ENVIR ST 360 1st Edition Exam 2 Study Guide Lectures 6 12 Lecture 6 September 25 Communities 3 Part Definition of Community Two or more species living in the same place and interacting A community can be divided spatially through transitions and ecotones and vertical and horizontal structure An Ecotone is a zone where two ecosystems meet that shares characteristics of both Interactions o Direct or indirect o Positive negative or neutral o Often relates to competition Succession Primary Succession Disturbance in which new land is created presence of bare rock Secondary Succession Disturbance in which soil is still present Ecological Debate over Communities Super Organism They are balanced though competitive reaction among species Individualistic View They are unpredictable and a result of random events What determines how communities form Conditions that individual species can tolerate Competition between species for space and resources Random Events Keystone vs Dominate Species Dominant Example Jack Pine Keystone Example Sea Otters Lecture 7 September 30 Dominant vs Keystone Species Dominant species have the most biomass Keystone species have large impacts when removed the system collapses Regulation Top down o Consumers down to autotrophs o 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 up o Autotrophs to consumers o If you add more nutrients to the ecosystem there s typically a positive effect on the whole community Succession and Stability Disturbances are considered a maintaining force they can be cyclical Lecture 8 October 2 Natural Disturbances Animal Disturbances o Typically small scale disturbances that create a little microhabitat Weather Disturbances o Typically larger scale disturbances Idea of Climax Community Disturbances maintain communities but sometimes they occur cyclically which prevents a 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 time Impacts of Disturbances on Society While disturbances may be helpful in maintaining communities they can inflict very negative impacts on human societies Lecture 9 October 7 Disturbance Regime Scale how large Frequency how often Intensity how much energy is released Predictability Generally there should be some predictability to patterns of disturbance but ultimately the disturbances are very unpredictable Responsibility 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 pressures Evolution of Animals to suit Environment Species that belong to different ecosystem typically have adapted traits to better suit themselves for that environment Climate versus Weather Variables for both o Precipitation o Temperature o Humidity o Winds and atmospheric pressure Climate Weather Long Term Short term Regional Location specific Predictable Less predictable 10 day forecast always changing Changes slowly compared to weather Changes quickly Measuring Changes in Climate and Weather Changes in Weather o Digital records o Written records Changes in Climate o Ice Cores o Tree rings Lecture 11 October 14 H I P P O Habitat Loss and Fragmentation o Societies building on habitats o Societies building and affecting natural processes Invasive Non Native Species o 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 invasive o Human impact has escalated the rate distance and frequency of introductions of non native species Pollution o We are a messy species and pollute the environment with really nasty stuff due to our technology Population o Human population is growing o The Earth is not sustainable to support our immense population o Resource consumption is a problem o Economic growth of undeveloped counties will largely elevate resource consumption and pollution Overharvesting o Human ability to drive species into extinction Lecture 12 October 16 Examples of Dominant Species Islands Oak trees grasses Jack Pine Forests Jack Pine Examples of Keystone Species Yellow Stone Wolves Barrier Islands Monarch butterfly responsible for pollinating plants Examples of Primary Succession Hawaiian Island Chain Volcanic eruptions Examples of Secondary Succession Yellowstone Fire Jack Pine Fire Barrier Islands Hurricanes Major Human Impacts Caribbean Coral Reefs Diving Caribbean Coral Reefs Coastal Development Jack Pine Forest Invasive species