What are climate patterns influenced by on a fundamental level?
They’re shaped by the uneven input of energy from the sun.
How does the angle of entry of sunlight into the atmosphere affect the amount of energy reaching the surface?
- The angle of entry of sunlight into the atmosphere affects the amount of energy reaching the surface in two ways:
- Sunlight entering at an angle means more energy is spread in a larger area.
- Sunlight entering at an angle must travel through larger distances of the atmosphere, which leads to the dissipation of energy.
What creates seasons?
- The tilt of the Earth leads to seasons and explains the reason behind why days and nights are longer at the poles.
- Example: Even during the equinox, when every place on Earth experiences 12 hours of daylight and 12 hours of night, the sunlight enters the poles at an oblique angle, leading to a lower ratio of energy over area.
What causes atmospheric circulation? What is atmospheric circulation?
Varying amounts of solar energy reaching various parts of the earth leads to the formation of atmospheric cells. (Hadley between 0 and 30 and Ferrel between 30 and 60) High air pressure leads to deserts and decreased rainfall, whereas low air pressure (moisture in air condenses as air rises) leads to high precipitation.
What factors affect patterns of precipitation on earth?
- Atmospheric circulation (cells)
- Rotation of earth
- Locations and sizes of mountain ranges (topography)
How does the rotation of the earth affect precipitation patterns?
The coriolis effect (All positions on earth complete a single rotation in a day. However, they go at varying velocities. (equator must be faster than poles for example) The difference in velocities causes air and water to be westward when moving towards the equator and eastward when moving away from the equator.) This is what drives the rotation of large storms and hurricanes.
What are biomes?
Generalizations of communities in given climates (temperatures and precipitation patterns)
What are the three abiotic factors affecting biome structure, function and location?
- Rate of photosynthesis and productivity
What is the tricellular model?
- Explains differences in atmosphere pressure belts, temperature and precipitation.
- 0 to 30 is hadley
- 30 to 60 is ferrel
- 60 to 90 is polar cell
- 30 is desert
- 60 degree is temperate forest
- 0 is tropical rainforest
What are the qualities of a tropical rainforest biome?
- Constant high temperature
- High rainfall
- Near the equator, little seasonal variation between the tropic of capricorn and cancer
- High levels of biodiversity and NPP
- Soil is low in nutrients
- Dense canopy, lower biodiversity in understory.
What are the qualities of temperate forests?
- Between 40-60 N
- Cold winters and warm summers
- Some ecologists recognize 3 different kinds of temperate forests based on the types of trees: coniferous (needles or waxy / pines) trees or broad-leaf evergreen trees( holly, rhododendron) or broadleaf deciduous trees (oak, maple, beech, birch)
- Less biodiversity due to the forests being made one species tops 6 species. But whereas the rainforests have very high dense canopies, there’s grass and ferns and more biodiversity in the understories of temperate forests.
What are the qualities of deserts?
- 30 N
- Water is limiting factor , NPP is very low
- Xerophytic adaptations, low decomposition due to low water, high salinity, low leaching
- Roots either deep or extended on surface. However, opportunistic species such as poppies grow rapidly when dormant leaves receive rainfall.
What are the qualities of tundra?
- High latitude, low insolation
- Water is ice, sunlight is low, NPP low
- Decomposition is slow, nutrition is low, biodiversity is low
- Larger animals for energy efficiency (caribou and musk ox)
- formed due to the retreat of glaciers
- Permafrost soil
- Recent human activities for oil or gas have shaped these biomes.
- Mosses, lichens and dwarf trees.
What are the qualities of polar ice biomes?
- Very low precipitation
- Lower than freezing temperature all year long
- Very little vegetation except for microscopic algae.
- No herbivores.
What are the qualities of tropical seasonal forests?
- Brazil, panama, vietnam, cambodia, india
- Distinct wet and dry seasons
- More sunlight reaches the ground, less dense canopy
- North and south of equator
- Wet season is around 27 degrees, dry season can reach up to 37 (more variation however still high)
- Generally deciduous or semi-deciduous
What are the qualities of tropical Savanna?
- Temperate grasslands (high biodiversity, lower production)
- Warm and receive significant amounts of precipitation, however have dry periods (3-4 months)
- Fire and grazing are important factors in maintaining the structure of this biome.
What are the qualities of temperate grasslands?
- More rain than deserts but less than temperate forests.
- Because precipitation is low, decomposition is also low. Thus, the soil is rich and fertile (wtf)
- Large herds of migratory animals such as kangaroos or bison.
- Recent grazing with domesticated animals is devastating to the biome.
- Steppes (short grasses), prairies (long grasses)
What are the qualities of chaparral?
- Found in the mediterranean with winter rains and summer draughts.
- (maki) short shrubs with waxy, thick and waxy leaves.
- Used to have high biodiversity with deer, elk, mountain lions and wolves but longtime human association has largely depleted the biodiversity.
What are the qualities of lakes?
- Deep, stratified bodies of water with vertical zonation on nutrients, oxygen level and light.
- Stratified lakes in temperate zones undergo “lake turnover” and are mixed twice a year to facilitate nutrient and oxygen dispersal due to seasonal differences.
- In tropical zones, lake turnover is very rare, which may lead to dead zones.
- Although lakes are high biodiversity areas, they’re threatened by human activities (agricultural and industrial run-off, invasive species)
What are the qualities of taiga forests?
- North america and eurasia
- Evergreen coniferous boreal trees.
- Low evaporation rates due to low temperature
- High precipitation.
- High snowfall
- Wolves, deer
What are the qualities of mountain ecosystems?
- Relatively isolated with strong elevational gradients which may lead to vastly different climatic zones across short distances. Thus, they have a surprising degree of biodiversity and endemic species.
- Adaptations include waxy and thick leaves and tolerance to both low atmospheric pressure and intense sunlight.
- Found on high elevation slopes and plateaus. (alpine and subalpine climates found in tropical, subtropical and temperate areas)
- Threatened by overgrazing, fire regime interruptions and large-scale cultivation.
What are the qualities of oceans
- Ocean biomes vary with depth as well as latitude.
- Coastal biomes include coral reefs, larger organisms and multicellular algae (seaweed)
- In open oceans, most primary productivity is facilitated by unicellular phytoplankton.
- Threatened by climate change, habitat depletion and pollution.
Why are ecoregions important?
- Many ecologists believe that conservation begins with mapping the ecoregion of the endangered animals due to the following reasons:
- Ecoregion mapping allows us to identify areas with exceptional biodiversity.
- Allows ecologists to identify which regions are unique, redundant or representative.
- Helps set strategic conservation priorities that both target areas that are most threatened and reflect the conservation values that the ecologists aim to protect.
- REMEMBER: These are unique LARGE SCALE conservation units.
Why are there no biomes on the corner of the diagram?
- Such areas don’t exist on earth.
- Such areas wouldn’t be able to sustain life.
2. Trade-offs and Species Distributions
What is physiological ecology?
It is the study of physiology in the context of the resources and environments available on our planet.
What factors affect the species living in an ecosystem?
- While temperature and precipitation tend to set the broad region where the species’ physiology allows it to exist, local patterns are determined by other environmental and ecological factors such as:
- Underwater / above water
- Availability of various nutrients
- Soil texture
- Other species living in the area.
HOWEVER: The two most important factors, especially for terrestrial species, are temperature and moisture.
What is the general numerical relationship between plant health - precipitation and temperature?
Every 10 degree Celsius rise in temperatures requires 20 mm of precipitation per month to stay healthy.
What are physiological tolerances?
The limits on environmental conditions that an organism can tolerate.
What is evapotranspiration? Why is it important?
The overall rate of transpiration + the overall rate of evaporation from soil and other surfaces. The total amount of water available to plants is a balance between incoming precipitation and outgoing evapotranspiration.
What is potential evapotranspiration (PET)?
The maximum amount of water lost from an ecosystem at a given temperature. Plants need access to either an amount of water equal to or greater than PET to avoid desiccation. PET is approx. 2x temperature.
What is actual evapotranspiration (AET)?
- Is the actual amount of evapotranspiration that will occur at a given temperature.
- If the ground is wet (precipitation is higher than PET), AET = PET and the excess water will remain on the ground. If the ground is dry (precipitation is lower than PET), AET will be less than PET and will instead equal precipitation (all the water that reaches the ground evaporates)
What is desiccation?
To lose water to the point of drying out.
What is a niche?
Is the total set of abiotic and biotic conditions under which a species will survive.
What consequences can a change in the abiotic conditions of an environment have on species distribution?
- It can lead to extinction
- It can lead to acclimation (changes in physiology and morphology in response to environmental conditions at an individual level) or adaptation (at a population level)
- The species distribution might shift following the climatic shift.
How does convergent evolution connect to biomes and biome distributions?
- Different species have niches for temperature and precipitation combinations, yet similar biomes
- in faraway locations on earth look similar. For a given biome, similar form and function in vegetation
- across the planet are a result of convergent evolution (similar selective pressures due to climate
- leading to similar evolutionary outcomes irregardless of any common taxonomic or genetic background)
How are biome distributions affected by climate change?
- Biomes occur where they do because of climate. Throughout history, climate has changed slowly and
- Biomes have responded accordingly. However, human caused global warming is occurring at a rapid
- Rate and may have unprecedented consequences for the integrity of biomes.
- Almost all energy on earth comes from photosynthesis (+chemosynthesis)
- As a result of light reactions, NADPH + ATP + O2 is produced. ATP and NADPH are used in light
- Independent reactions.
- Rubisco fixes CO2 to a 5 carbon compound, which then turns into 3 carbon compounds called PGA. The 3
- carbon compounds then either turn back into glucose or are recycled to 5 carbon compounds.
Where is energy stored in glucose?
Energy is stored in C-H bonds in glucose.
What is fixation?
Fixation is turning CO2, H2O and Sunlight into glucose and water
What is respiration?
Respiration is turning glucose and oxygen into CO2, H2O and ATP
What is photorespiration?
- Instead of rubisco, CO2 binds to O2, which results in the destruction of the sugars and a loss (waste) of
- energy. This depends on the temperature, concentration of O2 and concentration of CO2.
What must plants do in order to minimize photorespiration?
- Adjust temperature
- Increase CO2 concentration
- Decrease O2 concentration.
- In reality, however, they’re only able to control CO2 concentration through transpiration and the stomata.
What is C4 photosynthesis?
- It is an adaptation to hot environments. (in cooler environments, plants perform transpiration at
- a faster rate to keep O2 concentration low. However, this isn’t possible in hot environments due to
- The limiting factor of water availability.) In C4 photosynthesis, the light dependent (mesophyll cells)
- and light independent (bundle sheath cells) reactions are in two separate cells (called the Kranz anatomy).
- In addition, the mesophyll cells use some of the ATP generated by light reactions to add CO2 to a 3 carbon
- Compound called PEP. This new 4 carbon compound (malate) is then transported to bundle sheath cells
- Where the extra CO2 is released in order to increase the overall CO2 concentration. The increased CO2
- Concentration allows for the plant to resist transpiration, decreasing overall water loss.
What is water potential?
- Water potential is the amount of free energy water has at a specific point. Water moves from areas with
- High water potential to areas with lower water potential. (energy per volume mPA) (trident shape)
- Water potentials are generally negative. More negative means more pull. (sanki eksik olan)
- The speed that water travels through a plant depends on the difference in water potentials.
What is cavitation?
- This occurs to plants in very hot days. When the pull from the surrounding is too high (water potential of
- Atmosphere too low, too negative), cohesion is much weaker than adhesion and bubbles form in the stem
- Of the plant.
What happens to water potential as the stem increases in height?
- Water potential decreases (more likely for cavitation to occur) because it takes more tension at the top
- To balance the increased gravity pulling the water down. tridentP subtracts about -0.01 mPA from the trident
How does soil type affect water potential?
- Pure water has the highest (least negative) water potential, as the attraction to surrounding materials decreases water
- Potential. Thus, water in soil has lower water potential (harder to pull up). Lower water potential in soil
- Increases risk for cavitation, as more suction is needed to pull water up, which increases tension.
How do solutes affect water potential?
- Like soil, they decrease the osmotic potential of water. (tendency of water to move from low concentration to
- High concentration.) This also increases the risk for cavitation.
What are the adaptations of xylems to protect against cavitation?
- While pit membranes make the plant more prone to cavitation, it takes more pressure to cause
- Spontaneous cavitation in xylem to occur simultaneously. Xylems with smaller pits and smaller diameters
- Make the plant less prone to cavitation. However, there’s an important trade-off between small xylems and
- The speed of water traveling through the stem.
What is the CAM adaptation?
- Plants open their stomata at night, storing CO2 in the form of malate in vacuoles. During the day, they keep
- Their stomata closed and reverse the carbon storage reactions.
What are the trade-offs for C4 and CAM?
- Energy is used to temporarily store and reverse reactions, reducing the energy available for light
- Independent reactions. C3 plants outperform CAM and C4 at lower temperatures.
What are the trade-offs between specialists and generalists?
- Specialists are more efficient at digesting specific foods, but it may starve if conditions change. Specialists
- Have more choice, but may not be as efficient.
What is basal metabolic rate (BMR)?
C * mass^(¾) where C is the constant rate for different taxa
What is physiological ecology?
- It is the form of ecology focusing on the individual and its environment. It places special emphasis on the
- Acquisition and utilization of energy and thermoregulation. Physiological ecology has its roots in adaptation.
In which two ways can environmental conditions vary?
- Spatial variation: from place to place (at one time)
- Temporal variation: from time to time (in one place)
How do organisms cope with environmental variation?
- There are two methods:
- Tolerance: Ability of an organism to survive stressful conditions.
- Avoidance: A behavioral or physiological response of an organism to a stressful condition that
- Minimizes exposure.
- Most species have a combination of both.
Why care about solar radiation?
- Energy source for photosynthesis which is the primary source of energy for the biological diversity on earth
- Role in the maintenance of body temperature in animals.
What micro and macro molecules does photosynthesis require?
- Phosphorus (ATP, membranes)
- Nitrogen (DNA, RNA, aminoacids, protein)
- Magnesium (chlorophyll)
- Calcium (cell wall)
- Sulfur (some aminoacids and proteins)
What are the roles of transpiration in plant biology?
- Moves water to the leaves (along the plant)
- Keeps solutes dissolved.
- Provides H2O for photosynthesis.
What is the visible light spectrum? Explain photosynthesis with regard to the light spectrum.
- 400-700 nm. Also called (PAR) photosynthetically active radiation.
- Photosynthesis peaks 450 and 650. Plants are green because green light is reflected.
How do plants know whether they’re shaded because of neighboring plants or because of clouds/ rocks etc.?
- A low ratio of red : far red light is an indication of being shaded by neighboring plants, as they absorb red
- Light whereas clouds etc. don’t. Exposing plants to far red light makes them grow longer but not faster, and
- May even lead to less biomass accumulation due to the energy put into growing a taller stem. This ratio
- Is detected by phytochrome.
What are other ways (other than photosynthesis) to gain energy in an ecosystem?
- Chemosynthesis performed by bacteria turns CO2 into C(CH2O) using rubisco. An example is nitrifying
- Bacteria in soil that turn nitrite into energy (NO2). Another example is green or purple sulfur bacteria, which
- Turn hydrogen sulfide (H2S) into energy. These are found in hot springs, sea vents etc. There are also
- Parasitic and carnivorous plants!