ecology - east pennsboro area school district · ecology- the scientific study of ... the result of...

Ecology- The scientific study of interaction between organism and their environments.

◦ Environments:

Biotic factors –all the living organism that inhabit an environment

Abiotic factors – the nonliving parts of the environment

Ex: air currents, temperature, moisture, light, and soil

Population – is a group of organisms of one species that interbreed and live in the same place at the same time

◦ Organisms compete for food, water, mates.

Determines how large each population can become

Ecosystem-The interacting system of a biological community and its nonliving environment.

Community – is a collection of interacting populations

◦ A change in one population in a community will cause changes in the other populations

Habitat- Place where an organism lives;

◦ Even in the same ecosystem, different organisms differ in their habitats.

Producer- Organisms that produce their own food are called autotrophs.

Ex: Plants

all of the species of the ecosystem depend on autotrophs for nutrients and energy.

Consumer- They obtain food by eating other organisms.

All the organisms that cannot make their own food (and need autotrophs) are called heterotrophs.

◦ There are different levels of consumers:

Those that feed directly from producers, i.e. organisms that eat plant or plant products are called primary consumers.

1. Herbivores- consumer that eats only plants

◦ Ex: grasshoppers, mice, rabbits, deer, beavers, moose, cows, sheep

2. Carnivores- consumer that eats only other animals.

◦ Ex: Foxes, frogs, snakes, hawks, and spiders.

3. Scavengers – consumer that eats the remains of dead animals.

◦ Ex: vultures, buzzards, crows, ants, beetles

4. Omnivores- eats both plants (acting as primary consumers) and meat (acting as

secondary or tertiary consumers).

◦ Ex: Bears --They eat insects, fish, moose, elk, deer, sheep as well as honey, grass

5. Decomposers- organisms that break down the remains of other organisms.

◦ Found at the bottom of the food web.

◦ Ex: Bacteria, yeast, fungi, worms and many insects

Symbiosis – permanent, close association between two or more organisms of different species

1. Commensalism – one species benefits and the other species is neither harmed nor helped

◦ Ex: an orchid growing on the branch of a larger plant

2. Mutualism – relationship that is beneficial to both species

◦ Ex: acacia trees (provides food/shelter for ants) and ants (protect tree by attacking any herbivore)

3. Parasitism – one species benefits at the expense of the other species

◦ Ex: ticks, tapeworms live on or in the organism

Food Chain- Show one prey-predator relationship and how each living thing gets its food.

◦ Some animals eat plants and some animals eat other animals.

◦ Ex: Trees/shrubs giraffes lions

Each link in this chain is food for the next link.

Always starts with plant life and ends with an animal.

Trophic levels-link represented by each organism in a food chain;

◦ Represents a feeding step in the transfer of energy and matter in an ecosystem.

All energy in an ecosystem originates with the sun.

◦ Plants transform solar energy into chemical energy (food) via photosynthesis

◦ This is consumed by plant-eating animals, which are in turn consumed as food.

The total energy transfer from one trophic level to the next is only about 10 %, the other 90% is lost as heat

Heat is lost by:

1) Organisms fail to capture and eat ALL food available at the trophiclevel below them

2) Not all food that is captured and eaten gets digested

3) Digested food is used by the organism as a source of energy.

Food web- model used to express feeding relationship among the members of a community.

◦ A group of interlinked food chains

Illustrates:

1. Who eats who?

2. Energy flow through the community

3. Functional feeding groups

4. Important ecological interactions

1) Food chains ONLY show one prey-predator relationship. The source of food is also often seasonal with many animals adapting to changes in the season by eating different types of food.

2) Food webs show a better picture of interrelationships between plants and animals.

Biomagnification = The process of increasing a chemical concentration through the food chain (Examples: DDT and PCB)

◦ Animals that eat other animals have HIGHER levels of contaminants than animals that eat plants.

◦ Some contaminants are persistent -once they are in the animal's body, they stay there for a long time.

So when smaller animals are eaten by bigger animals, all the contaminants stored in their tissues are then passed on to the bigger animal.

The result of biomagnification is that animals at the "top" of their food chain have higher contaminant levels than animals at the "bottom".

The top predators at the end of along food chain, such as lake trout, large salmon and fish-eating gulls, may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low.

The concentration of some chemicals in the fatty tissues of top predators can be millions of times higher than the concentration in the open water.

Ex: Mercury, DDT, PCB’s, arsenic

Succession = orderly, natural changes that take place in the communities of an ecosystem

◦ The community of organisms inhabiting an area gradually changes.

◦ Difficult to observe since it can take decade or centuries for one type of community to completely succeed another.

Figure 1: Succession of plant species on abandoned fields in North Carolina. Pioneer species consist of a variety of annual plants. This successional stage is then followed by communities of perennials and grasses, shrubs, softwood trees and shrubs, and finally hardwood trees and shrubs. This succession takes about 120 years to go from the pioneer stage to the climax community.

Primary succession = the colonization of new sites by communities of organisms

◦ Ex: Lava flowing from a volcano destroys everything in its path, but when it cools it forms new land

◦ Ex: Streams gradually deposit silt along their banks, creating new soil in which plants can take root.

◦ After some time, primary succession slows down, and the community becomes fairly stable.

A stable, mature community that undergoes little of NO succession is called a climax community.

Secondary succession = the sequence of community changes that takes place when a community is disrupted by natural disasters or human actions

Ex: Hurricanes, forest fires, farmers abandoning fields

Biomes = a large group of ecosystems that share the same type of climax community

Two factors that will determine which biome will be dominant on land:

1. Temperature

2. Precipitation

Occurs between the taiga and the permanently frozen polar regions

Annual precipitation is usually less than 250 mm, and water is not available for living organisms most of the time.

During summer months (mostly July and August), the upper layer of the soil thaws, but half a meter underground the soil remains frozen = permafrost.

As a result of the permafrost, short summers and very long cold winters, NOtrees occur in the tundra.

Bogs, ponds and herbaceous plants (and billions of mosquitoes) characterize the landscape, and even the few woody plants (Dwarf Birch, Arctic Willow) are dwarf.

Occupies a wide belt between the tundra and the temperate forests on the American and Eurasian continents.

Characterized by short cool summers (but longer than in the tundra) and long, dry, cold winters.

Precipitation is only 300-500 mm annually, and most of it is in the form of snow.

The forest trees are typically different species of firs, spruces and larchesmixed with birch toward the south.

The soil is grayish with a shallow humus layer, poor in nutrients and acidic with a permanently frozen layer at various depth.

Or broadleaved deciduous forests receive 600-2500 mm precipitation annually, which is more or less evenly distributed throughout the year.

The winters are much milder and shorter than those in the taiga with only one or two month below freezing.

Characterized by many species of oak, ash, beech, maple and elm, this biome is also rich in understory shrubs and herbaceous plants that are particularly dominant in the spring.

The vegetation exhibits seasonal changes with growth mostly occurring during spring and summer.

The soil has a well developed and thick humus layer which is usually brown; however, due to the large amount of precipitation, the soil is typically acidic.

Occur close to the Equator, where temperature fluctuates only little, and the precipitation is more or less evenly distributed throughout a year.

The annual rainfall is between 2000-5000 mm (up to 17 feet!), and as a consequence, the humidity is very high.

Due to the excess rainfall and rapid decomposition, the soils are very devoid of nutrients. Most of the organic matter is in the form of litter (dead material) or in living organisms.

The lowland rainforests (or jungle) are located near the sea level, whereas at higher elevations, montane rainforests or cloud forests develop.

The vegetation is lush with many layers in the canopy that support an incredible diversity of life.

Usually occur between the broadleaved forest and desert biomes.

They receive 250-600 mm rainfall during mostly the summer months.

The winters are cold and dry.

Due to slow decomposition, the soil accumulates huge amounts of humus, whose black layer may be more than a meter thick (hence the name of the soil: black earth, black land, chernozem).

The little precipitation does not support trees, but grasses and herbs are present in great abundance.

Depending on the amount of rainfall, there are varieties of grasslands such as tallgrass, mixedgrass or shortgrass prairies and steppes. In the latter, drought tolerant grasses (such as feathergrass and buffalograss) and annual plants predominate. Grasslands in North America are called prairie, in Eurasia they are called steppe (in Hungary it is the puszta), and in South America pampa.

support a large number of herbivores from antelopes, horses and bisons to mice, groundsquirrels and gophers.

There is less than 250 mm annual precipitation. The precipitation is unpredictable; there are long periods of drought lasting for eight to ten years.

Warm deserts experience very mild winters with few freezing days (Sonoran, Chihuahuan, Saharan deserts), whereas cold deserts have an extended period of winter with temperatures well below freezing (Taklimakan, Gobi).

Plant cover is sparse, and characterized by drought tolerant brushes, succulent and annual plants.

Deserts are particularly rich in reptiles (snakes and lizards) and rodents (gerbils, jerboas and kangaroo rats), and most of the animals are nocturnal (active at night).

The soil is very poor in nutrients, and the humus layer is absent or only weakly developed.