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Biomes are
large biological communities shaped by the physical environment, particularly climatic variation based on morphological similarities, not taxonomic.
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Convergence:
Evolution of similar growth forms among distantly related species in response to similar selection pressures.
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The Biosphere occurs between
(zone of life) occurs between the lithosphere and the troposhere.
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Biomes are based on
similarities in the morphological responses of organisms to the physical environment, not on taxonomic similarities.
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Terrestrial biomes are classified by
the growth form of the most abundant plants?
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Selection pressures of the terrestrial environment include ----- ------------- ------- --------- ----------
aridity, high and subfreezing temperatures, intense solar radiation, grazing by terrestrial animals, and crowding by neighbors.
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which biome is most often used as farm land
temperate decidious forest
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Land use change:
Conversion of land to agriculture, logging, resource extraction, urban development.The potential and actual distributions of biomes are markedly different. Human influence
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Wet and dry seasons in Tropical seasonal forests and savanahs associated with
movement of the Intertropical Convergence Zone
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Tropical rainforests are disappearing rapidly due to --------
About-----------of the tropical rainforest biome has been altered.
- logging and conversion to pasture and croplands.
- half
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-------- is an important factor in
Tropical seasonal forests and savanahs
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Tropical seasonal forests and savanahs have
Shorter trees, deciduous in dry seasons, more grasses and shrubs.
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hot deserts are located at
Associated with high pressure zones around 30° N and S.
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Hot deserts have
- High temperatures, low water availability
- Sparse vegetation and animal populations
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Plants in hot deserts exhibit
Many plants exhibit stem succulence—cacti in the Western Hemisphere, euphorbs in the Eastern Hemisphere
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temperate grassland located at
Between 30° and 50° latitude
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Temperate grassland threats
- Most converted to agriculture
- Threats from habitat alteration and desalinization
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Temperate grassland weather and landscape
- Seasonal temperature variation—warm, moist summers and cold, dry winters
- Grasses dominate; maintained by frequent fires and large herbivores such as bison
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temporate shrublands and woodlands location
Mediterranean-type climates—west coasts of the Americas, Africa, Australia, and Europe, between 30°–40° N and S.
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temporate shrublands and woodlands climate
Wet season in winter; hot, dry summers.
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temporate shrublands and woodlands threats
Conversion to viticulture and urbanization threats
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temporate shrublands and woodlands landscape
Vegetation is evergreen shrubs and trees.Fire is a common an important feature.
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Sclerophylly
the normal development of much sclerenchyma in the leaves of certain plants, as some desert plants, resulting in thickened, hardened foliage that resists loss of moisture.
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Temporate Evergreen forest threats
- Threats from logging
- Very little old-growth temperate evergreen forest remains.Fire suppression is a threat.
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Temporate Evergreen forest location
At 30° to 50° N and S, in coastal and maritime zones.
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Temporate Evergreen forest landscape
- Leaves tend to be acidic, and soils nutrient-poor.
- Temperate rainforests receive 50–400 cm rain per year.
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Temporate Evergreen forest diversity
Lower diversity than tropical and deciduous forests
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Boreal Forests location
Between 50° and 65° N.
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Boreal Forests climate and plants
- Long, severe winters
- Permafrost (subsurface soil that remains frozen year-round) impedes drainage and causes soils to be saturated
- Trees are conifers—pines, spruces, larches
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Boreal Forests soil
High organic matter soils; low decomposition=peat bogs
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Boreal Forests threats
- Logging, oil and gas development
- Climate warming may result in release of carbon stored in boreal soils, creating a positive feedback to warming.
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Tundra location
Above 65° latitude, mostly in the Arctic
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Tundra climate and seasons
- Cold temperatures, low precipitation
- Short summer with long days
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Tundra soil and life
- Vegetation is sedges, forbs, grasses, low-growing shrubs, lichens, and mosses
- Permafrost is widespread
- Not as much human settlement; more pristine
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Tundra threats
- Loss of predators
- Global change
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On mountains, ------------ and --------- change with elevation, resulting in-----------
- temperature and precipitation
- bands of biotic assemblages similar to biomes.
- There are also smaller scale variations associated with slope aspect, proximity to streams, and prevailing winds.
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Biological zones in freshwater systems are associated with the ----------- (5) of the water.
velocity, depth, temperature, clarity, and chemistry of the water.
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Freshwater streams and lakes are a key connection between
terrestrial and marine ecosystems.They process inputs of chemical elements and energy from terrestrial systems and transport them to the oceans.
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Pelagic zone:
Open water; dominated by plankton (small and microscopic organisms suspended in the water).Photosynthetic plankton (phytoplankton) are limited to the upper layers through which light penetrates (photic zone).
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Marine biological zones are determined by ocean depth,
light availability, and the stability of the bottom substratum.
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Oceans cover -------- of Earth’s surface and contain a
- 71%
- rich diversity of unique biota.
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Marine zone are categorized by
depth and relationship to shorelines.
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Salt marshes are ---------- dominated by---------
- shallow coastal wetlands
- emergent plants such as grasses and rushes.
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Plants occur in zones that --------that result from --------. The highest zone is ------------.
- reflect salinity gradients
- periodic flooding at high tide
- most saline (gets least flooding)
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In North America, the last continental glaciers were receding about 13,000 years ago, and the Great Plains supported a high diversity of
megafauna:Woolly mammoths and mastodons, several species of horses, camels, giant ground sloths, saber-toothed cats, cheetahs, lions, and giant short-faced bears.
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About ----------years ago, many of the large mammals of North America went extinct.
10,000–13,000
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temperate decidious forests
- Occur at 30° to 50° N, on continental edges, in areas with rainfall to support tree growth
- Leaves are dropped during winter.
- Oaks, maples, and beeches occur everywhere in this biome.
- Species diversity lower than tropical rainforests
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-------- organisms are bottom dwellers, and include many kinds of invertebrates.
Benthic
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Some benthic organisms feed on ------------ (dead organic matter), others are predators.
detritus
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Some benthic organisms live in the hyporheic zone—the -----------------------------------------------------------
substratum below and adjacent to the stream, where there is water movement from the stream or from groundwater.
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Human effects on streams include (6)
- pollution sediment inputs,
- introduced species.
- disposal of sewage and industrial wastes (toxic levels)
- Excessive fertilizer use
- Deforestation increases sedimentation
- Dam construction and channelization
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Lakes and still waters (lentic) occur ------------------- Lakes can be formed by -----------, from -----------, in ----------, in -----------, or by ---------------
- where depressions in the landscape fill with water.
- glacial processes
- river oxbows
- volcanic craters
- tectonic basins
- animal activities, including humans and beavers.
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Marine zones next to continents are influenced by the ------- and ---------
tides and wave action.
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Tides are generated by the ---------- between -----------------
- gravitational attraction
- Earth and the moon and sun
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The magnitude of tidal ranges varies by ------------- and is related to ----------- and ------------
- location
- shoreline morphology
- ocean bottom structure
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The open ocean beyond the continental shelves is called the
pelagic zone.
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The -----------, which supports the highest densities of organisms, extends ------------
- photic zone
- to about 200 m depth.
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Below the photic zone, energy is supplied by
falling detritus.
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Estuaries occur at the junctions of ----------
-----------also bring terrestrial sediments and nutrients, contributing to the productivity of estuaries.
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Salinity varies as -------------
fresh water flows in from the river and salt water flows in from the sea.
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The Rocky intertidal zone environment alternates between
marine and terrestrial with the rise and fall of the tides.
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Bands of organisms result in the rocky intertidal zone, depending on
their tolerance to drying, salinity, temperature, and interactions with other organisms.
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Sandy Shores location, trends, life
- Long Island, Bahamas
- low food, high wave energy
- invertebrates (clams, sea worms, and mole crabs, polychaete worms, hydroids, and copepods), few vascular plants, vertebrates
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Shallow Ocean Zones allow------------
light to penetrate to the bottom and support photosynthetic organisms that support other organisms.
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Coral reefs are restricted to----------- .Corals are related to , form -----------, and have associated -----------
- jellyfish-
- large colonies
- algal partners.
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Many corals extract -------------- from seawater to build a --------------
- calcium carbonate
- skeleton-like structure that over time, forms large reefs
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Although coral reefs grow slowly, over millions of years, corals have constructed------------.Rates of production of biomass are some of the highest in the world.
thousands of kilometers of coastline and many islands
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Coral reefs support up to a------------, the highest diversity on Earth.---------------rely on coral reefs for habitat
million species of organisms
economically important fishes
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Coral reef dangers (5)
- Sediments carried by rivers can cover and kill the corals
- Excess nutrients increase the growth of algae on the surface of the corals
- Warming ocean temperatures can result in the loss of the algal partners from the corals, resulting in coral bleaching.
- Increased incidence of fungal infections may be related to increased dust associated with desertification.
- Future changes in ocean chemistry may inhibit the ability of corals to form skeletons.
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The seaweed ------------ has gas-filled bladders to keep it afloat. It forms large floating islands that are habitat for other organisms.
Sargassum
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Organisms in the pelagic zone must have ways to prevent
sinking out of the photic zone, such as swimming.
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Below the photic zone, (Temp and pressure)
temperatures drop and pressure increases.
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Crustaceans such as copepods graze on the
rain of falling detritus from the photic zone.
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(3) are the predators of the deep sea.
Crustaceans, cephalopods, and fishes
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Ocean bottoms (--------) are sparsely populated, with -----------------(temp and pressure)
- (benthic zone)
- temperatures near freezing, and very high pressure.
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Benthic zone sediments are rich in --------, contain ----------. Sea stars and sea cucumbers graze the ocean floor or filter food from the water. ----------- is also used by benthic predators to lure prey.
- organic matter, contain bacteria, protists, and sea worms.
- Bioluminescence
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Paul Martin
over kill hypothesis
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The “overkill hypothesis” has received increasing support such as
- Archeological evidence shows that humans butchered some of these extinct animals.On small islands, human arrival and extinctions coincided.
- Humans also brought diseases as well as predators such as rats and snakes.
- Other mechanisms -spread of diseases by humans and dogs, climate change, and the loss of some species that depended on others, such as mastodons.
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Between 1700 and 1900, human activities caused profound changes, one being the Spanish introduction of --------.
Horses , facilitating bison hunting.Arrival of Euro-Americans and their conflicts with Native Americans led to the near extinction of bison.
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Humans began to use more ------------- to manage habitat and for small-scale agriculture between 1700 and 1900
fire
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After 1850, ------ and ------------ transformed the landscape.
mechanized agriculture and domesticated animals
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Today only ------------ of the eastern tall grass prairie remains.----------- and ------------practices led to the “Dust Bowl” of the 1930s. Drought and windstorms resulted in substantial losses of ------------
- 1%
- Overgrazing and unsustainable agricultural
- fertile topsoil.
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