Ecology Notes Week 3
Ecology Notes Week 3 Bio 369
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This 7 page Class Notes was uploaded by Joseph Notetaker on Friday September 9, 2016. The Class Notes belongs to Bio 369 at Missouri State University taught by Brain Greene in Fall 2016. Since its upload, it has received 5 views. For similar materials see General Ecology in Biology at Missouri State University.
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Date Created: 09/09/16
Ecology Notes Week 3 Chapter 4 Climate and Weather: Climate: The long term conditions of a particular area Weather: The short term conditions of a particular area The importance of Solar Radiation: o Causes most heating of the atmosphere o Some is deflected by the atmosphere (25%) o Some is absorbed by the atmosphere (25%) o Some reaches the surface (45%) Some that reaches the surface is immediately reflected back into the atmosphere (5%) o 29% of heat absorbed by the surface is lost through evaporation, the rest becomes surface radiation which is radiated to atmosphere and either Radiated to space (12%) Radiated back to the surface (88%) Greenhouse effect Air Temperature: o Sensible heat produced by collisions between molecules o Density of gasses decreases with elevation resulting in lower temperatures o The cooling of air due to pressure differences is the adiabatic rate o (6-10 C/1000m) o Also dependent on humidity Air masses: o Movement of air masses is driven by heating and cooling of air Tubes of circulating air form rings at specific latitudes: o Hadley Cells (0-30o) Ferrel Cells (30-60 ) Polar Cells (60-90 ) Air movement in adjacent cells is in opposite direction Hadley: air rises at oquator and moves north o Ferrel: air rises at 60 and moves south, descending at 30 The convergence of air in upper atmosphere at the boundaries of Hadley/Ferrel and Ferrel/polar cells forms jet streams o Surface winds are directed at angles within cells due to Coriolis Forces The planet earth spins but it doesn’t take the air with it Surface winds move in opposite directions in adjacent cells Rising air at equator moves faster toward the east than at other latitudes Surface winds (trades) in tropics move east to west as descending air travels south Temperate winds (westerlies) move west to east o Terrestrial climates are influenced by heating and cooling of moving air masses Ecosystems: o The location of ecosystems is strongly influenced by the atmospheric distribution of heat and water Tropical rain forests occur in equatorial regions due to high precipitation from condensation of moist, rising air Dry air descends to the north and south edges of Hadley Cells, drying land areas and creating deserts This effect is negated in areas near large bodies of water Seasons: o Seasonal changes in climate are caused by tilting of the earth’s axis o In the tropics this causes differences in rainfall o Seasonal movement of the solar equator drives tropical seasonality Currents: o Circular currents (gyres) form in open ocean areas based on Coriolis forces, heating, differences in water density, wind, and the location of continents o Ocean currents and the high thermal inertia of water affect regional climates by redistributing heat o Ocean currents affect marine ecology by influencing nutrient availability o Upwelling Zones: currents push nutreints close to the surface El Nino o Normally, equatorial Trade Winds create an east-west movement of water in the Pacific Pulls cold water from the depths along south America o El-Nino events caused by a weakening or reversal of Trade Winds No upwelling o Change in distribution of heat influences global climates The ecology of lakes is strongly influenced by seasonal changes in temperature Regional Climates: o Regional climates are influenced on various scales by topographical features Mountain ranges can cause regional climate changes with rain shadow effects The Sierra Nevada mountains is a great example of this Aspect influences solar radiation absorbed resulting in different local climate differences on north and south-facing slopes Can be shown by differences in vegetation density Causes differences in species on each slope Urban climates differ from surrounding landscapes due to heat island effects and inversions Surface features can influence local climate by creating thermoclines Static air in cities can cause terrible backups of air pollution Soil: o Climate and bedrock composition influence soil characteristics Soils contain a combination of organic and inorganic material formed from biological activity and weathering of bedrock through physical and chemical processes Rate of formation determined by climate Faster in wet conditions o Soil formation Soils are organized into horizons that result from components and processes at different levels Organic material in top layer Topsoil Soluble materials may leach out as deposits in lower layers Water washes away the nutrients o Climate influences Temperate climates with moderate precipitation often result in fertile soils Boreal forests and tropical rainforests both have low soil fertility due to leaching of minerals Boreal forests have acidic soil caused by pine needles o Makes leaching much easier (Podsolization) Rainforests have high decomposition rates o Nutrients leave very easily and quickly Chapter 5 Biogeography of Ecosystems Vegetational Zones: Vegetational zones change in response to both temperature and moisture Climatic changes due to altitude reflect latitude on a smaller scale 300m change in elevation equals 160km change in latitude Biomes: A Biome is a regional biotic unit characterized by the climax vegetation type for the area Many terrestrial categories each defined by climate Biome Name Climate Zone Vegetation Tropical Rainforest Always moist and warm Evergreen tropical forest Tropical Seasonal Summer Rainy season Seasonal forest, scrub, or forest/Savanna and winter dry season savanna Subtropical desert Highly seasonal and arid Sparse desert vegetation Woodland/shrubbed Winter rainy season and summer drought Temperate rain forest Occasional frost, high Temperate evergreen rainfall forest Temperate seasonal forest Temperate grassland/desert Boreal forest Tundra Very short summers and Almost none long winters Ecoregions: o Hierarchical classification system showing regional patterns of climate, vegetation, and topography o Classification criteria Climate (domains) Climate subdivisions (divisions) Land covers (provinces) Terrain (sections) Tropical Rainforest: o Very stable climate O Constant Temperature (26 C) High rainfall (10-50cm per month) o Very old, highly weathered soils with low nutrient content Leaching due to high precipitation Rapid uptake of nutrients o Extremely high biodiversity Abundance-diversity trade-off Up to 283 tree species in small areas o Extensive vertical structure Emergent giant trees Dense middle canopy Lower layer of small tress Shrubs and young trees Herbaceous angiosperms and ferns o Adapted to wet conditions Trees have shallow root systems Buttresses stabilize tall trees Epiphytes are abundant Plants that grow on the tree Temperate Rainforest: o Dominated by conifers o High precipitation o Many mosses, ferns and epiphytes Temperate seasonal forest: o Regions with less severe winters than boreal forest-down to 12 CO o Strong Seasonality with winter leaf drop o Annual rainfall exceeding 80-200cm o High diversity of tree species that vary geographically along rainfall gradients Usually a few dominant species represented Tropical Seasonal Forest/Savanna: o Disturbance minimizes tree density o Competition between trees is high o Wet/dry seasons with strongly seasonal growth Woodland/Shrubland: o Mediterranean climates dominated by shrubs Mild, wet winters Long, dry, hot summers Coastal regions associated with cold ocean currents o Plants are sclerophyllic Low, dense woody structure Fire adapted, drought-resistant Conserve limited nutrients Growth concentrated at end of set season Temperate Grassland: o Largest general Vegetational type o 25-70cm annual rainfall o Highest productivity of all terrestrial ecosystems due to rich soil o Significant portion of natural grassland has been converted to cropland o Subtypes Tallgrass prairie Named for the dominant tall species such as Big Bluestream Mixed-grass prairie Ecotone between tallgrass and shortgrass prairie Variable precipitation Shortgrass prairie Dominated by shallow-rooted sod-forming grasses that exploit surface moisture o Two dominant growth forms Bunchgrass- grows in clusters Sod-forming- spreading mat over ground surface Growth can be facultative Sod-forming in good conditions, bunch in dry soil Grasses partition growth activity Warm and cool-season species All grasses have extensive root systems with 50% or more of plant biomass below ground Can penetrate to depths of >1m Resistance to disturbance (fire and grazing)