Download 3.3 Notes

3.3 – Studying Organisms in Ecosystems
Organisms are not distributed evenly across Earth.
 Climate is determined by temperature and precipitation, which, in turn,
results from the unequal heating of Earth, and other factors, such as
proximity to large bodies of water and local geography.
 The unequal heating of Earth’s surface causes Earth’s major climate
zones from the tropics near the equator, through the temperate zones, to
the cold regions near the North and South Poles.
 The pattern of precipitation influences the soil that forms in these
different regions. Soil conditions, moisture levels, altitude, latitude and
temperature determine the types and abundance of plants.
 The plants determine the variety and population sizes of organisms that
inhabit an area.
http://player.discoveryeducation.com/views/hhView.cfm?guidAssetId=ce4b
192b-495b-414a-bfcc-9870d68bbb9c&play=true&skin#
A biome is a large geographical region with a specific climate, and the
plants and animals that are adapted to that climate.
 Contain a dominant species such as prairie grasses in a grassland
biome.
 Biomes consist of many different habitats, each defined by the
particular local biotic and abiotic factors.
 A habitat is a place, or physical setting, in which an organism lives.
Each species is found in the specific habitat that it’s physical,
physiological, and behavioral adaptations equip it to survive and
reproduce in.
 The range of a species is the geographical area where the species is
found.
The hoary marmot (Marmota caligata)
feeds on plants found in high altitude
meadows.
Range of the hoary marmot
Canada has 4 major Biomes as well as contact with fresh water & marine
biomes.
Terrestrial Ecosystems – ecosystems
found anywhere on Earth not covered
by water.
Alberta: 2 major Biomes
1) Taiga
2) Grassland
Ecosystems of the Taiga Biome (Boreal Forest)
 Found along the Rocky Mountains and throughout northern Alberta.
 Dominated by conifers (needle trees)
o Adapted to warm, moist summers and cold dry winters.
o Thin needles = less water loss
o Wax coats the needles further preventing water loss and protects
against frost damage
o Pyramid shape, small needles and flexible branches help shed
heavy snowfall.
 Different regions of the taiga forest can have different ecosystems.
o The forest canopy is the upper layer of vegetation. It receives
lots of sunlight. Mature conifer trees, such as spruces and pines,
reach this area. Conifers are suitable as food for about 50 species
of birds.
o The forest floor receives very little light. Vegetation found here
is shade loving such as shrubs, mosses, and ferns. Primary
consumers include moose, voles, and white tailed deer. Predators
include bears, weasels, owls, and wolverines.
http://videos.howstuffworks.com/discovery/28108-assignment-discoverytaiga-biomes-video.htm
http://dsc.discovery.com/videos/planet-earth-forests-taiga-forest.html
Muskeg Ecosystems
 Within the taiga biome, there is a range of climate conditions,
and thus, a range of ecosystems.
 In areas with warmer ground temperatures, there is rapid
decomposition of organic matter = good soil.
 The decomposition of needles produces acidic soil in which
only certain plants can grow.
 The northern regions are cold enough that a layer of
permafrost is found beneath the soil that never melts.
 Rain and melted snow cannot drain away, and the water soaks
the decomposing plants and peat moss.
 This forms muskeg, ground that is swampy or boggy in the
summer.
 Decomposition of plant and animal material is slow.
 Plants adapted to this ecosystem grow close to the ground and
have fibrous roots that anchor them into the shifting soil.
Plants include lichen, mosses, tall grasses, small shrub.
Ecosystems of the Grassland Biome
 Central and southern Alberta
 Very fertile soil.
 Short-lived grasses with deep roots provide a large biomass for
decomposition.
 Warm temperatures cause rapid decay and the formation of a
rich layer of humus (decaying plant and animal matter).
 Grass length is controlled by precipitation.
 Grassland ecosystems have only one layer in which to support
the biotic community, limiting the number and diversity of
organisms.
 Producers include rough fescue, wheat grass, and spear grass.
Deer, squirrels, and rabbits graze on the grass.
http://videos.howstuffworks.com/discovery/28110-assignmentdiscovery-temperate-grassland-biomes-video.htm
Deciduous Forest Ecosystems
 Found at the edges of the grassland biome, before it turns into
taiga (central Alberta)
 Increased sunlight and warmer temperatures compared to
muskeg and taiga biomes
 Deciduous trees and shrubs found here.
 Warms temps, more precipitation, and large amounts of humus
from the leaves create rich soils.
 In the spring, most of the sunlight reaches the forest floor and
the understory (below the canopy layer; shrubs and smaller
trees).
 In the summer, only 6% of the sunlight reaches the ground.
 Supports a great diversity of animals.
o Thick layer of leaf litter supports many insects.
o Insects support a variety of insect eating birds and
mammals.
o Rich vegetation and understory support large browsers
such as deer and moose.
http://videos.howstuffworks.com/discovery/28109-assignmentdiscovery-temperate-forest-video.htm
Aquatic Ecosystems
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Water covers 2/3 of our planet
Ponds, rivers, lakes, and oceans
97% saltwater
Oceans provide a constant supply of freshwater through evaporation
 In Alberta, the major aquatic ecosystems are freshwater
 Zones in a lake have different physical properties, such as differing
temperatures and amounts of light. This results in a variety of habitats
within an ecosystem
 Littoral zone – the area from the shore of a lake or pond to the point
where no ore plants grow in the lake bottom
o Bulrushes and water lilies
 Limnetic zone – the area of a lake or pond in which there is open water
and sufficient light for photosynthesis to occur.
o The word plankton is used to describe both the autotrophic (tiny
plants and algae) and heterotrophic (invertebrate animals)
microorganism found in this zone.
o Plankton are the food for consumers at the higher trophic levels,
such as fish, tadpoles, and birds
 Profundal zone – the region of a lake beneath the limnetic zone, in
which there is insufficient light for photosynthesis to occur.
o Not found in ponds
o The source of nutrients in this zone is the rain of dead plants and
animals that falls from the limnetic zone.
o Detritus is slowly broken down by bacteria or consumed by other
bottom-dwelling invertebrates and fish, called detritus feeders.
o Bacteria use O2 to decompose detritus = ↓O2 for other organisms
which means only those that can live with ↓O2 can be found in
this area.
o Benthic zone = bottom of the lake.
http://videos.howstuffworks.com/discovery/28105-assignmentdiscovery-aquatic-biomes-video.htm
http://www.mefeedia.com/video/22787183
Ecological Niche
• Ecological niche – an organism role in the ecosystem.
 Its place in the food web, its habitat, its breeding area,
and the time of day it’s most active, etc.
• The variety of niches and habitats within an ecosystem allow it
to support a diversity of organisms.
 For example, even though the red-tailed hawk and the
great grey owl eat some of the same food, they are not in
competition because they have a different ecological
niche.
Factors Limiting Growth in Ecosystems
• A limiting factor is any biotic or abiotic element that controls
the number of individuals in a population.
• Abiotic factors include: soil, water, sunlight, air, or minerals
Limiting factors prevent these
bacteria from reproducing infinitely.
• Biotic limiting factors include competition, predation, and
parasites.
 Interspecific competition – competition between two or
more populations for limited resources, such as nutrients,
light, or living space.
http://www.youtube.com/watch?v=xfYAj1k9uZM&feature=related
 Intraspecific competition – competition for limited
resources among members of the same species.
Sea
Anemones
compete for
the territory
in tide pools
Bacteria
 Predation – interaction that involves the consumption of
one organism by another.
http://www.youtube.com/watch?v=hYpeC_YbqBw
 Parasitism – one organism (the parasite) derives its
nourishment from another organism (the host).
http://www.youtube.com/watch?v=rLtUk-W5Gpk
Density-dependent factor: a biotic factor that limits a habitat’s
carrying capacity (max pop. size that an environment can sustain),
the impact increases with the density of the population (e.g.,
parasites, disease)
Density-independent factor: an abiotic factor that limits a habitat’s
carrying capacity (e.g. fire, flood); the impact is not affected by the
density of the population
Biotic potential – highest growth rate for a population given
unlimited resources and ideal living conditions.
 Under these conditions population growth is exponential and we
expect to see a J curve on a graph.
 Only exists in theory, in practice there are always limiting factors.
So true population growth creates an S curve as populations
encounter environmental resistance (limiting factors.)
Sampling Populations in Ecosystems
• Organisms can be sampled using transects or quadrats situated
randomly in a sample area. From these samples, the density of
a population can be estimated.
A 5m × 100m transect
A quadrat is a square (of either metal, wood, or plastic) used in ecology to
isolate a sample, usually about 1m2 or 0.25m2. The quadrat is suitable for
sampling plants, slow-moving animals (such as millipedes and insects), and
some aquatic organisms.
Assignment: p. 108 #’s
1-5
Review p. 110
1→4, 6, 7, 8, 9, 11, 13,
14, 15, 16, 18