Cruise Summaries

Fixed plot vs. Variable point Cruises Comparing Fixed plot vs. Variable point Cruises

Basal Area by tree size

Volume per acre by diameter

Summary of Major Points Fixed Plot Variable Point Sampling based on Frequency of occurrence Tree size Expansion Factor Same for all trees Varies by tree Best for Total stems and number of small trees Number of large trees Long term and repeated measuring Temporary plots Distribution of DBHs Basal area and volume estimation Tally determined Distance from plot center Angle device over point Misc Slope correction harder than angling prism Missing large distant trees, Missing hidden trees in dense stands

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

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?

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.

Crop tree release Accelerated growth provided by removing competitors Cost vs. benefit?

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)

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)

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.

60 ft2 of BA per acre by tree size

Volume per Acre Takes your measurements to the 3rd dimension Along with grade and species, used to assign value to stand Stand Valuation = another lecture