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Cruise Summaries

Cruise Summaries

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Cruise Summaries

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Presentation Transcript

  1. Cruise Summaries

  2. Zigzag Transect Method • Used by NRCS foresters • Simple and Quick way to determine • Average tree diameter • Range of tree diameters • Trees per acre • Stand composition • Stand Condition

  3. Main Stand

  4. Zigzag Transect Method • 1. Select MainStand • 2. Choose a Route (X-section of stand) • 3. Select a Starter Tree (unmeasured) • 4. Choose a Direction • 5. Locate Closest Tree of main stand • 6. Determine Distance, Species, and Diameter • 7. Rate Tree Condition • 8. Repeat until at least 20 sampled

  5. Zigzag Transect Sequence

  6. Zigzag Summaries + Calculations • Average Stand Diameter = sum of DBHs/# of trees • Range of Diameters – smallest tree to largest tree • Average Tree Spacing = total distance/# of trees • Trees per acre = 43560/spacing2 • Percent of each species of all sampled trees • Stand condition = percent of each grade of total

  7. Thinning Recommendations • D + x Rule of Thumb • X usually equals 6, smaller for western pines • Example • If you determined that the average tree spacing was 12 feet, then trees per acre was estimated as • 43560/122 = 303 • If average tree diameter was 9 inches, 9 + 6 = 15 • Ideal trees per acre = 43560/152 = 194 • Thus 303 – 194 = 109 trees per acre need to be removed to provide adequate spacing

  8. Comparing Fixed plot vs. Variable point Cruises

  9. Basal Area by tree size

  10. Volume per acre by diameter

  11. Summary of Major Points

  12. Expanding Measurements • Number of tallied stems for the tract by species • Average DBH, DBH range, QMD • Merchantable Height (average number of logs) • Basal Area Estimates • Board Foot Volume Estimates • Cull Deductions • Tree Grades

  13. Trees per Acre • Number of trees measured can be expanded to express number of stems per acre for each species. There is no index of tree size. Generally more stems = smaller stems. Are they too crowded to grow well?

  14. Trees per acre • A young natural stand of hardwood trees starts with 4000 to 6000 stems per acre. At maturity, when they measure about 20 inches in diameter, less than 100 trees per acre will survive. This is a natural selection process and it is slow, requiring 150 to 200 years or more to complete. • Mechanical thinning allows ‘crop’ trees room to grow at a faster rate, obtaining mature size in fewer years.

  15. Crop tree release • Accelerated growthprovided byremovingcompetitors • Cost vs. benefit?

  16. DBH • Could summarize and report average DBH of stems. If population isn’t normally distributed, this could lead to false conclusions. Adding an indicator of variance sheds more light. • Could use other measures of central tendency like median or mode. • Merchantability depends on that local mills are buying. (species, size, grade)

  17. Average logs per tree • Merchantable height indicator of stand age and quality • When dominant trees harvested, most will have similar heights (total and merchantable) • Bucked into manageable sizes for hauling (16’ or less) • Each log graded for lumber yield estimate • (more specific than standing tree grading)

  18. Basal Area per Acre • DBH is used to calculate BA, cruise summaries should include this • BA can be used to calculate QMD • Area per area index.

  19. 60 ft2 of BA per acre by tree size

  20. Volume per Acre • Takes your measurements to the 3rd dimension • Along with grade and species, used to assign value to stand • Stand Valuation = next topic