200 m from the nest, and not just specific qualities of the habitat immediately adjacent to the nest.

Based on Baker, et. al.'s analysis, we looked in large peatlands on the Kenai Lowlands (Relict Glacial Lakebed ecosystem wetlands) for suitable blocks (open water mixed with islands or emergent vegetation) greater than 30 acres.  Specifically, we selected Relict Glacial Lakebed ecosystem wetlands with open water or emergent vegetation (LB12 or LB21 or LB31 or LB1-3 or LB1-4 or LB1-5 or LB14 or LB41 or LBSF) that were larger than 30 acres [acres > (200m^2*π hectares)2.471acres/hectare] and coded them: "Probable Sandhill Crane Nesting Habitat".

Caribou (Rangifer tarandus) Habitat Analysis

Caribou were extirpated from the Kenai Peninsula during the late 1880's, and re-introduced during the 1960's.  Two herds have formed, one is named the "Lowlands Herd".  During the summer it calves and feeds in two large peatlands on the northern lowlands.  This herd has been monitored since it was re-introduced and has spent time all over the lowlands, until finally settling into a pattern of calving and summer use in large peatlands outside the Kenai National Wildlife Refuge, then migrating to other large peatlands within the refuge during winter.

Current satellite GPS collar data were used along with the wetland map and interviews with Rick Ernst, a biologist with the Kenai National Wildlife Refuge, to identify which peatland polygons supported Lowlands Caribou Herd summer and calving habitat.  The satellite GPS collars indicate that the herd heavily concentrates in two relatively small clusters, in the large Relict Glacial Lakebed ecosystem wetlands just north and south of the Kenai River.  Working with Mr. Ernst, we selected wetland polygons corresponding with the densest concentration of radio collar locations and coded them: "Lowland Caribou calving and summer habitat".

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04 May 2007 10:17