Download Lab lecture #2

Sampling Techniques
THE SEQUEL
Warning!
• Material included on Lecture Exam #1!
Importance
• Which plants “important?”
• Measures importance (sp. A)
– Density of A = No. inds. per unit area (reflects
abundance A)
– Frequency of A = No. times sp. A in samples
divided by total samples taken (reflects pattern A)
– Cover of A = Area occupied by A (reflects
biomass A)
Methods
• 1) Quadrat
• 2) Belt transect
• 3) Line intercept
• 4) Plotless (distance) methods
Plotless (distance) methods
• Based on points (0 dimensional method)
• Often trees along transect
Plotless (distance) methods
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Collect:
1) tree ID
2) tree size (reflects biomass/cover)
3) distance measurement (from something to
something)
Plotless (distance) methods
• Method 1: Nearest individual method
Plotless (distance) methods
• Method 2: Nearest neighbor method
Plotless (distance) methods
• Method 3: Point centered quarter method
Plotless (distance) methods
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Information Collected:
1) tree ID
2) tree size (reflects biomass/cover)
3) distance measurement (from something to
something)
• IV= Rel. density + Rel. frequency + Rel. cover
• <300%= <100% + < 100% + < 100%
• How get rel. density, rel. frequency, rel. cover
values?
Plotless (distance) methods
• Cover: have DBH
• Convert DBH to area trunk each species
Plotless (distance) methods
• Cover: have DBH
• Convert DBH to area trunk each species
• % rel. cover species Y:
– Cover Y/Cover all species X 100%
– IV= Rel. density + Rel. frequency + Rel. cover
Plotless (distance) methods
• Frequency: tree identities each point
• % frequency species Y:
– No. pts. with species Y/Total number pts. X 100%
• % rel. freq. sp. Y:
– Freq. Y/Freq. all species X 100%
– IV= Rel. density + Rel. frequency + Rel. cover
Plotless (distance) methods
• Density: ?? No areas measured??
• Geometric principle: as density increases
distances measured decrease
– Note importance random placement points!
Plotless (distance) methods
• Steps:
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1) Calc. mean distance (D) for all trees sampled
2) Use formula:
Density (all species) = A/(correction factor)(D)2
For metric units:
A=10,000 m2/hectare (ha)
D in meters (m)
• Correction factor?
Plotless (distance) methods
• Steps:
• Correction factor?
– 2 nearest individual method
– 1.67 nearest neighbor method
– 1 point centered quarter method
Plotless (distance) methods
• Steps:
• Correction factor?
– 2 for nearest individual method
– 1.67 for nearest neighbor method
– 1 for point centered quarter method
• 3) Calc. density species Y:
– No. Y/No. all species X Density (all species)
• 4) % rel. density Y:
– Density Y/Density all species X 100%
Plotless (distance) methods
• IV species Y
• IV= Rel. density + Rel. frequency + Rel. cover
• <300%= <100% + < 100% + < 100%
• Repeat calcs. other species
Plotless (distance) methods
• Point Centered Quarter method:
– 1) More data/point
– 2) Relatively simple
– 3) No correction factor in density formula
(correction factor = 1)
How place sample units?
• Generally, random best
• Define?
• All potential samples have equal chance
inclusion
• Why best?
– Eliminate bias
– May be required: statistics/equations (e.g., density
formula for plotless methods)
How place sample units?
• Random not same as:
• Arbitrary: Attempt eliminate conscious bias
• Systematic: Use numeric pattern (ex, every 5th
tree)
• Deliberate: Choose with criteria (ex, all trees >
30 cm dbh)
How place sample units?
• Random not always representative sample
• Ex:
X
X
X
X
X
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X
X
X
X
X
How place sample units?
• Techniques:
• Random
• vs.
• Stratified random (subdivide area & sample
randomly in each division)
How place sample units?
• Techniques:
• Systematic
How place sample units?
• Techniques:
• Random-Systematic (start random, place
points systematically: or vice versa)
random
random
OR
Ch. 4: Soils, Nutrition etc.
• Definition:
Soil
– Natural body: layers (horizons)
• Definition:
Soil
– Natural body: layers (horizons)
– Mineral + organic matter (OM)
– Differs from parent material: substance from
which soil derived
Weathering Factors
• Mineral component: generated by weathering rock
Soil Texture
• Major particle sizes (know these)
know these
B: clays
A: Sand & silt
Textural triangle
• Distribution particles by size class: texture
• Loam: mix sand, silt, clay
• Texture important: fertility, water availability
Soil Structure
• Particles form peds
• Affect water + root penetration
How important??
Organic matter (OM)
• Humus: partly decomposed OM
• Negatively charged:
– carboxyl groups (-COOH)
– phenols
Soil Horizons
Soil Horizons
• Vertical gradients
– Leaching: wash material upper to lower layers
– Weathering: great at surface
– Biotic effects: great at surface
Soil Horizons
• Major horizons:
• O: organic matter (surface)
• A: surface soil. High organic
matter
• E: leaching strong
Soil Horizons
• Major horizons:
• B: subsurface soil.
– Deposition
– Chemical changes (secondary
minerals/clays)
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Soil Horizons
Major horizons:
B: subsurface soil.
Hardpan: cemented soil grains
Claypan: dense clay
Both: interfere water
penetration, roots
• Humic layer: organic matter
from E
Soil Horizons
• Major horizons:
• C: weathered parent material
• R: unweathered parent material
Soil Horizons
• Layers subdivided (numbers)
Fig. 4.5
Organisms
• Plants influence soil & vice versa
• How?
• 1) Roots
– Depth: record 394 ft: fig tree (Echo Caves, South Africa)
– Amount (biomass/unit volume/yr)
– Size: woody (shrub/tree) vs. fibrous (grasses)
Organisms
• How plants influence soil?
• 2) Base cycling
• Nutrients “in play”
Organisms
• Fertile island effect: under desert shrubs soil fertile
• Ex, creosote bush: under shrubs--more nutrients
Organisms
• How plants influence soil?
• 3) Litter acidity
• Ex: soils under spruce (conifer) vs hardwood
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Parent Material
Within climate, parent material major influence
Ex, serpentine soil
High Mg, low Ca
Lots Ni, Cr
Parent Material
• Extreme cases, serpentine
“barrens”
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Parent Material
Within climate, parent material major influence
Ex, granite outcrop soil
Forest on granite
Lots sand (coarse texture)
in Australia
Soil dry (water drains)
Time
• General trends (as time increases):
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pH decreases
organic matter increases
clay increases
depth increases
Soil Fertility
• Defn.: Ability soil hold & deliver nutrients
• Determined by texture, organic matter, pH
Holding soil….
• Texture: clays
Soil Fertility
– Negative charge: hold useful
cations (Ca++, K+, Mg++, Zn++)
• Huge surface
Soil Fertility
• Humus negative charge: clay & humus hold cations
Soil Fertility
• Cation Exchange Capacity: amount
negative charge/unit soil
• Units: centimoles charge/kg dry soil
(cmolc/kg)
• Represents “potential fertility”
Soil Fertility
• Exs:
• US prairie: 30 cmolc/kg
• NE US conifer forest: 2 cmolc/kg
Soil Fertility
• H+ (& Al+++) also attracted negative charge.
– Not useful.
• Base saturation (BS): % sites “good” cations
(bases: Ca++, Mg++, K+) plus Na+
Soil Fertility
• BS, pH & CEC determine “actual fertility”
– 1) High CEC + high BS = more fertile
– 2) If BS low: pH low (lots H+)
Actual fertility:
Multiply BS
by CEC
Soil pH
• Most AL: 4.5-5.1 (strongly acid)
• Black Belt: 7.9-8.4 (alkaline)
Soil pH
• pH effects:
• 1) H+ damages roots (@ extreme pH values)
• 2) soil microflora
– Acid favors fungi (incl. mycorrhizae)
– Alkaline favors bacteria
• 3) soil structure (sometimes)
Soil pH
• 4) nutrient availability.
Major influence!
• Nutrient deficiency:
• Acid: N, P, Ca, Mg, K,
S
Soil pH
• 4) nutrient availability.
Major influence!
• Nutrient deficiency:
• Acid: N, P, Ca, Mg, K,
S
• Alkaline: Fe, Mn, Zn,
Cu, Co, B
• 4) nutrient availability.
Major influence!
• Nutrient toxicity:
• Acid: Fe, Mn, Zn, Cu,
Co
• Alkaline: Mo
Soil pH
• Plant sensitivity &
nutrient needs
• Black Belt lab (#2):
– Black Belt soil:
Soil pH