Botany and Wetlands Study Report - McMillen, LLC

Botany and Wetlands Study ReportSoutheast Alaska Power Agency3.4 Plant Species Newly Documented in AlaskaPopulations of two plant species, Wallace’s spikemoss (Selaginella wallacei) and bog St. John’swort(Hypericum anagalloides), that have not previously been documented in Alaska wereobserved in the Swan Lake Expansion Project analysis area. Sources checked for distribution ofthese species include: the Consortium of Pacific Northwest Herbaria (2012), Plants NationalDatabase (USDA NRCS 2012), and University of Alaska Museum of the North Herbarium.3.5 General Vegetation TypesFour general vegetation types are present in the analysis area: old‐growth, young‐growth,unproductive forest and forested muskeg areas (Figure 3; Table 3). Additionally, a smallpercentage (approximately 2.2 percent) of the analysis area consists of open water associatedwith the Swan Lake Reservoir. General vegetation types were mapped using the Tongass NF’s Sizeand Density Mapping Model (SD7 model) that categorizes vegetation into seven categories.The predominant vegetation type in the analysis area is old‐growth forest which makes upapproximately 104.6 acres, or 74.6 percent of the analysis area (Table 3). Approximately 17.5acres (12.5 percent) of the analysis area consits of unproductive forest. Unproductive forest isdefined as forest land incapable of yielding crops of industrial wood because of adverse siteconditions (Forest Service 2008, Chapter 7). Young growth forest comprises approximately 4.6acres (3.2 percent) of the analysis area. Young growth characteristics vary with age; theyoungest stands are typically densely vegateted with a mix of young saplings and a dense shrublayer. As these stands progress in age, they develop a canopy that is predominantly closed andconsequently has limited understory vegetation.Table 3. General Vegetation Types in the Analysis Area 1/Acres in the AnalysisVegetation TypeAreaPercent of the Analysis AreaOld Growth 104.6 74.6Young Growth 4.6 3.2Forested Muskeg 10.5 7.5Unproductive Forest 17.5 12.5Water 2/ 3.1 2.2Total 140.3 1001/ Data comes from the Tongass NF tree Size and Density mapping model (SD7).2/ Consists of open water associated with the Swan Lake Reservoir.Swan Lake Hydroelectric Project January 2013FERC Project No. 2911 Page 12 Version: Agency Review