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PLANT SCIENCE EXAM 4 STUDY GUIDE:Lecture 21: Ecology and Plant Succession1. Ecology- the study of the effects of the environment on living organism, the effect of living organisms on the environment, and the effect of living organisms on each othera. Deals with studies of organisms, populations, communities, ecosystems and the biosphereb. Plant ecology- the interaction among plants and between plants and the environment2. Population- all the members of a single species living together3. Habitat- the location where the population is found4. Niche- the functional role an organism plays in the ecosystema. Includes habitat plus relationships with other organisms in the ecosystem5. Plant community- different populations of plants living together in the same geographical area6. Dominant species- the most influential species in the communitya. Control structure and species composition of the community7. Physical factors of plant communitya. Light (provide shade)b. Wind (wind screen)c. Humidity (higher than in open areas)8. Chemical factors of plant communitya. Nutrientsb. pH9. Ecosystem- the functional unit of study in the environment; a community with all its living organisms (BIOTIC) and non-living organisms (ABIOTIC)10.Biotic- many organisms in a community that interact in food chainsa. Producers à 1st order consumers à 2nd order consumers(photosynth.) (herbivores) (carnivores)b. Food Chain- Primary producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers= last levelc. TROPHIC level – energy is lost at each level! (80-95%)memorize d. Biomass is REDUCED at each leveli. Bacteria and fungi are decomposers of dead material- natures recyclersii. DETRITUS food chain- consumers (fungi/ bacteria) degrade the remains of plants and animals and their wastee. A food WEB is more realistic because…1. There are multiple interactions between food chains2. Normally more than one producer and primary consumer3. Consumers have alternative food sources11.Abiotic factors- non-living components of the environment: climate, light, soil, inorganic substances12.Biochemical Cycles:a. Carbon cyclei. CO2 enters plants through photosynthesisii. Carbon is released back to the air through respiration, or combustion of fuelsiii. Fossil fuels (oil, coal, gas) were formed from remains of ancient organismsb. Water cyclei. Water enters the atmosphere as vapor from the landand transpiration from plants11. Plant transpiration- Transpiration of large plant populations (like treesin a tropical rainforest) can actually alter the rainfall patterns in the areaii. Vapor condenses à rainfall, into rivers, streams, oceansc. Nitrogen cyclei. Nitrogen gas is fixed by bacteria in plant root nodulesii. Plants assimilate N and incorporate it into organic nitrogen compoundsiii. Animals assimilate N by ingesting plantsiv. Animal waste and organic nitrogen compounds are broken downv. Nitrogen is not biologically available in the air. 1. Pee is a useful type of nitrogenvi. Humans upset the nitrogen cycle because different pollution releases a lot of nitrogen into the atmosphere.vii. Excessive use of fertilizer turns into runoff and disturbs the cycled. Phosphorus cycle 13.Biosphere- areas on earth in which organisms are found; ALL COMMUNITIES on earth14.Biomass- the organic material in LIVING organisms15.Ecosphere- interactions among Earth’s biosphere, atmosphere, water, and land16.Greenhouse Effect:a. Humans upset the balance of the Carbon Cycle by:i. Global Deforestationii. More CO2 released due to burning fuelsb. Result: a 25% increase in global CO2c. Carbon dioxide acts as a heat trap, capturing sunlightd. Consequence: global warming; Earth’s temperature has increased 1o F, more expectede. Less agricultural areas, shifting northf. Diseases such as malaria – affecting more peopleg. Ocean levels would increase, floods, hurricanes17.Global Warming- Carbon dioxide and other gases TRAP SOLAR ENERGY, reradiating it back to the Earth as heat – therefore warming the atmosphere. 18.Plant Succession- a series of predictable changes over time in the kinds of plants growing in an areaa. **Ecosystems mature and CHANGE WITH TIME, and are determined by the PHYSICAL parameters in the ENVIRONMENT b. **As Ecosystems age, the types of organisms change until a stable type of community forms i. Initial stages – unstable, high rate of replacementii. Later stages – more stable, low rate of change19.Climax community- relatively stable community at the end of succession- can be hundreds orthousands of years latera. In equilibrium with the environmentb. Permanent (until some major change)c. Varies depending on conditions20.2 Types of SUCCESSIONa. Primary Succession- when plants become established on land completely devoid of soil and vegetation (EX: new volcanic islands)i. Lichens (attach to rock, very independent; algea and fungi mixture)à mosses à grasses à shrubs à treesii. (Pioneer species) ferns2iii. *Each stage prepares the way for the next invasion of speciesiv. Pioneer species- first inhabitants; forms the soil and it thickens1. Eventually community is mature (climax) and primary succession begins as pioneer species (lichens and mosses) invade bare rock. v. Soil- portion of earths surface of disintegrated rock and organic materials (humus?); a PRODUCT of the living environment1. Provides essential NUTRIENTS to all plants2. Holds WATER and MINERALS3. Soil is influenced by:a. Climateb. Topography- mountains or valleysc. Parent materiald. Time vi. Soil characteristics:1. Parent material- soil particles of naturally occurring inorganic material2. Soil texture- all soils contain 3 kinds of particlesa. Sand- small rocky materialb. Silt- very fine material, small particlesc. Clay– most important: it holds nutrients for plants3. Organic matter – humus is decomposing organic matter in the soil4. Soil pH – acid (low pH) or basic (high pH) soil influences soil fertility andnutrient availabilitya. Best soil is neutral or slightly acidic pHb. Secondary Succession- natural forces or human intervention destroy the existing vegetation (fire, flooding, logging, agriculture)i. When the disturbance stops, community begins secondary succession à back to climax communityii. Since soil is already in place, secondary succession can take place 5 to 10 times faster than primary successioniii. Abiotic factors affect the nature of the plant community 1. Weather 2. Temperature3. Humidity

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