2. Ecology
Ecology:
Scientific study of the interactions between organisms and the environment
Rediscovery of the nearly extinct harlequin toad in Costa Rica raises many ecological questions
What environmental factors limit their geographic distribution?
What factors affect population size?
3. Weather vs. Climate
Weather:
Local area’s short term temperature, precipitation, humidity, wind, cloud cover and
other physical conditions of the atmosphere measured over hours or days
Climate:
Long-term prevailing weather conditions in an area
Major components of climate are temperature, precipitation, sunlight, and wind
Macroclimate:
Consists of patterns on the global, regional, and landscape (multiple ecosystems) level
Microclimate:
Consists of very fine patterns, such as those encountered by the community of organisms
underneath a fallen log
Determined by fine-scale differences in the environment that affect light and wind patterns
5. Biomes
Biomes:
Major life zones characterized by vegetation type (terrestrial biomes) or physical environment
(aquatic biomes)
Climate is very important in determining why terrestrial biomes are found in certain areas
Climate affects the latitudinal patterns of terrestrial biomes
Biomes are affected not just by average temperature and precipitation, but also by the pattern
of temperature and precipitation through the year
Leads to formation of tropical (hot), temperate (moderate) and polar (cold) regions – deserts,
grasslands and forests
Terrestrial Biomes:
Often named for major physical or climatic factors and for vegetation
Characterized by distribution, precipitation, temperature, plants, and animals
Usually grade into each other, without sharp boundaries which may be wide or narrow
6. Tropic of
Cancer
30°N
30°S
Tropic of Capricorn
Equator
Tropical forest
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Northern coniferous forest
Tundra
High mountains
Polar ice
Figure 52.9
8. Tropical Rain Forest
Tropical Rain Forests:
Hot temperature, moisture laden air rises resulting in constant rainfall (200 inches per year)
Temperature is high year-round (25–29C) with little seasonal variation
High Biodiversity: home to millions of animal species, including an estimated 5–30 million still
unknown species of insects, spiders, and other arthropods
2% of the land but ½ of world’s species; single tree can have several thousand insect species
Dominated by broadleaf evergreen plants; their dense tops block out most of the sun not
reaching the forest floor
Ground has little vegetation (those that do have large leaves); vines (lianas) grow on trees to
reach the sun
Little wind because of the dense vegetation; plants depend on bats, birds, bees and other
species for pollination
Rapid human population growth is now destroying many tropical forests
11. Temperate Rain Forest
Coastal Coniferous Forest or Temperate
Rain Forests:
Found in scattered coastal temperate
areas that have ample rainfall or
moisture from dense ocean fogs
Douglass firs and redwoods
12. Deserts
Desert:
Annual precipitation is low; often scattered unevenly throughout the year
Heat of day bakes the earth causing evaporation of water from leaves and soil
Soils have little vegetation and moisture to store the heat so you can roast during the day and
freeze at night
Tropical Deserts:
Hot and dry most of the year; few plants and a hard wind blown surface of rocks and some
sand
Temperate Deserts:
Daytime temperatures are high in the summer and low in winter; more precipitation than in the
topical deserts; drought resistance vegetation - cacti
Cold Deserts:
Vegetation is sparse; winters are cold; summers warm or hot and precipitation is low; plants
and animals have adapted to stay cool and get enough water
Fragile Ecosystem: slow plant growth; low species diversity; slow nutrient recycling and lack
of water
15. Savannah
Savannah
Equatorial and subequatorial regions
Warm temperatures year round with wet and dry seasons
Precipitation is seasonal
Temperature averages (24–29C) but is more seasonally variable than in the tropics
Contains widely scattered clumps of trees (aracia with thorns to prevent being eaten)
Grasses and make up most of the ground cover; fire-adapted and tolerant of seasonal drought
Plants have adapted to survive drought and extreme heat
Grazing animals (grass and herb eating; wildebeest) and browsing animals (twig and leaf
eating; giraffe) along with predators (lion)
17. Chaparral
Chaparral:
Occurs in mid-latitude coastal regions on several continents
Summer is hot (30C+); fall, winter, and spring are cool (10–12C)
Close to sea provides a slightly longer winter rainy season than nearby temperate deserts
Precipitation is highly seasonal with rainy winters and dry summers
Fogs in the spring and fall reducing evaporation
Consist of dense growth of low growing evergreen shrubs and occasional small trees with
leathery leaves to reduce evaporation
Dominated by shrubs, small trees, grasses, and herbs; adapted to fire and drought
Prone to fires in the dry season
Many plants produce seeds that only germinated after a wildfire
Animals include amphibians, birds, reptiles, insects, small mammals, and browsing mammals
People like to live here because of its moderate, sunny climate with mild wet winters and warm dry
summers; risk losing their homes to frequent fires and mud slides
20. Temperate Grasslands
Temperate Grassland
Found on many continents
Precipitation is highly seasonal
Winters are cold (often below –10C) and dry; summers are hot (often near 30C) and dry
Dominant plants are grasses and adapted to droughts and fire
Little tree growth
Large grazers such as bison and wild horses and small burrowers such as prairie dogs
Most grasslands have been converted to farmland (Midwest)
22. Mountains
Mountains:
Some of the world’s most spectacular environments are high on Mountains, steep or high
lands that cover ¼ of the Earth’s surface; dramatic changes in altitude, slope, climate, soil and
vegetation occur in a very short distance
1.2 bil people (18% of the world’s population) live on them or their edges; 4 bil (59%) depend
on mountain systems for all or some of their water
Majority of the world’s forests; habitats for biodiversity and contain endemic species found no
where on Earth
Help regulate the earth’s climate: mountains covered in ice and snow help to reflect solar
radiation back into space helping to cool the plant and offset global warming
Can affect sea levels: storing or releasing water in glaciers; as the earth warms, water can be
released in oceans causing them to rise
Major storehouses of water
Despite their significance, mountain ecosystems are not a high priority for governments
and/or environmental groups
25. Northern Coniferous Forest
Northern Coniferous Forest or Taiga:
Spans northern North America and Eurasia and is the largest terrestrial biome on Earth
Cold forests are often found just south of Artic tundra and above certain altitudes in the High
Sierras or Rockies
Precipitation varies; some have periodic droughts and others, especially near coasts, are wet
Winters are cold; summers may be hot (Siberia ranges from –50C to 20C)
Subarctic climate: winters are long, dry and extremely cold; sunlight may only be available 6-8
hrs; summers are short, with cool to warm temperatures; sun shines 19 hrs
Plant diversity is low as few species can survive the winters when soil moisture is frozen
Conifers such as pine, spruce, fir, and hemlock dominate; conical shape of conifers prevents
too much snow from accumulating and breaking their branches
Migratory and resident birds; large mammals such as moose, brown bears, and Siberian tigers
27. Temperate Broadleaf Forest
Temperate Broadleaf Forest:
Found at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa,
Australia, and New Zealand
Significant amounts of precipitation fall during all seasons as rain or snow
Winters average 0C; summers are hot and humid (near 35C)
Long warm summers, cold but not severe winters and abundant moisture, often fairly spread
throughout the year
Dominated by deciduous trees in the Northern Hemisphere; evergreen eucalyptus in Australia
Broad-leaf trees: oak, hickory, maple and beech; survive cold winters by dropping their leaves
in the fall and becoming dormant; each spring, new leaves form and turn colors in the fall
Mammals, birds, and insects make use of all vertical layers in the forest
Eastern US were home to bears, foxes and pumas (many have been killed) and the dominant
mammal often is deer
In the Northern Hemisphere, many mammals hibernate in the winter
Impact of human activities: disturbed more than any other for growing of crops, wood or cities;
within 100-200 years after it’s left undistributed, it can return to forest
29. Tundra
Tundra:
Covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes
Precipitation is low in arctic tundra and higher in alpine tundra
Winters are cold (below –30C); summers are relatively cool (less than 10C)
Treeless and bitterly cold
Swept by cold winds and covered by ice and snow
Winters are long and dark
Little precipitation
Permafrost, a permanently frozen layer of soil, prevents water infiltration
Vegetation is herbaceous (mosses, grasses, forbs, dwarf shrubs and trees, and lichen) and
supports birds, grazers, and their predators; alpine can be flowers
Most of the growth occurs in the 7-8 week summer when the sun shines almost 24 hrs
Mammals include musk oxen, reindeer, bears, wolves, and foxes; many migratory bird species
nest in the summer
31. Aquatic Biomes
Aquatic Biomes:
Account for the largest part of the biosphere in terms of area
Marine biomes have salt concentrations of about 3%
Largest marine biome is made of oceans, which cover about 75% of Earth’s surface and
have an enormous impact on the biosphere
Freshwater biomes have salt concentrations of less than 0.1%
Freshwater biomes are closely linked to soils and the biotic components of the surrounding
terrestrial biome
Stratified into Zones or layers defined by light penetration, temperature, and depth:
Pelagic Zone:
Photic Zone has sufficient light for photosynthesis; most animals live here
Aphotic Zone receives little light; extensive with little life
Deep in the Aphotic Zone lies the Abyssal Zone with a depth of 2,000 to 6,000 m
Benthic Zone:
Organic and inorganic sediment at the bottom of all aquatic zones
Communities of organisms are collectively called the Benthos
Detritus:
Dead organic matter, falls from the productive surface water; important source of food
33. Lakes
Lakes:
Natural bodies of freshwater formed from precipitation, runoff or groundwater that fill in
depressions in the surface caused by glaciers (Bear Mountain), volcanoes (Crater Lake) or
other ways such as supplied with water from rain (precipitation) or streams
Size varies from small ponds to very large lakes
Oligotrophic Lakes:
Nutrient-poor and generally oxygen-rich
Small supply of plant nutrients
Generally deep with steep banks; fed by glaciers and mountain streams with little sediment;
crystal clear
Eutrophic Lakes:
Nutrient-rich and often depleted of oxygen if ice covered in winter
Rooted and floating aquatic plants live in shallow and well-lighted area close to shore
Water is too deep to support rooted aquatic plants; small drifting animals called zooplankton
graze on the phytoplankton
Invertebrates live in the benthic zone; Fishes live in all zones with sufficient oxygen
35. Wetlands
Surface Water: precipitation that does not sink into the ground or evaporate
Runoff: precipitation that runs into a stream
Watershed, Drainage Basin: land that delivers runoff, sediment and dissolved substances into a
stream; small streams form rivers and rivers flow downhill to the ocean
Aquatic Life Zones:
Source Zone:
Headwaters or mountain highland streams; usually shallow, cold, clear and swift flowing;
waterfalls and rapids
Not productive because of lack of nutrients and producers; food is from decomposition;
algae; fishes
Transition Zone:
Middle; become wider, deeper and warmer; slower; more turbid (cloudier)
Producers; both cold and warm water fish (black bass)
Floodplain Zone:
Over time, they shape the land including leveling or cutting through mountains forming
canyons; streams can join others, forming wider and deeper rivers
Large amount of producers and fish; rivers end in a mouth or delta; absorb the floodwaters
and add nutrient rich land
36. Wetlands
Wetlands
Habitat that is inundated by water at least some of the time and that supports plants adapted
to water-saturated soil
High organic production and decomposition and have low dissolved oxygen content
Can develop in shallow basins, along flooded river banks, or on coasts of large lakes and seas
Wetlands are among the most productive biomes on Earth
Plants include lilies, cattails, sedges, tamarack, and black spruce
Wetlands are home to diverse invertebrates and birds, as well as otters, frogs, and alligators
Humans have destroyed up to 90% of wetlands; wetlands purify water and reduce flooding
39. Streams and Rivers
Streams and Rivers:
Most prominent physical characteristic of streams and rivers is current
Headwaters are generally cold, clear, turbulent, swift, and oxygenrich; they are often narrow
and rocky
Downstream waters form rivers and are generally warmer, more turbid, and more oxygenated;
they are often wide and meandering and have silty bottoms
May contain phytoplankton or rooted aquatic plants
Diversity of fishes and invertebrates inhabit unpolluted rivers and streams
Damming and flood control impair natural functioning of stream and river ecosystems
41. Coastal Wetlands
Estuaries:
Where rivers meet the sea; partially enclosed bodies of water where sea water mixes with
fresh water as well as nutrients from streams, rivers and runoff from the land
Coastal Wetlands:
Coastal land areas covered with water all or part of the year
Combined with Estuaries, they are some of the Earth’s most productive ecosystems because
of nutrients, rapid flow of water and ample sunlight:
Estuaries and Coastal Wetlands: include river mouths, inlets, bays, sounds, salt marshes and
mangrove forests
Seagrass Beds:
Species of plants that grow underwater in shallow marine and estuaries along the coastline
Highly productive and support a variety of marine species
Stabilize shorelines and reduce wave impact
Life is harsh; adapt to daily and seasonal changes in tidal and river flow; water temperatures and
salinity; and runoff from the land including soil sediment and pollutants; because of this, they may
have low plant diversity but high productivity
42. Coastal Wetlands
Mangrove Forests:
Found along 70% of gently sloping sandy and silt coastlines in the tropics and sub-tropics
Grow in salt water and have extensive root systems that can support during changes in water
levels
Coastal Aquatic Systems provide important ecological and economic services:
Maintain water quality by filtering toxic pollutants, excess plant nutrients, sediments and
absorb other pollutants
Provide food, habitats and nursery sites
Reduce storm damage and coast erosion by absorbing waves and storing excess water
produced by storms and tsunamis
Provide timber and wood for fuel
UN estimates that between 1980 and 2005 at least 1/5 of the mangrove forests were lost due
mainly to human coastal development
Loss of mangroves can lead to polluted drinking water caused by inland intrusion of saltwater into
fresh water aquifers used to supply drinking water
46. Coastal Shoreline
Intertidal Zone:
Area between high and low tides (gravitational pull of the moon and sun)
Organisms must adapt to movement of water; high tides to drying out at low tides
Oxygen and nutrient levels are high
Deal with daily salinity and moisture changes
Organisms need to “hold on”:
Rocky Shores:
Pounded daily by waves
Numerous pools and other habitats with a great variety of species; marine algae
Animals have adapted to attach themselves to the hard surface
Sandy Shores:
Barrier beaches
Many organisms are hidden from view by burrowing, digging or tunneling in the sand;
home to shore birds that feed on crustaceans – sea grass and algae
Barrier Islands:
Narrow islands that form offshore parallel to the coast
48. Oceanic Pelagic Zone
Oceanic Pelagic Zone:
Constantly mixed by wind-driven oceanic currents
Oxygen levels are high
Turnover in temperate oceans renews nutrients in the photic zones; year-round stratification
in tropical oceans leads to lower nutrient concentrations
Biome covers approximately 70% of Earth’s surface
Phytoplankton and zooplankton are the dominant organisms in this biome; also found are
free-swimming animals
Zooplankton includes protists, worms, copepods, krill, jellies, and invertebrate larvae
Other animals include squids, fishes, sea turtles, and marine mammals
50. Coral Reefs
Coral Reefs:
World’s oldest, most diverse and most productive ecosystem
Known as “Natural Wonders”
Biodiversity – marine equivalent of Tropical Rain Forests
Formed by tiny animals known as polyps – jellyfish; calcium carbonate
Occupy only 0.2% of the ocean’s floor
15% have been destroyed and another 20% damaged
They provide important ecological and economic services;
Moderate atmospheric temperatures
Act as natural barriers protecting coasts from erosion
Provide habitats
Support fishing and tourism businesses
Provide jobs and building materials
53. Marine Benthic Zone
Marine Benthic Zone:
Consists of the seafloor below the surface waters of the coastal zone
Organisms in the very deep benthic zone are adapted to continuous cold and extremely high
water pressure
Mainly soft sediments; some areas are rocky
Shallow areas contain seaweeds and filamentous algae
Deep-sea hydrothermal vents of volcanic origin on mid-oceanic ridges are surrounded by
unique chemoautotrophic prokaryotes, as well as echinoderms and arthropods
Benthic communities include invertebrates and fishes
55. Human Problem
Human activities are causing major threats to marine systems, especially coastal wetlands, shore
lands, mangrove forests and coral reefs; threatened by man is the biological diversity and
ecosystems provided by the oceans that cover 71% of Earth:
Coastal Development: by 2006, 46% of the world’s population (more than ½ of US) lived
along or near coasts; by 2040, up to 80% may
Overfishing: depletes population of commercial fish
Pollution: fertilizers or animal waste; sewage from ships; oil spillage
Habitat Destruction: development but also, trawler fishing
Introduction of Invasive Species (non-native)
Climate Change from Human Activities: rise in levels
Pollution of coastal wetlands and estuaries
56. Man-made Ecosystems
Agricultural Ecosystems
Essentially croplands which have been developed and maintained with human inputs like chemical
fertilizers, irrigation, heating systems, etc
.
Urban ecosystems
-“fuel-power” ecosystem. The presence of trees and plant life recycling carbon dioxide from
human, vehicular and industrial activities.
