Ecology- Week 2
Ecology- Week 2 Bio317
Virginia Commonwealth University
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This 10 page Class Notes was uploaded by Jayda Abrams on Sunday September 11, 2016. The Class Notes belongs to Bio317 at Virginia Commonwealth University taught by Dr. Bissett in Fall 2016. Since its upload, it has received 27 views. For similar materials see Ecology in Biology at Virginia Commonwealth University.
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Date Created: 09/11/16
Ecology Week 2 9/7/16 9/9/16 Chapter 2 Continued “The geographic distribution of terrestrial biomes corresponds closely to variation in climate, especially prevailing temperature and precipitation.” o The leeward side is called the rain shadow Temperature and moisture interact and represent the principal components of climate. - Timing of precipitation with respect to temperature is more important than the amount - Strong influence on plant distribution - Therefore, affects animal distribution, because of the effect from plant distribution. Climate Diagrams Summarize climatic information using standardized structure: Temperature plotted on the left vertical axis and precipitation plotted on the right vertical axis 10 deg c equivalent to 20mm precipitation Relative position of lines reflects water availability Adequate moisture for plant growth when precipitation above temperature. Note: Greater blue shading demonstrates that there has been a change in scale. Biomes: Tropical Rainforest o Mostly occur within 10˚ latitude of equator o Little temperature variation between months (high temps year round) o Annual rainfall of 2,000 – 4,000 mm relatively evenly distributed Quickly leaches soil nutrients Myccorhizae help gather nutrients o Organisms add vertical dimension. o Harbor of staple foods and medicines for world’s human populations – increasingly exploited. Tropical Dry Forest o Usually located between 10 ˚ and 25˚ latitude. o Climate more seasonal than tropical rainforests. o Soils are generally richer in nutrients, but vulnerable to erosion o Shares many animals and plant species with tropical rainforest o Heavily settled by humans with extensive clearing for agriculture. Tropical Savanna o Mostly occur north and south of tropical dry forests within 10 ˚ and 20 ˚ of the equator o Climates alternate between wet and dry seasons Drought associated with dry season leads to lightning and causes wildfires. o Soils have low water permeability. Desert o Major bands at 30 ˚ north and 30 ˚ south. Occupies about 20% of earth’s land surface. o Water loss usually exceeds precipitation. o Soil is usually extremely low in organic matter. o Plant cover ranges from sparse to absent. o Animal abundance is low, but biodiversity may be high. Mediterranean Woodland/Shrubland o Occurs in all continents except Antarctica. o Climate is cool and moist in the fall, winter, and spring, but can be hot and dry in the summer. o Fragile soils with moderate fertility. o Trees and shrubs typically evergreen. o Fire-resistant plants due to fire regime. o Long history of human intrusion. Cleared for agriculture. Temperate Grassland o Widespread distribution. o Annual rainfall of 300 – 1000 mm. o Experiences periodic droughts. o Soils tend to be nutrient. Temperate Forest (Old Growth) o Majority lies between 40 ˚ and 50 ˚ latitude o Rainfall average is between 650-3000 mm. o Fertile soils Long growing seasons dominated by deciduous plants Boreal Forest o Confined to northern hemisphere. o Covers 11% of earth’s land area. o Thin, acidic soils low in fertility. o Generally dominated by evergreen conifers. o Relatively high animal density. o Historically low levels of human intrusion. Tundra o Covers most of lands north of the Arctic Circle. Climate typically cool and dry with short summers. 200 to 600 mm of precipitation. o Low decomposition rates. o Supports substantial numbers of native mammals. o Human intrusion historically low, but increasing as resources become scarce. Mountains: Islands in the Sky o Built by geological processes and thus concentrated in belts of geological activity. o Climate changes with elevation and latitude. o Soils are generally well-drained and thin. o Flora and fauna change with elevation. o Historically used as a source of raw materials for human settlements. o In West Virginia, there are salamanders that are distinct per mountain, like they are separated by islands. This can lead to speciation. Macroclimte is on a bigger scale. Example: The whole mountain, whole state, etc. Macro- vs Microclimate/ Large scale vs small scale: A. Microclimate: Climate on a local scale. Within 1m of the ground, (tufts of grasses, around an individual plant, etc.) Climate surrounding individuals. Climate surrounding organism parts. Examples: a single leaf or a tick/flea on a deer. Another example of microclimate is North vs. South Slope A classic comparison (a good comparison to do when trying to look at differential effects of temp) S slope: sunnier > warmer > drier> greater fluctuations in temperature. N slope: just the opposite. Results in differences in the distribution of plant species; which will then influence the animal distribution. What about animals? Need plants for food and cover. Ex: Deer use N slopes in summer, but rely on S slopes in winter and spring – less snow, warmer, spring growth begins earlier. General Rules: Macroclimate correlates well with the general distribution pattern of species; and Microclimate is more important to individuals of species, resulting in a patchy dispersion within the general distribution or range. Chapter 3 A Primer on Aquatic Ecology * = Wetland ecosystems interaction with the terrestrial environments. What is the salinity of waters? Saltwater Brine Water Saline Water Brackish Freshwater Water (from oceans) (Brine pools, where saltwater gets washed in and sits there, Great Salt Lake) 35ppt 50+ppt 30-35ppt Between 1-30 Less than 1 5-30ppt 0-.5 Aquatic Systems Saltwater (marine) o Oceans o Reefs o Shorelines o Land – sea interface* Freshwater o Rivers and streams (lotic – moving) o Lakes (lentic) Estuaries* o Largely diverse o Lots of productivity o Mixing of freshwater and salt water o Current change if there is channelization o Lots of O2 o High light environment o Salt pans occur- A salt pan is an area where water washes over and then is evaporated leaving a hyper salinized area. o Nutrient rich (vs ocean water which does not carry nutrients) o Micro niches o High faunal diversity-Complex food webs Over 97% of the Earth’s surface is saltwater. Aquatic Microclimates are typically more stable. Why? Because the temperature is more moderate in water. Aquatic Systems vs. Terrestrial System: o Temperature variations o Aquatic systems are wet o Pressure gradient is greater in aquatic systems o Light attenuation is greater in aquatic systems o Plants respond to environmental and alter the environment o In aquatic systems physical factors control distributions of plants o Aquatic Systems are more stable Hydrologic Cycle Most water in the ocean evaporates in solar energy. Freshwater mostly forms ice and glaciers. Atmospheric water fluctuates from different sources. 1. Oceans and seas- About 71% of the Earth is made up of oceans and seas and some are greater than four miles deep. The average depth is 4000 meters. They have a low surface area to volume ratio and have reduced sunlight and low productivity. 2. Ocean Zones- Based on both and shore line. 3. Epipelagic Zone-Surface water of open sea with more sunlight. 4. Mesopelagic-Decrease in light temperature 5. Other zones include: Bathypelagic zone, abyssal zone and the hadal zone As you go down, light and temperature decrease and pressure increases. Important Gradients: Thermocline- Change in temperature. Pycnocline-Change in pressure. This can be felt. Halocline-Change in salinity. This has more to do with proximity to the coast but it also changes in depth. Major Ecosystems under Oceans: 1. Coral reef- Everything is colorful and tropical. These have lots of diversity and it is “terribly charismatic”. Coral Reef bleaching is a major issue. There are 3 types of coral reef systems: Fringing- Forms around young islands Barrier-Around a subsiding island, in a lagoon space Atoll-When an island is completely submerged 2. Intertidal Zones- Very diverse with tidal fluctuation. Water is raised from the tide and salt comes in and out. The tidal fluctuations are all based on the degree of exposure. High variables: Salinity Nutrients Wave energy Atmospheric exposure Lunar derived ocean tides 3. Salt marsh- Some of the most productive habitats. The moon is tugging on the oceans for about six hours cycles, four times a day. These are semi diurnal tides. Some places only have two tides and they are diurnal tides. Example: South China. This is NOT typical! This applies to estuaries salt marshes and mangroves. When freshwater comes in there is a salt wedge because saline water is denser than freshwater. At tide the salt wedge will reach up and rise farther up than the freshwater. Mixing occurs but the freshwater sits on top of the saltwater. Estuarine Salinity Gradients Estuary Food webs: o -Very diverse o -Productive because of the tide o -Animals include: zooplankton, crabs, and fish o -Lots of plants and sun Freshwater: o 3% of the Earth’s water is freshwater. Of that 3% 2.5% is ice and .75% is liquid water (ex: ground water) and this little bit can still support 8 billion people o Water is a renewable resource o Rivers and streams are moving water and are lotic o Ponds and lakes are still water and are lentic Wetlands o Great deal of interface between water and land Ranking of Streams- Starts at the top and works its way down. There has to be 2 of the same rank to move up in order (Ex: 2 first order streams meet = a second order stream). There is always a question of scale Macro vs Micro Stream Structure: Riparian Zone- Wet soil without trees Active Channel- Height of ground water Riffle- Flash moving water over roots Pools will have temperature differences! Hypothetic Zone- Exchanges water and nutrients with the benthic zone. It is located right under the benthic zone. Phreatic Zone- Where rocks and soil is saturated with water Organisms live in all of these zones but some more than others. River Continuum Concept: Everything is supplied through head water CPOM- Corse Particulate Organic Matter: Example leaves and dead insects. It gets broken down to the FPOM- Fine Particulate Organic Matter. It is broken down by invertebrates and water. Wider River System goes to more open water.
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