05 10 2013 BSCI 124 UNIT 4 Review Sheet Ecology Populations Habitats Niche o All the members of a single species living together o The location where the population is found the address of an organism o The functional role an organism plays in the ecosystem it encompasses habitat plus relationships with other organisms in the ecosystem Community dominant species o Plant Community different populations of plants living together in the same geographical area o Dominant species the most influential species in the community For ex Redwood forest They control the structure and species composition of the community through Light provide shade Wind wind screen Humidity higher than in open Physical factors areas Chemical factors Nutrients pH Biotic vs abiotic factors chains Ecosystem organisms o Biotic there are many organisms that live in a community Organisms interact in food o Abiotic non living components of the environment climate light soil inorganic substances Biogeochemical cycles o Functional unit of study in environment A Community with all its abiotic and biotic Food Chains Trophic levels o Producers photosynthesis 1st order herbivores 2nd order carnivores o Each step is a trophic level 85 90 energy lost at each level o Bacteria and fungi are decomposers of dead material Food webs o More realistic than food chain Multiple interaction between several food chains Usually more than one producer and primary consumer Consumers have alternative food sources Biogeochemical cycles o Carbon cycle what disrupts it CO2 enters plants through photosynthesis Carbon is released back to the air through respiration or combustion of fuels Fossil fuels oil coal gas were formed from remains of ancient organisms Greenhouse Effect Humans upset the balance of the Carbon Cycle 1 Global deforestation 2 More CO2 released due to burning fuels Result a 25 increase in global CO2 Carbon dioxide acts as a heat trap capturing sunlight Consequence global warming Earth s temperature has increased 1o F more expected o Water cycle rain seas rivers Water enters the atmosphere as vapor from the land and transpiration from plants Vapor condenses rainfall into rivers streams oceans Transpiration of large plant populations like trees in a tropical rainforest can Plant Transpiration actually alter the rainfall patterns in an area Trees can create rainfall through transpiration o Nitrogen cycle role of legumes Nitrogen Cycle Nitrogen gas is fixed by bacteria in plant root nodules Plants assimilate N and incorporate it into organic nitrogen compounds Animals assimilate N by ingesting plants Animal waste and organic nitrogen compounds are broken down o Phosphorous cycle not much from living organisms Phosphorous is absorbed by plants and goes back into the earth by animal waste Phosphorous is used a lot in fertilizers which run off a lot onto waterways This kicks the system out of balance and upsets the balance of phosphorous in ecosystems Primary vs secondary succession area o Primary Succession o Plant Succession predictable changes over time in the kinds of plants growing in an Ecosystem are not static they change over time When plants become established on land completely devoid of soil and vegetation Soil portion of Earth s surface of disintegrated rock and organic materials Pioneer species first inhabitants forms soil Each stage prepares the way for the EX new volcanic islands humus next invasion of species o Secondary Succession Secondary succession natural forces or human intervention destroy the existing vegetation fire flooding logging agriculture When the disturbance stops community begins secondary succession back to Since soil is already in place secondary succession can take place 5 10 times climax community faster than primary succession An example of secondary succession on barren rock or lava is Mount St Helens in Washington State 1980 eruption Mt St Helens recovery after the eruption Also plant community affects these abiotic factors For example in the tropical rain forests the vegetation creates the rainfall through plant transpiration When trees are removed rainfall stops and land becomes arid The resulting new climax community is often desert shrubs Secondary succession example an abandoned corn field Climax community o Relatively stable community at the end of succession 1 in equilibrium with the environment 2 permanent until some major change 3 varies depending on conditions o Humans usually knock out climax condition Soil characteristics o Parent material soil particles of naturally occurring inorganic material o Soil texture all soils contain 3 kinds of particles Sand Silt Clay most important it holds nutrients for plants o Organic matter humus is decomposing organic matter in the soil o Soil pH acid low pH or basic high pH soil influences soil fertility and nutrient availability o Best soil is neutral or slightly acidic pH BIOMES Climate characteristics o Determined by the tilt of the Earth 23 5 o Temperature how hot or cold it can get and the length of the growing season o Precipitation rain snow annual precipitation and seasonal distribution Influenced by physiographic features like mountains rivers oceans o Wind differences in atmospheric heating create winds o Humidity light fire soil type o Elevation altitude In N America weather patterns move from west to east Elevation altitude influences biomes Cooler temperatures high in the mountains favor biomes similar to biomes near North Pole Biomes o Tundra land without trees Geographical location northernmost land biome around arctic circle Climate very cold and dry little precipitation Temp Freezing temperatures can occur any day of the year rarely over 15 deg Soil type Wet shallow or with permanently frozen soil called permafrost Only Most are perennials 20 100 years and short Low shrubs and herbs grass like plants Short growing season plants bloom in summer plants adapted to cold temperature antifreeze sap hairy leaves that help retain heat Celsius top 0 5m thaws Plants No trees Lichens mosses Animals Migratory birds wolves fox polar bear rain deer voles black flies Low biodiversity and productivity Human impact Sensitive to human disruption takes a long time to recover slow growth Arctic national wildlife refuge o Boreal Forest Taiga 17 of Earth s land surface area Geographical location Area near arctic circle Alaska Canada Great Lakes Climate severe winters extreme cold up to 100F and little precipitation Short growing season 90 120 days