PLANT SCIENCE EXAM 4 STUDY GUIDE Lecture 21 Ecology and Plant Succession 1 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 other a Deals with studies of organisms populations communities ecosystems and the biosphere b Plant ecology the interaction among plants and between plants and the environment 2 Population all the members of a single species living together 3 Habitat the location where the population is found 4 Niche the functional role an organism plays in the ecosystem a Includes habitat plus relationships with other organisms in the ecosystem 5 Plant community different populations of plants living together in the same geographical area 6 Dominant species the most influential species in the community a Control structure and species composition of the community 7 Physical factors of plant community a Light provide shade b Wind wind screen c Humidity higher than in open areas 8 Chemical factors of plant community a Nutrients b pH 9 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 chains a Producers 1st order consumers 2nd order consumers photosynth herbivores carnivores b Food Chain Primary producers primary consumers secondary consumers tertiary consumers quaternary consumers last level c TROPHIC level energy is lost at each level 80 95 memorize d Biomass is REDUCED at each level i Bacteria and fungi are decomposers of dead material natures recyclers ii DETRITUS food chain consumers fungi bacteria degrade the remains of plants and animals and their waste e A food WEB is more realistic because 1 There are multiple interactions between food chains 2 Normally more than one producer and primary consumer 3 Consumers have alternative food sources 11 Abiotic factors non living components of the environment climate light soil inorganic substances 12 Biochemical Cycles a Carbon cycle i CO2 enters plants through photosynthesis ii Carbon is released back to the air through respiration or combustion of fuels iii Fossil fuels oil coal gas were formed from remains of ancient organisms b Water cycle i Water enters the atmosphere as vapor from the land and transpiration from plants 1 1 Plant transpiration Transpiration of large plant populations like trees in a tropical rainforest can actually alter the rainfall patterns in the area ii Vapor condenses rainfall into rivers streams oceans c Nitrogen cycle i Nitrogen gas is fixed by bacteria in plant root nodules ii Plants assimilate N and incorporate it into organic nitrogen compounds iii Animals assimilate N by ingesting plants iv Animal waste and organic nitrogen compounds are broken down v Nitrogen is not biologically available in the air 1 Pee is a useful type of nitrogen vi Humans upset the nitrogen cycle because different pollution releases a lot of nitrogen into the atmosphere Excessive use of fertilizer turns into runoff and disturbs the cycle vii d Phosphorus cycle 13 Biosphere areas on earth in which organisms are found ALL COMMUNITIES on earth 14 Biomass the organic material in LIVING organisms 15 Ecosphere interactions among Earth s biosphere atmosphere water and land 16 Greenhouse Effect a Humans upset the balance of the Carbon Cycle by i Global Deforestation ii More CO2 released due to burning fuels b Result a 25 increase in global CO2 c Carbon dioxide acts as a heat trap capturing sunlight d Consequence global warming Earth s temperature has increased 1o F more expected e Less agricultural areas shifting north f Diseases such as malaria affecting more people g Ocean levels would increase floods hurricanes 17 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 area a 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 ii Later stages more stable low rate of change Initial stages unstable high rate of replacement 19 Climax community relatively stable community at the end of succession can be hundreds or thousands of years later a In equilibrium with the environment b Permanent until some major change c Varies depending on conditions 20 2 Types of SUCCESSION a 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 mosses grasses shrubs trees Pioneer species ferns ii 2 iii Each stage prepares the way for the next invasion of species iv Pioneer species first inhabitants forms the soil and it thickens 1 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 environment 1 Provides essential NUTRIENTS to all plants 2 Holds WATER and MINERALS 3 Soil is influenced by a Climate b Topography mountains or valleys c Parent material d Time vi Soil characteristics 1 Parent material soil particles of naturally occurring inorganic material 2 Soil texture all soils contain 3 kinds of particles a Sand small rocky material b Silt very fine material small particles c Clay most important it holds nutrients for plants 3 Organic matter humus is decomposing organic matter in the soil 4 Soil pH acid low pH or basic high pH soil influences soil fertility and nutrient availability a Best soil is neutral or slightly acidic pH b Secondary Succession natural forces or human intervention destroy the existing vegetation fire flooding logging agriculture i When the disturbance stops community begins secondary succession back to climax community ii Since soil is already in place secondary succession can take place 5 to 10 times faster than primary succession iii Abiotic factors affect the nature of the plant community 1 Weather 2 Temperature 3 Humidity iv Also plant community affects these abiotic factors 1 For example in the tropical rain forests the vegetation creates the rainfall through plant transpiration 2 When trees are removed rainfall stops and land becomes arid