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Ecology and the Environmental Sciences 12 November 2015. Physics. Physics Chemistry Astronomy Geology/ Ecology Biology. Question.
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Ecology and the Environmental Sciences12 November 2015 Physics Physics Chemistry Astronomy Geology/Ecology Biology
Question At least one carbon atom in your left arm (e.g., bone) originated from a star in a far away galaxy of the Universe. And at least one carbon atom in your right arm (e.g., bone) originated from a different star in another far away galaxy of the Universe. A. True B. False
Question One of the carbon atoms in your leg bone has a high probability of being “recycled” on Earth in geological history of millions to billions of years from ____. A. dinosaurs B. trees living at the time of dinosaurs C. fossil fuels, including coal, natural gas and oil D. carbon dioxide in the atmosphere E. All of the above
No Matter Where the Ecosystem is … Agricultural Ecosystem Coral Reef Ecosystem
Week 11: Ecology and Environmental Science • A bit of history upon which to chew • Functional unit of ecology: ecosystem • Characteristics of ecological systems • Systems ecology and feedback processes • Environmental science: a few case studies
Brief History of Ecology • 1800’s and before: natural history (observations on nature) • Through the mid-1900’s: challenge of new technologies and environmental problems (e.g., Rachel Carson, harnessing the atom) • Mid-to-late 1900’s: new era in ecology • Emergence of sub-disciplines of ecology (e.g., human ecology, marine ecology) • Interdisciplinarity of ecology: mathematics, physics, chemistry, biology and geology (unique feature of ecology) • 2000 and continuing today … • Interdisciplinary challenges (e.g., changing climate, deforestation, biodiversity, Fukishima) • Diffusion of ecology to the general public (e.g., debates on climate change, water quality, mercury and human health, GMO’s, renewable energies, tropical rain forests, aquifer depletion, pesticide)
Ecological Hierarchies: Why Ecosystems? Earth Biosphere Biome Ecosystem Community Population Organism Hierarchy Theory and Ecology Ecosystem Analogue: Physics and Chemistry: atom Biology: cell (coming soon to a lecture near you!)
Ecosystems as “the” Functional Unit • Central role of energy • Central role of cycling of elements and materials • Hierarchy theory • Species have niches • Cybernetics at play in ecosystems
Ecosystems • Ecological systems - ecosystem • Components • Biotic components • All living organisms - plants, animals and microbes • The “ecological community” • Abiotic components • All non-living components - soil, atmosphere, water, climate, nutrients, etc. • Ecosystem • Scientific understanding and research • Unit of study and organization
Structure of Ecosystems: Energy • Structure underpinned by flow of energy • Autotrophs: fix energy (C-C) from sunlight (i.e., plants; 1st Law of Thermodynamics) • Heterotrophs: consume energy in C-C bonds (2ndLaw of Thermodynamics) • Herbivores • Carnivores • Omnivores (combination of the above) • Decomposers (dead organic matter) • All organisms classified by their source of energy • Humans = __________. • Eagles = _________. • Corn plants = _______. • Microbes in a decomposing log = ___.
Trophic Levels of an Ecosystem and Energy Rule of 10 10% 10% 10%
The Physics of Energy (Joules) Flow in Ecosystems Where does energy/J go?
Keys to Ecosystem’s Energy • Energy flows through ecosystems unidirectionally • First law of thermodynamics (physics again!) • As energy flows, amount of energy available to do work always decreases (90%) • Only 10% goes to the next higher trophic level (Rule of 10) • 90% as heat energy • Second law of thermodynamics (physics … again) • Flow of energy limits the number of organisms in higher trophic levels • Predatory fishes (sharks) • Predatory birds (owls, hawks and eagles) • Predatory mammals (African Serengeti)
Energy Flow and Nutrient/Element Cycling Heat Heat 10% Herbivores/Carnivores Sun Autotrophs 10% 10% Flow of Energy Soil, air and water Decomposers “Cycling” of Nutrients/ Elements Heat
Ecosystems as the Functional Unit Hierarchies in ecology Role of energy Cycling of elements and materials Hierarchy theory Species have niches Cybernetics at play in ecosystems
Cycling of Materials and Elements in Ecosystems: Track a Carbon Atom Carbon atom in your arm came from where?
Simple Ecosystem Model - Cycling of Elements (e.g., C) and Materials • Attributes of model • Biotic component • Abiotic components • Fluxes between spheres/reservoirs • Cycle (contrast with energy) • Example: carbon atom • Star to atmosphere to dinosaur to fossil fuel to atmosphere to corn plant to your femur and then back to atmosphere Energy Element & Material
Standard Ecosystem Model of Cycling in Ecosystems Keys Reservoirs Fluxes Cycling Linkage among all reservoirs Atmosphere Biosphere Hydrosphere Geosphere Others: Water & Mercury
Attributes of Ecosystems • Ecosystems comprised of both biotic and abiotic components • Communities: collection of all plants, animals and microbes • Energy flows through ecosystems in one direction • Materials cycle through ecosystems • Every species has a unique ecological niche • Ecosystems operate as cybernetic systems, being controlled by feedback processes • Change in ecosystems: the norm (succession)
Geographical “Footprint” of American Beech Tree and Black Bear
Geographical Footprint of the Cultivated Grape • Footprint: function of species niche • Every species: unique niche
Niche in Ecology Wetland Habitat • Physical (e.g., temperature and water) and biological (e.g., pest) factors control the distribution of species • Each species: unique in the set of factors that affect its “place” in an habitat (physical and biological factors) • Example: lizard in the desert • Example: oak tree in forest Forest Habitat
Niche in Ecology Every species’ niche is unique
Niche of the Sandpiper • Niche factors • Abiotic Factors 1. 2. • Biotic factors 1. 2.
Attributes of Ecosystems • Ecosystems comprised of both biotic and abiotic components • Communities: collection of all plants, animals and microbes • Energy flows through ecosystems in one direction • Materials cycle through ecosystems • Every species has an ecological niche • Ecosystems operate as cybernetic systems, controlled by feedback processes • Change in ecosystems: the norm not the exception (succession) (this requires a re-thinking of ecology)
Change in Ecosystems: the Norm • Disturbances are common (natural and anthropogenic) • Fire • Hurricanes • Floods • Ice ages • Grazing animals • Invasive species • Deforestation • Weather and climate Ecological Succession and Feedback Processes
Ecology and the Environmental Science • A bit of history upon which to chew • Functional unit of ecology: ecosystem • Characteristics of ecological systems • Systems ecology and feedback process • Environmental science: few case studies
Cybernetics of Ecological Systems Feedbacks (+ and -), and cybernetics Examples Succession Climate change and temperature on Earth’s surface Positive Feedback Control Center/ Sensor Set Point Effector Negative Feedback Cybernetic Systems: Ecosystems Cybernetics of Human Body • Feedbacks (+ and -), homeostasis and cybernetics • Examples • Thermostat • Body temperature
Cybernetics in Ecology: an Example Using Ecological Succession
Question The mix biotic and abiotic factors that determine the survival of species and its geographical distribution is called its ___. A. ecological habitat B. trophic level C. ecosystem requirements D. ecological niche E. community
Question In a typical ecosystem the percentage of energy in a plant trophic level passed onto the next trophic level (i.e., herbivores) is ___ %. A. 10 B. 20 C. 50 D. 75 E. 90
Question Which of the following trophic levels has the largest store of energy as Joules? A. Autotrophs/plants B. Herbivores C. Carnivores D. Omnivores E. Decomposers
Ecology and the Environmental Science • A bit of history upon which to chew • Functional unit of ecology: ecosystem • Characteristics of ecological systems • Systems ecology and feedback process • Environmental science: few case studies
Case Studies • Ozone and UV-B in the atmosphere (text) • Acid rain (text) • Climate change and greenhouse gases (text and lecture) • Landfills and recycling (text) • Over-harvesting of marine fisheries • Biodiversity or loss of species • Mercury in the environment (lecture) • Endocrine disruptors (lecture) • Invasive species (text)
Climate Change • First principles: radiatively-active greenhouse gases (you know this) • Retrospective analysis: what is it and what do the data suggest? • Prospective analysis: what is it (forward looking) and why use models?
Radiative Properties In absence of radiatively-active trace gases in atmosphere, temperature would be 25 F degrees colder!!!
Trace Gases in the Atmosphere • Carbon dioxide or CO2 • Source: fossil fuel combustion (C-C to CO2) • Methane or CH4 • Sources: rice patty agriculture and cattle • Radiatively active (meaning?)
Based on first principles of physics and chemistry (you know this too!), YOU would predict that as CO2 in the atmosphere increases ~30% over five decades, temperature in the atmosphere would do which of the following: decrease, increase or remain unchanged?
Retrospective Correlation: CO2 and Temperature First principles (couple slides ago) and now some experimental data
Retrospective Sea Level Change 1850 1900 1950 2000
Climate Change • First principles of radiatively-active greenhouse gases • Retrospective analysis: what is it and what do the data suggest? • Prospective analysis: what is it (forward looking) and why use models? • Example: weather models
Case Studies • Ozone and UV-B in the atmosphere (text) • Acid rain (text) • Climate change and greenhouse gases (text and lecture) • Landfills and recycling (text) • Over-harvesting of marine fisheries • Biodiversity or loss of species • Mercury in the environment (lecture) • Endocrine disruptors (lecture) • Invasive species (text)
Mercury (Hg) in the Environment • Mercury as an element (elemental Hg - naturally occurring) • Mercury in the environment (methyl-Hg) • First principles: Hg cycles in ecosystems • Methyl-Hg: uneven distribution in the environment - preference for higher trophic levels • predatory birds (e.g., eagles) • carnivorous fish (e.g., tuna) • predatory cats (e.g., panther) • humans