Ecology. Climate. Global Climate. Chapter 52: Introduction to Ecology and the Biosphere

Transcription

1 Chapter 52: Introduction to Ecology and the Biosphere Ecology oikos - home! logos - to study! Ecology - the study of interactions between organisms and the environment! Answer important questions:! Where do organisms live?! Why do organisms live where they live?! What factors determine how many organisms live in one place? Climate Climate - long-term prevailing weather conditions in a particular area! Major components: temperature, precipitation, sunlight, and wind! Macroclimate - patterns on global, regional, and landscape level! Microclimate - defined by fine-scale differences in the environment that affect light and wind patterns Global Climate Determined by input of solar energy! Sun s warming of the atmosphere, land, and water that causes temperature variations, cycles of air movements, and evaporation of water all determine latitudinal variations in climate Atmosphere Low angle of incoming sunlight Sun overhead at equinoxes Low angle of incoming sunlight Latitudinal variation in sunlight intensity 90 N (North Pole) 60 N 23.5 N (Tropic of Cancer 0 (Equator) 23.5 S (Tropic of Capricorn) Fig S 90 S (South Pole)

2 Indian Ocean Subtropical Gyre Antarctic Circumpolar Current California Current North Pacific Subtropical Gyre Equator South Pacific Subtropical Gyre Gulf Stream Labrador Current North Atlantic Subtropical Gyre South Atlantic Subtropical Gyre Global Air Circulation Water evaporates in the tropics, and warm, wet air masses flow from the tropics toward the poles! Rising air masses release water! Dry, descending air masses create arid climates (30 degrees north and south of the equator)! Trade winds blow east to west in the tropics and westerlies blow from west to east in the temperate s 66.5 N (Arctic Circle) 60 N Westerlies ARID ZONE Descending dry air absorbs moisture. 0 Northeast trades Southeast trades Ascending moist air releases moisture. Westerlies 0 Fig. 52.3b 60 S 66.5 S (Antarctic Circle) Global air circulation and precipitation patterns Seasonality Variations of light and temperature increase steadily toward the poles! Impacted by tilt of the Earth at high latitudes March equinox December solstice Constant tilt of 23.5 June solstice 60 N 0 (equator) September equinox Fig Regional, Local, and Seasonal Effects Bodies of water! Ocean currents (ex. Gulf Stream)! Coastal s (climate moderation) 2 Air cools at 1 Warm air high elevation. over land rises. 3 Cooler air sinks over water. 4 Cool air over water moves inland, replacing rising warm air over land. Fig Regional, Local, and Seasonal Effects Mountains! Effect amount of sunlight reaching an area! Air flow Leeward side of mountains Effect rainfall! Mountain range Temperature! Ocean Rain shadow Fig. 52.6

3 Global Climate Change Greatly impact the biosphere! May be able to predict impact by studying previous changes (ex. glaciers retreating)! Species that have difficulty dispersing may have smaller ranges or become extinct Current range Predicted range Overlap (a) 4.5 C warming over next (b) 6.5 C warming over next century century Fig Sweden Finland Expanded range in 1997 Range in 1970 Fig Biomes Major types of ecological associations that occupy broad geographic regions in land and water! Climate is key to determination! Characterized by vegetation type (terrestrial biomes) and physical environment (aquatic biomes) Climographs Plot temperature and precipitation in a region! Biomes are affected by the pattern of temperature and precipitation (not just the averages) Figure Annual mean temperature ( C) Desert Temperate grassland Temperate broadleaf forest Northern coniferous forest Arctic and alpine tundra Annual mean precipitation (cm) Tropical forest General Features of Terrestrial Biomes Usually grade into each other (no sharp boundaries)! Ecotone - area of integration between biomes (may be wide or narrow)! Fig Vertical layering! Provides diverse habitats! Convergent Evolution! Can arise in distant biomes Euphorbia canariensis Cereus peruvianus

4 Disturbance and Terrestrial Biomes Disturbance - event such as a storm, fire, or human activity that changes a community! Fire suppression Aquatic Biomes Largest part of the biosphere by area! Freshwater vs. Marine! Oceans! 75% of earth s surface! Evaporation of oceans provides most of the planet s rainfall! Temperature has major impact on climate and wind patterns! Algae and photosynthetic bacteria supply a substantial portion of the world s oxygen and consume carbon dioxide! Freshwater - linked to soils and biotic components of the surrounding terrestrial biome Zonation in Aquatic Biomes Many are stratified into s or layers defined by light penetration, temperature, and depth! Pelagic : made of the photic and aphotic! Deep aphotic is the the abyssal (2,000 to 6,000m)! Benthic : organic and inorganic sediment at the bottom! Detritus - dead organic matter that falls from the productive surface (b) Marine zonation m Continental shelf 2,000 6,000 m (a) Zonation in a lake Intertidal Neritic Benthic Photic Photic Benthic Littoral Oceanic Aphotic Pelagic Abyssal Aphotic Limnetic Pelagic Fig Thermocline In oceans and most lakes this temperature boundary separates warm upper layer from cold deeper water! Many lakes undergo semiannual mixing of the waters (turnover)! Turnover mixes oxygenated water from the surface with nutrient-rich water from the bottom Winter Spring Summer Autumn C 4 C Thermocline 4 C 4 C Fig

5 Lakes Great size variation! Oligotrophic lakes - nutrient poor and oxygen-rich! Eutrophic lakes - nutrient rich and oxygen poor! Littoral - shallow, welllighted, close to shore! Limnetic - deep water, small drifting animals (zooplankton) that graze on phytoplankton An oligotrophic lake in Grand Teton National Park, Wyoming A eutrophic lake in the Okavango Delta, Botswana Fig Distribution of Species Result of ecological and evolutionary relationships through time! Events in ecological time can lead to evolution Kangaroos/km 2 > < 0.1 Limits of distribution Southern Australia has cool, moist winters and warm, dry summers. Climate in northern Australia is hot and wet, with seasonal drought. Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year. Southeastern Australia has a wet, cool climate. Tasmania Red Kangaroo! Abiotic factors! Biotic Factors Factors Limiting Distribution Why is species X absent from an area? Yes Does dispersal limit its distribution? No Area inaccessible or insufficient time Yes Does behavior limit its distribution? No Habitat selection Yes Do biotic factors (other species) limit its distribution? No Predation, parasitism, competition, disease Do abiotic factors limit its distribution? Physical factors Chemical factors Temperature Light Soil structure Fire Moisture, etc. Water Oxygen Salinity ph Soil nutrients, etc. Fig Dispersal and Distribution Dispersal - movement of individuals away from centers of high population density or from area of origin New areas occupied Year

6 Natural Range Expansion and Adaptive Radiation Natural range expansions show influence of dispersal on distribution (ex. cattle egrets)! Adaptive radiation happens in rare cases of long-distance dispersal (ex. Hawaiian silverswords) 1966 Current Fig Species Transplants Organisms intentionally or accidentally relocated from their original distribution! If successful, it indicates that the species potential range is larger than current range. Biotic Factors RESULTS Impact distribution! Predation, herbivory, competition Seaweed cover (%) August 1982 Sea urchin Limpet February 1983 Both limpets and urchins removed Only urchins removed Only limpets removed Control (both urchins and limpets present) August 1983 February 1984 Fig Abiotic Factors Also impact distribution! Temperature, water, sunlight, salinity, wind, rock and soil Fig 52.21