Chapter 2 Ecological Conditions and Trends Chapter 2 Ecological Conditions and Trends Introduction Chapter 1 described the Chugach National Forest planning area and the three different geographic areas of the national forest. This chapter describes the overall ecological integrity of the area. Ecological integrity for this assessment is defined as: “The quality or condition of an ecosystem when its dominant ecological characteristics (for example, composition, structure, function, connectivity, and species composition and diversity) occur within the natural range of variation and can withstand and recover from most perturbations imposed by natural environmental dynamics or human influence.” (36 CFR 219.19) The ecosystems described in this chapter include terrestrial (soils, vegetation, and wildlife), aquatic (freshwater and coastal marine ecology) and the interface between the two (riparian areas and wetlands).These ecosystems are evaluated at the forestwide and geographic area scales where appropriate. Key characteristics of each ecosystem are identified, including species composition and diversity, structure, function, and connectivity. Existing conditions and trends of the key characteristics are described for each ecosystem. System drivers are also discussed and include dominant ecological processes, disturbance regimes, and stressors for the different ecosystems. This chapter also includes a discussion of federally recognized threatened, endangered, proposed, and candidate species that occur within the Chugach National Forest and a discussion of potential species of conservation concern. It concludes with a discussion and summary findings of the ability of the aquatic, terrestrial, and riparian ecosystems in the plan area to adapt to a rapidly changing climate. Physical properties of the environment both constrain and enable the development of some ecological systems within the Chugach National Forest. A brief overview of the physical properties of the Chugach National Forest environment follows. Those that most directly influence ecosystems are emphasized. The Chugach National Forest includes the northernmost coastal temperate rain forests in North America and areas transitional to boreal forests. It is almost entirely within the Kenai-Chugach mountain system. The Kenai-Chugach mountain system is a topographically continuous mountain chain that extends from Kodiak Island through the Kenai Peninsula and around Prince William Sound, eventually connecting to the Saint Elias Range to the east. The principle fault systems in the area follow the same curved trend as the Kenai-Chugach mountain system. The Border Ranges fault lies in the lowlands along the mountain front and nearly parallels the western border of the Chugach National Forest (Karl, Vaughn, & Ryherd, 1997 Guide to geology of the Kenai Peninsula, Alaska, 1997). Rock type and geologic processes work together to affect the surficial geology of the Chugach National Forest. Ecological and physical dynamics of the national forest are strongly influenced by snow and ice. Glaciers, in conjunction with both tectonic forces and the erosion from rivers, are responsible for carving the topographic relief of the national forest and associated marine environment. Topography in turn affects environmental elements, such as slope, soil types, weather, drainage patterns, and vegetation types. Past episodes of glacial scouring and tectonic activity result in a legacy of disturbance apparent in regionwide patterns of directional change in topography and ecology. In addition to the long-term effects of glaciers and icefields, annual snow accumulation has an impact on vegetation, streamflow and chemistry, stream morphology, fish, wildlife, recreation opportunities, and a myriad of other things. 21 Chapter 2 Ecological Conditions and Trends Aquatic Ecosystems—Watersheds This section describes the watershed component of the aquatic ecosystems evaluation. Specific items evaluated include key ecosystem characteristics by geographic area, such as water quantity and water quality, drivers and stressors, and watershed condition and trends. This section also provides a summary of the overall watershed conditions across the national forest based on the national Watershed Condition Framework (WCF) and the Forest Service Watershed Condition Classification (WCC) Technical Guide (Potyondy & Geier, 2010) and an evaluation of watershed integrity. Relevant Information • Watersheds within the Chugach National Forest generally are in good condition, are functioning properly, and have good water quality. Natural processes, such as glaciers, mass wasting, and natural bank erosion, remain the primary sources of sediment loads and turbidity in streams and rivers across the national forest. Human associated water quality concerns exist in limited locations primarily in heavily visited areas close to roads and in developed areas. The following localized water quality concerns exist: erosion, sedimentation, and/or wetland damage from off-highway vehicles (OHVs) on authorized and unauthorized routes; sedimentation and pollutants associated with backcountry motor vehicle use; fecal coliform pollution from recreation related human waste; sedimentation from mining activities; and sedimentation from roads, trails, and recreational activities. • A number of watershed improvement projects have occurred within the national forest since 2002. These projects have improved the function of streams and riparian areas impacted by past or historic land management activities. • Changes in watershed characteristics, such as surface and groundwater quantity, quality, and flow regimes as well as erosion and deposition of sediments are occurring across the national forest. • The primary system driver to Chugach National Forest watersheds is climate change with additional limited and localized stressors of spruce bark beetle infestation, increased invasive aquatic organism and plant infestations, and increased population and/or national forest use. Ecosystems Evaluated Watersheds are useful units to delineate aquatic and terrestrial ecosystems. A watershed is the area of a landscape where water from rain or melting snow and ice drains downhill into a body of water, such as a river, lake, reservoir, or ocean. Watersheds include streams and lakes and shallow aquifers, as well as the land surfaces from which water drains. Topography and geology determine where the water flows along with the boundary of each watershed. Small watersheds drain into progressively larger ones, creating a hierarchical structure, or watersheds levels. These watershed delineation levels are based on hydrologic unit codes (HUCs). The Chugach National Forest has 275 6th-level HUC (HUC 6) watersheds that range from 8,000 to more than 300,000 acres spread across the three geographic areas (see table 2 and map 2). Prince William Sound holds nearly half of these. Three watersheds span two geographic areas. Within the Chugach National Forest, most are standard watersheds with a drainage flowing to a single outlet point. Prince William Sound is the exception where the majority of the HUC watersheds are frontal and include several small drainages with more than one outlet along the coastline of the ocean. More than half of Chugach National Forest watersheds have had no modification to natural overland flow and a little more than 40 percent have some glacial component. 22 Chapter 2 Ecological Conditions and Trends Table 2. Number of HUC 6 watersheds for the three different geographic areas Geographic Area HUC 6 Watersheds Both the Copper River Delta 3 and Prince William Sound Copper River Delta 72 Kenai Peninsula 67 Prince William Sound 133 Total 275 23 Chapter 2 Ecological Conditions and Trends Map 2. Chugach National Forest Service delineated HUC 6 watersheds by geographic areas and the results of the WCC rating (adapted from (MacFarlane, Zemke, Kelly, Hodges, & DeVelice, 2011)). 24 Chapter 2 Ecological Conditions and Trends Each Chugach National Forest watershed is a network of stream channels that differ in character and are referred to as channel types. Channel types across the national forest vary with landscape and topography and are characterized in the Alaska Region by stream process groups (USDA 2010). These stream process groups are based on primary differences in hydrologic function, landform, and channel morphology and include: estuarine (ES), palustrine (PA), glacial outwash (GO), flood plain (FP), low gradient contained (LC), moderate gradient contained (MC), alluvial fans (AF) and high gradient contained (HC) (see figure 1). Figure 2 displays the lengths and distribution of the different channel type process groups across the geographic areas. Overall, Prince William Sound has the most stream miles, followed by the Copper River Delta and then the Kenai Peninsula. The Copper River Delta has the highest percentage of GO, PA, and ES channel types with the Kenai Peninsula having very minimal ES channels due to its more interior and mountainous topography. Prince William Sound and Kenai Peninsula tend to be dominated more by HC channel types, followed by GO and then some of the more moderate gradient channel types (MM and MC). Individual channel type classification units within each process group are defined by physical attributes, such as channel width and/or incision depth, gradient, and channel pattern. Figure 1. The Alaska Region channel type process groups displayed across the typical landscape (USDA, 2010b). 25 Chapter 2 Ecological Conditions