Forests

IUCN GET 2.0

Categorizes forests by two biomes: Tropical-subtropical forests and Temperate-boreal forests & woodlands.

Tropical-subtropical forests

biome is comprised of these Ecosystem Functional Groups (EFG): Tropical-subtropical lowland rainforests, Tropical-subtropical dry forests and thickets, Tropical-subtropical montane rainforests, Tropical heath forests. The Tropical-subtropical forests biome includes moderate to highly productive ecosystems with closed tree canopies occurring at lower latitudes north and south of the equator. Fragmented occurrences extend to the subtropics in suitable mesoclimates. High primary productivity is underpinned by high insolation, warm temperatures, relatively low seasonal variation in day length and temperature (increasing to the subtropics), and strong water surpluses associated with the intertropical convergence zone extending to wetter parts of the seasonal tropics and subtropics. Productivity and biomass vary in response to: i) strong rainfall gradients associated with seasonal migration of the intertropical convergence zone; ii) altitudinal gradients in precipitation, cloud cover, and temperatures; and iii) edaphic gradients that influence the availability of soil nutrients. Species diversity and the complexity of both vegetation and trophic structures are positively correlated with standing biomass and primary productivity; however, trophic webs and other ecosystem processes are strongly regulated from the bottom-up by the dominant photoautotrophs (trees), which fix abundant energy and carbon, engineer habitats for many other organisms, and underpin feedbacks related to nutrient and water cycling and regional climate. Complex nutrient cycling and/or sequestering mechanisms are common, countering the high potential for soil nutrient leaching due to high rainfall. Plant species exhibit leaf plasticity, shade tolerance and gap-phase dynamics in response to the periodic opening of canopy gaps initiated by tree death, storm damage, and lightning strikes. Fires may occur in ecotonal areas between these forests and savannas. Biogeographic legacies result in strong compositional distinctions and consequently some functional differences among land masses within the biome.

Temperate-boreal forests & woodlands

biome is comprised of these Ecosystem Functional Groups (EFG): Boreal and temperate high montane forests and woodlands, Deciduous temperate forests, Oceanic cool temperate rainforests, Warm temperate laurophyll forests, Temperate pyric humid forests, Temperate pyric sclerophyll forests and woodlands. Temperate-boreal forests and woodlands biome include moderate to highly productive tree-dominated systems with a wide range of physiognomic and structural expressions distributed from warm-temperate to boreal latitudes. Although generally less diverse than Tropical-subtropical forests (T1) in taxa such as flowering plants, primates, and birds, these Temperate-boreal forests exhibit greater temporal and spatial variability in productivity, biomass, phenology, and leaf traits of trees. Temporal variability is expressed primarily through seasonal variation in water balance and/or temperature, which regulate the length and timing of growing and breeding seasons. Inter-annual variation is usually less important than in some other biomes (i.e. T5), but nonetheless may play significant roles in resource availability and disturbance regimes (e.g. fire and storms). Gradients in minimum temperatures, soil nutrients, and fire regimes differentiate ecosystem functional groups within this biome. These influence traits such as leaf form (broadleaf vs. needleleaf), leaf phenology (evergreen vs. deciduous), ecophysiological and morphological traits promoting nutrient acquisition and conservation, and morphological traits related to flammability, fire resistance, and recovery. The dominant photoautotrophs (trees) engineer habitats and underpin trophic webs. Resource gradients exert strong bottom-up controls on trophic processes, but in some temperate forests, fires are significant top-down consumers of biomass, as well as influencing flammability feedbacks and timing of life-history processes, such as reproduction and recruitment.

ESVD

ESVD and TEEB separate forests into tropical and temperate:

Tropical forests include Tropical rain forest, Tropical dry forest, Tropical cloud forests, Other (tropical forests)

Temperate forests include Temperate rain or evergreen forest, Temperate deciduous forest, Boreal/coniferous forest (‘Taiga’), Other (temperate forests)

FEMA ESV

Forests: Areas dominated by trees (evergreen and/or deciduous) generally greater than 5 meters tall that – on average – comprise greater than 20% of the total vegetation cover within the area or unit of analysis (e.g., pixel, polygon, parcel).

FEMA Ecosystem Service Value Updates 2022 uses the 2019 National Land Cover Database (NLCD) as modified from the Anderson Land Cover Classification System.

Other

IUCN Red List, USGS, ESRI, and Dynamic World uses Forest or Trees and do not sub-categorize.