1. Other Cruise Methods

2. Cruising Approaches
Area Based Methods
Tree Based Methods

3. Area Based Methods Main Types Varieties for specific applications
Strip Cruise
Fixed Plot
Point Sampling
Remote Sensing
Fixed Count
Fixed Count Measure
Fixed Plot with 3P subsample
Point Count Measure
Point Sampling with 3P subsample
3P Point Sampling

4. Tree Based Methods Sample Tree Method 3P
For stands too variable in density to plot cruise or where trees are not suitable for cruising by other methods
Examples – partial cutting, small clearcuts, stratification by species or size class is desired
Small or irregular shaped harvest units
Widely scattered trees
Very large stands
Used where a wide volume range occurs within a species group
Measure as few trees as possible
Cut tree marking
Not used in this region

5. Strip Cruising
Strips could be randomly allocated. Hard to stratify without bias.

6. Zigzag Transect Method
Used by NRCS foresters
Simple and Quick way to get estimates for
Average tree diameter
Range of tree diameters
Trees per acre
Stand composition
Stand Condition

7. Main Stand

8. Zigzag Transect Method
1. Select Main Stand
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

9. Zigzag Transect Sequence

10. 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

11. 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, = 15
Ideal trees per acre = 43560/152 = 194
Thus 303 – 194 = 109 trees per acre need to be removed to provide adequate spacing

12. Smaller Trees Measured on Smaller Plots
Fixed Area Plot Sampling
Nested Circular Plots
Smaller Trees Measured on Smaller Plots
Area (ac)
Radius(ft)
1/500
0.002
5.3
1/100
0.01
11.8
1/10
0.1
37.2
1/10 acre plot
Sawtimber
1/100 acre plot
Poletimber
1/500 acre plot
Regeneration

13. Photogrammetry

14. Remote Sensing Best for low value products
Best for even-aged, single canopy and species stands (tree farms)
Needs recent high resolution photos
Pre-sampling needed to establish relationships i.e. volume versus canopy cover estimates
Photos must be geo-referenced
Entire courses are taught on this subject in areas where it is useful

15. Measuring Tree Heights by ParallaxdP
h = (H)
P + dP
h = height of measured object
H = height of aircraft above ground datum
dP = differential parallax
P = absolute stereoscopic parallax at base of object being measured
Visual accuracy varies +/- 5 to 10 ft.

16. Exercises 78 73 dP h = (H) -------------- P + dP
H = 7,000 ft; P = in; dP = in. What is the tree height (h) in feet?
H = 5,900 ft; P = in; dP = in. What is the tree height (h) in feet? 78 73

17. Measuring Crown Diameters
The ability to measure crowns from aerial photos can be correlated to diameters especially for open grown trees.

18. A tally of trees per unit area is a commonly used measure of stand density. Normally representative areas are subsampled then that tally is expanded for the entire area. This is similar to ground cruising timber. Photos must be high resolution and be georeferenced (known scale). Lowest success in counting shade tolerant species where many overtopped stems are less visible.
Tree Counts

19. Individual Tree Volumes
INDIVIDUAL TREE AERIAL VOLUME TABLE FOR SECOND-GROWTH SOUTHERN PINE, CUFT
Measured crown areas (which are highly correlated to DBH) and total tree heights can be modeled to predict stem volumes for certain areas with uniform species.
Still the result is less precise estimation of volumes but can be useful in inaccessible areas and when ground surveys are cost prohibitive.
Crown diameter class (ft)
Total tree height (ft) 50 60 70 80 90
100
110 10
9.5
11.5
12.5
15.0
17.5
19.5 12
14.5
16.5
18.0
20.5
22.5 14
17.0
19.0
23.5
25.0
27.5
30.5 16
24.0
33.0
36.0 18
27.0
34.5
38.0
42.5 20
28.0
33.5
40.0
45.5
49.0 22
32.5
37.0
46.5
52.0
57.5 24
48.5
54.5
60.0
66.0 26
47.5
54.0
61.0
67.5
75.5 28
53.0
60.5
70.5
76.0
83.0 30
68.0
78.0
86.5
94.5

20. Crown Closure
Aerial estimation of large areas can be done more cost effectively than ground estimation. Crown closure percentages along with stand height of even aged stands can be associated with stand volume. The higher resolution photos the better.

21. Ground Truthing
Comparing volume estimates from photos to actual measurements is usually needed establish a correction factor to be applied to the photo estimate.