Lecture 8Lecture 8Forestry 3218Forestry 3218
Forest Mensuration IIForest Mensuration II
Lecture 8: Inventories with Sample Strips or PlotsLecture 8: Inventories with Sample Strips or Plots
Avery and Burkhart,Avery and Burkhart,Chapter 10Chapter 10
Lecture 8Lecture 8Forestry 3218Forestry 3218
Strip cruising Plot cruising
Sample areaSample area
X
Fixed-area sampling
Selecting sample trees with probability proportional to frequency
Lecture 8Lecture 8Forestry 3218Forestry 3218
Strip System of Cruising
Sampling Sampling intensity intensity
Orientation of Orientation of stripsstrips
Lecture 8Lecture 8Forestry 3218Forestry 3218
Strip System of Cruising
Nominal cruise intensity (I)
Actual cruise intensity
Expansion factor (EF)
100DW
I
Strip width
Distance between strips
100areatracttotal
sampleinareaa
I
I
100EF
Lecture 8Lecture 8Forestry 3218Forestry 3218
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
Lecture 8Lecture 8Forestry 3218Forestry 3218
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
Lecture 8Lecture 8Forestry 3218Forestry 3218
Line-Plot System Cruising
100drepresente area
plots of number *size plot
As with the strip method, line-plot inventories are often planned on a percent cruise basis
Lecture 8Lecture 8Forestry 3218Forestry 3218
Line-Plot System Cruisingplanning
ProblemProblem– Develop a plan of Develop a plan of
line-plot cruising with line-plot cruising with a given sampling a given sampling intensity, plot size, intensity, plot size, and line distanceand line distance
Example:Example:– A stand of 10 ha (A stand of 10 ha (AA))– Sampling intensity = Sampling intensity =
10% (10% (PP))– Plot size = 0.04 ha (Plot size = 0.04 ha (aa))– Line distance = 100 m Line distance = 100 m
((LL)) What we need to knowWhat we need to know
– How many plots (How many plots (nn))– How to space the plots How to space the plots
((BB))
Lecture 8Lecture 8Forestry 3218Forestry 3218
Line-Plot System Cruisingplanning
2504.0
1.010
aAPn
1.0100400
LPaB
Area of all plots = Ap
Lecture 8Lecture 8Forestry 3218Forestry 3218
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.
Lecture 8Lecture 8Forestry 3218Forestry 3218
Permanent Sample Plots
Purpose: To measure changes in forest conditions
Standard procedures for measurements
Remeasured at periodic intervals
Can determine causes of change
Lecture 8Lecture 8Forestry 3218Forestry 3218
Ontario Permanent Sample Plots Networks
Provincial growth and yield PSPs Provincial wildlife sample plot
network National Forest Plot Network Forest company PSPs
Lecture 8Lecture 8Forestry 3218Forestry 3218
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
Lecture 8Lecture 8Forestry 3218Forestry 3218
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)
