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S15 Temperate & Boreal Forest & Woodland Subclass

The U.S. National
Vegetation Classification
Type Concept Sentence: Temperate & Boreal Forest & Woodland is typically dominated by broad-leaved deciduous and needle-leaved trees, with some broad-leaved evergreens in warmer regions, and a climate that varies from warm-temperate with only rare frosts to very cold subarctic conditions. It is found across the globe in the mid-latitudes, typically between 25° and 60-70°N and S latitude, and includes boreal, cool-temperate, and warm-temperate/Mediterranean forests.
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Common (Translated Scientific) Name: Temperate & Boreal Forest & Woodland Subclass
Colloquial Name: Temperate & Boreal Forest & Woodland
Hierarchy Level: Subclass
Type Concept: Temperate & Boreal Forest & Woodland is typically dominated by broad-leaved deciduous and needle-leaved trees, with some broad-leaved evergreens in warmer regions. It is found across the globe typically between 25° and 60-70°N and S latitude, but is far more abundant in the Northern Hemisphere than the Southern Hemisphere. The climate varies from warm-temperate with only rare frosts and snow to cold subarctic conditions. The gradation from warm-temperate (including Mediterranean) to boreal vegetation is often subtle and occurs across broad regions, so they are treated together as one subclass (Table 1).

Temperate & Boreal Forest & Woodland includes temperate rainforest, temperate deciduous forest and woodland, and temperate evergreen forest and woodland. These forests are dominated by broad-leaved or needle-leaved growth forms. Trees typically range in height from 10 to 30 m, but rainforest trees may attain great height, exceeding 50 m. Temperate broad-leaved deciduous and needle-leaved forests grow in cool-temperate climates, with summer rainfall and cold winters (during which the broad-leaved trees lose their leaves), extending to the treeline of temperate regions, where they resemble boreal forests. Temperate broad-leaved evergreen forests, often mixed with broad-leaved deciduous and needle-leaved trees, occur in warm-temperate climates, with either mild winters and moist, warm summers, or winter-rain winters and dry, warm summers (Mediterranean).

Boreal Forest & Woodland contains primarily needle-leaved evergreen trees, with or without boreal broad-leaved deciduous trees. Structure varies from tall, closed-canopy (but rarely exceeding 15 m) to open, low (<5 m) subarctic and boreal subalpine woodlands at treeline. Nonvascular mosses and lichens may predominate in the ground layer. Winters are very cold and vary from arid to moist. Temperate high montane forest may resemble boreal forest. Tree species diversity is very low.

Table 1. Comparison of Boreal, Cool Temperate and Warm Temperate Formations (adapted from Kuennecke 2008).
Criterion BOREAL FOREST & WOODLAND
(upland and wetland)
COOL TEMPERATE FOREST & WOODLAND
(upland and wetland)
WARM TEMPERATE FOREST & WOODLAND
(upland and wetland)
Dominant growth forms Needle-leaved (usually evergreen) conifer, often strongly conical-shaped, and simple, broad-leaved, small mesophyll deciduous hardwoods. Broad-leaved deciduous or evergreen needle-leaved conifer, alone or in mixes, variable leaf and crown shapes, and leave sizes typically mesophyll with a seasonal green understory of herbs. The tall-shrub layer is variable, and is often broad-leaved deciduous, but the short-shrub layer may be heath. The moss layer is often sparse, but more dominant in cold, rainy and/or high montane needle-leaved evergreen stands. Broad-leaved evergreen trees, microphyll to small mesophyll leaves, sometimes dwarfed stems, sclerophyllous or small-leaved trees (e.g., eucalypts, sclerophyllous oaks); or various combinations of broad-leaved deciduous, broad-leaved evergreen or evergreen needle-leaved conifer trees.
Location Northern Hemisphere south of the arctic treeline. Middle latitudes of North America, western and far-eastern Eurasia, and an isolated small area in the middle latitude of South America. Mediterranean Basin and Mediterranean and warm temperate regions in North America (California, Southeast Coastal Plain), Chile, South Africa, Australia, India and Southeast Asia.
Climate type Cold snow climates, with extended cold winters and short mild summers, frozen soils in winter. Humid temperate climates with distinctive spring, summer, autumn, and cool to cold winter seasons, with freezing temperatures. Mild (mostly frost-free) winter, temperate humid spring, hot-dry summer, and mild, often dry autumn seasons. Rainy season in winter and dry summers (Mediterranean).
Temperature Lengthy periods of freezing temperatures with the coldest month isotherm -3o C, with the growing season generally averaging less than 100 days, occasionally interrupted by nights of below-freezing temperatures. Freezing temperatures usually of moderate duration, although of frequent occurrence during winter months. Potential growing season generally from 100 to 200 days and confined to late spring and summer when freezing temperatures are infrequent or absent. Freezing temperatures of short duration but generally occurring every year during winter months. Potential growing season more than 200 days with less than an average of 150 days a year subject to temperatures below 0o C or chilling fog.
Precipitation controls Seasonal shift of polar front. Summer convectional storms, Atlantic hurricanes, Asian monsoons. Stationary high-pressure cells in summer.
Precipitation (annual) 38-50 cm (15-20 inches) 75-125 cm (30-50 inches). 25 to 100 cm (10-40 inches) (Mediterranean).
Dominant Soil-Forming Process Podzolization Podzolization. Severe weathering.
Major Soil Orders (Soil Survey Staff 1999) Gelisols, some Spodosols in south. Alfisols and Ultisols, some Spodosols in north. Various, Ultisols and Alfisols common.
Soil characteristics Sandy ash-colored A horizon; accumulation of minerals in B horizon; generally low in natural fertility. Gray forest soils with accumulated silicate clay minerals in B horizon; some (Alfisols) with relatively high natural fertility; more leached soils in southern areas (Ultisols) due to higher precipitation levels. Naturally productive soils, some regions worn by thousands of years of human use.
Biogeographic History Recent-post Pleistocene migration of plants and animals. Recent-post Pleistocene to ancient Tertiary origins. Recent to more ancient, some regions influenced by thousands of years of human use.
Diagnostic Characteristics: Temperate & Boreal Forest & Woodland is typically dominated by broad-leaved deciduous and needle-leaved trees, with some broad-leaved evergreens in warmer regions [see Table 1]. Climate varies from warm-temperate with only rare frosts and snow to cold subarctic conditions. It is found across the globe typically between 25° and 60-70°N and S latitude.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Warm-temperate forests and woodlands are defined here to include both the classic Mediterranean forests and woodlands and the more humid warm-temperate forests. Both share increasing levels of broad-leaved evergreen trees, including sclerophyllous-leaved trees, as well as evergreen shrubs and herbs, as compared to other temperate forests and woodlands. Walter (1985) recognizes two warm-temperate biomes, the "Zonobiome of the Winter-Rain Region with an Arid-Humid Climate and Sclerophyllic Woodlands" (Zone IV) and the "Zonobiome of the Warm-Temperate Humid Climate" (Zone V), distinct from the cool-temperate biome "Zonobiome of the Temperate-Nemoral Climate" (Zone VI) and the boreal biome "Zonobiome of the Cold-Temperate Boreal Climate" (Zone VIII). Schultz (1995) also recognizes the two warm-temperate regions, which he refers to as: "Mediterranean-Type subtropics" (with world distribution shown in his Figure 129) and "Humid subtropics" (with world distribution shown in his Figure 171).
Similar NVC Types:
S17 Tropical Forest & Woodland, note: There is a strong dominance by broad-leaved evergreen trees, and deciduousness is caused by drought rather than forest composition.
S18 Temperate & Boreal Grassland & Shrubland, note: Tree cover is <10%.
CSC01 Woody Agricultural Vegetation, note: Long-rotation plantations or woody restoration plantings of Temperate & Boreal Forest & Woodland (S15) with an irregular structure and a largely spontaneous ground layer may initially be similar in their early stages of development to Woody Agricultural Vegetation (S22), especially if planted in rows and the understory is strongly manipulated.
Physiognomy and Structure: Temperate forests and woodlands include temperate rainforest, temperate deciduous forest, and temperate evergreen forests and woodlands. They are dominated by broad-leaved or needle-leaved growth forms. Trees typically range in height from 10-30 m, but rainforest trees may attain great height, exceeding 50 m. Temperate broad-leaved deciduous and needle-leaved forests and woodlands grow in cool-temperate continental climates, with summer rainfall and cold winters, during which the broad-leaved trees lose their leaves, extending to high montane regions, where they resemble boreal forests and woodlands. Temperate broad-leaved evergreen forests and woodlands, often mixed with broad-leaved deciduous and needle-leaved trees, occur in warm-temperate climates, with either mild winters and moist, warm summers, or winter-rain winters and dry, warm summers (Mediterranean). Tree species diversity is low in temperate forests and woodlands (Whittaker 1975).

Boreal Forest & Woodland contains primarily needle-leaved evergreen trees, with or without boreal broad-leaved deciduous trees. Structure varies from tall, closed-canopy (but rarely exceeding 15 m) to open, low (<5 m) subarctic woodlands. Nonvascular mosses and lichens may predominate in the ground layer. Winters are very cold and vary from arid to moist. Temperate high montane forest may resemble Boreal Forest & Woodland (Whittaker 1975).
Floristics:
Dynamics: No Data Available
Environmental Description: Soil orders in Table 8 are described using the U.S. soil orders (Soil Survey Staff 1999). See Brady and Weil (2002) for comparison of U.S. soil orders with Canadian and FAO systems.
Geographic Range: Temperate forests and woodlands range from the giant forests of the Pacific Coast of North America, or the Australian temperate rainforests, to New Zealand and Chile, to montane forests in various locations. Temperate forests and woodlands occur across much of the United States and southern Canada, in limited parts of Mesoamerica, western Europe, Mediterranean regions, Southeast Asia, southern Australia, and limited parts of Chile. Boreal forests and woodlands occur in the northern regions of North America and Eurasia. A few isolated areas may occur in the Southern Hemisphere.
Nations: CA, US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: High
Confidence Level Comments:
Grank: GNR
Greasons:
Name:Database Code:Classification Code:
Class 1 Forest & Woodland C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland S15 1.B
Formation 1.B.4 Boreal Forest & Woodland F001 1.B.4
Formation 1.B.5 Boreal Flooded & Swamp Forest F036 1.B.5
Formation 1.B.2 Cool Temperate Forest & Woodland F008 1.B.2
Formation 1.B.1 Warm Temperate Forest & Woodland F018 1.B.1
Formation 1.B.3 Temperate Flooded & Swamp Forest F026 1.B.3
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: = Temperate Forest Biomes (Kuennecke 2008) [Kuennecke includes boreal, cool-temperate, and warm-temperate (Mediterranean) formations as part of his "temperate forest biomes" concept.]
= Temperate and boreal woodlands & scrub (Mucina 1997) [Mucina created this type as an organizational category for Braun-Blanquet classes and did not define it as a formal type.]
> Temperate broad-leaved forests and scrub (Rodwell et al. 2002) [European cool- and warm-temperate forests and floodplain forests are included in the subclass, but boreal forests are excluded.]
Concept Author(s): Hierarchy Revisions Working Group, Federal Geographic Data Committee (Faber-Langendoen et al. 2014)
Author of Description: D. Faber-Langendoen
Acknowledgements:
Version Date: 17Oct2014
References:
  • Brady, N. C., and R. R. Weil. 2002. The nature and properties of soils. Thirteenth edition. Prentice Hall, Upper Saddle River, NJ.
  • Faber-Langendoen, D., T. Keeler-Wolf, D. Meidinger, C. Josse, A. Weakley, D. Tart, G. Navarro, B. Hoagland, S. Ponomarenko, J.-P. Saucier, G. Fults, and E. Helmer. 2015c. Classification and description of world formation types. General Technical Report RMRS-GTR-000. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.
  • Kuennecke, B. H. 2008. Temperate forest biomes. Greenwood Press, Westport, CT.
  • Mucina, L. 1997. Conspectus of classes of European vegetation. Folia Geobotanica et Phytotaxonomica 32:117-172.
  • Rodwell, J. S., J. H. J. Schamineé, L. Mucian, S. Pignatti, J. Dring, and D. Moss. 2002. The diversity of European vegetation. An overview of phytosociological alliances and their relationships to EUNIS habitats. Report EC-LNV nr. 2002/054. National Reference Centre for Agriculture, Nature and Fisheries, Wageningen,The Netherlands.
  • Schultz, J. 1995. The ecozones of the world. Springer-Verlag, New York.
  • Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. Second edition. USDA Natural Resources Conservation Service, Washington, DC.
  • Walter, H., translated by O. Muise. 1985. Vegetation of the Earth and ecological systems of the geo-biosphere. Third edition. Springer-Verlag, New York. 149 pp.
  • Whittaker, R. H. 1975. Communities and ecosystems. Second edition. Macmillan Publishing Co., New York. 387 pp.