Warm Up 1 1.The living parts of an ecosystem are called? 2.A series of events in nature that happen over and over? 3.Two ways in which nitrogen can be “fixed”. 4.What is the difference between a food chain and a food web? 5.The lower end of a river that feeds into an ocean is called a ? 6.Name the 6 land based and 2 water based biomes. ( name as many as possible) 7.What is an energy pyramid?

Warm up 2 1.An interaction between two species that benefits both 2.An interaction between two species in which one species benefits, and one is harmed 3.A relationship between two species in which one is benefits, the other unaffected. 4.The struggle between individuals or species for limited resources 5.Animals eaten by other animals 6.Animals that eat other animals 7.Organisms within species working together

Ecology Section 2.3 Science 7 Mister Nigh

What to Expect 1. Limiting factors 2. Carrying capacity 3. Succession

Factors and Relationships That Affect an Ecosystem

Factors Affecting Populations For any population to thrive, there must be enough food, water, light and living space. These factors are known as limiting factors For any population to thrive, there must be enough food, water, light and living space. These factors are known as limiting factors. Limiting factors determine how many organisms can live inan environment. Limiting factors determine how many organisms can live in an environment. An environment contains only limited amounts of water, food, or living space. When any of these factors becomes scarce it can affect population size.

How Limiting Factors Affect A Population Plants make their own food. All other organisms obtain food and energy by eating other organisms. Food is a limiting factor because only so much is available in an ecosystem Food is a limiting factor because only so much is available in an ecosystem. Food

The cells and tissues of plants and animals are made primarily out of water. All living organisms need water to move materials around in their body’s tissues and cells. Water

Plants and other organisms that make their own food need sunlight to carry out photosynthesis. If light is limited, the growth of these organisms will also be limited. Light

Organisms need space to live, reproduce and obtain resources. Living space

Carrying Capacity The largest population that an environment can support over a long period of time is known as the environment’s carrying capacity.

The Concept of Succession Succession is the natural, orderly change in plant and animal communities that occurs over time. If left undisturbed, an open field may become an "aging" forest in years. However soil conditions, climate, permafrost, topography, and natural and unnatural forces may affect the pattern of succession

The Succession of Plant Species Stages

Primary Succession

Primary succession starts from an environment that is mostly empty of life. Example: After the retreat of glacier or after new rock is produced from a volcano, life begins to return when moss and lichens take hold of the rock and weaken the surface breaking it back into soil so small plants can re-establish themselves. Pioneer species are the first living things that move into a barren environment and begin the task of creating new soil and vegetation.

Moss and Lichens stage Mosses and Lichens with help from erosive rainfall breakdown the rock into smaller and smaller particles until they become soil

Herb Stage In the herb stage soil contains seed plants whose stems wither away to the ground each winter. Insects and small rodents feed on the grasses, herbaceous plants, and seeds As the diversity of plants increases so does the variety of wildlife species.

Shrub Stage The shrub stage includes low woody plants with several permanent stems instead of a single trunk A Larger variety of wild-life attracts predators

Young Forest Stage In the young forest stage quantity and diversity of shrubs and herbaceous plants decreases With less variety in food available, the number of wildlife species decreases. Birds of prey nest in the trees of a young forest

Mature Forest Stage In the mature forest stage hardwood trees begin to die, opening the canopy for the growth of spruce Shrubs return and make more food and cover available to songbirds, game birds and rodents.

Climax Forest Stage In the climax forest stage dead trees called snags provide homes for woodpeckers and other cavity-nesting birds. Porcupines, squirrels, spruce grouse, and several songbird species typically make homes of old stands of spruce trees.

Secondary succession is the sequence of changes that occur when an environment is disrupted by natural disasters such as a flood, earthquake, forest fire or human actions such a deforestation. Despite the disturbance, soil remains and there are still roots and seeds below the surface. The damage is only surface damage and after time grasses and shrubs return and eventually other plants, trees and animals return.

Secondary Succession

The final stable plant community is called a climax community. This community may reach a point of stability that can last for hundreds or thousands of years.

What can cause Succession Seismic Events: earthquakes, tidal waves, or volcanic eruptions hurricanes or tornadoes. the movement of glaciers or even of plates in Earth's crust wildfires or sudden infestations of insects Humans causes such as plowing up ground, logging, clearance for construction even by causing explosions on a military reservation or battlefield

Eutrophication Eutrophication is a process by which plant growth increases in a lake or pond. In time, eutrophication may cause plants to completely fill in the area where a lake or pond once stood

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