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Ecosystems & Communities: Organisms and their Environments. Ecosystems have living and non-living components. What are ecosystems?. What is an Ecosystem?. A community of biological organisms plus the non-living components with which the organisms interact.
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What are ecosystems?
15.2 A variety of biomes occur around the world, each determined by temperature and rainfall.
Three-toed Sloth (Bradypusvariegatus) with baby - Costa Rica
Old Field Habitat, Ohio
Ironweed (Vernoniasp.)with Hedge Bindweed Vine (Calystegiasepium)
Grassland, North Dakota
Joe Pye Weed
Queen Anne\'s Lace (Daucuscarota)
Bison (Bison bison) on the range, Theodore Roosevelt National Park, North Dakota
Przewalski\'s horse (Equuscaballusprzewalskii), The Wilds, Ohio
American Black Bear
Zebratail Lizard - Callisaurusdraconides
Rock hyrax (Procaviacapensis)
Bactrian Camel, Camelusbactrianus
Oaks (Quercus sp.)
Eastern Gray Squirrel
Anaktuvuk Pass, Alaska
Arctic Tundra Wildflowers - Alaska
(photographed in Ohio, not on the Tundra)
Caribou On Autumn Tundra Denali National Park Alaska
UmbrellaThorn AcaciaAcacia tortillis
Common SagebrushArtemisia tridentata
Golden JackalCanis aureus
From left: a view across Manzanita Lake toward Mt. Lassen, California; a forest pond near Donnelly, Idaho; a Great Blue Heron; Paranagat Lake, southeastern Nevada.
From left: McArthur-Burney Falls State Park, California; trout; Green River, Utah; Brooks River, Alaska.
From left: Pescadero Marsh, California; coastal marsh at Umpqua Dunes, Oregon; trees and bogs on Esther Island, Alaska.
From left: mussels, worms, and a spider crab at a hydrocarbon seep community in the Gulf of Mexico; a sea fan and brain coral in the Florida Keys National Marine Sanctuary; a school of Atlantic amberjack off North Carolina.
From left: reef life in the Gulf of Aqaba, Red Sea; a reef at Fanning Island atoll in the central Pacific; a reef in the Florida Keys National Marine Sanctuary.
From left: Mangrove roots, south Florida; wetlands and tidal streams in the Ashe Island area, ACE Basin National Estuarine Research Reserve, South Carolina; a salt marsh in Winyah Bay National Estuarine Research Reserve, South Carolina.
These are the biomes, in order of their productivity (highest first)
In order to be productive and have a lot of living material standing around (biomass), an ecosystem has to have 4 basic necessities for plant life to thrive (if there are enough plants, the ecosystem will also support a lot of animals). The four things are:
Energy flows from producers to consumers.
Losses at every “step” in a food chain
Inefficiency of energy transfers
A grasshopper eats a plant. A mouse eats the grasshopper. A snake eats the mouse. A hawk could eat the snake or the mouse. In this food web, how would we categorize the hawk?
Energy from the sun passes through an ecosystem in several steps.
First, it is converted to chemical energy in photosynthesis.
Herbivores then consume the primary producers, the herbivores are consumed by carnivores, and the carnivores, in turn, may be consumed by top carnivores.
Detritivores and decomposers extract energy from organic waste and the remains of organisms that have died.
At each step in a food chain, some usable energy is lost as heat.
Energy pyramids reveal the inefficiency of food chains.
flow of energy through a food chain
trophic level: position that an organism occupies in a food chain - what it eats, and what eats it
You go out to eat at a fancy restaurant. You have a salad, salmon, and for dessert ice cream! Which part of the meal was the most energy efficient food for you to eat?
Energy from the sun passes through an ecosystem in several steps known as trophic levels.
Energy pyramids reveal that the biomass of primary producers in an ecosystem tends to be far greater than the biomass of herbivores.
The biomass transferred at each step along the food chain tends to be only about 10% of the biomass of the organisms being consumed, due to energy lost in cellular respiration.
As a consequence of this inefficiency, food chains rarely exceed four levels.
Essential chemicals cycle through ecosystems.
Each chemical is stored in a non-living part of the environment.
Organisms acquire the chemical from the reservoir, a non-living part of the environment.
The chemical cycles through the food chain (biogeochemical cycles).
Eventually, the chemical is returned to the reservoir.
Because it is necessary for the production of every plant protein, and because all nitrogen must first be made usable by bacteria, plant growth is often limited by nitrogen levels in the soil.
For this reason, most fertilizers contain nitrogen in a form usable by plants.
component of protein
cycles in both a gas and sedimentary cycle
source : earth\'s crust
enters the atmosphere as hydrogen sulfide (H2S) during fossil fuel combustion, volcanic eruptions, gas exchange at ocean surfaces, decomposition
H2S is immediately oxidized to sulfur dioxide (SO2)
SO2 + water vapor H2SO4 (falls to earth in rain)
sulfur in soluble form is taken up by plant roots, incorporated into amino acids such as cysteine
travels through food chain
eventually released through decomposition
It is “fixed” by bacteria.
It is a product of cellular respiration.
Burning of fossil fuels.
2 and 3.
All of the above.
These chemicals are not efficiently recycled in the soil.
Nitrogen and phosphorous need to be “fixed” by bacteria or the plant.
Nitrogen and phosphorous are found at high levels in the atmosphere but not in the soil.
Nitrogen and phosphorous only enter the soil through erosion.
Chemicals essential to life—including carbon, nitrogen, and phosphorus—cycle through ecosystems.
They are usually captured from the atmosphere, soil, or water by growing organisms; passed from one trophic level to the next as organisms eat other organisms; and returned to the environment through respiration, decomposition, and erosion.
These cycles can be disrupted as human activities significantly increase the amounts of the chemicals utilized or released to the environment.
Symbiosis: close relationship between organisms of two different species
At least one participant gains some sort of benefit (usually nutritional)
Types of symbiosis:
Parasite derives nutrition from the host
This harms the host but a true parasite does not usually kill its host (directly)
Remain outside the host
Ticks, fleas, leeches
Live inside the host’s body
Tapeworms, malarial parasites
Many parasites live on or in a single organism
Some will alternate between 2 or more host species
Vertical transmission – from mother offspring
Horizontal transmission – between members of a population
Direct contact (head lice)
Neither species is totally dependent on the other
One benefits – no effect on the other
Feeding or protection
Porcelain anemone crabs and anemones
Both species benefit
Food or shelter
Plants and microbes (rhizobium in root nodules)
Plants and fungi (orchids and mycorrhizae)
Protists and fungi (lichen)
Plants and insects (pollination)
Animals and bacteria (ruminants)
Animals and other animals (crocodiles and plover birds)
Rhizobium in root nodules of certain plants convert nitrogen in soil to usable form.
Fungi aid the plant in the uptake of nutrients.
Fungi ingest some of the food from plant photosynthesis
Most of the lichen is composed of fungal filaments, but living among the filaments are algal cells, usually from a green alga or a cyanobacterium.
The lichen fungus provides its partner(s) a benefit (protection) and gains nutrients in return.
Ruminants are characterized by their four-chambered stomach and "cud-chewing" behavior. Cud is a food bolus that is regurgitated, rechewed, and reswallowed. The rumen is a large fermentation vat containing billions of microorganisms, including bacteria and protozoa, which allow ruminants to digest fibrous feeds such as grass and hay that other animals cannot efficiently utilize.
The bird gets into the crocodile\'s mouth and picks out the tiny bits of food stuck in his teeth, then eats it (the tiny bits).
This cleans the crocodile\'s teeth and keeps his mouth fresh and free from infections.