How to deal with ecological complexity Seek simplicity and mistrust it Alfred North Whitehead Understanding ecological patterns and processes requires both Reductionist approaches seeking mechanisms causal processes And Holistic approaches determining boundaries of the system all that must be included necessary for understanding and predicting outcomes of ecological interactions in the real world Multiple working hypotheses T C Chamberlain 1897 Attempt to falsify each or evaluate relative importance Acknowledge that answers are never certain Attempts at prediction useful postdiction Ecological Forecasting acknowledging uncertainty and context dependency 1 Zoom lens ecology focus in for mechanism zoom out for context and consequences 2 Climate biomes and habitats Landscape of Fear Squirrel lab http judson blogs nytimes com 200 9 09 29 where tasty morsels fearto tread Thanks Aric Newton 3 Land cover change in Glacier National Park 5 4 The Earth s major terrestrial biomes are most clearly separated on a graph of temperature vs precipitation 6 What causes spatial and temporal variation in temperature and moisture Same photon flux spread over larger land surface near poles than at equator Tilt of Earth s axes sets up seasonality of northern and southern hemispheres 7 Adiabatic cooling rising air experiences lower atmospheric pressure expands in volume losing temperature First Law of Thermodynamics work done to expand air parcels comes at expense of heat energy If it cools below dew point air will lose its moisture it condenses as clouds or precipitation Warm air has more moisture holding capacity Law of Conservation of Energy energy can be transferred from one system to another in many forms but can not be created or destroyed 8 These factors set up global moisture patterns Hadley cells Wet tropics around equator Deserts at 30 o N S latitudes Temperate rain forests at 60 o N S latitudes 9 Coriolis effect Earth is a sphere not a cylinder An object at equator is moving east at 24 000 miles per day If it moves north the earth beneath moves more slowly so it veers right If it moves from north towards equator also goes right Reverse is true in southern hemisphere Northeast trade winds pile the Atlantic against Central America Earth rotates west to east Fig in Campbell Antarctic and artic deserts at poles 10 Gulf Stream that warms England was first discovered by Benjamin Franklin Return flow is the Gulf Stream 11 12 Winds displace ocean water off the west coast of North and South America causing upwelling cold nutrient rich water pulled up to replace displaced surface water California summer winds blow from the north curve west creating upwelling along coast enhancing nutrient supply to phytoplankton Winter winds blow from the south curve east favoring downwelling along the coast Mediterranean climate e g California if land warmer than ocean moisture not dropped until adiabatic cooling over mountains summer drought If land cooler than ocean moisture dropped winter rains But coastal fog occurs in summer if air rising from Central Valley pulls moist marine air in over the coast range May intensify if land heats up more than the sea Rain shadow Eastern Sierra upwelling Rich fisheries 13 Lake temperature and mixing regimes water is densest at 4oC winter and summer stratification spring and fall overturn Thermocline stratum of rapid temperature change Can separate oxygenated from hypoxic habitat Water ends up in lakes rivers or ground water 14 Eutrophic river lake estuary nutrient rich likely to produce noxious or harmful algal blooms cyanobacteria toxic dinoflagellates Mesotrophic intermediate nutrient concentrations Oligotrophic low nutrient concentrations very clear water good water quality for humans and fish Mixing replenishes nutrients for algae in photic zone 15 River networks Easier for wind to stir nutrients in shallow basin making such lakes vulnerable to eutrophication 16 Cover or refuges Downstream concentrative fluxes of water sediment solutes detritus and passive organisms Headwaters woody debris forest cover Upstream and upslope dispersive backflows of mobile organisms A 5 km2 Meandering middle reaches clean gravel beds hyporheic under the stream bed habitat undercut rooted bank vegetation off river habitat Systematic downstream increases in discharge solar radiation and changes in sediment size habitat structure and disturbance regimes Confluence nodes pulses of enrichment adjacency of contrasting habitats refuges David Schindler s experimental lakes Lowland floodplain rivers 17 floodplain marshes or forests off channel water bodies 18 Energy carbon sources change downstream Camille McNeely downstream changes in energy sources to grazers Terrestrial detrital carbon e g dead leaves that fall into streams Attached algae Fine particulate detritus and phytoplankton Detritus dead organic matter 19 20 Meandering middle reach mainstems wood bank vegetation clean gravel beds Estuary where rivers empty into oceans fresh water 0 salt meets salt water 3 salt tidal prisms with heavier salty water underneath Important nurseries for offshore fisheries Tidal prism wedge of fresh water overlies denser salt water 21 22 Neritic nearshore subtidal Plankton passive drifters Nekton active swimmers Benthos life on substrate or bed of sea lake spring or rivers and streams zooplankton 23 phytoplankton 24 Pelagic Offshore beyond Continental Shelf Structure Cover Food 25
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