Changes in Ecosystems: Ecological Succession

What is Ecological Succession? Natural, gradual changes in the types of species that live in an area Can be primary or secondary The gradual replacement of one plant community by another through natural processes over time

Primary Succession Begins in a place without any soil: Sides of volcanoes Landslides Flooding First, lichens that do not need soil to survive grow on rocks Next, mosses grow to hold newly made soil Known as PIONEER SPECIES

Pioneer Species Low, growing moss plants trap moisture and prevent soil erosion Lichens break down rock to form soil.

Primary Succession Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

Primary Succession Simple plants like mosses and ferns can grow in the new soil

Primary Succession The simple plants die, adding more organic material (nutrients to the soil) The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession These plants die, and they add more nutrients to the soil Shrubs and trees can survive now

Primary Succession Insects, small birds, and mammals have begun to move into the area What was once bare rock, now supports a variety of life

Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Example: after forest fires

Climax Community A stable group of plants and animals that is the end result of the succession process Does not always mean big trees Grasses in prairies Cacti in deserts

How ecosystems change? Seasonal changes can affect ecosystems. All organisms depend on resources from their environment for survival. Climate Change – Drastic changes to the Earth’s temperatures over many years. Miami (top) Chicago (bottom) Stable temperature. Rainy season vs dry season. How does this season change affect the animals? Chicago—animals have spring coming although there is fairly stable temperatures. Plants do not do well in winter, no resources for animals. Therefore, the animals hybernate, suffer through having little food, or migrate.

How ecosystems change? Natural disasters can affect ecosystems. Earthquakes Volcanoes Hurricanes Tornadoes Wild Fires Floods/Storm surges Mount St. Helens eruption destroy entire ecosystems. 32 years later is all back. What happens when there is a fire in the Everglades? Do you think that fires have a negative effect on the Everglades? Why? Neg: Kills plants, destroys forest. Positive: Burns weeds that do not allow necessary plants to grow. Before these weeds grow back, plants in these areas can sprout seeds and grow to re-take over this niche that they were competing for. These fires are a natural part of an enviornment. Organisms in these ecosystems have been able to respond to these natural disasters. They are able to come back. Why do wild fires in California destroy so much?

How ecosystems change? Human intervention can affect ecosystems. Urban development Oil spills Canals in Miami (diverging water from the Everglades) Land Fills Deforestation Which one is easier for ecosystems to return from: human intervention or natural disasters? Which one is easier for ecosystems to return from: human intervention or natural disasters? SWBAT understand that organisms have bounced back from natural disasters for millions of years. Human intervention is unnatural. Ecosystems have not evolved adaptations to human intervention. EX: Yellowstone National Park. 1900s US Gov decided wolves are bad for the ecosystem bc the farmers in the area of Yellowstone (Idaho?) thought the economy of the state was affected negatively by the wolves’ predation on the cattle. All of the wolves were hunted by man and removed. What happened to the ecosystem? The deer overpopulated the land, and the vegetation suffered. Disease, overpopulation, and more consumption of the farmlands. 1980s pact from Canada and brought the wolves back In 2012 there are none of the disease and overpopulation issues bc the wolves have stabilized the deer population.

How are succession communities different? Pioneer Community Climax Community Harsh environment. Biomass increasing. Energy consumption inefficient. Some nutrient loss. Low species diversity. Fluctuations common Little stability Most favorable environment. Biomass stable. Energy consumption efficient. Nutrient cycling. High species diversity. Fluctuations do not usually occur. Great stability.