![]() ![]() In southeast Alaska, salmon support an annual commercial and sport fisheries harvest of 30–70 million fish per year with a value estimated at $600 million to $1 billion (Waters 2010). 2003) and northern British Columbia (Temple 2005) contain a combined estimate of 7700 anadromous salmon streams with six Pacific salmonids ( Oncorhynchus spp.). ![]() For example, the total carbon stock in the forest and soils of the Tongass National Forest in southeast Alaska is 8 % of that in the conterminous United States (Leighty et al. 2014).Īlthough species diversity is low relative to other rainforests globally, ecosystem productivity is extraordinarily high (Alaback 1996). ![]() For instance, water temperatures in rainfall dominated watersheds are 5–12 ☌ warmer during summer than snowmelt and glacial watersheds (Fellman et al. Within this framework, a primary control on the timing and magnitude of stream flow is the proportion of the watershed that lies above the rain-snow transition zone, making the hydrology of this region particularly sensitive to changes in snowline elevation. Glacial watersheds are found almost exclusively in mainland provinces (1, 3, and 8). Finally, high-elevation glacial watersheds export little water during winter and early spring, and have their main peak discharge during late spring to early fall. These watersheds can be found on central parts of mountainous islands and in mainland provinces (1, 3, 7, and 8). Snowmelt watersheds are characterized by a spring snowmelt peak, a summer discharge minimum and an autumnal flow peak. These watersheds are predominantly found on island provinces (sections 2, 4, 5, and 6 in Fig. ![]() In lowland forest streams, the annual pattern of watershed discharge tracks the annual pattern of precipitation. The governing watershed dynamics in this ecoregion can be grouped into three general categories: glacial melt, snowmelt, or rainfall systems (Edwards et al. Our collaborative synthesis of potential impacts highlights the coupling of social and ecological systems that characterize the region as well as a number of major information gaps to help guide assessments of future conditions and adaptive capacity. These projected changes are anticipated to result in a cascade of ecosystem-level effects including: increased frequency of flooding and rain-on-snow events an elevated snowline and reduced snowpack changes in the timing and magnitude of stream flow, freshwater thermal regimes, and riverine nutrient exports shrinking alpine habitats altitudinal and latitudinal expansion of lowland and subalpine forest types shifts in suitable habitat boundaries for vegetation and wildlife communities adverse effects on species with rare ecological niches or limited dispersibility and shifts in anadromous salmon distribution and productivity. Five IPCC CMIP5 global climate models (GCMs) and two representative concentration pathways (RCPs) are the basis for projections of mean annual temperature increasing from a current average (1961–1990) of 3.2 ☌ to 4.9–6.9 ☌ (5 GCM range RCP4.5 scenario) or 6.4–8.7 ☌ (RCP8.5), mean annual precipitation increasing from 3130 mm to 3210–3400 mm (3–9 % increase) or 3320–3690 mm (6–18 % increase), and total precipitation as snow decreasing from 1200 mm to 940–720 mm (22–40 % decrease) or 720–500 mm (40–58 % decrease) by the 2080s (2071–2100 30-year normal period). Our synthesis is based on an analysis of projected temperature, precipitation, and snowfall stratified by eight biogeoclimatic provinces and three vegetation zones. We synthesized an expert review of climate change implications for hydroecological and terrestrial ecological systems in the northern coastal temperate rainforest of North America. ![]()
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