SWEET Ontology
type: Ontology
version info: 2.3
imports: relaSpace.owl
imports: rela.owl
imports: matrWater.owl
imports: state.owl
imports: statePhysical.owl
imports: realm.owl
imports: humanResearch.owl

AlpineTundra
type: Class
subclass of: Tundra
comment: Alpine tundra is an ecozone that does not contain trees because it has high altitude. Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also lacks trees, but the lower part does not have permafrost, and alpine soils are generally better drained than permafrost soils. Alpine tundra transitions to subalpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as Krummholz. Alpine tundra occurs in an alpine zone

IceSheet
type: Class
subclass of: Glacier
comment: An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square km (19,305 square mile).

Tundra
type: Class
subclass of: Land
subclass of: Restriction
  some values from: FrozenGround
  on property: hasRealm
comment: In physical geography, tundra is an area where the tree growth is hindered by low temperatures and short growing seasons. There are two types of tundra: Arctic tundra (which also occurs in Antarctica), and alpine tundra. In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline.

FrozenGround
type: Class
subclass of: Land
subclass of: Restriction
  on property: hasState
  has value: Frozen
comment: Soil within which the moisture has predominantly changed to ice, the unfrozen portion being in vapor phase. Ice within the soil bonds (adfreezes) adjacent soil particles and renders frozen ground very hard. Permanently frozen ground is called permafrost. Dry frozen ground is relatively loose and crumbly because of the lack of bonding ice. Frozen ground is sometimes inadvisedly called frost or ground frost.

SeaIce
type: Class
subclass of: Ice
subclass of: Restriction
  on property: hasRealm
  some values from: Ocean
comment: Specifically, ice formed by the freezing of seawater; as opposed, principally, to land ice. Generally, any ice floating in the sea.