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F 311: EXAM 2
soil development: What are driving variables? |
climate
parent material
topography
Land use |
soil development:
What are State Variables |
vegetation, animals, microbes & soil structure, chemistry, fertility |
characteristics of soil
|
properties and profile develop with depth |
Where is ecosystem species diversity its highest |
95% of diversity is in the soil |
why are soils important? |
-soils are alive
-95% of diversity
-forests can only be sustained if soils are |
What is soil made out of? |
Air 20-30%
water 20-30%
Mineral 45%
Organic 5%
soils ar often half pores
all chemical reactions occur in organic material |
What is the size ratio of minerals: clay slit and sand |
clay small
slit medium
sand big |
Why does mineral and organic size matter? |
Determines the size of surface area
the capacity of soil to hold water
-sands don't hold as well as clay and clay holds more of it |
Importance of soil pores
macropores?
compaction? |
macropores drain with gravity and provide space for organic organisms and plant roots
compaction causes water loss and the ability to absorb less water
|
What are the important elements/nutrients for plant growth? (5) |
-Nitrogen:good of enzymes, proteins, DNA
-Phosphorus: lipids, ATP, DNA
-Potassium: activating enzymes,
salt levels
-Calcium: cell wall
-Magnesium: chlorophyl, enzymes |
How do nutrients increase growth?
(fertilizers) |
more nutrients (fertilizer) increases tree growth more leaves and more growth/leaf |
how to test and interpret nutrient dependency in plants |
comparing nutrients and having test areas and control areas of different values |
NPP |
Net primary production
=gpp-R |
R |
how much respiration occurred |
GPP |
Gross Primary production
sum of all photosynthesis done in the system |
carbon balance |
the amount of carbon put out by humans minus the amount taken up by the earth |
How much solar energy goes into the biomass?
Where does it go? |
about 50%
foliage= 10-31%
wood r=4-25%
root production and respiration 25-62% |
Production ecology equation |
resource * fraction captured*efficiency of conversion*fraction to component |
efficiency of larger tree resource use vs. smaller tree use |
smaller trees are less efficient at using resources (less photosynthesis or more allocation away from wood) |
CAI |
current annual increment
(volume growth rate for current year or between measurement periods)
|
MAI |
mean annual increment (average volume growth rate over entire life of stand) |
define
succession |
observed process of change in species structure of an ecological community
|
arguments against succession |
1. succession is not a process
2.the specifics of ecosystem change are unpredictable and influenced by numerous legitimate process that vary in importance over time
3. On-the-ground evidence of succession is rare |
trends in forest change:
common trends |
long lived conifers can survive after aspen die |
trends in forest:
size of deviations from the trends |
aspen-conifer stand shifts conifer about 1/3 of the time |
What is the importance of riparian ecosystems? |
most diverse, productive and important ecosystems
-plant richness of 20-80 species per .1 ha
-about 48% of birds only net here
-flood mitigation and erosion control
-economic value of sport fishing |
changes in river flows impact on vegetation |
-changes in plant communities through space and time
-soil nitrogen patterns
-plant diversity |
absence of floods on the cottonwood |
stresses out seedlings & causes adults to grow deeper roots to access water tables |
What are rapid ways for trees to die? |
wind
insects
fire |
difference between disturbance vs stress |
disturbance= less predicable more rapid
stress= more predictable more chronic |
are all disturbances the same? |
NO
different causes, effects, and extent |
probability od disturbance
if we have a 10,000 area and each year 100 ha burns then... |
odds of a fire in a given area each year is 1%
the average interval (time between fires at a given area) is 100 yr |
Bark beetles mass attack: |
kill the tree or be killed by the tree |
bark beetles go from an endemic to an epidemic why? |
an attack on a few trees to warm temperatures and droughts enabling tree death
|
winds effect on soil |
pit mounds by tree roots being pulled out of ground |
beetle effects on soil |
wetter soil not much impact on nutrient release |
fire effects on soil and nutrients |
causes nutrients to turn to gas and ash and be lost
wet soil is safer & ground fires are fires effecting soil most |
tree mortality from beetles is about equal to that of fires true or false |
true |
What is fire? What about energy release? |
some organic compounds break into small pieces and evaporate (vaporize or volatilize) These gases rise, and then mix
with
oxygen
and
combust
releasing
energy
|
wood vs. charcoal |
wood burns easier at 500 F
while charcoal won't burn unless its 1100F |
ground fire |
burning organic soil layer |
surface fire |
burning fuels a few m above surface |
crown fire |
burning canopy |
passive crown fire (torching)
|
surface fire ignites individual trees from below |
Active crown fire
(running) |
crown fire spreads from tree to tree |
erosion with fire |
usually increase a bit after fire sometimes a lot |
hydrophobic areas after a fire |
usually higher than the control |
fire regime |
usually summarized by frequency and severity (variance also important) |
fire regime extent, intensity & severity |
extent-size of fire
intenisty- energy released from fire
severity-impact of a fire |