1 2 Climate and Biodiversity Chapter 5 Question * What is the difference between weather & climate? * Is it possible for an area to have a climate different from the rest of the region it is in? 3 Many Different Climates Weather is an area s short-term temperature and other physical conditions of the lower atmosphere Climate is an area s general pattern of atmospheric conditions over long periods of time Climate is determined by: Average temperature Average precipitation However latitude and elevation, air & water movement determine average temperature and precipitation Cities and mountain areas can have their own microclimates. 4 5 What Factors Influence Climate? An area s climate is determined by: solar radiation the earth s rotation global patterns of air and water movement gases in the atmosphere the earth s surface features * Uneven Warming * The angle at which the sun s rays strike Earth. * Tropics- right angle, rays travel shorter distance * mid-latitude and polar regions- oblique angle * The variation in the amount of surface area over which the sun s rays are distributed. * Tropics receive more solar energy per square meter than mid-latitude and polar regions. 1
* Tropics receive more solar energy per square meter than mid-latitude and polar regions. * Some areas of Earth reflect more solar energy than others * Earth s albedo about 30%, Clouds 90%, Ice 90% 6 7 8 9 * Earth s Tilt & Seasons * Earth s tilt is 23.5 * Sun s rays strike the equator directly twice a year; March and September equinox * Earth is closest to the sun in winter! * This is of course for the Northern hemisphere. * Elliptical orbit (accounts for closeness) * Tilting into or away from sun determines season Question * What causes wind? Global Air Circulation * Four factors determine how air circulates and helps distribute heat and moisture. * Uneven heating of earth s surface * Rotation of the earth- tilted axis * Variations in properties of air, water, and land * Water- lends moisture to air, warm air holds more vapor * Land- vegetation adds moisture & cools by removing CO 2 * Air- convection currents; hot air rises cool air sinks * Ocean & Wind currents redistribute heat Winds Winds play a major role in the redistribution of heat. Prevailing winds are generated by the rotation of Earth deflecting the wind off to the East or West. Equator spins faster than polar regions Any deflection due to rotation is called the Coriolis effect. Produce ocean currents 10 11 Convection Cells 2
Convection: heat rises; cold sinks 6 giant convection cells caused by: Air convection (circulation) Prevailing winds Mixture of continents & oceans Called Hadley Cells & Polar Cells 12 13 Effects of Pressure on Heating & Cooling * Adiabatic cooling is when the rising air meets the lower pressure of higher altitudes; as a result it expands and cools. * Hot air rises and when it expands it cools. * Adiabatic heating is when the cool air sinks due to convection; encountering higher pressure of low altitudes. As a result it shrinks and gets hotter. * Cool air sinks and when it shrinks it warms. Animation: Air Circulation and Climate 14 15 Adiabatic Heating & Cooling * Wind Motion: * Move from high pressure to low pressure * Coriolis Effect * Rotation * 30 latitudes have high pressure * Due to sinking air that cooled off as it moved away from the Equator * The Equator has low pressure b/c all of the warm air is rising and moving away. * 60 latitudes have low pressure, but colder. 16 17 Question * What do you remember about density? Global Ocean Currents 3
* Affects regional climates * Near water climate is more constant * Due to the specific heat of water * Warm and cold currents created by differences in water density * Thermohaline circulation responsible for mixing surface and deep water due to high salt concentration. * Altered by earth s rotation and continents (block) * Redistributes heat, mixes ocean waters, and distributes nutrients and oxygen 18 19 20 21 22 Question * Has anyone here ever heard of the term El Niño? * If so, what is usually mentioned along with it? Animation: El Nino Southern Oscillation * Animation: Upwelling Along Western Coasts El Niño * Normally trade winds blow water in the South Pacific West, but when the trade winds weaken (or even reverse direction) El Niño occurs. * During an El Nino year, there is no upwelling to replace warm westward moving water w/ cool water. Instead, the warm water stays blows East inland and levels out. * Fish that depended on upwelling nutrients die. * So now instead of dry air & cool nutrient rich water off the coast of South America there is warm water and moist air= storms & flooding. * Causes a flip in atmospheric conditions over the globe. 23 24 La Niña * An abnormal cooling effect, more or less the opposite of El Niño and often follows an El Niño year. 4
* An abnormal cooling effect, more or less the opposite of El Niño and often follows an El Niño year. * Trade winds are stronger than usual, causing more than the usual amount of warm water to move away from the Americas toward the East. * Causes a larger than normal upwelling of cool water contributing to the cooling effect on the waters and surrounding areas. * And wetter than normal conditions towards the East coast of continents. 25 Greenhouse Gases * Warm the lower atmosphere * Global warming may cause changes in the climate in various places * Different types of matter have varying abilities to trap heat. Just as water does, so do gases of different types. Major Greenhouse Gases: * CO 2, methane, nitrous oxide, water vapor Effects of Global Warming: * Alter precipitation patterns, sea levels, and crop growing areas 26 27 28 1 Biodiversity through Biomes Biomes are large terrestrial regions characterized by similar climate, soil, plants, and animals Average temperature and precipitation (climate) determine the biome Climate & vegetation vary with latitude and elevation Biomes consist of a mosaic of patches of communities Not uniform b/c resources are not uniformly distributed; human activities Types of Biomes Classify by Temperature 5
2 3 4 Classify by Temperature * Tropical (hot) * Temperate (moderate) * Polar (cold) Classify by Kind * Deserts * Grasslands * Forests 29 30 31 32 33 34 Animation: Soil Profile Importance of Mountains * Contain majority of the world s forests * Regulate climate * Reflecting solar radiation * Key in the hydrological cycle * they are storehouses of water * Snow & ice melts replenish streams * Water for human consumption Deserts are Fragile * Soils take many decades to recover from disturbances (e.g. vehicles) * Slow plant growth * Low species diversity * Slow nutrient cycling (low bacterial activity) * Lack of water Grasslands * Grassland biomes can be found in the middle latitudes, in the interiors of continents. * In grasslands, seasonal droughts and large herbivores keep large numbers of shrubs and trees from growing. 6
large numbers of shrubs and trees from growing. * Grasses can survive fires because they grow from the bottom instead of the top and have extensive root systems. * The lower horizons of soil tend to be dry, because the grasses absorb all of the moisture making it more difficult for trees to grow. * Erratic precipitation and windy conditions 35 36 37 Growth in the Grassland * There are two real seasons: * growing season- no frost; lasts from 100-175 days * dormant season- nothing can grow too cold * In tropical and subtropical grasslands the length of the growing season is determined by how long the rainy season lasts. * But in temperate grasslands the length of the growing season is determined by temperature. * The amount of rainfall is very important in determining which areas are grasslands because it s hard for trees to compete with grasses in places where the upper layers of soil are moist during part of the year but where deeper layers of soil are always dry. Loss of a Grassland Temperate: Erosion due to monoculture Salinization of soil; irrigation Loss of soil fertility; due to removal of plant residues Loss of soil fertility due to land overuse. Tundra Global warming causing melting of permafrost & subsidence (sinking of land) 14% CO 2 in permafrost; melting is releasing that CO 2 What Are the Major Types of Aquatic Systems? * There are two types of aquatic life zones: marine & freshwater. * Saltwater (marine) and freshwater aquatic life zones cover almost three-fourths of the earth s surface(71%) with oceans 7
* Saltwater (marine) and freshwater aquatic life zones cover almost three-fourths of the earth s surface(71%) with oceans dominating the planet. * Most aquatic organisms live in the surface, middle, or bottom layers of saltwater and freshwater systems. * Since water is slower to heat and cool than air, temperatures in aquatic biomes fluctuate less than in terrestrial biomes. 38 39 40 41 Distribution of Aquatic Organisms * Organisms occupy surface, middle, or bottom layers * Factors determining types and numbers of organisms * Temperature * Access to sunlight * Dissolved oxygen * Nutrient availability Types of Aquatic Life * Plankton phytoplankton, zooplankton * Free floating weakly swimming * Nekton- fish, turtles, whales * Strong swimming consumers * Benthos- oysters, worms, crabs * Bottom dwellers; burrow, anchor, or walk about * Decomposers- mostly bacteria Stratification of the Ocean * Coastal zone- shallow, warm, nutrient rich * Ends at edge of continental shelf * Wetlands, mangrove forests, coral reefs * Open ocean- past the coastal zone; also divided * Nutrients in short supply * However, upwellings bring nutrients up for producers * Ocean bottom- bottoms of deep ocean * Feed on dead phyto & zooplankton that drift down * Organisms here reproduce slowly 8
* Organisms here reproduce slowly 42 43 44 45 46 Open Ocean * Euphotic zone- upper layer; photosynthesis * Depth of this zone can be reduced by excessive algal growth * Nutrients low, but dissolved oxygen levels are high * Large predatory fast swimming fish live here * Bathyal zone- dim; no producers; smaller fish & zooplankton live here; but migrate up to feed. * Abyssal zone- extends to ocean floor * dark, cold, little oxygen, still lots of life * Marine snow (dead organisms) drift down as food Animation: Ocean Provinces * Hydrothermal Vents * At convergent and divergent plate boundaries * Hydrothermal vents are cracks in the ocean floor that spew hot water * Heat comes from magma underneath * Rapid temp change causes minerals to precipitate out * Sulfides, barium, calcium, etc. * Chimneys: Black & White * The cooling minerals form chimneys around these jets. * Vents become inactive when away from rising magma. * Chemosynthetic bacteria in these vents get energy from the chemical bonds of hydrogen sulfide. * precipitated by the action of the vents * Vent Communities * These chemosynthetic bacteria have symbiotic relationships with mussels, clams, and tubeworms. * some of which have reduced digestive ability * gain energy from these bacteria * Secondary consumers are drawn to these locations to feed on these organisms. 9
47 1 2 on these organisms. * When vents become inactive, scavengers come to reap the benefits. Effects of Human Activity CAUSE * Coastal development * Overfishing * Runoff of nonpoint source pollution * Point source pollution * Invasive species * Climate Change 48 3 4 EFFECTS/Examples * Habitat destruction, erosion * Depletes population and habitat destruction w/ drag weighted nets * Wastes, fertilizer, eroded soil * Oil spills & cruise ship wastes * Outcompete or consume native species; lionfish * Destroy coral reefs, increase acidity, raise ocean temps, flood marshes Freshwater Systems * Standing water * Flowing water * Dissolved oxygen content affects the amount of wildlife living in that aquatic zone. * Water temperature: gases stay dissolved at lower temperatures * Amount/rate of decomposition in that aquatic zone * Water movement * Ecological Services: * Moderate Climate, flood control, waste treatment, nutrient cycling, provide habitats, recharge ground water, resources * Economic Services: * Food, drinking water, irrigation water, hydroelectricity, transportation corridors, recreation, employment 10
* Food, drinking water, irrigation water, hydroelectricity, transportation corridors, recreation, employment 49 50 51 Lakes * Lakes are depressions in the earth s surface that are filled with freshwater. * Depression in the earth s surface come from: * Glaciation- Great Lakes * Crustal displacement- Lake Nyasa in East Africa * Volcanic activity- Crater Lake in Oregon * Freshwater comes from: * Mountain glacier melts & stream runoff, surface runoff, precipitation, ground water seepage. Four Lake Zones * Littoral zone- the top layer near shore, high diversity * Ample sunlight and nutrient input from surrounding land. * Limnetic zone-open away from shore, depth of light, main photosynthetic body of the lake * Produces the food & oxygen that supports consumers * Profundal zone- deep, no photosynthesis, DO is low * Cooler temperature * Benthic zone- nourished mainly by dead matter that falls from upper levels & sediment wash * Decomposers, detritus feeders, nomadic fish Nutrient Content of Lakes Lakes classified by nutrient content and primary productivity * Oligotrophic- are often deep w/ small supply of plant nutrients. Supplied by glaciers & mountain streams. * Clear water & low NPP. * Light penetrates to the bottom; deep limnetic zone * Eutrophic- are well nourished often shallow, water has poor visibility; high NPP. * These lakes become O 2 depleted due to high bacterial activity in decomposition of large amounts of dead phytoplankton 11
phytoplankton * Mesotrophic Lakes impacted by nutrients from human activity * Cultural eutrophication- sewage, fertilizers, farms, feedlot runoff 52 53 54 55 Nutrients and Lakes Streams and Rivers * Streams and rivers move continuously toward the sea. * Headwaters of most streams- cold & clear little sediment and nutrients. Swift current over rocky sediments. * Downstream- tributaries have joined to form rivers, more turbid, more sediment & nutrients. * What s in the water often depends on what was in the land. * Factors that influence flow: nutrient and oxygen content, turbidity, stream & riverbed consistency. * Rough bottom-turbulent flow; oxygenates the water * Deep water, smooth bottom; steady flow * Nutrient content depends on terrain it flows through. Watershed * Where does the water go? * A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. Flowing Water * Surface water becomes runoff into streams * Streams begin in mountains or at higher elevation * Everything rolls downhill * Streams join to form rivers * Watersheds & drainage basins are lands that deliver runoff, sediment, and dissolved substances to streams. 56 57 The Coastal Zone * Coastal wetlands among most productive zones * Covered with water all or part of the year 12
* Covered with water all or part of the year * Inlets, marshes, mangroves * Estuaries- river meets sea * Saltwater & fresh mix * Mix nutrients & pollutants * Provide ecological & economic services 58 59 60 Freshwater Wetlands * Inland wetlands * Marshes- grasses, reeds, few trees * Swamps- mostly trees & shrubs * Prairie potholes- depressions caused by glaciers * Floodplains- get excess water during floods & heavy rain * Arctic tundra * Seasonal wetlands- prairie potholes, floodplains, hardwood swamps * Ecological services: filter toxic wastes, habitats, reduce flooding & erosion, replenish streams, recharge aquifers * Economic services- recreation & food products Human Impacts on Freshwater Systems * Dams and canals fragment 40% of world s largest rivers * Reduce water flow, destroy habitats, storm damage * Flood control levees alter rivers & destroy habitats * Cities and farmlands add pollutants * Many wetlands drained or filled for human use Coral Reefs * Form in clear, warm coastal waters of the subtropics and tropics * Polyps symbiotic relationship with zooxanthellae algae that live in their tissues * Algae provide color, food, & oxygen * Polyps provide a protected home and some nutrients * Polyps slowly build reefs by secreting a protective crust of calcium carbonate (limestone) * Their dead crusts serve as a platform for more growth 13
* Their dead crusts serve as a platform for more growth * Very diverse habitat 61 Coral Reef Threats * Global warming raising water temperature above survival range of 18-30 degrees Celsius * Increasing levels of CO 2 in the atmosphere and ocean are raising the acidity of ocean water * Making it harder to produce calcium carbonate * Reef death causes habitat loss to other animals * Overfishing * Pollution 14