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FOREST STRUCTURE: Key to function

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Title: VEGETATION MEASUREMENT: Upper Canopy Author: Eric Turnblom Last modified by: Eric Turnblom Created Date: 11/20/2006 4:55:53 AM Document presentation format – PowerPoint PPT presentation

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Title: FOREST STRUCTURE: Key to function


1
FOREST STRUCTURE Key to function
  • ESRM 304

2
Why Sample Forest Vegetation?
  • Need information on forest vegetation for making
    sound decisions
  • What is the recreation potential?
  • What silvicultural treatment will result in best
    critical habitat enhancement?
  • What silvicultural treatment will result in best
    growth regeneration of the trees?
  • What species is / are most suitable for
    reforestation?
  • What is the value of the timber and the land?
  • Is there sufficient value in timber to offset
    cost of silvicultural treatments?
  • What is the status of biodiversity on the area?
  • What is the status of the forest as a carbon
    sink?

3
Why Sample Forest Vegetation?
  • Ultimate objective is to obtain quantifiable
    information about the resource that allows
    reasonable decisions on its destiny, management,
    and use

4
Forest Systems
  • Forests are dynamic, biological systems changing
    continuously
  • Trees change in size (growth)
  • Trees die when old, when harvested, and/or when
    damaged by pathogens (mortality)
  • New trees enter the system (recruitment)

5
Forest Systems
  • Four major stages of stand development
  • Stand initiation stage
  • Grass-forb
  • Seedling-shrub
  • Stem exclusion stage
  • Sapling-pole
  • Intermediate
  • Understory re-initiation (mature)
  • Old-growth stage
  • Provide different habitats and growth potential

6
Major stages of stand develop-ment
Forest Systems
7
Stand dynamics vector
Forest Systems
8
Visualizing Stand Dynamics
Lowland site, St. Edward State Park in 2004
C.E. SVS under LMS v2.0 Developed in
Silviculture Lab here in SFR (then CFR)
9
Visualizing Stand Dynamics
Lowland site, St. Edward State Park 50
years later, i.e. in 2054 C.E.
10
Forest Structure / Constitution
  • Determined by
  • Size variability
  • Diameter
  • Height
  • Crown
  • Frequency of occurrence shape, location of size
    distribution
  • Age shape, location of age distribution
  • Spatial arrangement of trees in stand

11
Forest Structure / Constitution
  • Five Typical Stand Structures
  • Even-aged stand
  • Two-aged stand
  • Balanced uneven-aged stand
  • Irregular uneven-aged stand
  • Even-aged stratified mixture
  • Represent different management options /
    potentials

12
Five Typical Stand Constitutions
  • Even-aged stand

13
Five Typical Stand Constitutions
  • Balanced uneven-aged stand

14
Five Typical Stand Constitutions
  • Even-aged stratified mixture

15
Can we see the trees for the forest?
  • Individual tree measurement forms the basis for
    all forest assessment / inventory
  • Many relationships can be derived from individual
    tree attributes
  • Species
  • Age
  • Diameter
  • Height
  • Direct measurement, sampling, prediction are all
    involved

16
Individual Tree Measurement
  • Diameter
  • Most frequently measured diameter is Diameter
    Breast Height, or, DBH for short
  • DBH is average stem diameter (in inches!) outside
    bark of the tree measured at breast height above
    ground level
  • In U.S., breast height is taken to be 4.5 ft.
  • On steep slopes measure on the uphill side of
    tree
  • Leaning trees require measurement along the bole
  • Trees forking below breast height are treated as
    two
  • Trees forking above breast height avoid swells
  • Other stem deformities move above it
  • Most commonly used measurement device is the
    D-tape

17
DBH
18
Diameter Measurement
  • Diameter classes
  • Very often expedient to summarize inventory data
    into size classes based on DBH
  • No matter the size of class used still measure
    to nearest 0.1 !
  • 1-inch classes
  • 2 class (1.6 to 2.5), 3 class (2.6 to 3.5),
  • 2-inch classes
  • 4 class (3.1 to 5.0), 6 class (5.1 to 7.0),

19
Diameter Measurement
  • Diameter (size) distributions

20
Diameter Measurement
  • Basal Area
  • Cross sectional area of the tree at breast height
    assuming stem circularity always in square
    feet! (in U.S.)
  • Area of circle, A p r 2
  • Basal area, g p (DBH/2)2 (1/12)2 0.005454
    DBH2
  • Average stand DBH is a useful statistic for
    management
  • Quadratic Mean DBH (QMD) is the diameter of the
    tree corresponding to the tree of mean basal area

21
Individual Tree Measurement
  • Age
  • Trees in temperate zones grow one distinctive
    layer of wood per year so age is found by
    counting these annual rings
  • Care is needed to avoid counting false rings
  • Tree Age
  • Total Age Elapsed time since germination of a
    seed or time since budding of a sprout or cutting
  • Breast-height age Elapsed time since tree height
    exceeded breast height
  • Stand Age
  • Plantation age Elapsed time since planting
    regardless of seedling age
  • Even-aged vs. Uneven-aged

22
Individual Tree Measurement
  • Tree Height
  • Total height distance from tree base to tip
    (volume, biomass, site quality)
  • Height-to-crown distance from tree base to base
    of live crown
  • Merchantable height Height to a minimum top
    diameter
  • Instruments are called hypsometers
  • Direct measurement Height poles
  • Indirect measurement
  • Similar triangles
  • Trigonometric principles (clinometer)

23
Height Measurement Tree Height DT BD.
DT/OD tan(TOD), therefore, DT OD x
tan(TOD) DB/OD tan(DOB), therefore, DB OD
x tan(DOB), Tree Height OD x tan(TOD) OD
x tan(DOB), or, Tree Height OD x tan(TOD)
tan(DOB). Horizontal distance OD is measured
with a tape. Clino measures tangents of angles
TOD, DOB in percent (100 x tan), so Tree Height
OD x TOD / 100 DOB / 100, or Tree Height
OD / 100 x TOD DOB
24
Slope correction for height measurement
OD/OD cos(DOD) OD OD x cos(DOD) Measure
angle DOD with clinometer in degrees plug into
height equation Tree Height OD x cos(DOD)
/ 100 x TOD DOB
25
Individual Tree Measurement
  • Height in relation to age - Site Quality
  • Trees are resource integrators
  • Site Index The average height of undamaged
    dominant trees at a reference age
  • Dominant tree height insensitive to crowding
  • Reference, or base, or index age chosen
    appropriately
  • Species dependent
  • Sometimes dominant trees are unavailable
    challenge esp. in mixed stands
  • Requires trees on the site

26
Site Index
  • James King (1966) published site index curves
    for Douglas-fir in the Pacific Northwest

27
Continuous Forest Inventory
  • The ONLY way to get a complete historical record
    on forest change is to monitor permanently
    monumented plots
  • Data from Permanent Sample Plots (PSPs) is for
  • Forecasting growth, i.e., developing and testing
    forest simulation models
  • Studying the effects of cultural practices,
    insect attacks, weather, climate, etc.
  • Studying how biodiversity, wildlife habitat
    quality, etc. change over time
  • Chief purpose is to assess change so forest
    stewards are alerted to potential need for
    changing practices or policies

28
Continuous Forest Inventory
  • CFI is generally very low intensity
  • TSPs will typically be used to supplement PSPs
  • CFI plots must be representative of the forest
    no special reserve status
  • Systematic sampling is often used
  • Stratified sampling is often messed up by natural
    disaster, natural changes in species composition
  • Sample size determination is difficult
  • Must be applicable now AND in the future
  • Large enough to be precise for several forest
    attributes
  • Sampling intensities often range from 0.1 to 1

29
Continuous Forest Inventory
  • Plot locations are usually determined using a
    transparent grid with pin pricks on an
    appropriately scaled grid, then overlain onto a
    photomosaic or other map of the ownership, then
    transferred to 9 x 9 photos to take into the
    field
  • Distance bearing to plot center is determined
    from the photo or map from a known permanent
    location (primary control) to avoid bias
  • Plot center is marked with aluminum stake,
    re-bar, or PVC pipe
  • Trees on plot are stapled, nailed and / or
    painted near breast height

30
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31
Continuous Forest Inventory
  • Five percent of all plots (randomly selected) are
    normally check-cruised for accuracy
  • Measurement interval is typically 3 to 10 years
  • Repeat measurement cycle is either annual or
    periodic
  • In a periodic survey, with periodic measurement
    interval p, EVERY plot is measured every p years
  • In an annual survey, 1/p plots will be measured
    EVERY year

32
Summary Remarks
  • Measurement data collected from trees in a forest
    system yields information
  • - Forest Structure / Function
  • Four major stages of stand development
  • Five major age constitutions
  • Sound data enables sound stand, forest, and
    landscape management decisions

33
Permanent Sample Plot Layout
  • Large Tree measurement plot
  • 0.1 acre plot ? 37.2 foot radius
  • white PVC pipe at plot center plot number
    written on it w/ indelible ink
  • all trees within the plot have aluminum tags
  • first tree on plot marked with pink flagging
  • Small Tree measurement plot
  • 0.025 acre plot ? 18.6 foot radius
  • same plot center as large plot
  • trees are not tagged
  • perimeter is not marked

34
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35
Upper Canopy Surveys
  • Field Trip to St. Edward State Park
  • Tue and Wed (24th 25th)
  • Depart from behind Bloedel Hall (C-10 parking
    lot) promptly at 1230 P.M.
  • Bring warm clothes, sturdy footwear, rain gear,
    etc.
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