Why Use Count Plots? A Comparison of Various Count to Measure Ratios In the BC Interior

1. Why Use Count Plots?A Comparison of Various Count to Measure RatiosIn the BC Interior Presented by: Jim Wilson RFT, ATE May 2008

2. Overview • Why are we sampling? • What are we sampling? • Why sample with count plots? • Variations of count plots • Study • Results • Recommendations

3. Why are we sampling? • Cost prohibitive to measure every tree • For appraisal purposes, we require cruise estimates to calculate the stumpage rate • Decision is based on: • What sampling error can we live with based on our budget? • unfortunately, the min 2SE is set for us

4. What are we sampling? • For appraisals – net volume ±15% 2SE • Sampling for net volume has two equal parts: • BA/ha (tree count) • VBAR (measure trees) • We could just as easily sample for any other attribute: $ value, stems/ha, etc.

5. What are we sampling? Questions: • Are the items to sample: • More or less variable? • More or less costly to collect?

6. Why sample with count plots? • More variability, more samples needed • Tree count is usually more variable than the measure trees • Countingtrees is easy and cheap,measuring trees is costly • Measuring trees is 50% of the answer, getting tree count is the other 50% • You decide how much of each to sample

7. Variations of Count Plots

8. Variations of Count Plots • Which sample better covers the ground and covers the variability of the stand? • Selecting trees with a Big BAF better distributes measure trees – moreefficient • Count:Measure plots clump measure trees into clusters – less efficient

9. Study • Selected 7 interior cutting permits • Northern and Southern Interior • Stand types: SB, FPyL, Pl(S) • All full measures: • Randomly selected plots to start • Ratios 0:1, 1:1, 2:1, 3:1, 5:1 (count:measure) • Graphed net vol/ha, ISR $/m3, cruising costs

10. Results : Net Vol/ha SB stand

11. Results: Stumpage Rate SB stand

12. Results : Net Vol/ha PlS stand

13. Results: Stumpage Rate PlS stand

14. Results Tree Count CV: SB stand: 0:1 – 5:1 86 plots - 39% PlS stand: 0:1 – 5:1 117 plots - 38% • Each of the runs by stand had the same number of plots and therefore the same CV

15. Results VBAR CV: • SB stand: • 0:1 – 397 trees - 28% • 1:1 – 195 trees - 28% • 2:1 – 136 trees - 28% • 3:1 – 107 trees - 29% • 5:1 – 74 trees - 30% • PlS stand: • 0:1 – 653 trees - 23% • 1:1 – 337 trees - 24% • 2:1 – 212 trees - 22% • 3:1 – 161 trees - 24% • 5:1 – 117 trees - 23% • Why are we measuring so many trees?

16. Results Trends: • Net vol/ha does not change using count plots • averaged within ± 2% • Stumpage rate does not change using count plots • averaged within ± 5% • CV is stable for VBAR (we are measuring too many!) • Cruising costs are 30% less using 1:1 ratio and 50% less using 5:1 ratio versus full measure plots

17. Results Optimal solution to reach 15% 2SE (using Kim Iles’ star_bar.xls): SB stand: • Using TC CV of 39% and VBAR CV of 28% • 41 count plots & 41 VBAR trees • Equivalent to 3.5 counts to 1 measure plot PlS stand: • Using TC CV of 38% and VBAR CV of 23% • 37 count plots & 31 VBAR trees • Equivalent to 7.2 counts to 1 measure plot

18. Recommendations • Use count plots in highly variable stands to meet sampling error (more counts) • Use count plots in homogenous stands to decrease effort (less measure trees) • Use count plots in partial reduction areas • Use Big BAF to select measure trees and increase efficiency • Use count plots and spread out the trees!

19. Acknowledgements Srdjan Kragulj, RPF Timberline - Vancouver • he helped provide all the stumpage calculations for each of the runs Kim Iles, PhD • for spoon feeding me time and time again • his STAR_BAR.xls program should be used by everyone to plan cruises John Bell, PhD • for his short course and newsletter (http://www.proaxis.com/~johnbell/) Walter Bitterlich, PhD • for making cruising so much easier

20. Questions? Jim Wilson, RFT, ATE Cruise Compilation Manager Timberline Natural Resource Group Phone: 604-714-2897 Cell: 778-858-9123