Lecture 21 Ecology and Plant succession UNIT IV ECOLOGY Ecology study of effects of environment on living organisms and living organisms on the environment Organisms populations communities ecosystems biosphere Population members of a single species living together Habitat location where the population is found Niche functional role an organism plays in the ecosystem Dominant Species most influential in community ex Redwood forest Control structure and species composition of community through Physical factors light wind and humidity Chemical factors nutrients and pH Plant Ecology the interactions among plants and between plants and the environment Plant Community different populations of plants living together in the same geographical area Ecosystem study of environment Communities with all its living organisms biotic and non living organisms abiotic Biotic organisms interact in food chain or food web o Producers photosynthetic 1st order consumers herbivores 2nd order consumers carnivores o Trophic level each step in food chain energy is lost at each level o Food web realistic multiple interactions between several food chains consumers have alternate food Abiotic non living components of the environment climate light soil inorganic substances choices o Biogeochemical cycle o Carbon cycle fossil fuels were formed o Water cycle falls into river streams oceans o Nitrogen cycle o C02 enters plants through photosynthesis carbon is released through respiration or combustion o Water enters atmosphere as vapor from land transpiration from plants vapor condenses rain o Nitrogen gas is fixed by bacteria plants assimilate N and incorporate it into organic nitrogen animals assimilate N by ingesting plants animal waste and organic nitrogen compounds are broken down Biosphere areas on Earth in which organisms are found All of the communities on earth Biomass the organic material in living organisms Ecosphere interactions among Earths biosphere atmosphere water and land Greenhouse effect human upset balance of carbon cycle o Global deforestation more C02 released due to burning fuels o Result 25 increase in global C02 o Carbon dioxide acts as a heat trap capturing sunlight o Consequence global warming less agricultural areas diseases such as malaria ocean level increase floods hurricanes warming the atmosphere o Global warming C02 and other gases trap solar energy reradiating it back to the earth as heat Plant Succession series of predictable changes over time in the kinds of plants growing in an area Ecosystems mature and change with time predetermined by the physical parameters in the environment As ecosystems age organisms change until a stable 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 succession o In equilibrium with environment o Permanent until major change o Varies depending on conditions Types of succession 1 Primary succession when plants become established on land completely devoid of soil and vegetation a Soil portion of earths surface of disintegrated rock and organic materials humus i Provides essential nutrients water minerals to all plants ii Produced by the living environment influenced by climate topography parent material iii Parent material soil particles of naturally occurring inorganic material iv Soil texture 3 types of particles sand silt clay most important holds nutrients v Organic matter humus is decomposing organic matter in soil vi Soil pH acid low or basic high influences soil fertility and nutrients best is slighting time acidic b Forest habitats lichens mosses grasses shrubs trees c Begins as pioneer species for inhabitants invade bare rock and form soil climax community is spruce fir and birch forest d Each stage prepares the way for the next invasion of species 2 Secondary succession logging agriculture community begins secondary succession back to climax natural forces human intervention destroy existing vegetation fire flooding a Since soil is in place 5 10x faster than primary b Abiotic factors affect nature of plant community weather temp humidity i Tropical rainforests vegetation creates rainfall through plant transpiration when trees are removed rainfall stops land becomes arid resulting climax desert shrubs Natural systems maintain themselves whereas disturbed systems cannot Human influence on succession knock out climax community Ex maintaining a greed weed free law constant battle with nature planting grass mowing Lecture 22 Terrestrial Biomes Biome largest terrestrial divisions of the biosphere large distinct ecosystems climax communities for huge regions of the land recognized and defined by distinctive vegetation and animal life Controlled by o Temperature o Precipitation annual and seasonal distribution o Wind humidity light fire soil type Role of Climate of atmospheric circulation o Seasons are determined by the tilt of the earth o Daily and seasonal cycles influence prevailing o Climate is global and ever changing differences in atmospheric heating create winds drive global patterns Elevation altitude In NA weather patterns move from west to east Precipitation influenced by physiographic features mountains rivers oceans Elevation altitude influences biomes cooler temperatures high in the mountains favor biomes similar to biomes near North Pole 1 Tundra a Northernmost land biome around the arctic b Climate very cold and dry little precipitation c Short growing season d Soil wet shallow or permanently frozen called permafrost e Plants perennials 20 100 years and short i No trees many low shrubs and herbs grass like lichens and mosses ii Strategies to deal with cold and wind f Animals i Migratory birds wolves fox polar bear rain deer g Very low biodiversity and productivity h Sensitive to human disruption takes a long time to recover 2 Boreal Forest taiga 17 of earths land surface a Area near the arctic circle Alaska Canada and great lakes b Climate severe winters extreme cold and little precipitation c Short growing season snow is common d Soil wet deep permafrost nutrient poor may be acidic e Vegetation trees dominate especially pines conifers fir spruce birch aspen i Ground cover of lichens and mosses ii Shrubs and flowering plants are uncommon f Animals caribou wolves fox bear moose mink and migratory birds i Hunting is leading to a loss of many species ii Mineral exploitation and lumbering also threaten this biome 3