Forest Mensuration II. Lecture 8: Inventories with Sample Strips or Plots Avery and Burkhart, Chapter 10. Fixed-area sampling. Strip cruising Plot cruising. Sample area. Sample area. X. Selecting sample trees with probability proportional to frequency. Strip System of Cruising.
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Forest Mensuration II Lecture 8: Inventories with Sample Strips or Plots Avery and Burkhart, Chapter 10
Fixed-area sampling Strip cruisingPlot cruising Sample area Sample area X Selecting sample trees with probability proportional to frequency
Strip System of Cruising • Sampling intensity • Orientation of strips
Strip width Distance between strips Strip System of Cruising • Nominal cruise intensity (I) • Actual cruise intensity • Expansion factor (EF)
Strip System of Cruising • Advantages • Less time wasted in traveling between strips than for a plot cruise of equal intensity. • Fewer borderline trees, because the total perimeter of the sample area is smaller • Less risk to personnel in remote areas: two people generally work together
Strip System of Cruising • Disadvantages • Errors are easily incurred through inaccurate estimation of strip width • Brush and windfall are more of a hindrance in this system • Spot-checking the cruise is difficult because strip centerline is rarely marked
As with the strip method, line-plot inventories are often planned on a percent cruise basis Line-Plot System Cruising
Problem Develop a plan of line-plot cruising with a given sampling intensity, plot size, and line distance Example: A stand of 10 ha (A) Sampling intensity = 10% (P) Plot size = 0.04 ha (a) Line distance = 100 m (L) What we need to know How many plots (n) How to space the plots (B) Line-Plot System Cruisingplanning
Line-Plot System Cruisingplanning Area of all plots = Ap
Line-Plot System Cruising • Advantages • Suitable for one-person cruising • Cruisers do not have to tally trees while following a compass line • Cruisers pause at plot centers, allowing more time to check measurements • Tree tally is separated by plots, permitting quick summary of timber types, species composition, etc.
Purpose: To measure changes in forest conditions Standard procedures for measurements Remeasured at periodic intervals Can determine causes of change Permanent Sample Plots
Ontario Permanent Sample Plots Networks • Provincial growth and yield PSPs • Provincial wildlife sample plot network • National Forest Plot Network • Forest company PSPs
Regeneration survey with Sample Plots • Purposes • To evaluate regeneration status • To determine effectiveness of regeneration treatment • To identify additional treatments needed • To collect data to predict growth and yield • To demonstrate compliance with laws
Regeneration Survey with Sample Plots • Methods • Stocked-quadrat method (proportion of land utilized) • Plot-count method (number of trees per acre) • Staked-point method (like permanent plots)