Biomes and Ecosystems Flashcards
Biomes
Broad categories of living systems
Defined mainly by climate
vary in biodiversity, productivity, and structure
Terrestrial biomes
communities shaped by temperature ranges and availability of moisture (precipitation)
Tropical Rainforests
Abundant rainfall; warm and hot temperatures all year
soil: thin, acidic, nutrient-poor
- 90% of nutrients in organisms
species: very high number
Types of Tropical Rainforest:
- tropical moist forests
- tropical seasonal forests
Tropical Seasonal Rainforests
Distinct wet and dry seasons
Drought-deciduous trees and shrubs
- lose leaves and cease growing with low water availability
More agriculturally productive than moist forests
Highly endangered
- more humans living near
Tropical Savannas and Grasslands
Savanna: grassland with sparse tree cover
Rainy season: less abundant; less dependable
Dry season: risk of fires
- plant adaptations: deep, persistent roots
Threat: grazing from livestock
Deserts
Temperature: extreme hot and extreme cold
Precipitation: low and sporadic
Plant adaptations: drought-deciduous
Animal adaptations: nocturnal; concentrated excrement
Temperate Grasslands
Enough rain to support grass: not enough for a forest
like plants in the savanna - deep, persisten roots
- produces thick, organic-rich soils
Main threats: agriculture and overgrazing
Decidious forests
aka broad-leaf forests
Trees lose leaves in winter
Dense canopy in summer; diverse understory in spring
Greatest Threat: rapid deforestation
Coniferous forests
aka evergreen forests
often occur with limited moisture
in pacific coast: known as temperature rainforests (cool, rainy, often enshrouded in fog)
pines, spruce, fir, and other species of trees
Boreal Forests
Dominated by conifers with some deciduous trees
- low species diversity due to allelopathy
extreme cold and short summer
- limit growth rate of trees
Tundra
Below freezing temperatures most of the year
occurs at high latitudes or on mountaintops
Low productivity
- short growing season
- frost any month of the year
Low diversity
Not directly threatened
- indirectly affected by climate change and air pollution
Arctic Tundra
Extensive nights (winter) and 24-h sunshine (summer)
- important for migratory birds
Alpine Tundra
on or near mountaintops; conditions and vegetation similar to arctic tundra
- alpine tundra plants: deep pigmentation, leathery leaves - protect against UV
Marine Environments
Depend on tiny, free-floating phytoplankton; ocean currents and upwelling currents: transport nutrients; vertical stratification due to temperature and light decreasing with depth
Open Ocean
Described by depth and proximity to the shore
relatively low productivity but have thriving communities
Features that support communities in the open ocean:
- sea mounts (undersea mountain chains and islands)
- ocean currents
- free floating mats of brown algae
Deep-sea Thermal vents
Unkowng until 1977
- alvin (deep-sea submarine)
Communities based on microbes that capture chemical energy
- taken from sulfur compounds released from vents
Magma under oceanic crust provide heat to vents
Littoral and Intertidal Communities
Vary with depth, light, and temperature
- like the open ocean
high productivity and density
- nutrients washing from land
- shallow, clear, warm waters supporting photosynthesis
Coral Reefs
Very high productivity and biodiversity
Occurs where waters are shallow and clear
- enough for sunlight
Calcium-rich skeletons
- shelter algae and other species
Coral Polyps
- colonial animals symbiotic with photosynthetic algae
Vulnerable to human activities and ocean warming
Seagrass beds
Occur in shallow, warm, sandy coastlines
support rich communities of grazers
same vulnerabilities as coral reefs
Vulnerable to human activities and ocean warming
Tidal Pools
Depressions in rocky shoreline
subjected to violent wave action
- prevents plant growth and sediment accumulation
High tide: flooded
Low tide: minimal water with hot desiccating sunshine
Specialized animals and plants
Estuaries
Bays where rivers empty into the sea; fresh water mixes with salt water
calm, warm, and nutrient-rich
Rivers: provide nutrients and sediments
Biologically diverse and productive; spawning for marine fish and shellfish
Salt Marshes
Shallow wetlands regularly or occasionally flooded with seawater; occurs in estuaries
Freshwater Lakes
Distinct Vertical zones;
Littoral zone: emergent plants create functional links between layers
Benthic zone: lowest oxygen due to little mixing; lowest light
Wetlands
Shallow ecosystems; saturated or submerged part of the year
described by vegetation; adapted in saturated conditions
support rich biodiversity; essential for breeding and migratory birds
Reduce flooding; replenish groundwater supplies; filters run-off
Swamp
wetlands with trees
shallow water; full sunlight penetration
high productivity
Marsh
Wetlands without trees
shallow water: full sunlight penetration
high productivity
Bog
Water-saturated; deep layers of peat
nutrient-poor
low productivity
Streams and rivers
aka lotic environments
form when precipitation is greater than evaporation; surplus water drains from the land
constantly changing conditions and inhabitants
Riffles
water runs rapidly over rocks
- well mixed and oxygenated
Pools
Stretches of slowly moving current
- collect silt and organic matter
Watershed
Headwaters (sources) to mouth of a drainage
