Individual Tree Measurement: Key to Forest Assessment

Individual Tree Measurement: Learning Objectives … Key to Forest Assessment Ø Know why we measure and sample vegetation

Ø Know how to measure basic tree attributes

Ø Know what basic tree & stand attributes are important

Ø Know basic forest development patterns and structures ESRM 304

Why Sample Forest Vegetation? Why Sample Forest Vegetation?

Ø Need information on forest vegetation for making sound decisions

l What is the recreation potential? v Ultimate objective is to obtain quantifiable l What silvicultural treatment will result in best critical habitat enhancement? information about the resource that allows l What silvicultural treatment will result in best growth & reasonable decisions on its destiny, regeneration of the trees? management, and use l What species is / are most suitable for reforestation? l What is the value of the timber and the land? l Is there sufficient value in timber to offset cost of silvicultural treatments? l What is the status of biodiversity on the area?

l How is the forest currently storing carbon?

1 Individual Tree Measurement Need to see the forest for the trees ! l Diameter Ø Individual tree measurement forms the basis l Most frequently measured diameter is Diameter Breast Height, for all forest assessment / inventory or, DBH for short l DBH is average stem diameter (in inches!) outside bark of a Ø Many relationships can be derived from tree measured at breast height above ground level individual tree attributes l In U.S., breast height is taken to be 4.5 ft. l Species l On steep slopes measure on the uphill side of tree l Age l Leaning trees require measurement along the bole l Diameter l Trees forking below breast height are treated as two l Height l Trees forking above breast height – avoid swells l Other stem deformities – move above it Ø Direct measurement, sampling, prediction are all involved l Most commonly used measurement device is the D-tape

Diameter Measurement … DBH

l Diameter (size) distributions

2 Diameter Measurement … Some Stand Attribute Definitions …

l Basal Area (ba) l ba (or g) is directly related to crown surface area l Average stand DBH is a useful statistic for l Cross sectional area of the tree at breast height – silviculture, stewardship, management assuming stem circularity – always in square feet! (in U.S.) l Mean DBH (DBH) - The simple arithmetic mean 2 a = πr DBH of all trees in the stand 2 ⎛ d ⎞ l Quadratic Mean DBH (DBHq, QMD, or a = π sometimes Dg) – the DBH of the tree with ⎝⎜ 2 ⎠⎟ mean basal area 2 ⎛ D ⎞ a = π = 0.005454154D2 g ⎜ ⎟ QMD = Dg = ⎝ 2 ⋅12⎠ 0.005454 2 g = 0.005454154DBH

Individual Tree Measurement … Individual Tree Measurement … l Age l Tree Height l Trees in temperate zones grow one distinctive layer of l Total height: distance from tree base to tip wood per year so age is found by counting these annual rings (volume, biomass, site quality) l Care is needed to avoid counting ‘false’ rings l Height-to-crown: distance from tree base to base l Tree Age: of live crown l Total Age: Elapsed time since germination of a seed or l Merchantable height: Height to a minimum top time since budding of a sprout or cutting diameter l Breast-height age: Elapsed time since tree height exceeded breast height l Instruments are called “hypsometers” l l Stand Age: Direct measurement: Height poles l Plantation age: Elapsed time since planting – regardless l Indirect measurement of seedling age § Similar triangles

l Even-aged vs. Uneven-aged § Trigonometric principles (clinometer)

3 T

Height Measurement Slope correction for height measurement

Tree Height = DT + BD.

O D O D

DT/OD = tan(TOD), therefore, DT = OD x tan(TOD) B DB/OD = – tan(DOB), therefore, DB = – OD x tan(DOB), D’ Tree Height = OD x tan(TOD) + [– OD x tan(DOB)], or, Tree Height = OD x [tan(TOD) – tan(DOB)]. OD/OD’ = cos(DOD’)

Horizontal distance OD is measured with a tape. OD = OD’ x cos(DOD’) Clino measures tangents of angles TOD, DOB in percent (100 x tan), so Measure angle DOD’ with clinometer in degrees & plug into height equation: Tree Height = OD x [TOD% / 100 – DOB% / 100], or Tree Height = [OD’ x cos(DOD’)] / 100 x [TOD% –DOB%] Tree Height = OD / 100 x [TOD% – DOB%]

Some Stand Attribute Definitions Tree Crown Classes

l Trees per unit area (TPA) – Average number of live trees existing on a characteristic unit of area. The most basic measure of stand density. (In U.S.A., units are Trees Per Acre.) l Stand Basal Area (SBA, BA, or G) – sum of individual tree basal areas in a stand. D = Dominant: Crowns extend above general level of canopy; l Species Composition – proportion of each receives light from above and substantially from sides, C = Codominant: Crowns form general level of canopy; receives species present in a stand light from above, but comparatively little from sides, l Height – (H, AveHt) Arithmetic mean height of all I = Intermediate: Shorter than two preceding with crowns extending trees in a stand well into general level of canopy; receiving some light from above O = Overtopped: Crowns entirely below general level of canopy; receives no direct sunlight 16

4 Stand Attributes … Stand Attributes … l Dominant Height l Dominant Height in relation to age - Site Quality l Definitions vary l l Average height of just dominant trees (crowns extend Trees are resource integrators above general level of canopy) l Site Index: The average height of undamaged dominant trees at a reference age l Average height of dominants and co-dominants (trees whose crowns form the general level of the canopy) l Dominant tree height insensitive to crowding l Reference, or base, or index age chosen l Predominant Height – average height of 100 tallest trees per hectare (40 per acre) appropriately l Species dependent l Top Height – average height of 100 largest diameter trees (40 per acre) l Sometimes dominant trees are unavailable; challenge esp. in mixed stands 17 l Requires trees on the site 18

Site Index Site Index & Basal Area - An application James King (1966) published site index curves for Douglas-ﬁr in the Paciﬁc Northwest

5 Permanent Sample Plot Layout

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

Plot and Tree Enumeration Card Page of Upper Canopy Surveys Date Team Forest

Compartment Stand Plot l Field Trip to St. Edward State Park Aspect Slope Elevation

o l Tu, We 19, 20 Nov Tree Spp DBH Ht. Dist S ( ) B. (%) T. (%) C. (%) Add-on Comment(s)

l Depart from behind Bloedel Hall (C-10 parking lot) promptly at 12:30 P.M.

l Dress appropriately: long pants, sturdy

footwear (with ankle support), rain gear(!!!), etc.