生态学中的环境因子精品文稿.ppt

生态学中的环境因子第1页，本讲稿共40页Biotic:organisms.Organisms compete with,parasitize,eat or are eaten by and change the environment for other organisms.第2页，本讲稿共40页Ecology explores a wide range of questions about what factors control the distribution,abundance and behavior of organisms.For example,Red Kangaroos occur primarily in the Australian interior in semiarid regions.第3页，本讲稿共40页Distribution of Kangaroos suggests an abiotic factor(precipitation)influences it,but perhaps populations also influenced indirectly by biotic factors such as competitors,predators,food availability and parasites.Ecologists have to consider multiple factors to explain patterns of abundance and distribution.第4页，本讲稿共40页第5页，本讲稿共40页Ecology has many subfields of study ranging from ecology of individual organisms to dynamics of landscapesOrganismal EcologyPopulation EcologyCommunity EcologyEcosystem EcologyLandscape EcologyWe will explore these sequentially第6页，本讲稿共40页第7页，本讲稿共40页Distribution of species Biogeography:study of the broad patterns of distribution of organisms across the globe.Patterns strongly influenced by historical factors such as continental drift(see chapter 26)and barriers including mountain ranges and seas.第8页，本讲稿共40页第9页，本讲稿共40页For example,Australia populated by marsupial mammals(e.g.kangaroos,wombats,koalas)because placental mammals did not colonize it before it separated from other landmasses.Tapirs found only in southeast Asia and South America.Ancestral populations separated when land masses diverged.第10页，本讲稿共40页Role of dispersal in distributionAbility to cross barriers affects distribution.Thus,species of birds often more widely distributed than mammals.第11页，本讲稿共40页However,inability to reach an area not only factor that limits distribution.Ability to survive in new area is critical.To survive and thrive species must be able to cope with both biotic and abiotic factors.第12页，本讲稿共40页Biotic factorsThe presence of competitors or predators may limit an organisms ability to establish itself.For example,algae are eaten by sea urchins and limpets,which limits the ability of seaweeds to establish themselves on rocks第13页，本讲稿共40页第14页，本讲稿共40页Biotic factorsConversely,absence of predators and competitors has allowed many organisms introduced into new areas to increase so much they become pests.E.g.Japanese beetles(from Asia),zebra mussels and purple loosestrife from Europe)(Melaleuca(Eucalyptus trees from Australia)and many other invasive species have spread widely in the U.S.第15页，本讲稿共40页Abiotic factorsThe major factor affecting distribution of terrestrial organisms is climate,which incorporates temperature,sunlight,wind and precipitation.第16页，本讲稿共40页Abiotic factorsClimate is determined by global factors such as inputs of solar energy and the movement of the earth through space.Study discussion of climate patterns pages 1088 and 1089第17页，本讲稿共40页第18页，本讲稿共40页第19页，本讲稿共40页ClimateLocal factors such as the presence of mountains and large bodies of water also affect climate.Mountains force up moist air moving across them.As the air cools the water condenses and falls as rain.The result is that one side of the mountain range is wet and the other side is drier(and perhaps a desert e.g.Mojave and Gobi Deserts.)第20页，本讲稿共40页第21页，本讲稿共40页ClimateLarge bodies of water moderate climate.Land heats faster than water and warm air rises.Cooler air over water moves in and replaces the warm air.The warm air that was over land cools at high altitude and sinks over water.Results is steady flow of cool air over land.第22页，本讲稿共40页第23页，本讲稿共40页Terrestrial BiomesBiomes are major types of ecosystems that cover large areas of the earth and are classified by their dominant vegetation types.(an ecosystem is the community of organisms in an area and their physical environment)第24页，本讲稿共40页Each biome also is populated by a diverse array of animals,fungi and microorganisms adapted to that environment.第25页，本讲稿共40页Major terrestrial biomes includeTropical forestDesertTemperate GrasslandSavannaTemperate broadleaf forestConiferous forest(Taiga)Tundra(see descriptions pages 1100-1104)第26页，本讲稿共40页Savannah第27页，本讲稿共40页Terrestrial biomesTerrestrial biomes often vertically stratified.Layers defined by different size plants(e.g.in forests there is an upper canopy of tall trees,low tree layer,shrub layer,ground layer of herbaceous plants,litter layer and root zone).第28页，本讲稿共40页Stratification provides multiple different habitats for animals which occupy specialized feeding niches.第29页，本讲稿共40页Convergent evolutionActual species in a biome differ from one area to another but they possess similar adaptations.This is convergent evolution(development of same evolutionary solutions to ecological problems)第30页，本讲稿共40页Convergent evolutionFor example vegetation in all deserts worldwide characterized by extensive root systems,long-term water storage capability,thick waxy coverings to reduce water loss,and extremely small(if any)leaves第31页，本讲稿共40页Biomes often maintained by disturbance.Wildfires are an essential factor in maintaining many biomes(e.g.grasslands,savannahs,some coniferous forests).Fire favors trees such as longleaf pine whose bark resists fire and grasses,which recover quickly after burning.第32页，本讲稿共40页Aquatic biomesAquatic biomes less influenced by climate than terrestrial biomesWhy?第33页，本讲稿共40页Aquatic biomesWater is more thermally stable.It takes a lot of heat to change the temperature of a body of water.第34页，本讲稿共40页Major aquatic biomesLakesRiversEstuariesIntertidal zoneMarine pelagic zoneCoral reefsMarine benthic zone(benthic zone is sea/lakefloor)See pages 1094-1097.第35页，本讲稿共40页Aquatic biomes often stratified by light and temperature.Light intensity decreases with depth.Upper(photic)zone supports photosynthesis.In ocean photic zone narrow but contains most organisms.第36页，本讲稿共40页第37页，本讲稿共40页Aphotic zone sparsely populated.Benthic zone(bottom)organisms often depend on rain of dead organic matter(detritus)from above.第38页，本讲稿共40页Thermal stratification of lakesIn temperate areas lakes are thermally stratified in summer and winter.Water densest at 4C so water at this temperature sinks through colder or warmer water.Thus,in spring and fall all water in lake mixes which redistributes nutrients throughout the lake.第39页，本讲稿共40页第40页，本讲稿共40页