fundamentals of ecology
energy balance:
Hs= Hcv+Hm+Hcd+Hr-He
what is ecology?
The study of relationships between organisms and their environment containing biotic (living) and abiotic (non-living) components
acclimation
(short-term) physiological adjustments to new environmental conditions such that performance is improved
Temperate Grasslands:
- Extremely widespread distribution. • Annual rainfall 30 - 100 cm. • But, experience periodic droughts and fire. • Soils tend extremely nutrient rich and deep. • Dominated by herbaceous vegetation. Peak in temp=peak in precip winters=cold and dry
Microclimate
-Microclimate - small-scale climate -Microclimate can change drastically over small distances -Organisms may take advantage of this by selecting microclimates that most closely match their temperature optima for performance
Climate graphs:
-Once above 100, rises by 200 (dark blue) -Blue: adequate water -red: months above freezing -no shading: below or at freezing -blue above red: moist conditions -Gold: temp above precip=dry -m-S=growing season
C4 (hatch and slack pathway)
-involved PEP carboxylase, NOT RuBP/rubisco -c3 cycle in ALL C4 plants -photorespiration doesn't happen because CO2 outcompetes O2 -C4 only in warm climates
C3 photosynthesis
-most common type used by plants -Co2+RUBP(5 carbon sugar)=2pga -Rubisco packed in mesophyl of leaves -Photorespiration competes with photosynthesis and consumes energy -Hence for a given amount of stomatal opening or water loss, and CO2 let in, C3 plants fix less carbon than plants with other pathways (they have a lower Water Use Efficiency (WUE=photos(co2 fixed)/transpiration)) -Photorespiration increases with leaf temperature -calvin cycle: Co2+RUBP=sugar(light independent)
Electromagnetic radiation
-wavelength and wavebands (higher temp of object, lower the wavelength of radiation emitted) -Planck's Law (lower wavelenght, higher the energy)
In late spring (when water was most limiting), leaf water potentials (and leaf water content) were higher in
. Encelia frutescens
Which species allocated relatively more of its biomass to roots or belowground parts?
. Encelia frutescens
visible spectrum
400-700 nm
turnover time of evapotranspiration
9 days
What does the coriolis effect describe?
The winds rising and moving away from equator: in order top to bottom: polar easterlies, westerlies, Northeast trade winds, Southeast trade winds, westerlies, polar Easterlies
Mountain (orographic) effect
As air rises, less pressure, expands, cools • As it cools it may saturate: precip (higher elev > greater precip) • Also rainshadow effect: leeward (east) side drier than windward (west) at a given elevation
air
As temperature decreases so does the H2O holding capacity of air • As air rises it expands and cools- but concentration doesn't increase • This cold air can't hold as much H2O, often leading to saturation and condensation (precipitation) saturation
What moderates temperatures?
By currents/large bodies of water: Humboldt Current (cold), along the west coast of South America, moving north • Gulf Stream Current (warm), moderates British Isles
How does C4 and CAM differ from C3?
C4 and CAM initially fix CO2 into a C4 acid=OAA?
Main factor contributing to a biome?
Climate
Light colored hairs on the surface of a leaf would strongly reduce (compared to a leaf without the hairs):
amount of solar radiation received by leaf
Greenhouse gas effect
by Svante Arrhenius in 1895 - absorb much of the longwave radiation or heat from the earth
Latent heat flux
change in state of water
If a cloud passes in front of the sun, Hr of an organism would:
decrease
Leaf pubescence often becomes more pronounced or developed within individuals of a species across landscapes as the environment becomes ____.
drier
Hcd
heat lost or gained by conduction (physical contact with another solid objects) (temp of objects in contact(gradient))
Hcv
heat lost or gained by convection (from a moving fluid such as air) (boundary layer (wind speed, size), temp gradient) the greater the thickness of the boundary layer, the greater the resistance to convective heat flow, and the lower the convection rate. "size" of object (larger surface area, lower wind speed at surface, less convection)
Hr
heat lost or gained through (electromagnetic) radiation (absorbance, orientation)
He
heat lost through evaporation/evapotranspiration (ET rate)
Hm
heat released (gained) within an organism (metabolism)
when is oxygen more dissolvable in photorespiration?
hot days
Why would the open growth form (sparse, low density canopy) common in shrubs of hot deserts be advantageous?
it increases heat dissipation via greater convectional heat loss
Why would large leaves (having a large surface area) typically be warmer during the daytime than small leaves under identical conditions and stomatal apertures? Assume that the leaves have the same orientation and surface optical properties.
large leaves would have a thicker boundary layer, reducing convectional heat flux
Two leaves are identical in terms of their stomatal apertures, leaf surface optical properties (percentage sunlight they absorb), and leaf surface area or size. They are growing adjacent to each other in full sun. However, leaf A has a vertical orientation while leaf B has a horizontal (parallel to the ground) orientation. Which leaf would have a higher temperature at noon on a sunny day
leaf b
Which scenario would lead to the greatest convectional heat loss from the lizard to the surrounding air?
lizard surface temperature 10oC higher than air temperature, and high wind speed
The author had previously found that one of the advantages of leaf hairs in Encelia farinosa was "reducing leaf temperatures and therefore also transpiration rate". How would lower leaf temperatures reduce transpiration rate?
lower leaf temperatures would cause lower leaf-to-air vapor pressure deficits, lowering transpiration rates
Compare the water loss rates from a lizard here in the desert during a typical early summer day and night. Assume that the aperture of the pores and any other openings (that allow water vapor loss) on the lizard's surface are similar day and night. Also assume that the air vapor pressure is similar day and night (a reasonable assumption unless a storm system happens to come through). The temperature during the day is many degrees higher than at night. Assume the lizard's surface temperature is the same as its surrounding air temperature. The rate of water loss from the lizard would be much lower at night because the VPD is lower at night. Why is the VPD lower at night?
lower nighttime lizard surface temperatures mean lower saturation vapor pressure, which means a lower lizard-to-air VPD
What happens when sun directly hits the equator?
more surface area heat absorbed directly
light dependent reaction
needs tap & nadph (photosynthesis)
Does the photosynthetic temperature response of Encelia farinosa differ from that of Encelia frutescens?
no
CAM
no bundle sheath -doesnt separate calvin or C4 cycles= happens at same time in different parts of cell -cacti -only uses rubisco when CO2 is high -
heterotrophs
other feeders
Air masses typically rise at equator during the day. Which of the following would increase as the air rises?
relative humidity of the air
Consider a leaf that closes its stomates in the afternoon because of water stress. Closing its stomates would cause leaf temperature to _________, because this would _____.
rise, lower He (lower the cooling afforded by vaporization)
Autotrophs
self-feeders use inorganic matter do photosynthesis
heliotropism Paratropism Diatropism
solar tracking parallel to suns rays perpendicular to rays
Hs
stored heat (total heat stored in an organism)
two most important deterring factors when considering a biome
temperature and precipitation
Concerning leaf temperatures of Encelia farinosa and frutescens the author found that:
temperatures were surprisingly similar in these two species
fgf
the water vapor content of air does not change in the cloud situation. Rather, the water vapor content at the evaporating surface of beetle is lower, which lowers the VPD.
Deserts:
water loss exceeds precip<20-30cm Plant cover ranges from sparse to absent. Animal abundance low, but biodiversity may be high. cold or temperate desert: 5 red months with precept below temp
when do plants transpire
when they can afford to loose the water-do not transpire to cool:it is a side effect of opening stomata to let in co2
Where are the arctic and antarctic circles located?
~66.6 N and S
Tropical Rainforests
• Most occur within 10o latitude of equator. • Little temperature variation between months. • Annual rainfall of 200 - 400 cm relatively evenly distributed. • High biodiversity & Net Primary Productivity (NPP)
Layer of soil:
• O horizon: Organic Layer freshly fallen organic material - most superficial layer. • A horizon: Mixture of minerals, clay, silt and sand. • B horizon: Clay, humus, and other materials leached from A horizon - often contains plant roots. • C horizon: Weathered parent material.
Temperate/deciduous forests
• Rainfall averages usually 65 - 300 cm. • Fertile soils - Long growing seasons dominated by deciduous(shed leaves) plants. • Biomass production can be very high.
Boreal/coniferous forests (Taiga)
• Thin, acidic soils low in fertility. • Dominated by evergreen conifer (pine cones and needles) • Shorter growing season (colder) than deciduous forest biome
precipitation axis does what versus a temp axis?
Double
airidity
Dry
Under similar conditions (incoming solar radiation and leaf orientation), the amount of solar radiation absorbed by a leaf (per unit leaf surface area) would be greater in which species?
Encelia frutescens
Which species had consistently higher leaf conductance and transpiration rates?
Encelia frutescens
Biomes:
Large regions of land with distinct vegetation (forest grassland desert)
What is an ecosystem?
The community and the abiotic factors of the system
Differences between climate and weather
Weather: Short term instant Climate: Long term average
