United States Department of Agriculture Classification of Community Forest Service Pacific Northwest Types, Successional Research Station General Technical Sequences, and Report PNW-GTR-469 March 2000 Landscapes of the Copper River Delta, Alaska Keith Boggs Author Keith Boggs is the staff vegetation ecologist, Alaska Natural Heritage Program, Environment and Natural Resources Institute, School of Arts and Sciences, University of Alaska Anchorage, 707 A Street, Anchorage, AK 99501. This publication is the result of a cooperative study between the U.S. Department of Agriculture, Forest Service, Chugach National Forest and the Alaska Natural Heritage Program. Abstract Boggs, Keith. 2000 Classification of community types, successional sequences, and landscapes of the Copper River Delta, Alaska. Gen. Tech. Rep. PNW-GTR-469. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 244 p. A classification of community types, successional sequences, and landscapes is pre- sented for the piedmont of the Copper River Delta. The classification was based on a sampling of 471 sites. A total of 75 community types, 42 successional sequences, and 6 landscapes are described. The classification of community types reflects the existing vegetation communities on the landscape. The distribution, vegetation composition and structure, soils, and successional status of each community are discussed. The community types were placed within successional sequences reflecting their succes- sional trends. Geomorphic and soil development were closely aligned with vegetation succession on the study area and, consequently, are described in detail. Each succes- sional sequence was named after the oldest community type identified in the sequence and the landscape on which it occurs. Diagnostic keys, based on indicator species, are provided to aid in field identification of community types and successional sequences. The dominant landscapes, including outwash plain, tidal marsh, and floodplain, are described by using environmental processes, such as geomorphology, hydrology, and soil development, and by integrating communities and successional sequences into these processes. Keywords: Alaska, Copper River Delta, classification, community type, succession, landscape, outwash, floodplain, delta, dune, barrier island. Summary A classification is presented to provide resource managers with an understanding of the vegetation communities, successional processes, and landscapes of the Copper River Delta. A classification integrating communities, succession, and landscapes is important because vegetation succession and communities can best be described and understood by first interpreting the landscapes on which they exist. The study area is a discontinuous series of coastal deltas and alluvial piedmonts in south-central Alaska encompassing about 700,000 acres. Mountain range spurs inter- rupt the piedmont, and the largest glacial system in North America (Bering Glacier) borders the eastern side. Elevation on the study area ranges from 0 to 300 feet above sea level. Human-caused disturbance is limited primarily to timber harvesting on proximal outwash plains. The vegetation on the Copper River Delta is dynamic and unstable because of tectonic uplift and geomorphic processes, such as erosion and deposition of sediments on tide- flats and glacial river channels. Of special concern is the change in vegetation initiated by an earthquake in 1964 that uplifted the area 6 to 12 feet. Before 1964, the seaward portion of the piedmont was covered by tidal marshes dominated by sedges (Carex spp.) and mixed grass/forb communities. The earthquake lifted these marshes above the tidal influence, initiating massive changes in vegetation composition and structure. Some tidal marsh communities described as common in previous studies are now rare or absent. The uplifted tidal mudflats are presently developing tidal marshes. These vegetation changes in turn have strongly affected such management concerns as nesting habitat for the dusky Canada goose, staging ground for shorebirds, and the moose population of the delta. This classification is divided into three sections: (1) landscape descriptions, (2) suc- cessional sequence descriptions, and (3) community type descriptions. Landscapes (analogous to landtype association from ECOMAP 1993) comprise the broadest level of the classification. Six landscapes were identified: (1) outwash plain, (2) floodplain, (3) linear dune, (4) uplifted marsh, (5) tidal marsh, and (6) barrier island-spit-coastal dune. Sediment deposition or erosion from fluvial and aeolian processes are the domi- nant driving successional forces on these landscapes. Landscape descriptions include landform, distribution, effect of the 1964 earthquake, and geomorphic processes. Each landscape adds greatly to the biological, habitat, and landform diversity of the Copper River Delta, often with community types, plant species, and successional sequences showing a high fidelity to specific landscapes. The successional sequence classification level describes the full sequence of vegeta- tion succession and landform-soil development. Community types are placed within successional sequences reflecting their successional trends and pathways. Geomorphic and soil development are closely aligned with vegetation succession on the study area and, consequently, are described in detail. A total of 42 successional sequences are identified, and each is named after the oldest community type identified in the sequence and the landscape on which it occurs. A diagnostic key, based on indicator species and landform, is provided to aid in field identification of the sequences. Each successional sequence exhibits high fidelity to specific landscapes. Community types describe existing vegetation and are analogous to the plant associa- tion level of “The National Vegetation Classification Standard” (Bourgeron and Engelking 1994) and to types described at level V of “The Alaska Vegetation Classification” (Viereck and others 1992). Seventy-five communities (plus 35 under- sampled communities) are described. Community type descriptions include other studies of the region, distribution of the community type, vegetation structure and composition, environmental factors such as soils and hydrology, and how each com- munity type fits into succession. A diagnostic key, based on indicator species, is pro- vided to aid in field identification of community types. Contents 1 Introduction 4 Study Area and Climate 6 Ecological Terms and Concepts 6 Community Types, Successional Sequences, and Landscapes 9 Methods 10 Field Methods 14 Data Analysis 15 Rarity Status of Landscapes and Community Types 15 Landscapes 16 Community Types 17 Statewide Rare Communities 18 Landscape Descriptions 18 Overview of Processes Forming the Copper River Delta 20 Outwash Plain Landscape 24 Floodplain Landscape 26 Uplifted Marsh Landscape 29 Linear Dune Landscape 31 Tidal Marsh Landscape 35 Barrier Island-Spit-Coastal Dune Landscape 40 Key to Successional Sequences 41 Instructions 42 Key to Life Forms and Landscape Groups 43 Key to Tidal Marsh Successional Sequences 43 Key to Tree Successional Sequences 45 Other Successional Sequences 50 Successional Sequence Descriptions 50 Outwash Plain and Floodplain Successional Sequences 57 Uplifted Marsh Successional Sequences 64 Linear Dune Successional Sequences 65 Tidal Marsh Successional Sequences 68 Barrier Island-Spit-Coastal Dune Successional Sequences 72 Key to Community Types 72 Instructions 72 Key to Life Form Groups 73 Key to Tree Communities 75 Key to Shrub Communities 76 Key to Sitka Alder Communities 77 Key to Willow Communities 79 Key to Sweetgale Communities 80 Key to Dwarf Shrub Communities 80 Key to Graminoid Communities 83 Key to Forb Communities 85 Key to Aquatic Communities 86 Tree Community Type Descriptions 86 Picea sitchensis/Alnus crispa Community Type 87 Picea sitchensis/Bryophyte Community Type 89 Picea sitchensis/Echinopanax horridum Community Type 90 Picea sitchensis/Rubus spectabilis Community Type 91 Picea sitchensis/Sphagnum Community Type 91 Picea sitchensis/Vaccinium ovalifolium Community Type 93 Picea sitchensis/Vaccinium ovalifolium-Echinopanax horridum Community Type 95 Picea sitchensis/Vaccinium ovalifolium/Lysichiton americanum Community Type 96 Populus trichocarpa/Aruncus sylvester Community Type 97 Populus trichocarpa/Alnus crispa Community Type 99 Populus trichocarpa-Picea sitchensis Community Type 100 Populus trichocarpa/Young Community Type 102 Tsuga heterophylla/Vaccinium ovalifolium Community Type 103 Tsuga heterophylla/Vaccinium ovalifolium-Echinopanax horridum Community Type 105 Tsuga heterophylla/Vaccinium ovalifolium/Lysichiton americanum Community Type 106 Shrub Community Type Descriptions 106 Alnus crispa/Calamagrostis canadensis Community Type 107 Alnus crispa/Equisetum arvense Community Type 108 Alnus crispa/Rubus spectabilis Community Type 110 Alnus crispa/Salix Community Type 110 Empetrum nigrum-Carex pluriflora Community Type 112 Myrica gale/Carex lyngbyaei Community Type 113 Myrica gale/Carex sitchensis Community Type 115 Myrica gale/Empetrum nigrum Community Type 116 Myrica gale/Epilobium angustifolium Community Type 118 Myrica gale/Equisetum variegatum Community Type 119 Undersampled Myrica gale (Sweetgale) Community Type 119 Rubus spectabilis-Echinopanax horridum Community Type 119 Salix alaxensis Community Type 119 Salix arctica/Carex lyngbyaei Community Type 120 Salix barclayi/Carex pluriflora