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Density and Stocking

Density and Stocking. Density and Stocking. Potential of the land to produce wood is determined mainly by its site quality . The actual production or growth of wood fiber achieved on a given site is determined by the number, distribution and species of trees on the site.

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Density and Stocking

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  1. Density and Stocking

  2. Density and Stocking • Potential of the land to produce wood is determined mainly by its site quality. • The actual production or growth of wood fiber achieved on a given site is determined by the number, distribution and species of trees on the site. • Two measures of the number and distribution of trees on a given site are "density" and "stocking". • Density is a measurable "fact". • Stocking is a "relative" assessment.

  3. Measures of Stand Density • 1. Number of trees per acre • 2. Basal area per acre • 3. Stand Density Index • 4. Crown Competition Factor

  4. BA/ac = S /

  5. Stand Density Index • Based on the observed maximum size-density relationship, using • 1) number of trees per acre (TPA) and • 2) mean quadratic tree diameter (Dq), a.k.a. • diameter for tree of mean basal area • Incorporates both number and basal area per acre measurements

  6. Stand Density Index

  7. Stand Density Index Slope ~ -3/2

  8. Stand Density Index • Equates observed Dq and TPA to an equivalent TPA for the indexed Dq=10 in.

  9. Crown Competition Factor • Reflects the area available to the average tree relative to the maximum area it uses if it were open-grown

  10. Crown Competition Factor CCF < 100

  11. Crown Competition Factor CCF > 150

  12. Stocking • Involves the comparison of a given stand to a "normal", or fully-stocked stand. • Problem: "Has anyone ever seen a normal stand?" • Assumes that "natural" mortality is solely a result of over-stocking. • Concept of stocking is very subjective in nature. • Stocking guides are the main method for assessing stocking.

  13. Stocking • 1) Stocking Guides • 2) Stand Density Management Diagrams

  14. 1. Stocking Guides • 1. Species Specific • 2. Require that you know trees per acre and basal area per acre. • 3. Usually have 2 or 3 lines that are important: the A-line, the B-line, and sometimes the C-line. • Above the A-line: overstocked • Between A-line & B-line: fully stocked • Below the B-line: understocked • C-line: lower limit of “understocking” to reach the B-line in 10 years on an average stand

  15. Generic Stocking Guide

  16. Generic Stocking Guide

  17. White Pine Stocking Guide

  18. 2. Stand Density Management Diagrams • What are they? • Graphic tools which illustrate how DIAMETER, HEIGHT, DENSITY and VOLUME change over time for pure, even-aged stands • Why use them? • Lead to understanding of stand dynamics • To plan/evaluate initial spacing and thinning regimes

  19. 2. Stand Density Management Diagrams

  20. Spacing effects on tree size

  21. Relationship between density and tree size

  22. 9th re-measurement 2nd re-measurement 1st re-measurement Baseline measurement

  23. Stands under-stocked Zone of OptimumDensity Management Zone of ImminentCompetition Mortality Maximum size-density line Mortality initiation line Crown closure line Stand trajectories

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