Chapter 52 An Introduction to Ecology and Biosphere Ecology The scientific study of the interactions between organisms and their environment Latitudinal Variation in Sunlight Intensity Sunlight is more intense in the Tropics than at higher latitudes Global Air Circulation and Precipitation Patterns Warm Moist air from the tropics moves towards the poles As the warm moist air from the tropics rises in latitude it releases much of the water content which results in precipitation in tropical regions The air becomes drier and absorbs moisture form the land as you move away from the topics 60 degrees North and South which results in arid climates After that the air masses rise again and release precipitation The air then sinks and absorbs moisture from the poles making the poles very dry 52 1 EARTH S CLIMATE VARIES BY LATITUDE AND SEASON AND IS CHANGING RAPIDLY Climate is the long term weather conditions of an area and is made up of 4 factors temperature precipitation sunlight and wind MACROCLIMATE is weather patterns on the global regional and landscape level MICROCLIMATE is the very localized weather pattern community of animals GLOBAL CLIMATE PATTERNS Determined by input of solar energy and Earth s movement in space REGIONAL AND LOCAL EFFECTS ON CLIMATE Can be modified by seasonal variation mountains and large bodies of water Seasonality Earth s titled axis of rotation and its annual passage around the sun cause strong seasonal cycles in the middle to high latitudes Changes in day length solar radiation and temperature occurs due to the changing angle of the sun Belts of wet and dry air move slightly north or south which results in wet and dry seasons Ocean currents get altered which upwells cold water and brings nutrients to the surface helping grow phytoplankton for fish Bodies of Water Ocean currents heat or cool the overlaying air masses that pass across the land Coastal regions are usually wetter than inland regions The California current helps support the redwood forests and coniferous forests The Gulfstream warms Western Europe which has higher temperatures than Canada lower latitude during the Winter time The high specific heat of water allows for lakes and oceans to moderate the climate of nearby land On hot days the rising warm air draws a breeze from the water When land temperatures fall warm air from the bodies of water rises drawing cooler air back towards the bodies of water Mountains Influence air flow over land When warm moist air rises and cools it releases moisture on the windward side The leeward side cooler dry air descends and absorbs moisture creating an arid climate and a rain shadow Mountains can also influence the amount of sunlight reaching an area and thus local temperatures and rainfall Southern slopes of mountains receive more sunlight than north facing slopes and thus are drier and warmer Every 1 000 meter increase in elevation produces an average temperature drop of 6 degrees Celsius Microclimate Many features in the environment alter microclimate such as evaporation from soil and local wind patterns Forest trees help moderate climate for the species living below This is an abiotic factor that effects the way organisms live GLOBAL CLIMATE CHANGE Burning of fossil fuels and deforestation increase the concentrations of CO2 and other green house gases in the atmosphere This could effect tree distributions by forcing them to disperse pollen towards the North 52 2 THE STRUCUTRE AND DISTRUBTION OF TERRESTRIAL BIOMES ARE CONTROLED BY CLIMATE AND DISTURBANCE Biomes major life zones characterized by vegetation type in terrestrial biomes or the physical environment in aquatic biomes CLIMATE AND TERRESTRIAL BIOMES Climate determines the location of terrestrial biomes CLIMOGRAPHS plot of the annual mean temperature and precipitation in a particular region and are determined by annual averages Forests are wetter than grasslands which are wetter than deserts GENERAL FEATURES OF TERRESTRIAL BIOMES Named for major physical and climatic features and predominant vegetation Temperate grasslands are found in middle latitudes and have various grass species Each biome is characterized by the type of micro organisms fungi and animals that live there Temperate Grasslands tend to have grazing mammals and arbuscular mycorrhizal fungi ECOTONE is the area of intergradation boundary between various biomes Vertical layering of Vegetation is an important feature of terrestrial biomes In forests the layers go from the Upper Canopy to low tree layer the shrub understory the ground layer of herbaceous plants the forest floor litter layer and the root layer Similar environments lead to convergent evolution DISTRUBANCE AND TERRESTRIAL BIOMES Biomes are dynamic and unstable Wildfires are important in grasslands savannas chaparral and coniferous forests Coniferous forests need wildfires to replace pines by shedding their seeds when it gets hot 52 3 AQUATIC BIOMES ARE DIVERSE AND DYNAMIC SYSTEMS THAT COVER MOST OF EARTH Unlike terrestrial biomes aquatic biomes are characterized primarily by their physical environment and show far less latitudinal variation Oceans make up the largest marine biome and cover close to 75 of the Earth s surface Water evaporated from the oceans provides most of the rainfall and its temperatures have a major effect on global temperatures Marine algae and photosynthetic bacteria provide most of the worlds oxygen and consume large amounts of CO2 Freshwater biomes have a high effect on the biotic components of the surrounding terrestrial biomes and surrounding soil ZONATION IN AQUATIC BIOMES The ocean is made up of many layers that differ physically and chemically The layers are Photic Zone sufficient life fro photosynthesis Aphotic Zone no light penetrates Pelagic Zone Made up by Aphotic and Photic zone Abyssal Zone lies in deep Pelagic Zone Benthic Zone bottom most zone made up of sand and organic and inorganic sediments o Occupy by communities of organisms called Benthos which are detritivores Thermocline Zone narrow layer of abrupt temperature change separates the warm upper layer and the cooler lower layers Semi annually a TURNOVER of water occurs and this is when oxygenated water from the surface flows to the bottom and nutrient rich water flows to the top This Turnover usually occurs in Spring and Autumn 52 4 INTERACTIONS BETWEEN ORGANISMS AND THE ENVIRONMENT LIMIT THE DISTRIBUTION OF SPECIES Species distributions are a consequence of both ecological and