Ecology test #1


Terms in this set (...)

Research Hypothesis
Is a relationship between variables and indicates the nature of the relationship
Non-directional Hypothesis
there is a difference or there is a relationship
Directional Hypothesis
If this happens, then that specific outcome will happen
Null Hypothesis
Ex: Exposure to a pesticide has no measurable impact on microbial community composition
Climate System
-The single best predictor of ecosystem structure and functioning
-Geographic distribution of climate is relatively predictable from general principles
-Temporal variation in climate depends on solar input, surface properties, and the capacity of the atmosphere to trap heat
-If you understand causes of spatial and temporal variation in climate, you can predict many of the ecosystem patterns that are observed
Net Primary Productivity
the rate at which biomass accumulates in an ecosystem
Climate gradients
East (Mesophytic forest) -> West (Desert)
South (Tropical Forest) -> North (Tundra)
A group of interacting ecosystems that are spread over a large geographic area. They are characterized by vegetation and largely defined by temperature and precipitation
Important Climate Drivers
1. Solar radiation: greenhouse effect, differential heating, vertical circulation
2. Earth's rotation: wind & water circulation
3. Earth's tilt & orbit around sun: seasons
4. Landforms: rain shadows
Solar Radiation
Warms the Earth. Longwave radiation is reflected back into space as shortwave radiation. Greenhouse effect traps this shortwave radiation heating the Earth.
Solar E
-Ultimate climate driver
-Greater heating at the Equator where the sun's rays are most perpendicular
-Uneven heating creates atmospheric circulation
Hadley Cells
Circulation cells exist at the equator,warm air rises and cools dropping rains at equator, cooled air is pushed polewards, dense, dry air descends warms and absorbs moisture
Coriolis Effect
The rotation of the Earth (West to East) on its axis deflects the atmosphere toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere, resulting in curved paths. Deflects currents to the right in the Northern Hemisphere and left in the Southern.
Oceanic Circulation
Accounts for 40% of poleward heat transport, driven by the Coriollis forces and surface winds. It has a strong effet on regional climate patterns.
Thermohaline Circulation
Important in poleward heat transport driven by deep water formation at poles drives upwelling at eastern margins of ocean basins
Earth's rotational axis
-23.5 degrees
-Responsible for seasonal variation in latitude of most intense solar heating
-Increased in seasonal variation, equator --> poles
Soil Composition
-Organic Matter
Mechanical Weathering
The process of breaking rocks into smaller particles by water, wind, freeze/thaw, roots, etc.
Chemical Weathering
The process of breaking rocks into smaller particles by water, acids, root exudates.
Factors that affect soil development
-Parent Material
-Biota Present
Soil Profiles
-Develop over time
-Occurs from top down
O - organic
A - topsoil
B - subsoil
C - unconsolidated material
-dry soils found in most desert areas; salinization common
-supports drought-adapted shrubs and annual grasses, not suitable for crops
moist, rich soils
Positive nutrients bond to negative soil particles
Desert Biome
-Located at 30 N and 30 S latitude
-Water loss usually exceeds precipitation
-Soil usually extremely low in organic matter
-Plant cover ranges from sparse to absent
-Animal abundance low, but biodiversity may be high (strong behavioral adaptations)
-Increasing human intrusion
-Min temp above 0 C
Mediterranean Woodland and Shrubland
-Occur in all continents except Antarctica
-Climate cool and moist in fall, winter, and spring, but can be hot and dry in summer
-Fragile soils with moderate fertility
-Trees and shrubs typically evergreen
-Fire-resistant plants due to fire regime
-Long history of human intrusion (mostly agriculture)
-Summer droughts and moist cool seasons
-Moderate year round temperature
Temperate Forest (Old Growth)
-Majority lie between 40 and 50 degrees latitude
-Rainfall averages 650-3000 mm
-Fertile soils
-long growing season dominated by deciduous plants
-short growing season dominated by conifers
-High biomass production
-Many major human population centers
-Low seasonality variation
-Conifer forests have seasonal drought
-Cool and wet
-Covers most of lands North of the Arctic Circle
-Cool and dry climate with short summers
-Low decomp rates
-Supports substantial number of native mammals
-Human intrusion historically low, but increasing as resources become scarce
-Proximity to sea brings moderate temps
-Short growing season
-Temps below 0 C
Hydrologic Cycle
Precipitation -> Infiltration -> Groundwater -> deep storage
Precip -> infiltration -> groundwater -> transpiration -> evaporation
Precip -> surface runoff -> transpiration -> evaporation
Unique Properties of Water
1. Polarity - hydrogen bonding
2. Cohesion - water molecules stick to each other (surface tension)
3. Solvent - polarity of water molecules dissolves substances. High concentrations of minerals in water
4. Thermal Properties - resists temp changes, conducts heat rapidly, resists changes in state, less dense as ice (floats)
5. Viscosity - frictional resistance (retards movement of organisms)
Process by which some organisms, such as certain bacteria, use chemical energy to produce carbohydrates
Epipelagic Zone
-Photosynthetic organisms
-Phytoplankton and zooplankton
-Due to size, oceans contribute 1/4 of total photosynthesis in the biosphere
With Depth in Ocean
-Light decreases
-Temperature decreases
Oligotrophic Lake
A nutrient-poor, clear, deep lake with minimum phytoplankton.
Eutrophic Lake
Lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates. Turbid water, shallow slopes, and shallow bottom.
Human Influence
-oceans previously acted as a buffer against humans
-humans threaten oceans through over harvesting and dumping
-large populations have negative effects on lakes and rivers through agriculture runoff and introduction of invasive species
Large scale weather variation
Small scale weather variation, usually measured over short periods of time
Higher altitude = lower temp
Offers contrasting environments
Ecologically important microclimates
Ground color
Darker colors absorb more visible light
Create shaded, cooler environments
Shrubs and microclimates
-soil surface in full sun heats to high temps
-shrubs shade soil surface and let's max temp
-leaf litter let's max temp more
-large green leaves intercept more light
Aquatic temperatures
Riparian vegetation influences stream temps by providing shade
Organismal ecology
The branch of ecology concerned with the morphological, physiological, and behavioral ways in which individual organisms meet the challenges posed by their biotic and abiotic environments
Principal of Allocation
Organisms allocate limited energy to a certain function which then reduces the amount for others to function. This trade off in energy allocations will differ among environments with functions that include growth, reproduction, and defense against predators
Levin's Principle of allocation
Evolutionary consequences of this trade of results in populations having high fitness in one environment, but lowered fitness in another environment
Optimal photosynthetic temperatures
-boreal forest photosynthesis at a max rate of 15°C
-desert shrubs photosynthesize at 44°C
Temperature and microbial activity
-psychrophililic bacteria (cold loving): peaks around 4°C
-thermophyllic bacteria (heat loving): peak at about 63°C
Body T°s
-homeothermic: steady internal temp
-poikilothermic: internal temp various with external
Modes of regulating T°
Animals that rely on the environment to control their body temperature
An organism that is internally warmed by a heat-generating metabolic process
Metabolic heat. Energy released from an organism thigh the process of cellular respiration
Heat transfer through two touching objects
Convection. Great transfer due to circulation of liquid or gas
Radiation. All substances emit and absorb radiation E ( electromagnetic heat). Influenced by wavelength, angle of incoming E, color (absorption vs reflection)
Evaporation. Water absorbs heat during evaporation.
-homeothermic at certain times
-incubating eggs
-in flight
-at night
Body temp changes with air temp
Water availability
The tendency of water to move down concentration gradients, determine whether an organism trends to lose or gain water from its environment
Water Regulation on Land
-evaporative loss to environment
-reduced access to replacement water
Water content of air
Evaporation accounts for much of water lost by terrestrial organisms. As water vapor increased, evaporative loss decreased
Water acquisition by plants
-water moving between soil and plants flowed down a potential gradient.
-water potential is the potential energy of water relative to pure water in reference conditions
An attraction between molecules of different substances
Pore-like openings in leaves that allow gases (CO2 and O2) and water to diffuse in and out of the leaves.
Water acquisition by animals
-most terrestrial animals satisfy their water needs via eating or drinking
-can also be gained via metabolism through oxidation of glucose
Water conservation by plants and animals
- waterproof outer covering
-concentrated time and feces
-condensing water vapor in breath
-behavioral modifications
-drop leaves
-thick leaves
-few stomata
-periodic dormancy
Water movement in aquatic environment
-moves down gradient
-aquatic organisms can be viewed as an aqueous solution bounded by a selectively permeable membrane floating in another aqueous solution
Diffusion through a semipermeable membrane
Body fluids and external fluid are at the same concentration
Body fluids are at a higher concentration than the external environment
Body fluids are at a lower concentration than the external environment
Plants use the sun's energy to convert water and carbon dioxide into sugars
Light harvesting reactions
Converts light into chemical energy
Carbon fixation reaction
Used chemical energy to convert CO2 into sugar
Calvin cycle
A biochemical pathway of photosynthesis in which carbon dioxide is converted into glucose using ATP and NADPH.
Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).
Reacts to CO2 to produce sugars. Leads to carbon gain
Reacts with oxygen to concert sugars to CO2. Respires 20-40% of fixed carbon
C3 photosynthesis
The most common photosynthetic pathway in which the product of the initial reaction is PGA, a 3-carbon carbon compound.
C4 photosynthesis
The two-step photosynthetic pathway in which CO2 is first fixed in mesophyll cells to form 4-carbon acids, and then the 4-carbon acids are broken down into 3-carbon acids in the bundle sheath cells.
Crassulacean acid metabolism
An adaptation for photosynthesis in arid conditions, first discovered in the family Crassulaceae. In this process, a plant takes up CO2 and incorporates it into a variety of organic acids at night; during the day, CO2 is released from organic acids for use in the Calvin cycle.