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 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 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: –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 m 2 /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 X X X X XX

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 systematic random OR

Ch. 4: Soils, Nutrition etc.

Soil Definition: –Natural body: layers (horizons)

Soil Definition: –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) A: Sand & silt B: clays know these

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

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)

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

Parent Material Within climate, parent material major influence Ex, serpentine soil High Mg, low Ca Lots Ni, Cr

Parent Material Extreme cases, serpentine “barrens”

Parent Material Within climate, parent material major influence Ex, granite outcrop soil Lots sand (coarse texture) Soil dry (water drains) Forest on granite in Australia

Time General trends (as time increases): –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….

Soil Fertility Texture: clays –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 (cmol c /kg) Represents “potential fertility”

Soil Fertility Exs: US prairie: 30 cmol c /kg NE US conifer forest: 2 cmol c /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: (strongly acid) Black Belt: (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

Soil pH 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: