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Ecology 4: Ecosystem Structure

4 of 4 of Ecology Unit

Sarah Blechacz

on 27 March 2017

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Transcript of Ecology 4: Ecosystem Structure


Where Are We?
Ecology is the study of organism interactions with each other and the enviornment.

Ecological processes occur at multiple levels of organization on Earth.

Each level of organization emerges from the processes of the level below it
Behavior is an Organism-Level phenomenon.
Big Questions:
Make Sure You Can
How are ecosystems structured?

How do ecosystems function?
Explain the effects of all aspects of Earth's processes and features discussed in this presentation that determine climate.

Describe the characteristics of the terrestrial and aquatic biomes disucssed in this presentation, and explain why they occur where they occur on Earth.

Explain how ecosystems can function while adhering to physical laws.

Describe the effects of limiting factors on terrestrial and aquatic ecosystems and provide examples.

Explain how energy is transferred in an ecosystem and the consequences of that transfer for the structure of the ecosystem.

Diagram all nutrient cycles discussed in this presentation and explain their biological significance.
and the
abiotic factors
in a contiguous area
The related ecosystems of a large geographic area
What Determines Climate?
Earth is not uniform
Different latitudes receive sunlight at different incident angles.
The tilt of the earth and its revolution around the sun combine to produce seasons.
: most direct sunlight.
: least direct sunlight.
Opposite in northern and southern hemispheres.
Global Circulation
Uneven heating of Earth's surface contributes to uneven evaporation and precipitation, which leads to longitudinal bands of particular climatic conditions.
Uneven heating of the ocean is the major contributor of global ocean currents.
Surface Features
The local landscape has major effects on the local climate.
A Biome Tour!
Not shown:
Polar Ice
High Mountains
Precipitation and Temperature are the major factors that determine where terrestrial biomes occur on Earth
Latitude is the major determinant of precipitation and temperature, which restricts biome occurrence to particular latitudes.
The Major Biomes
There are fresh water, salt water, and
brackish (mixed salt & fresh)
aquatic biomes.
Light is a limiting factor in aquatic biomes, with all photosynthetic activity occurring in the
photic zone

of aquatic biomes is more pronounced than terrestrial biomes.
Lakes undergo a
seasonal turnover
, which exchanges oxygen-rich, nutrient-poor surface waters with oxygen-poor, nutrient-rich deep water

This seasonal process keeps the biome functioning at all levels
Ecosystems Obey Physical Laws
Laws of Conservation
Limiting Factors
Energy Transfer
Nutrient cycles
Life has to adhere to conservation of energy and conservation of mass.

Energy: Must be constantly input to an ecosystem.

Matter: Cycles in an ecosystem
How an ecosystem works
are crucial for energy transfer.
are crucial for matter cycling.
are not really necessary (sorry).
Any resource that limits the distribution and abundance of organisms in an ecosystem
Nutrients play a crucial role in limiting primary production in aquatic ecosystems
Primary Production:
The total amount of free energy stored in organic compounds by producers in an ecosystem.

Determines the structure and complexity of the community.
Satellite measurements of global primary productivity.
Soil Quality, Precipitation, and Climate determine the primary production of terrestrial ecosystems.
Gross Primary Productivity
: Total photosynthetic production.

Net Primary Productivity
: Total photosynthetic production available for consumers.
It's a plant's world. We're just guests.
Energy transfer between trophic levels is a major limiting factor on the number of organisms who occupy higher trophic levels in an ecosystem.

An average of
of energy is transferred from one trophic level to the next.
In this example, of the 200J of net primary production consumed by the caterpillar only 33J (16.5%) available to the next trophic level as
secondary production
of solar energy is utilized for photosynthesis.

of ecosystem production is transferred to each trophic level.
In most cases, production will be measured by analyzing the amount of dry mass present at each trophic level.
Nutrients must cycle through an ecosystem.
This cycling includes biotic and abiotic reservoirs & organic and inorganic forms
Generalized nutrient cycle
4 Example Nutrient Cycles
Technically, water is not a nutrient
Carbon and Oxygen cycles are "mirror images"
The Nitrogen Cycle demonstrates extensive microbial action... and the importance of another surprising force...
How phosphorus cycles
through ecosystems...
and why haboobs aren't always the worst things!
A "why is a species absent?" algorithm
An "Energy Pyramid"
Conditions and life?
High winds, low temps
Herbaceous vegitation (mostly mosses, grasses and some dwarf shrubs and trees)
Large grazing animals, bears, wolves, foxes, many migratory birds in the summer
Human Impact?
Sparsely settled but has become the focus of significant mineral and oil extraction in recent years!
Northern Coniferous Forest
Conditions and life?
Cold long winters, summers may be hot
Cone-bearing trees (Fun fact- the conical shape of many conifers prevents excessive snow from accumulating and breaking their branches!)
Birds, moose, brown bears, Siberian tigers
Human Impact?
Desert... home sweet home!
Human Impact?
Conversion of desert to irrigated agricultural have reduced natural biodiversity
Conditions and life?
Low, and highly variable, precipitation (ex: the great Corona flood of 2014... never forget)
Temperature varies greatly seasonally... and daily (Why? Hint... it's the answer to everything!!)
Lots of C4 or CAM plants!
Lots of reptiles, seed-eating rodents, nocturnal animals
Temperate Broadleaf Forest
Conditions and life?
Significant precipitation during all seasons
Deciduous and evergreen trees, depending on location
Mammals, birds, and insects make use of all vertical layers of the forest
Human Impact?
Heavy logging and land clearing for agriculture and urban development has destroyed nearly all original deciduous forests in North America
Human Impact?
Deep, fertile soil makes for ideal farmland... hence most grassland in North America & Europe has been converted... in some places overgrazing and farming have turned the grassland to desert
Conditions and life?
Dry, cold winters, wet, hot summers
Grasses (obviously!), well adapted to periodic fires and droughts
Large grazing animals and burrowing mammals
Temperate Grassland
Tropical Forest
Conditions and life?
Virtually constant rainfall & hot temperatures
Vertically layered forests where competition for light is intense!
Millions of species of plants, insects, spiders, amphibians, birds, reptiles, and mammals
Human Impact?
Agricultural and development is destroying some tropical forests.
Human Impact?
Chaparral areas are highly heavily settled by humans... brings agriculture, urbanization, fires
Conditions and life?
Rainy, cool winters & long, dry summers
Shrubs and small trees dominate landscape... many are well-adapted to fire (ex: some shrubs produce seeds that will germinate only after a hot fire)
Many deer and goats, amphibians, birds, reptiles & insects
Conditions and life?
Distinct wet and dry seasons (dry can last 8 to 9 months)
Warm year-round
Scattered trees, which are well-adapted to drought, & grasses
Large plant-eating mammals
Human Impact?
Earliest humans likely lived here!
Cattle ranching & over-hunting have led to declines in large-mammal populations
Diverse systems that cover most of the earth!
Read "The Power of Poo" & then answer the following question on a separate sheet of paper:
How does whale poop have an influence on the rest of the ecosystem?

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