ENVIR ST 360 1st EditionExam # 2 Study Guide Lectures: 6-12Lecture 6 (September 25)Communities3 Part Definition of Community: Two or more species living in the same place and interactingA community can be divided spatially through transitions and ecotones and vertical and horizontal structureAn Ecotone is a zone where two ecosystems meet that shares characteristics of bothInteractions …o Direct or indirecto Positive, negative or neutral o Often relates to competitionSuccessionPrimary Succession: Disturbance in which new land is created (presence of bare rock)Secondary Succession: Disturbance in which soil is still presentEcological Debate over CommunitiesSuper-Organism: They are balanced though competitive reaction among speciesIndividualistic View: They are unpredictable and a result of random eventsWhat determines how communities form…Conditions that individual species can tolerateCompetition between species for space and resourcesRandom EventsKeystone vs Dominate Species Dominant Example: Jack Pine Keystone Example: Sea OttersLecture 7 (September 30)Dominant vs Keystone Species Dominant species have the most biomass Keystone species have large impacts (when removed the system collapses)RegulationTop downo Consumers down to autotrophso If you remove an apex predator, there will be typically be negative effects that cascade down the system. (Herbivores will increase and overgraze which eventually limits the herbivores in turn)Bottom upo Autotrophs to consumerso If you add more nutrients to the ecosystem, there’s typically a positive effect onthe whole communitySuccession and StabilityDisturbances are considered a maintaining force; they can be cyclical Lecture 8 (October 2)Natural Disturbances Animal Disturbanceso Typically small scale disturbances that create a little microhabitat Weather Disturbanceso Typically larger scale disturbancesIdea of Climax Community Disturbances maintain communities, but sometimes they occur cyclically which preventsa community from reaching what one would image to be its climax Sometimes the climax community can be considered the community of which the disturbances maintain over timeImpacts of Disturbances on Society While disturbances may be helpful in maintaining communities, they can inflict very negative impacts on human societiesLecture 9 (October 7)Disturbance Regime Scale: how large Frequency: how often Intensity: how much energy is releasedPredictability Generally there should be some predictability to patterns of disturbance, but ultimately the disturbances are very unpredictableResponsibility Responsibility can belong to property owners, insurance agencies or the government Typically the government is held responsible for disaster response Countries that lack resources and infrastructure often receive aid from worldwide agencies Lecture 10 (October 9)Temperature and Precipitation in Ecosystems Grassland: 40 inch average annual rainfall / 75 degree average annual temperature Tropical Rainforest: 130 inch average annual rainfall / 75 degree average annual temperature Tundra: 20 inch average annual rainfall / 14 degree average annual temperature Temperature and Precipitation are huge selection pressuresEvolution of Animals to suit Environment Species that belong to different ecosystem typically have adapted traits to better suit themselves for that environmentClimate versus Weather Variables (for both)o Precipitationo Temperatureo Humidityo Winds and atmospheric pressureClimate WeatherLong Term Short termRegional Location specific Predictable Less predictable (10 day forecast always changing)Changes slowly (compared to weather) Changes quicklyMeasuring Changes in Climate and Weather Changes in Weathero Digital recordso Written records Changes in Climateo Ice Coreso Tree ringsLecture 11 (October 14)H.I.P.P.O. Habitat Loss and Fragmentationo Societies building on habitatso Societies building and affecting natural processes Invasive / Non-Native Specieso Typically the arrival of non-native species is not problematic; however, under the right conditions, a foreign species could thrive in the new environment and become invasiveo Human impact has escalated the rate, distance and frequency of introductions of non-native species Pollutiono We are a messy species and pollute the environment with really nasty stuff due to our technology Populationo Human population is growingo The Earth is not sustainable to support our immense populationo Resource consumption is a problemo Economic growth of undeveloped counties will largely elevate resource consumption and pollution Overharvestingo Human ability to drive species into extinctionLecture 12 (October 16)Examples of Dominant Species: Islands: Oak trees, grasses Jack Pine Forests: Jack PineExamples of Keystone Species: Yellow Stone: Wolves Barrier Islands: Monarch butterfly (responsible for pollinating plants)Examples of Primary Succession: Hawaiian Island Chain: Volcanic eruptionsExamples of Secondary Succession: Yellowstone: Fire Jack Pine: Fire Barrier Islands: HurricanesMajor Human Impacts Caribbean Coral Reefs: Diving Caribbean Coral Reefs: Coastal Development Jack Pine Forest: Invasive
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