1. Ecology
Ecology is the study of the interactions among organisms and their interrelationships with the physical environment. All living organisms are dependent upon other living things as well as dependent on the nonliving environment.
Habitat – the place where an animal or plant lives.
Niche – the role an organism fits into within its ecosystem.

2. Organization

3. Ecosystems
The ecosystem is the structural and functional unit studied in ecology. It is the lowest level of organization in ecology in which all living and nonliving environmental factors exist and interact.
ECOSYSTEM STRUCTURE AND FUNCTION:
An ecosystem involves interactions between abiotic (nonliving) and biotic (living) factors. An ecological system is a self-sustaining unit if the following requirements are met:
It must have a constant source of energy and a living system capable of incorporating this energy into organic compounds.
It must have mechanisms to cycle and recycle materials between the organism and their environment.

4. Terrarium: Balanced Ecosystem

5. Carrying capacity – the largest population of any single species that an area can support.

6. Components of an Ecosystem
ABIOTIC FACTORS:
The abiotic environment includes physical and chemical factors which affect the ability of organisms to live and reproduce.
The abiotic factors include:
Intensity of light
Range of temperatures
Amount of moisture
Type of substratum (soil)
Availability of inorganic substances such as minerals
Supply of gases such as O2, CO2, N2 pH

7. Limiting Factors
Each of these factors varies in the environment and, as such, may act as a limiting factor, determining the types of organisms which may exist in that environment. Examples of limiting factors include:
Some plants live well on a forest floor under tall trees, but would not do well in an open field due to the increased intensity of light.
At low annual temperatures common to the northern latitudes determines in part what species of plants can exist in that area because enzymes of different species work best at different temperatures.
The amount of oxygen dissolved in a body of water will help determine which species of fish will exist there. Fish that need high oxygen levels would suffocate and die with a severe drop in the oxygen level in the water.
The salt-laden air and water of coastal areas limit what species can exist in those regions. Some species of fish, shellfish, and other marine species would die in freshwater due to an imbalance of water pressure in their tissues.
More than 200 lakes in the Adirondacks have virtually no life in them because of low pH caused by acid rain.

8. Biotic Factors
Biotic factors are all the living things that directly, or indirectly, affect the environment. Thus, the organisms, their presence, parts, interaction, and wastes, all act as biotic factors. Biotic factors interact in many ways such as in nutritional relationships and symbiotic relationships.

9. Nutritional Relationships: Nutritional relationships involve the transfer of nutrients from one organism to another within an ecosytem
Autotrophs- Organisms who can synthesize their own food (organic nutrients such as carbohydrates, proteins, lipids and nucleic acids) from inorganic compounds and a usable energy source.
Heterotrophs- Organisms who cannot synthesize their own food and are dependant upon other organisms for food
Saprophytes- Heterotrophic (nongreen) plants, fungi, and bacteria which live on dead matter and recycle materials in the environment. Ex: mushrooms, breadmold and bacteria of decay

10. Herbivores- Animals which consume plants
Herbivores- Animals which consume plants. Include the “grazing” animals such as cows, rabbits and deer.
Carnivores- Animals which consume other animals. Include: predators which kill and consume prey (wolves & eagles); and scavengers who feed on animals they have not killed (buzzards and crabs.)
Omnivores- Animals that consume both plants and animals. Ex: humans

11. Symbiotic Relationships
Different organisms live together in a close association which may include: nutritional, reproductive, and protective relationships. This living together in close association is known as symbiosis. Symbiotic relationships may or may not be beneficial to the organisms involved. Types of symbiosis include:

12. Commensalism- One organism is benefited and the other is not adversely affected (+,0). Ex: barnacles on whales and orchids & bromeliads on large tropical trees.
Mutualism- Both organisms benefit (+, +). Ex: nitrogen-fixing bacteria within the nodules of legumes, certain protozoa within termites, and a flower and bee.
Parasitism- The parasite benefits at the expense of the host (+, -). Ex: athlete’s foot fungus on humans and tapeworm, heartworm, and fleas in dogs.

13. Energy Flow Relationships
If an ecosystem is to be self-sustaining it must contain a constant supply of energy which is available to all the organisms within the ecosystem. The energy must flow from organism to organism.
ENERGY FLOW
Those life activities which are characteristic of living organisms require the expenditure of energy. The pathways of energy through the living components of an ecosystem are represented by food chains and food webs.
Green plants convert radiant energy from the Sun into chemical energy (food). A food chain involves the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten. Ex: Grass→Grasshopper→Frog→Snake

14. Food Chain

15. FOOD WEB. In a natural community, the flow of energy and materials is much more complicated than is illustrated by one food chain. Since practically all organisms may be consumed by more than one species, many interactions occur among the food chains of any community. These interactions are described as a food web. Interactions in a food web involve:

16. Food Web

17. Producers- The energy for a community is derived from the organic compounds synthesized by green plants. Autotrophs are the primary producers in all ecosystems.
Consumers- Herbivores are primary consumers. Carnivores are secondary consumers. Omnivores may be either primary or secondary consumers.
Decomposers- Organic wastes and dead organisms are broken down to simpler substances, where chemical substances are returned to the environment where they can be used by other living organisms.

18. Pyramid of Energy
There must be much more energy at the producer level in a food web then at the consumer levels. In turn, there is more energy at the primary consumer level than at the secondary consumer level. A pyramid of energy can be used to illustrate the loss of usable energy at each feeding level. Each consumer level of the food pyramid utilizes approximately 10% of its ingested nutrients to build new tissue. This new tissue represents the food for the next feeding level. The remaining energy is lost in the form of heat and unavailable chemical energy.
Eventually, the energy in an ecosystem is lost and is radiated from the Earth’s system. Thus, an ecosystem cannot sustain itself without the constant input of energy from the Sun.

19. Biomass pyramid
In general, the decrease of energy at each successive feeding level means that less biomass (amount of organic matter) can be supported at each level. Thus, the total mass of carnivores in a particular ecosystem is less than the total mass of producers.
For example, if the population of rabbits in a community decreases, there is less food available for the foxes. This will cause a decrease in the number of foxes born as there is too little food to support a larger population. With fewer foxes, the rabbit population has a chance to increase. The biomass relationship is a good example of the balance in nature, the homeostasis of an ecosystem.

20. Energy Pyramid Relationships
Prairie Ecosystem
bacteria
Prairie

21. Material Cycles
In a self-sustaining ecosystem, material must be cycled among organisms and the abiotic environment. Thus, the same materials can be reused by different living organisms.

22. Carbon-Hydrogen-Oxygen Cycle
The carbon-hydrogen-oxygen cycle involves the processes of respiration and photosynthesis. In respiration, oxygen and glucose are combined releasing energy and producing water and carbon dioxide. In photosynthesis, water and carbon dioxide with energy from the Sun are combined to produce glucose (containing the energy) and oxygen. Each process compliments the other, and the ecosystem maintains its balanced communities.
Water &
& Water

23. Water Cycle
Water is vital to all living organisms and is a primary limiting factor within any ecosystem. The water cycle involves the processes of photosynthesis, transpiration, evaporation, condensation, respiration, and excretion.
Photosynthesis

24. Nitrogen Cycle
The nitrogen cycle “cycles” nitrogen necessary for the production of proteins, essential to all living things. It is an example of a material cycle involving decomposers and other soil bacteria which, in part, break down and convert nitrogenous wastes and the remains of dead organisms into materials usable by autotrophs.
The essential parts of the nitrogen cycle include:
1.Atmospheric nitrogen is converted into nitrates by nitrogen-fixing bacteria.
Plants use nitrates for protein synthesis.
Animals which eat plants convert the plant protein into animal protein.
2.Nitrogenous wastes and the bodies of dead plants and animals are broken down by decomposers (bacterial decomposition) and ammonia is released.
3.Ammonia may be converted into nitrates by nitrifying bacteria.
4.Nitrogen containing compounds may also be broken down by denitrifying bacteria, resulting in the release of nitrogen into the atmosphere.

26. Atmospheric free nitrogen
Animal waste & dead plants
Denitrification
Nitrogen-fixing bacteria in soil
Decay Bacteria
Denitrifying bacteria
ammonia
Nitrifying Bacteria
Nitrates
Used by plants

27. Ecosystem Formation
Ecosystems tend to go through dynamic change with time until a stable system (climax community in a state of equilibrium is attained. The type of ecosystem that is formed depends on the climate limitations of a particular geographical area.
SUCCESSION
The replacement of one community by another until a stable stage (climax community) is reached is called ecological succession.
Succession may be said to begin with pioneer organisms, since these are the first living things to populate a given location. For example, lichens (a symbiotic association between fungus-alga) are the pioneer organisms on bare rock. Pioneer organisms modify their environment. Seasonal die-back and erosion, for example, would create pockets of “soil” in the crevices in bare rock.

28. Changes in Succession
Each community modifies the environment, often making it more unfavorable for itself, and apparently, more favorable for the following community which infiltrates the first community over a period of years. For example, as lichens grow and reproduce, they add organic matter and moisture to their substratum. After a period of time, humus is made and is too rich and moist for the lichen to survive. The lichens die but produce a richer substratum that will support seeds for the development of grasses and herbs, the next stage of succession. A typical successional sequence in New York State might be: lichen (pioneer), grass, shrub, conifer, and deciduous woodland (climax).

29. Conifers: pines & firs (softwoods)
Lichens & annuals
Perennials & Grasses
Shrubs
Conifers: pines & firs (softwoods)
Deciduous trees: maples, oaks, and beeches (hardwoods)

30. Plant species (flora) dominate in the sense that they are the most abundant food sources. Plant succession is a major limiting factor for animal (fauna) succession. Communities are composed of populations able to exist under the prevailing conditions and are identified by their own dominant plant species – the one that exerts the most influence over the other species present. Ex. a Sphagnum Bog
A climax community is a self-perpetuating community in which populations remain stable and exist in balance with each other and the environment. The oak-hickory and the hemlock-beech-maple associations represent two climax communities found in New York State.
A climax community continues until a catastrophe or a change in a major biotic or abiotic factor alters or destroys it, thus producing “nonclimax” conditions.

31. Some examples of natural and man-caused factors that affect a climax community include:
Forest fires
Abandoned farmlands
Areas where topsoil has been removed
Thereafter, succession once again occurs leading to another climax community. The original climax community may be reestablished or a new climax community may be established if the abiotic environment has been permanently altered.
Competition occurs when different species or organisms living in the same environmet (habitat) utilize the same limited resources, such as food, space, water, light, oxygen, and minerals. The more similar the requirement of the organisms involved, the more intense the competition. This competition between different species is called interspecies competition.

32. Biomes
The term biome refers to the most common climax ecosystem that will form in geographic regions of similar climatic conditions. Biomes are terrestrial or aquatic. The temperate deciduous forest of the U.S. is a terrestrial biome. The ocean is an aquatic biome.
Terrestrial Biomes
The major plant and animal associations on land are determined by the major climatic zones of the world, which are modified by local land and water conditions. Climates will vary as to temperature, solar radiation, and precipitation. The presence or absence of water is a major limiting factor for terrestrial biomes.

33. Temperate-Deciduous Forest
Characteristics:
Land biomes are characterized and sometimes named by the climax vegetation in the region. The major land biomes, and their characteristic flora, and fauna are listed in the following chart.
BIOME
CLIMAX FLORA
CLIMAX FAUNA
CHARACTERISTICS
Tundra
Lichens, mosses, grasses
Caribou, snowy owl
Permanently frozen subsoil (permafrost)
Taiga
conifers
Moose, black bear
Long, severe winters, summers with thawing subsoil
Temperate-Deciduous Forest
Trees that shed leaves (deciduous trees)
Grey squirrel, fox, deer
Moderate precipitation, cold winters, warm summers
Tropical Rain Forest
Many species of broad-leaved plants
Snake, monkey, leopard
Heavy rainfall, constant warmth
Grassland
grasses
Pronghorn antelope, prairie dog, bison
Rainfall & temperature vary greatly, strong prevailing winds
Desert
Drought-resistant shrubs and succulent plants
Kangaroo rat, lizard
Sparse rainfall, extreme daily temperature changes

34. Geographic Factors:
Climatic conditions change with latitude and altitude. Earth latitude and altitude are similar in that as both increase, the limiting factors change in a similar manner, and the organisms change as well.
high
altitude
low
high
low
latitude

35. Fresh Water Biomes:
The fresh water biome includes ponds, lakes, and rivers. The areas which make up a fresh water biome show considerable variation in:
Size
Current velocity
Temperature
Concentration of dissolved gases
Suspended particles
Rate of succession
Ponds and small lakes, for example, fill in due to the seasonal die-back of aquatic vegetation and the erosion of their banks. Eventually a small body of water enters into terrestrial succession terminating in a terrestrial climax community.

36. Marine Biomes
The oceans of the world are a continuous body of water that
Provides the most stable aquatic environment
Absorbs and holds large quantities of solar heat and helps to stabilize the Earth’s atmosphere
Contains a relatively constant supply of nutrient materials and dissolved salts
Serves as a habitat for a large number of diverse organisms
A great amount of food production in the world occurs in the oceans along the edges of the land masses (coastal waters), the deeper regions being too dark.

37. Biodiversity
Biodiversity is a measurement of the degree to which species vary within an ecosystem. There is a strong connection between biodiversity and the stability of an ecosystem.
The interactions between organisms may allow an ecosystem to remain stable for hundreds or thousands of years. Populations tend to fluctuate in predictable patterns. Loss of biodiversity upsets this stability. For example, when the prey population increases, a large food supply causes the size of the predator population to rise. Because each predator requires many prey to meet its energy needs, the prey population rapidly decreases. Soon, with the decline in a prey population, some of the predators begin to starve. When only a few predators remain alive, the prey population reproduces and greater numbers of prey survive. The cycle begins anew.

38. Ecosystem instability not only affects plants and animals, but also humans. For example, a natural forest contains many different species of trees. If disease or insects attack one population, nearby trees of another species are likely to survive. As opposed to a tree farm, where all of the trees planted are of a single species that could be seriously damaged by a single disease or insect attack. Entire crops may be lost from any disruption in an ecosystem.
Furthermore, biodiversity ensures a rich variety of genetic material for medicine, insecticides, and other useful resources.

39. Biosphere and Humans
Humans exercise a unique and powerful influence on the physical and living world and have modified their environment more than any other living thing.
Renewable resources:
Although many resources are renewable, they must used carefully. Increased consumption can stress the natural processes that renew some resources. As a result, the resource might be unable to renew itself. For example, commercial fishing can stress certain fish populations.
Nonrenewable resources:
Our increasing consumption of resources that cannot be replaced naturally is becoming a serious problem. Most metals, such as the aluminum we use for packaging, and other minerals, such as silicon we use for computer chips, are nonrenewable resources. Fossil fuels, such as the gas that runs our cars and the coal that powers many factories, are also nonrenewable resources.

40. Population growth:
Most species in new environments can have a period of rapid population growth. The population increase will eventually level off as it approaches the ecosystem’s carrying capacity, which is the number of individuals the environment can support.
Human Population Growth:
The total population of humans has risen at a rapid rate, partly because of the removal of natural checks on the population, such as disease. This continued increase in the human population has far exceeded the food producing capacities of many ecosystems in the world. The change in the world population is illustrated in the population graph below.

41. Growth curve for the human population worldwide
The Plague
Growth curve for the human population worldwide
A population growth curve: In new environment, the population usually increases quickly, but it stablilizes when it reaches the carrying capacity of that environment.

42. Negative Aspects
Disruptions that humans cause to the natural systems directly affect at least one of the components of an ecosystem and this, in turn, affects the remaining components.
Human Activities:
Some activities have led to the extinction or endangerment of numerous species of plants and animals as well as producing less favorable living conditions for many species, including humans.
Overhunting- many species have gone extinct. Ex: Dodo bird, Wooly Mammoth. Many countries still hunt whales, sharks, etc.

43. Importation of organisms- Non-native species disrupt stable ecosystems
Importation of organisms- Non-native species disrupt stable ecosystems. Ex: Japanese beetle, Gypsy moth, Purple loosestrife, Hogweed, Zebra Mussels, Dutch elm disease.
Australia – Cane Toad

44. Imported Organisms
Zebra Mussels
Purple Loosestrife
Hogweed

45. Exploitation- elephants and walruses killed for tusks, exotic birds endangered due to pets, rainforests depleted for plywood.

46. Poor land use management- urbanization disrupts natural habitats, agricultural land, and watersheds.
Water pollution- heat, sewage, and chemicals such as phosphates, heavy metals and PCB’s cause serious health problems and destroy life forms.
Air pollution- Nitrogen oxides and sulfur dioxide combine with water to form acid rain-kills living things and destroys buildings.
Biocide use- pesticides and insecticides contaminate soil, atmosphere, water supply and disrupt food webs. Ex: DDT
Disposal problems- human supplies accumulate solid, chemical, and nuclear waste. Nuclear plants produce permanent dangerous radioactive wastes.

47. Ozone depletion- the release of certain industrial gases (CFC’s) into the atmosphere has led to destruction of much of the ozone shield, the layer of ozone gas in the upper atmosphere that protects Earth from some of sun’s radiation.

48. Global Warming- atmospheric gases, called greenhouse gases, trap and absorb the infrared radiation that bounces off Earth’s warmed surface. Recently, greenhouse gases have increased, raising the Earth’s average temperature.

50. Positive aspects:
Population control- family planning has become accepted by much of the world to conserve limited resources.
Conservation of resources- reforestation and covercropping protect land, water, and energy conservations improve, as well as recycling.

51. Pollution controls- laws and new techniques of sanitation or the disposal of industrial hazardous materials have improved land, water and air quality. Why the Eagles Returned (11 min)
Species preservation- wildlife refuges, national parks, game laws, fisheries and endangered species protection have improved.

52. Biological control- encourages food webs and ecosystems by decreasing the use of pesticides. Ex: Japanese beetle traps, ladybugs for aphids.
In recent years, new and tougher laws which regulate and guide the use of natural habitats have been enacted throughout the country. For example, the Freshwater Wetlands Act.