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187 Cards in this Set
- Front
- Back
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soil water storage
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-important bc plants haven't developed h2o storing ability
-stores h2o in times when precipitation isn't available to plants ---systems can still have high productivity & buffer climate in dry periods |
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humid regions in relation to energy & water
available to plants |
rainfall exceeds the amt that can be evaporated
-energy limited (not h2o limited) |
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arid regions in relation to energy & water
available to plants |
have more energy than water
-water limited in terms of production |
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Actual Evapotranspiration
(AET) |
-actual amt of water evaporated at a site
-measurement of ENERGY & WATER availability -**most important predictor of patterns of Terrestrial Productivity |
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Potential Evaporation
(PET) |
highest in semitropical cloudless areas
(areas limited by h2o availability) |
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AET/PET
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= index of aridity
deserts = low humid = value approaches 1 [reversed eq: PET/rainfall dry = high values wet = values lower than one] *raising PET shows that we're warming the planet |
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matric potential
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ability of water to adhere to a surface
DEPENDS ON: 1)physical comp of soil 2)texture |
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3 classifications of soil water
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1) superfluous water
2)available water 3)unavailable water |
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"superfluous water"
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water in excess of field capacity
(susceptable to gravity) |
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available water
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amt of water found between field capacity & wilting pt
(soil characteristic) |
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"unavailable water"
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water held in soil below wilting point
1)inner capilary water 2)hygroscopic (basically nonliquid) water |
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soil textures in relation to plant available water
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loam > clay >> sand
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rules for soil / soil water
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-only water in excess of field capacity can be removed by gravity
-until the top layer of soil reaches field capacity there's no movement of water -arid soils are dried to permanent wilting pt on annual basis --humid zone soils recharge to field capacity each year |
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depth of soil wetting equation
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depth of wetting =
rain / (field capacity - current h2o content of soil) |
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wetting patterns
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soils with high field capacities retain more h2o / unit of soil
-soils w/ high field capacities wont be wetted as deeply as soils w/ low field capacities -only soil water held @ surface vulnerable to evaporation (few cm @most) -in arid zones clay soils more droughty than sand soil (opp in humid) |
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soils comp of solids v pore space
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50 % solids
(rest is gas & h2o) |
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formula for how much water is available to plants
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field capacity - wilting pt
= h2o available to plants |
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textures in relation to plant available water held
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loam > clay > sand
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after water's filled to field capacity
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extra water drains to deeper horizons
(how the soils recharge during dry seasons) *top soil can be at field capacity while lower soils are at perm. wilting pt* |
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plant survival in arid ecosystems
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plants attempt to use h2o as soon as its delivered
-when dry down proceeds plants can go dormant |
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plants compete for soil available water w/ surface evaporation
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but depth evaporation can take water from is limited
-deeper water is only available to plants (roots) |
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importance of sand in arid areas
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soil best for holding water for plants holds only 75% of water in sand ("droughty soil")
-how much water soil can hold/unit not important to plants -- its how much water can be provided -sandy soils are better in arid areas -sand soils grow more plants when rainfall < 37 cm {clays & loams grow more plants when rainfall > 37 cm} |
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"weather" is generated by
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latent heat & sensible heat
1)"ground heat flux" huge in deep lakes / oceans 2)smaller on land 3)storage (photosynthesis) trivial but veg effects huge bc -effect on albedo -effect on partitioning of heat (sensible & latent) due to evapotranspiration |
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regional/local controls
on water & energy cycles |
fate of water
Function Of: -available energy -vegetation type -soil texture [fate of water::: -ecosystem water budget -PET & AET |
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abreviations / terms
-Rn -S -a -L -LE -H -G -S |
-Rn = net radiation balance (increase/decrease in energy content)
-S = solar radiation -a = albedo -L = net longwave rad -LE = latent heat (used to evaporate water) -H = sensible heat (pumped into kinetic energy of atoms to change state) -G = energy transferred to & from ground -S = storage = vPs = energy into plant chemical energy |
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vegetation's effects on outputs
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albedo -- decreases
sensible heat -- decreases latent heat -- increases longwave rad -- decreases (bc of latent heat) |
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Potential Evapotranspiration
PET term |
the mm's of h2o that can be evaporated if water isn't limiting
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Actual Evapotranspiration
AET term |
actual amt of water evaporated at a site
FUNCTION OF: -how much solar energy present -if water is available to evaporate [deserts = lots of solar rad but no water = NO AET arctic = lots of water but little solar rad = little AET] **estimate of both water and energy** |
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AET in limited water areas
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annual AET = mm of rainfall
*but when h2o is more abundant than energy (humid areas) AET will be LESS than rainfall value* |
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Soil Profile
(listed horizons) |
O
A E B C |
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O horizon
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litter / soil organic matter (SOM)
-NO MINERALS |
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A horizon
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rooting zone
minerals & partially processed SOM |
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E horizon
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weathering / leaching zone
mostly mineral |
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B
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decomp of clays and minerals
predominantly minerals |
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C horizon
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parent material (unweathered)
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what makes nutrients available in the soil?
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ACIDS!
-provide mechanism to knock nutrients off exchange sites so they're in soil solution |
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weathering of parent material provides
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-nutrients
-secondary minerals (function as ion exchange sites) |
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Acids Provide
(carbonic acids, nitrate..) |
NECESSARY to drive weathering
AND Get ions off humus & ion exchange sites!!!!! |
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what do "new nutrients" to the system do?
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-come from either decaying plant material
-or weathering --KNOCK ACID (H+) OFF EXCHANGE SITES --H+ exchanged for nutrients ----so sites continually replenished & not lost to leaching &such |
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"wilting point"
|
water soil can hold against root uptake
-depends on soil texture AND plant adaptations |
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"field capacity"
|
moisture content not susceptible to gravity
--held by soil |
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"saturation"
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all pore spaces full
-SUBJECT TO GRAVITY |
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"plant available water"?
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(Field Capacity) - (Wilting Point)
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-Field Capacity
-Wilting Point -Plant Available Water FOR:: CLAY - LOAM - SAND |
FIELD CAPACITY:
-clay = .54 g/cm^3 (holds most water) -loam = .38 g/cm^3 -sand = .17 g/cm^3 WILTING POINT:: -clay = .36 -loam = .16 -sand = .08 (still plant available water til .08) PLANT AVAILABLE WATER:: -loam = .22 -clay = .18 -sand = .09 |
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residence time of soil component
calculated as |
residence time = 1 / (decay rate)
(decay rate = inputs/amt of storage) |
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"Net Ecosystem Production"
is |
-live biomass
-dead material |
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clements
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plant ecology
-concept of community as a superorganism |
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Tansley
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didn't like the way clements only focused on biota
-suggested that integration of biotic and abiotic can form ONE PHYSICAL SYSTEM -DEFINED ECOLOGY -advocate of hierarchy theory |
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Lindeman '40s
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trophic dynamic concept
patterns of energy flow |
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leopold '49
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sand county almanac
some nutrient cycling |
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Odum '53
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FIRST TRUE ECOLOGY BOOK
-a lot based on lindeman's energy flow work -only book til ~20 yrs later -ignored evolutionary ecology |
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'60s?
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first terrestrial ecosystem studies on nutrients conducted
-silent spring -first real wave of enviromentalism -"international biosphere program" -(funding) |
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70s?
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LTER network
long-term ecological research network -funding |
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the ecosystem approach
(of systems) based on |
hierarchy theory
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hierarchy theory
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-OBJECT (ecosystem / organism)
-has an ENVIRONMENT which constrains the object via energy & material ---provides the CONTEXT for which object is explained -how the object FUNCTIONS w/i the enviro is explained by looking at its PARTS -the parts are a system that gives the object its behavior & characteristics |
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level above the object?
(hierarchy theory) |
the context - the enviro
-WHY THE OBJECT IS THERE |
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level below / within the object
(hierarchy theory) |
PROVIDE THE MECHANISMS
-explain HOw the object works |
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"units" of ecosystem ecology?
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-energy
-mass recycling.... |
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an ecosystem studied for enviro change issues
must be looked at |
@level above
-showing consequences of change (the changing enviro of an organism) @level below / within:: -as a mechanism for change (ie part of a higher unit) |
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1st law of thermodynamics
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energy cannot be created or destroyed
-but may be converted from one form to another |
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2nd law of thermodynamics
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-all energy transfers result in some lost / unusable energy
(waste heat) -no energy conversion is 100% effective |
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calorie
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energy needed to raise 1 cm^3
of H2o 1*C @ 15*C |
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solar constant?
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2 calories / cm^2 / min
biosphere bathed in solar radiation at this rate -the amount of radiation received at surface perpendicular to sun @ outer space boundary |
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what form is solar radiation in?
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electromagnetic radiation
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max energy received @ outerspace boundary?
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2 cal / cm^2 / min
(the solar constant) -@ perpendicular surface -surfaces moving from 0 to 90* = amt of energy drops to 0 |
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departing energy = entering energy
on avg @ outerspace boundary |
solar rad in = albedo + longwave out
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vegetation albedo
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15 - 20 %
snow ~ 95% |
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albedo of clear water
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very low when perpendicular to light source
-unit of ocean absorbs more light than unit of land |
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energy exchange at outerspace boundary?
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all electromagnetic radiation
-open system w regard to energy --closed to matter ----energy needing matter as carriers can't pass |
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latent heat
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energy needed to change state of water
from frozen to liquid and liquid to water vapor |
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sensible heat
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associated w the heating of materials
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@ earth's surface
energy can.... |
-latent heat
-sensible heat -go into momentum (physical transport of mass) -chemical energy (photosynthesis) -transported into ground (sensible) |
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photosynthesis energy returned by respiration
energy transported into ground re-released into atmosphere Q's? |
annual average = 0
(numbers can be ignored) |
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avg surface at best will receive how much solar rad
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HALF the solar constant
only 44% of that half is visible light & can be used by photosynthesis -PLANTS ARE DOWN 1/4 OF THE SOLAR CONSTANT |
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2 reasons energy varies over globe?
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1) latitudinal patterns
2)land v water patterns |
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net radiation input
land v water |
net radiation input
lower over land higher over water -Lower Surface temp of water allows more solar energy to be stored (as sensible & latent heat) --than is lost by Longwave rad (function of temp of obj) |
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subsidy of energy from tropics to poles
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energy captured in tropics transfered to poles
---(eventually lost at poles as longwave rad) -poles would be MUCH colder w/o this energy transfer |
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linkage of energy & hydrologic cycles
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evaporation from land / ocean removes energy from surface
-transfers to atmosphere -rereleased in cloud formation (solar powered global water cycle) |
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hydrologic cycle
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-closed
-global -sizes / rates of components vary significantly (residence time for h2o in atmosphere = 11 days residence time in ocean = 3500 yrs) |
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global Precipitation patters
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-declines from tropics to poles
--but peaks at 40* N & 40*S ----the peak in N hemisphere is less extreme -land masses change precip patterns |
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el nino / southern oscillation
(ENSO) |
repeatable pattern
but largely unpredictable |
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rainfall & temp predict what type of ecosystem SHOULD be there..
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but varies greatly with overlab
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water's albedo
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100% for very low angles
-after sun 25% above horizon ---albedo's less than 10% |
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Jenny
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'41
state factors |
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soils are a function of
(jenny) |
-climate (cl)
-organisms (o) -topography (r) -parent material (p) -time (t) CL.O.R.P.T. |
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weathering definition
(formula) |
rocks + acid = secondary minerals + nutrients
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causes of weathering
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CL,O,R,P,T
-biota -temperature -moisture |
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essential plant elements
(must have for survival) |
C, H, O, P, K, N, S, Ca, Fe, Mg, Mn, B, Cl, Cu, Zn, Mo
chopkins cafe mightygood mighty night but for clara and cousin moe. |
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limiting nutrients
(not an abs quantity needed) (similar to stress) (can be limiting bc everything else isn't) |
-NITROGEN
-PHOSPHOROUS -OTHER --potassium (agroecosystems) --iron (polar oceans) |
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nitrogen limiting in ::
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-arctic
-boreal -temperate terrestrial -tropical -ocean |
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phosphorous limiting in ::
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-temperate aquatic
-tropical |
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limiting reasources can be...
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-single resouce
-multiple limitation -switching ---ecological succession ----geologic time ---growing season |
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source of soil fertility
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weathering of parent material
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2 factors important for weathering & creating soil
|
moisture
temperature |
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oldest soils?
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in tropics
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weathering of igneous & metamorphic rocks
1)in cold temperate 2)in tropical |
1) cold temperate::
silica sand 2) tropical iron & aluminum oxides |
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parent material produces
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1)nutrients
2)substrates (clays) --short term storage --w/o this storage there would be too much leaching |
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open ocean low in productivity
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bc no soil
-no site to store nutrients |
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"soil fertility"
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ability to provide plants with essential nutrients
fertile soils have: -large stores of nutrients -adequate water for delivery of nutrients |
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soil succession
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SAME THING AS WEATHERING
parent material + acids = nutrients + secondary minerals (2:1 clays) 2:1 clays + acids = nutrients + 1:1 clays 1:1 clays + acids = iron / aluminum oxides + nutrients iron / aluminum oxides + acids = dissolved iron / aluminum |
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2:1 clays =
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secondary minerals
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soil succession is....
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the decay of soil
(to dissolved iron / aluminum) -soils reappear 10 mill yrs later as new parent material (Cyclic by geologic time) |
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most important factors for soil @ GLOBAL scale??
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climate
time the process has had to occur |
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weathering of parent materials most extensive...
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in the tropics
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tropics soils can still be fertile due to
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disturbances
volcanos earthquakes landslides |
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soil horizons result from
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interaction of
Cl, O, R, P, T |
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horizons in old tropic soils
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only E (leached) zones
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Arctic soils
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raw organic matter
over frozen mineral soil (permafrost) O layer only |
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boreal / coniferous forests
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dissolve everything but silica
(white layer in soil) |
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most fertile soil?
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PRAIRIE!
-sufficient rainfall & temp == 2:1 clays .. well mixed w/ humus ONLY A B C horizons |
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very young soils?
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desert
lack of water = lack of acids = lack of nutrients |
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Soil Fertility
DEPENDS ON |
NUTRIENT AVAILABILITY & VULNERABILITY:
-nutrients for plants come from soil solution -nutrients in soil solution vulnerable to leaching & grabbed by plants / microbes -nutrients in clay / humus available & not vulnerable to leaching -nutrients locked in organic matter not available NUTRIENT STORAGE: -clays -humus Controllers of CLay & Humus? -weathering -------(parent material + acids = clay + nutrients) -humus made during decomposition nutrient storage sites have the ability to hold on to cations (& anions) |
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"Rn"
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NET radiation balance
(+/- in energy content) |
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"S"
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Solar Radiation
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"a"
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albedo
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"L"
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net longwave radiation
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"LE"
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Latent Heat
(used for evaporation of water) |
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"H"
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Sensible Heat
(kinetic energy of atoms... used to heat things) |
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"G"
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energy transfer in / out of ground
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"vPs" (S?)
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Storage
energy going into plant's chemical energy |
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factor determining plant available soil moisture?
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TEXTURE
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"matric potential"
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attraction between H2o & surfaces
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amount of water soil can hold
DEPENDS ON |
1) total surface area (amt of clay & humus)
2)porosity [surface area : volume clay > silt > sand] |
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texture w highest nutrient & h2o holding capacity
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CLAY
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highest h2o infiltration rate
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sand
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texture w highest permanent wilting point
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clay
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depth of moisture
formula |
depth of moisture = ppt / (field capacity - current)
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"ppt"
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precipitation
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coarse soils
v fine soils |
COARSE
-low field capacity --h2o goes deeper into soil FINE: -high field capacity --h2o hung up in top layers (carbonate accumulate - then blocks h2o) |
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"capillary action"
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brings salt to surface
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why can sand sometimes provide more water?
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because water goes deeper (isn't hung up in top layers)
-not susceptible to evaporation |
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best soil
when h2o isn't limited |
CLAYS
-have the CEC --hold the nutrients |
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boulder's
short grass v tall grass |
short grass = high clay content
tall grass = coarse soil |
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2 factors explaining
productivity |
1) texture
2) precipitation |
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plants in sand
(below ground v above ground) |
ground = 2/3
air = 1/3 |
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wilting point controlled by
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plants
-the amt of h2o they can pull off (doesn't vary too much tho between plant species) |
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rhizosphere
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area around root that they're able to gain h2o from
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plants get help gaining h2o from
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mycorrhizae fungii
-plants give them C, H, O (organic stuff) -they give H2o in return -plants control if relationship happens -used by both fibrous & tap roots |
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Tap Roots
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better at getting deep soil water
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fibrous roots
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better at getting shallow soil water
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micropores
effect on h2o |
preven h2o from going deep
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tropical shrublands
-roots? |
DEEP
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Boreal / Deserts / Coniferous / Deciduous / Grassland
-roots? |
-SHALLOW
---- no need for deep roots |
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Hydraulic Lift
|
-take h2o out of deep soil
-dumps it into shallow soil @ night -grabs same h2o in day (gets more nutrients -- bc in shallow soil) drawbacks: -susceptible to competitors |
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surface turbulance increases...
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the transfer of sensible & latent heat to the atmosphere
[caused by winds blowing across rough surface.. .transports warm moist air away & brings cool dry air back] |
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how does LE (latent heat) effect H (sensible heat)
|
latent heat = evaporation of water
--->cools the surface -reduces the difference in temp between surface and air --therefore REDUCING sensible heat (the temp difference between surface and air is what drives sensible heat) |
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how does H (sensible heat) effect LE (latent heat)
|
sensible heat warms the surface air
-which increases the amt of water vapor the air can hold --causes the movement of moist air away from surfaces |
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moist ecosystems
w regard to latent & sensible heat |
high moisture = higher rates of evapotranspiration (lower bowen ratios)
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turbulent winds
effect of latent & sensible heat |
turbulent winds prevent temperature buildup at surface... reducing sensible heat flux (lowering bowen ratio)
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a tight linkage between the energy budget & hydrologic cycle
mean..... |
a low bowen ratio
(low sensible heat, high latent heat) |
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"ecosystem processes"
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transfers of energy and materials from one pool to another
-energy enters w light -lost when organic matter goes back to co2 movement of materials: -weathering -evaporation biotic components -absorbtion of minerals by plants -decomp of dead matter |
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ecosystems range in size:::
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from rock ecosystem
to forest to global ecosystem |
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ecosystems at "steady state" if
|
balance between inputs and outputs to the system show no trend w time
(accept temporal and spatial variation == no ecosystem is in true equilibrium) -even at steady state - plant growth varies w the seasons |
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who?
systems approach to studying ecosystems |
ODUM
(systems approach = patterns of energy and such) |
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what enviro questions can be addressed by ecosystem ecology
that can't be addressed by population or community ecology |
-conserving biodiversity approach
(not just species approach) -how we're affecting global budgets of materials / energy -global patterns of co2 & pollutants in the atmospheregive evidence of major locations / causes of global problems |
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pools
& fluxes |
ecosystem analysis tries to understand factors that regulate
1)POOLS --- QUANTITIES 2)FLUXES ---- FLOWS OF MATERIAL/ ENERGY |
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state factors control on processes
-strengths & weaknesses |
strengths:
-considered the controls over processes (not just patterns) weaknesses: -ecosystem processes both control & are controlled by factors -"interactive controls" |
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differences between state factors & interactive controls
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state factors aren't controlled by the ecosystem
interactive controls both control the ecosystem and are controlled by the ecosystem (light, temp, moisture) |
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human activities affecting interactive controls
|
-water availability (we use ~ 1/2 world's runoff)
-disturbance regime -biotic diversity -transformation of land -gasses (cfc's---ozone destruction) -chemicals (ddt) |
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of the 100% shortwave that comes to outer space boundary...
|
100%
-31% albedo (shortwave reflected from clouds) -20% absorbed by atmosphere -49% reaches earth's surgace OF THE 49% THAT REACHES EARTH'S SURFACE 69% emitted as longwave (due to low surface temp) -the remaining is transferred from earth's surface to the atmosphere via latent or sensible heat |
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atmosphere absorbs how much long wave? (%)
|
atmosphere absorbs 90% of the longwave emitted by the surface
-its then reradiated in all directions as longwave (greenhouse effect!) |
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greenhouse gases?
|
-water vapor
-carbon dioxide -methane -nitrous oxide -CFCs (="radiatively active gasses") |
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without the greenhouse effect earth would be?
|
33*C cooler
-probably not support life |
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climate variability due to
|
-greater heating at equator than poles
-continents spread unevenly |
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clouds effects on radiation
|
-high albedo
--reflect more incoming shortwave than earth's surface (high clouds) -composed of water vapor --absorb a lot of longwave (low clouds) |
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unequal heating of earth's surface
|
-equator receives more incoming solar radiation
---rays perpendicular @noon ---high lat = rays spread out (less rad / unit ground area) -@ higher lat rays have longer path thru atmosphere ... more rad absorbed, reflected, scattered before reaches surface = higher temps in tropics (drives atmospheric circulation) |
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the movement of air from surface up! (beginning of atmospheric circulation)
|
at equator the transfer of energy from surface to atmosphere = strong heating @ surface
-warming causes air to expand - less dense --rises --decrease in pressure w height = continued expansion -->rising air cools -cooler air has lower capacity for water vapor --rains (releases latent heat) --latent heat lowers the rate @ which air cools --- so can make air warmer... continue to rise |
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atmospheric circulation in full
|
-surface air rises most strongly @ equator
-expansion of equatorial air creates horizontal pressure gradiant --causes the risen equatorial air to to flow toward the poles -poleward moving air cools due to longwave emission to space -gets smaller in volume bc earth's SA = smaller --denser --creates higher pressure --air subsides --pushes surface air back toward equator |
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hadley cell
|
driven by expansion & uplift of equatorial air
(0* - 30*) |
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Ferrel cell
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driven indirectly by changing processes
(30* - 60*) |
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polar cell
|
driven by subsidence of cold converging air at poles
(60* - 90*) |
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coriolis force
|
arises bc earth is rotating
-deflected right in N hemisphere -deflected left in S hemisphere (reason for 3 cells, not 1) -create jet streams & westerlies... ne trade winds |
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uneven distribution of land and oceans ....
|
creates uneven pattern of heating
-@ 30* N & S air descends stronger over cool oceans bc air is cooler and more dense over the ocean (S) -creates high pressure zones & low pressure zones (explains ferrel cells) -low pressure centers rise to balance subsiding air in high pressure centers |
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ocean circulation's effects on climate
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accounts for 40% of heat transfer from equator to poles
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vegetations effect of climate
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effects climate thru its effect on the surface's energy budget
-forests have lower albedo than grasslands -energy absorbed by vegetation transferred to atmosphere by L, LE, & H -forests = more precipitation = lower temp = more evapotranspiration |
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longwave radiation's dependence on surface temp
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-surface temperature higher when lower albedo
-also higher temp when there's little water to evaporate -also higher temp when surface is smooth (inefficient in transferring sensible & latent heat to atmosphere) HIGH SURFACE TEMPS = EMITS LONGWAVE |
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high pressure zones
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-N & S poles
-30* N & S -air descends, precipitation is low |
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high pressure zones
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-equator
- 60* N & S air rises, precipitation is high |
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soil properties result from a balance of
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soil formation
& soil loss |
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erosion rate
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-influenced by topography
-depositional areas at bases of slopes (deep fine textured soils) --higher rates of ecosystem properties |
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soil formation
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depends on balance between
-deposition -erosion -soil development -highly weathered landscapes = erosion renews soil fertility by exposing less weathered materials (new source of nutrients) |
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development of soil profiles
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soils develop thru:::
-addition of materials -transformation of these materials -loss of materials |
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additions to soils
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-precipitation
-wind -organisms w/i ecosystem |
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soil transformations
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-decomposition
(carbon dioxide and nutrients -weathering (produces more stable forms) - |
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"soil texture"
definition |
the proportions of soil particles of different sizes
clay < silt < sand clay = largest propotion of secondary minerals -largest SA:Volume ratio --hold most h2o |
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"ecosystem"
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an ecological system consisting of all the organisms and the abiotic enviro w which they interact in a given area
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source of acid in chemical reactions
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CARBONIC ACID
-most important -co2 dissolves and reacts with water -then ionizes to produce H+ ions |
