Ecology chapter 6 start

Definition: Biomes are primarily determined by two key climatic factors:
- Average annual temperature.
- Annual precipitation.
Climatic Spectrum: Biomes range from:
- Extremely dry and extremely cold (e.g., Tundra).
- Warm to hot and wet (e.g., Tropical Rainforest).
Note on "Wet Cold": This combination is less common because colder air holds less moisture, reducing the likelihood of significant rainfall.

Description: The most extreme dry and cold biome.
Categorization: Occurs as either Arctic or Alpine tundra, with some shared characteristics but distinct features.
Key Plant Adaptation: Shallow rooting depth for plants due to underlying barriers.
Arctic Tundra:
- Characterized by permafrost underneath the soil, typically about 1 meter down.
- Permafrost is a permanently frozen layer that obstructs root growth.
Alpine Tundra:
- Features shallow soils primarily over rock.
General Tundra Characteristics:
- Consistently cold temperatures.
- Relatively low rainfall.
- Long winters.
- Plants are typically low-growing, with a general absence of trees, and are adapted to an exceptionally short growing season.

Location on Spectrum: Next level from tundra, depending on relative dryness or wetness.
Temperate Grassland:
- Climate: Drier, cool to warm locations.
- Landscape: Often features flat to rolling terrains.
- Dominant Flora:
  - Primarily plants from the grass family (Poaceae).
  - Significant broadleaf plants include the sunflower family (Asteraceae) and the pea/bean family (Fabaceae).
- History of Grazing: Many grasslands have a long history of grazing by large herbivores.
  - North America: Historically, bison were the main grazers.
  - Australia: Kangaroos.
  - Africa: Various hoofed mammals like zebras and gazelles.
  - Central Europe: Originated many grazing livestock ancestors (e.g., cattle, sheep).
- Adaptations: Adapted to grazing and, at times, to fire, which was a common ecological factor in North America before European settlement.
Temperate Desert:
- Climate: Cooler than the typical hot deserts; some can experience snow.
- Precipitation: In some temperate deserts, snow constitutes the majority of annual precipitation.
- Example: Desert-like areas in Wyoming.

Alternative Names: Also known by its Russian term, Taiga, or Northern Coniferous Forest.
Dominant Flora: Primarily consists of pines and spruces, which often grow quite tall.
Biodiversity: Exhibits relatively low vegetation diversity.
Fauna: Abundant insect life and home to large mammals like elk.

Regional Relevance: The speaker's current location (Oklahoma/Texas region) fits within this biome, showing features of both grassland and woodland.
Woodland (Savannah):
- Defined by a grassy understory punctuated by scattered trees.
- The term "savannah" is often used synonymously.
Scrub:
- A type of vegetation frequently associated with fire-prone ecosystems.
- Predominantly composed of shrubby plants.
- Example: California Uplands features this type of scrub.
- Fire Adaptation: Many plants in scrub biomes possess aromatic oils in their leaves, which can cause them to "candle up" (ignite rapidly and intensely) with any ignition source. This explains the high frequency of fires in parts of California and the Western US.

Climatic Position: Slightly wetter than woodland/scrub biomes.
Regional Presence: The speaker's region is on the western edge of this biome type.
Upland Forests (Local Example):
- Dominated by species such as post oak, blackjack oak, and black hickory.
- Elms have increased due to the historical extirpation of fire from the region, which traditionally kept them in check.
Lowland/Wetter Areas (Local Example):
- Support species like elms, pecans, and persimmons.
- Near rivers, sycamores (known for waterborne fruits) and sweet gum trees are common.
Diversity: Moving further east into Oklahoma leads to very diverse forests.
- Appalachia: Features "cove forests," which are exceptionally diverse in tree species and represent a typical deciduous forest of that area.
Common Temperate Deciduous Forest Types (Speaker's Early Studies):
- Beech Maple Forest: Typically includes sugar maple, American beech, and related species such as American elm.
- Oak Hickory Forest:
  - General: Often comprises white oak and shagbark hickory.
  - Local (Speaker's Area): Dominated by post oak and black hickory.