Introduction to Ecology Lecture Notes

Chapter 1: Introduction to Ecology Ecology – branch of science dedicated to the study of relationships b/n organisms and the environment; understanding how organisms interact with each other and their environment -interdisciplinary science; ecologists needing to know other fields to perform studies (in field or even in lab) -ecologist = someone that applies scientific approach to understanding relationships between organisms + environment/ the mechanisms causing patterns that occur in natural world Overview of Ecology -subdisciplines of ecology = physiological and behavioural ecology Physiological ecology – centers on the morphological and physiological mechanisms organisms use to gether energy and cope with biotic and abiotic stressors Behavioural ecology – study the determinants of individual behaviour and how that can influence interactions among individuals and the environment -strong link b/n studies of indv and populations Population ecology – factors influencing population structure and dynamics; biotic + abiotic components of the environ. Community ecology – interactions such as predation, parasitism, mutualism, and competition and its effect on the species involved Ecosystem ecology – biological, chemical and physical processes and interactions that occur within a location (eg. Nutrient + energy flow) Landscape ecology – study of exchanges among other ecosystems and communities (macroecology – regions subjected to large-scale and long term region processes) Biosphere – largest spatial scale and highest level of ecological organization (global ecology) The Ecology of Forest Birds: Old Tools and New -Robert MacArthur study of birds -study five species of warblers which are approx. same size and shape -similar roles but co-existed? -five warbler species fed in different zones in spruce trees, so even though you live in same forest, extract food from different parts of it (reduces competition) -Norris research on migratory birds -studies show that field studies used to address ecological questions concerning species and their interactions with environ -some ecologists adopt the experimental approach when humans play a major factor in affecting the way animals live Ecosystem Controls: Using Large-Scale Experiments to Understand Ecosystems -eutrophication – process whereby clear lakes turn pea-green (nutrient rich lakes which promote algal growth) -common problem to lakes but the source of these nutrients was unknown; couldn’t do lab analysis so research began by putting in nutrients in different combinations to different lakes  response was measured -Schindler: phosphorus nutrient responsible for eutrophication HOW? Experiment : split lake in half adding nitrogen and carbon to one side and nitrogen carbon and phosphorus to the other =P addition caused dramatic shift in ecosystem -P sources coming from washing dishes -detergents containing phosphorus banned from many places nowadays Other scientists have been trying to solve this problem -why this one successful where others failed? -mechanism for eutrophication = ability of microflora and fauna to shift in species composition as nutrient levels increase  couldn’t really be done using beakers -exchange of nitrogen and carbon with the atmosphere in natural ecosystem but not in lab (algal growth in water would be limited by carbon as there’s no CO2 exchange in the lab) Change: Using Information About the Organism to Describe and Predict Temporal and Spatial Changes in Species Distribution -Margaret Davis: sample of lake sediments for pollen in Appalachian Mountains -pollen help document changes near the lake during past several thousand years -some pollen produced by nearby plants fall on lake surface  trapped in sediments  preserved + forms historical record of kind of plants that lived -lakeside vegetation changes  mix of pollen preserved changes Eg. Found spruce, then beech then chestnut mixture -pollen can be used to construct paleoecological record Trevor Platt: determining factors that control variation in marine primary productivity -understanding growth of phytoplankton -used knowledge of plankton bio to develop number of methods by which organisms could be sampled remotely -eg. Spectral reflectance patterns from satellite imagery -helps in understanding how marine systems change in response to shifting climates and how primary production can influence success/ failure of marine fisheries Marie Josee Fortin: expanding statistical tols available to ecologists -ecotones – transitions from one type of ecosystem to another (agriculture  surrounding forest) -these increases exponentially as humans fragment the enviro -measure location of transition zones measure if location changes over time -different quantitative tools needed to address different ecological questions The Scope of Ecology -ecologists = scientists answering complex questions in natural and manages systems (make predictions) -more quantitative discipline of biology Chapter 2: Life on Land -natural history = study of how organisms in particular area influenced by factors (abiotic) -Janzen: restoration success of tropical dry forest -guanacaste tree (Enterolobium cyclocarpum); produces a lot of fruit to promote seed dispersal by animals -no native animals of the size and behaviour to make them dependable dispersers -dispersers became extinct 10 000 years ago but Europeans introduced cattle/horses 500 years ago which were good dispersers -introduced horses into enviro Life on Land and Terrestrial Biomes -biomes – divisions of terrestrial environment; distinguished by commonly observed plant species and associated climate (diff. natural history) 2.1: Large-Scale Patterns of Climatic Variation -latitudinal variation in climate from uneven heating of earth’s surface by sun + tilt of earth -middle and high latitudes = lower average temperatures and more seasonal than near equator Temperature, Precipitation, Atmospheric Circulation -sun’s ray most concentrated where sun is directly overhead -sun directly overhead tropic of Cancer (July 21) -sun directly overhead tropic of Capricorn (December 21) -at the tropics, winters with low average temperatures and shorter days, summers longer day hours -between tropics, seasonal variation in temperature/ day length = slight -heating influences precipitation patterns as it drives circulation of atmosphere -warm moist air cools as it rises, creating clouds  produce heavy rainfall associated with tropical environments -equatorial air mass stops to rise and spreads north / south -dry air and as it moves away from equator gets cooler  more dense (sinks at about 30 degrees latitude and spreads north + south  draws moisture from the lands creating deserts (Hadley Cell) -Three atmospheric cells on either side of equator: -Hadley -Ferrel – mid-latitude; where subtropical + polar air masses meet creating abundant precipitation of temperate regions -Polar – 60 degree latitude; cooling at the poles N ortheast/Southeast trades – observing winds that blow from the northeast in North Hemisphere and southeast from the Southern Hemisphere Westerlies –observing winds at 30 and 60 latitude which blows mainly to the west Easterlies – observing winds at higher than 60 latitude which blow easterly Coriolis effect – effect whereby prevailing winds do not move in a straight north-south direction Climate Diagrams -tool to explore the relationship between the distribution of terrestrial vegetation and climate -summarize seasonal variation in temperature and precipitation, length and intensity of wet and dry seasons and portion of year when temp below 0. -in general, adequate moisture for plant growth = precipitation line lies above the temperature line -when precipitation line goes beneath the temperature line; region of space is gold shaded -darker blue shading = shift in scale -mean annual temperature in upper left corner and mean annual precipitation in upper right corner 2.2 Soil: Foundation of Terrestrial Biomes -soil structure results from long-term interaction of climate, organisms, topography and parent mineral material -soil = complex mixture of living and non-living material upon which most terrestrial life depends -surface of soil = majority of organic matter (O horizon or LFH horizon) -O horizon found in soils which plant material primarily aquatic in nature -LFH horizon generally found in more upland sites -organic litter at the surface; deeper portions of organic horizon contain highly fragmented and partially decomposed organic matter -small organic horizons in areas with little litter deposition (deserts/farmland) or high decomposition rates (tropical rainforest) -deep horizons found in areas with a lot of litter inputs/ low decomposition rates (bogs/ fens) A horizon – mixture of mineral materials derived from organic horizon above; supports a lot of biological activity, rich in mineral nutrients that are essential for plant growth; rainfall = leaching of minerals into B horizon B horizon – materials leached from A horizon C horizon – consists of weathered parent material which has been broken down though frost, water, microbial activity/ penetrating roots; production of sand, silt, clay, rock fragments; underneath = bedrock Root exudates – secreted by plants which serve as substrates for bacterial, fungal and animal species which allow for development and maintenance of complex canals of airspaces within soil from growth and development of organisms -climate affects composition of soil 2.3 Natural History and Geography of Biomes -geographic distribution of terrestrial biomes corresponds to variation in climate -dividing world into biomes = subjective process as they are not distinctive -change gradually along environmental gradients