Biomes
What two abiotic factors are the primary determinants of terrestrial biome distribution?
Temp/sunlight and precipitation
This biome is characterized by very low annual precipitation, often less than 25 cm per year. Temperatures can vary greatly between day and night. Vegetation is sparse and consists primarily of drought-adapted plants, including plants with water-storage tissues, extensive root systems, and reduced leaves. Productivity is limited primarily by water availability.
Desert
This biome occurs at very high latitudes, where winters are long and extremely cold and summers are short. The ground may contain permafrost, which limits drainage and prevents deep root growth. Vegetation is primarily low-growing mosses, lichens, grasses, and small shrubs, while trees are largely absent.
Tundra
This biome covers most of Earth's surface and contains water with relatively high and stable salinity. Conditions vary greatly with depth, temperature, and light availability. Photosynthetic organisms are concentrated near the surface where sunlight is available, while deeper regions receive little or no light. Nutrient availability can vary considerably, with areas of upwelling supporting particularly high levels of primary productivity.
Oceans
This freshwater ecosystem is characterized by flowing water, with physical conditions that change from the headwaters to the mouth. Near the headwaters, water is generally cool, clear, and well oxygenated, and the current can be relatively fast. Organisms are adapted to avoid being swept away, and primary productivity may be limited by light availability and nutrient availability.
Streams/rivers
What global process causes the worldwide distribution and boundaries of terrestrial biomes to shift as average temperatures and precipitation patterns change?
Climate Change
This biome experiences high temperatures throughout the year and abundant precipitation, generally receiving more than 200 cm annually. Vegetation forms multiple layers, including a tall canopy and understory. It has very high primary productivity and biodiversity, but rapid decomposition and heavy rainfall can result in relatively nutrient-poor soils.
Tropical Rainforest
This biome occurs in areas with warm, dry summers and mild, wet winters. Vegetation consists largely of brush, scrub and small, drought-tolerant trees with adaptations such as small, waxy leaves that reduce water loss. Periodic wildfires are an important ecological disturbance, and many plants are adapted to fire.
Shrubland
our biome!
<3
This ecosystem develops primarily in shallow, warm, clear marine water where sunlight can penetrate to photosynthetic organisms. Low turbidity is important because suspended sediments reduce light availability. Although the surrounding water may have relatively low concentrations of nutrients, this ecosystem can support exceptionally high biodiversity and productivity because nutrients are efficiently recycled.
Coral reefs
This freshwater ecosystem contains distinct zones based on depth and light availability. The shallow region along the shoreline receives enough sunlight to support abundant rooted vegetation and is known as the littoral zone. Farther from shore, decreasing light penetration limits photosynthesis, while the deepest areas may receive little or no sunlight.
Ponds and Lakes
As latitude decreases, what generally happens to biodiversity?
Increases
This biome is characterized by long, cold winters and short, cool summers. Precipitation is relatively low, much of it occurring as snow. The dominant vegetation consists of coniferous trees with needle-like leaves, which are adapted to cold temperatures and help reduce water loss.
Taiga
(aka Boreal Forest)
This biome has high precipitation and relatively moderate temperatures, but it is dominated by grasses and scattered trees rather than dense forests. Many of the trees and grasses have adaptations to seasonal drought and frequent fires. Large herbivores are common, and grazing can influence vegetation patterns and nutrient cycling.
Savanna
This ecosystem occurs in areas where land is frequently or permanently saturated with water. Vegetation is dominated by grasses, reeds, and other plants adapted to waterlogged soils. Decomposition can be relatively slow when soils contain little oxygen, allowing organic matter to accumulate. These ecosystems can filter pollutants, reduce flooding, and provide habitat for aquatic and terrestrial organisms.
Marshland
As this freshwater ecosystem moves toward its lower reaches, the channel generally becomes wider and deeper, the current slows, and water temperature increases. Increased sediment can raise turbidity, reducing the amount of light available for photosynthesis. Nutrients and organic matter can accumulate as material is transported downstream, supporting organisms living on or within the benthic zone.
Streams/rivers
How does seasonality change as we approach the equator from the poles?
Decreases
This biome experiences four distinct seasons, with warm summers and cold winters. It receives approximately 75–150 cm of precipitation annually, distributed relatively evenly throughout the year. Vegetation is dominated by broadleaf deciduous trees, which lose their leaves during the colder months. Soils tend to be relatively fertile because leaf litter decomposes and returns nutrients to the soil
Temperate Seasonal Forest
This biome is characterized by moderate temperatures, relatively high precipitation, and abundant vegetation. It contains a mixture of coniferous and broadleaf evergreen trees, with some of the world's tallest trees occurring in this biome. High precipitation and mild temperatures support relatively high biomass and productivity.
Temperate Rainforest
This ecosystem occurs where freshwater and saltwater mix, producing water with variable salinity. It is generally shallow and receives substantial nutrients and sediments from rivers while also being influenced by tides. High nutrient availability and adequate sunlight can support high primary productivity. Organisms living here must tolerate changes in salinity, temperature, and water level.
Estuary
During summer, a deep freshwater ecosystem may develop distinct thermal layers. The warm, well-lit surface layer supports most photosynthesis. Below it is a region where temperature changes rapidly with depth, followed by a colder, deeper region where sunlight is limited. In the deepest water and sediments, decomposition of sinking organic matter can consume dissolved oxygen, particularly when the water is poorly mixed.
Ponds and Lakes
What is the cause of the earth's seasons?
Tilt of the earth
This biome receives moderate, seasonal precipitation and experiences hot summers and cold winters. Frequent fires and periodic drought limit the establishment of trees. Most of the plant biomass is found belowground, and the decomposition of extensive root systems contributes to deep, nutrient-rich soils with high organic matter content.
Temperate Grassland
This biome has moderate annual precipitation, but much of its plant growth occurs during a relatively short growing season. Winters are cold, while summers can be warm. Wildfires and grazing by large herbivores are important ecological disturbances that help maintain the dominant vegetation. The soil is typically deep and rich in organic matter because a large proportion of plant biomass is concentrated below the surface. Trees are uncommon because of the combination of seasonal drought, fire, and limited precipitation.
Temperate Grassland
(this question isn't a biome):
What marine organisms supply a large portion of the Earth's oxygen and also take in carbon dioxide from the atmosphere
This resource is essential for human populations and is obtained from rivers, lakes, reservoirs, and groundwater. Although it makes up only a small fraction of Earth's total water, it is used for drinking, agriculture, industry, and sanitation. Contamination by pathogens, nutrients, pesticides, and other pollutants can reduce its suitability for human consumption.
Freshwater