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. T O D B Height MeasurementTree 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. D O D’ 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 (PSP’s) 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 • TSP’s will typically be used to supplement PSP’s • 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

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 • 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 • 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

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 12:30 P.M. • Bring warm clothes, sturdy footwear, rain gear, etc.