The Copper Plateau Taiga ecoregion occupies the site of a large Pleistocene lake. The low (420 m to 900 m), flat or gently rolling plain is completely surrounded by the high mountains of ecoregions 103 and 104. A shallow permafrost table and poor soil drainage have resulted in a landscape dotted with many lakes and wetlands. The vegetation also reflects these wet conditions. Coniferous forests and woodlands dominated by black spruce (Picea mariana) are the most common communities. The many wetland areas support low scrub bog communities dominated by birch (Betula glandulosa and B. nana) and ericaceous shrubs. Also found in wetland areas are wet graminoid herbaceous communities, dominated by sedges (e.g Eriophorum anjustifolium and Carex spp.) or codominated by sedges and herbs (e.g. Menyanthes trifoliata, Petasites frigidus, and Potentilla palustris). Exceptionally well drained sites support coniferous forests dominated by white spruce (Picea glauca) or broadleaf forests dominated by black cottonwood (P. trichocarpa), and/or quaking aspen (Populus tremuloides). (Gallant et al. 1995)
This ecoregion experiences a continental climate. Annual precipitation ranges from 250 mm to 460 mm, and increases from south to north. Winter daily minimum temperatures average -27°C, while summer daily maximum temperatures average 21°C. Soils, generally poorly drained and shallow to permafrost, include Histic Pergelic Cryaquepts, Aquic Cryochrepts, Typic Cryochrepts, Pergelic Cryaquolls, and Typic Cryoborolls. This region was extensively glaciated during the Pleistocene, in addition to containing the lake.
Wildfire occurrence in this ecoregion is low, and fires range in area from less than 1 ha to approximately 40 ha, averaging 5 ha. Because the permafrost is discontinuous and shallow, wildfire disturbance to the organic mat can significantly raise soil temperature, increase permafrost depth, and result in changes in soil hydrology and structure.
The many thaw lakes and wetlands of this ecoregion provide excellent nesting habitat for a variety of migratory bird species. The north central portion in particular supports very high numbers of breeding trumpeter swans. For the most part top-level predators are still present in numbers close to their natural variations. The western part of the ecoregion is used by the Nelchina caribou herd as part of their annual migration route.
The Copper River supports strong runs of salmon, particularly king and sockeye salmon. The large lakes in the central part of the ecoregion, including Lake Louise, Tyone Lake, and Susitna Lake support nesting waterfowl and fish and serve as the headwaters for the Sustina River.
Habitat Loss and Degradation
Total habitat loss is estimated to be 10 percent, due mostly to development in the Glenallen area and to timber harvesting in the Copper River Valley and on Native Corporation lands near Chitina.
Remaining Blocks of Habitat
The Copper Plateau Taiga ecoregion essential consists of one large block of contigous and generally intact habitat.
Degree of Fragmentation
The roads connecting the areas of development, the major rivers, and the areas of timber harvest are responsible for the majority of habitat fragmentation in the ecoregion. Probably the most important of the fragmenting features is the timber harvesting near Chitina, where the ecoregion is narrowed naturally.
Degree of Protection
Important protected areas include:
•Wrangell-St. Elias National Park and Preserve. The largest block of protected habitat
•The state-managed Nelchina Caribou Special Management Area affords protection for caribou and generally for maintaining intact habitat, but may not sufficiently protect top-level predators given a management emphasis throughout the region on meat producing species
One gap in the protected area system for this ecoregion is the lake country in the north-central portion of the ecoregion.
Types and Severity of Threats
This is a likely timber harvest area, and there is the potential for the use of unsustainable methods on the bottom lands of the Copper River, especially those owned by Native Corporations. Recreation, tourism, and recreational hunting are increasing as Park Service policies deflect tourism use to this area. Sport and subsistence hunting is generally well managed, but policies are generally designed to increase meat species (caribou, moose) at the expense of predators. This is especially problematic for the brown bear populations along the Denali Highway, in the northwest part of the ecoregion.
Suite of Priority Activities to Enhance Biodiversity Conservation
•Work with Native Corporations to limit timber harvest areas and to change logging practices to sustainable levels and methods.
•Monitor and manage impacts of increased tourism
•Create protected areas for trumpeter swan nesting habitats near Paxson Lake.
•Copper Country Alliance
•Copper River Watershed Forum
•National Parks and Conservation Association
Relationship to other classification schemes
This ecoregion is identical to Gallant (1995) ecoregion 117. Delineation features include low elevation (less than 900 m), relatively level or gentle terrain, and major vegetation type.
Prepared by: R. Hagenstein and T. Ricketts