05 11 2014 LECTURE 21 ECOLOGY PLANT SUCCESSION Ecology Ecology study of the effects of the environment on living organisms the effect of living organisms on the environment the effects of living organisms on each other Plant ecology the interaction among plants between plants and the environment Ecological hierarchy o Organisms populations communities ecosystems o Populations members of a single species living together o Community different populations living together o Ecosystem community with all of its living nonliving biosphere organisms o Biosphere all areas on earth in which organisms are found Population Population members of a single species living together Habitat location where the population is found o Address of an organism Niche the functional role an organism plays in the ecosystem o Encompasses habitat relationships with other organisms in the ecosystem Plant community Plant community different populations of plants living together in the same geographical area Dominant species the most influential species in the community o Example Redwood forest o Control structure species composition of the community through physical factors chemical factors Physical factors light provide shade wind wind screen humidity higher than in open areas Chemical factors nutrients pH Ecosystem Ecosystem community with all its living nonliving organisms o Functional unit of study in the environment o Biotic living o Abiotic nonliving o Climate light soil inorganic substances Abiotic factors Biogeochemical cycles o Carbon cycle Carbon dioxide enters plants through photosynthesis Carbon is released back into the air through respiration or combustion of fuels Fossil fuels formed from remains of ancient organisms oil coal gas Humans upset the balance of the carbon cycle see greenhouse effect o Water cycle Water enters the atmosphere as vapor from the land transpiration from plants Transpiration of large plant population like trees in a tropical rainforest can actually alter the rainfall patterns in the area Vapor condenses then turns into rainfall that goes into rivers streams oceans o Nitrogen cycle Nitrogen gas is fixed by bacteria in plant root nodules Plants assimilate nitrogen incorporate it into organic nitrogen compounds Animals assimilate nitrogen by ingesting plants Animal waste organic nitrogen compounds are broken down Nitrogen Not biologically available in the air Pee is a useful type Human effect We upset the nitrogen cycle because different pollution releases a lot of nitrogen into the Also excessive use of fertilizer turns into runoff atmosphere disturbs the cycle o Phosphorus cycle Biosphere Biosphere areas on earth in which organisms are found o All of the communities on earth Biomass the organic material in living organisms Ecosphere interactions among earth s biosphere atmosphere water land Food chains Producers photosynthetic 1st order consumers herbivores 2nd order consumers carnivores o Herbivore plant eater primary consumer o Carnivore meat eater o Primary producers primary consumers secondary consumers tertiary consumers quaternary consumers Trophic level each step in the food chain o 80 95 of energy is lost at each level o So only 10 of energy is passed on at each level o Biomass is also reduced at each level Detritus food chain o Detritus waste material left behind from other biological o Consumers degrade the remains of plants animals their processes waste o Consumers fungi bacteria o Fungi bacteria are decomposers of dead material nature s recyclers Food web several food chains More realistic than a food chain multiple interactions between Usually more than 1 producer more than 1 primary consumer Consumers also have alternative food sources Greenhouse effect Humans upset the balance of the carbon cycle through o Global deforestation main way o More carbon dioxide released due to burning fuels Result 25 increase in global carbon dioxide o Carbon dioxide acts as a heat trap capturing sunlight solar energy reradiates it back to the earth as heat global warming Consequence global warming earth s temperature has increased 1 degree Fahrenheit more is expected o Less agricultural areas shifting north o Diseases such as malaria are affecting more people o Ocean levels increase increases floods hurricanes Plant succession Plant succession a series of predictable changes over time in the kinds of plants growing in an area Ecosystems mature change with time not static o Determined by the physical parameters in the environment As ecosystems age the kinds of organisms change until a stable type of community forms o Initial stages unstable high rate of replacement o Later stages more stable low rate of change Climax community relatively stable community at the end of Climax community succession o In equilibrium with the environment o Permanent until some major change o Varies depending on conditions The climax community may occur hundreds or thousands of years later Primary succession 2 types of succession primary secondary see below Primary succession when plants become established on land completely devoid of soil vegetation o Example new volcanic islands Primary succession begins as a pioneer species o Pioneer species first inhabitants forms the soil Example ferns Soil is formed thickens Eventually the community is mature climax Forest habitats mixture o Possible primary succession on forest habitats o Lichens very independent attach to rocks algae fungi Lichens mosses grasses shrubs trees o Primary succession begins as pioneer species lichens mosses invade bare rock o Climax community is spruce fir birch forest Soil portion of earth s surface of disintegrated rock organic materials o Provides essential nutrients to all plants Holds water mineral nutrients o Product of the living environment o Influenced by Climate Topography mountains valleys etc Parent material soil particles of naturally occurring inorganic material Time 4 5 billion years ago earth was a mixture of rocks o Texture all soils contain 3 kinds of particles Sand small rocky material Silt very fine material small particles Clay most important holds nutrients for plants o Humus decomposing decaying organic matter in the soil Results in nutrient rich soil o Soil pH acidic low pH or basic high pH Influences soil fertility nutrient availability Best soil is neutral or slightly acidic Secondary succession Secondary succession natural forces or human intervention destroy the existing vegetation o Fire flooding