USDA Forest Service
 Sustaining Alpine and Forest Ecosystems
Research Locations
Fire Plan Research
National Search
Rocky Mountain Research Station
The Natural Inquirer
Fire Management in the Forest Service
Rocky Mountain Herbarium
First Gov for Kids
First Gov
Additional Questions:

Linda Joyce
Rocky Mountain Research Station
240 West Prospect
Fort Collins, CO 80526
Phone: 970-498-2560
 United States Department of Agriculture Forest Service.USDA logo which links to the department's national site.Forest Service logo which links to the agency's national site.

Aspen Regeneration Summary Computer Program 

This regeneration survey system is designed to produce summaries of aspen sprout populations categorized by size and damage classes.

To Download and Install Program

  • Click : RMRS Aspen Regeneration ver 2
  • Save file to disc (hard drive)
  • Choose a simple location on your C: drive
  • After downloaded, locate the file RMRS Aspen Regeneration ver 2.exe and double click
  • Follow the install instructions
  • This should place the program on the Windows Start button on the All Programs list

(Instructions may vary for different operating systems)



Wayne D. Shepperd
Research Silviculturist
Rocky Mountain Research Station
Ft. Collins, CO

Dave A. Weixelman
Tahoe National Forest
631 Coyote Street
Nevada City, CA 95959

Standard regeneration survey techniques that are used for conifers are inadequate for aspen. Sucker populations are often too dense to use large plot sizes. The susceptibility of aspen to numerous damaging agents and diseases require accurate assessment of the presence of these factors in the population. The regeneration survey techniques and summary program presented here has been used in numerous aspen research studies at the Rocky Mountain Research Station and has proven to meet these needs with a system of data collection that provides a quantitative assessment of the density, distribution, size and condition of aspen sucker populations. This windows-based summary program was written by Wexielman, based on an earlier DOS executable program written by Shepperd. It offers the flexibility of producing data summary reports and graphics from data entered into Excel spreadsheets and operates in a familiar Windows environment.

This regeneration survey system is designed to produce summaries of aspen sprout populations categorized by size and damage classes. The growth rate and development of aspen can be characterized by the size distribution and density of the sprout population. The distribution and type of damages that affect the suckers gives an indication of the health and vigor of the population and factors that might affect sprout survival.
Given the densities of many young aspen sprout populations, it is impractical to measure and record damages to each individual stem occurring in a sample plot. Instead, under this system, aspen sprouts are tallied by size and damage classes. The following size and damage codes are suggested, but may be re-defined by the user:

1 = 0 - 46cm (0-1.5ft)
2 = 46 - 137cm (1.5ft-4.5ft)
3 = 137cm - 2.5cm (<1.0")
4 = > 2.5cm (1.0") d.b.h.
9 = End of plot code

0 = OK (no damage)
1 = Browsing (terminal leader, or sufficient to affect tree vigor)
2 = Branches Stripped (open wound, or weakening of stem)
3 = Basal Stress Wound (Bark split at base of stem from sever bending)
4 = Poor Form (suppressed growth, or multiple factors affecting vigor)
5 = Frost (long split in bark of main stem)
6 = Disease (foliar, or stem canker)
7 = Stem Wound (undefined cause)
8 = Dead Leader (main growth axis only)
9 = Mortality (stem is dead)
10 = Insects (foliar, or stem borers)
11 = Snow Break (crunched stem base)
12 = Rodents (knawed bark)
13 = Elk (knawed bark)

Before beginning to collect data, visually survey the aspen sucker stand to be inventoried to determine the plot size and number of plots needed. Use a large enough plot so that at least one sucker will fall in more than half of the plots taken. A 1/1000 acre plot (3.72 ft. radius) works well in most young well-stocked aspen regeneration stands. Take enough plots to sample throughout the population (a minimum of 10 plots in small stands or one per acre in larger stands). Layout can be random or systematic (a grid), but the starting point should be randomly selected. Consider permanently locating plots to allow for future re-measurement.

Establish a circular plot by driving a stake, or chaining pin into the ground. Mark a starting point on the radius of the plot and sweep a stick cut to the length of the plot radius around the plot. Tally any aspen sucker touched by the stick by the numeric size and damage classes listed at the bottom of the data form (see file SUCKFORM.DOC) MAKE SURE ALL HEADER INFORMATION IS FILLED OUT, ESPECIALLY THE PLOT RADIUS USED AND THE UNITS OF MEASURE (FT, OR METERS)!

Size and damage classes can be coded in any order, but only one damage and size class combination (e.g. line of data containing suckers in that category) need be coded per plot. For each sucker tallied, CODE THE DAMAGE (if any) MOST LIKELY TO AFFECT THE FUTURE VIGOR OF THE TREE. For example, if a sucker has an uninfected stem wound and the terminal leader is browsed, code it as browsed. If the wound is infected, code the stem wound instead. The objective is to assess damaging agents that are most likely to affect future survival of the tree, not to inventory all damages that are present.

You do not have to use these code definitions. The summary program recognizes four size classes (numbered 1-4) and fifteen damage codes (numbered 0-14) and lists results by numeric code designation. You are free to invent new definitions within these limits, just keep track of what they are!

Once all suckers in a plot have been tallied, convert the dot count tallies in each size and damage class cell to numerals on the data form. End the plot by adding a line with a size class code of 9. Measure the height of the tallest sucker on the plot and record that data on this line too. REMEMBER, END EVERY PLOT WITH A LINE CONTAINING A SIZE CLASS 9 CODE - THIS IS HOW THE PROGRAM KNOWS WHERE TO SPLIT PLOTS.
All plots in a population should be the same size. Record the radius used at the top of each data form. The formula to calculate the plot size reciprocal in acres used by the program for per acre summaries is:
43,560 / (3.1416 * (radius in feet)^2)
For per hectare summaries use:
10,000 / (3.1416 * (radius in meters)^2
You may use either metric or English units. The program outputs the units it is given.

The following example shows how data should be entered from the data form into an Excel spreadsheet for analysis by the program. Only one header line for column labels is allowed. You may vary the width of the columns as desired, but EVERY LINE MUST CONTAIN A VALUE IN EACH COLUMN (Use zeros as placeholders). You can vary the width of the first column as needed for, Plot No., Treatment etc. A notes column may be added to the right of the Height column The program will prompt you for the plot radius, so it is a good idea to enter it as a note at the end of the first line of data for convenience and as a permanent record in the file.

(This data is in file EXAMPLE.XLS).
AZBURN 1 1 2 4 2 0.0 6.8 ft radius
AZBURN 1 1 2 8 1 0.0 (1/300AC PLOTS)
AZBURN 1 1 1 9 1 0.0
AZBURN 1 1 1 4 2 0.0
AZBURN 1 1 9 0 0 3.9
AZBURN 2 1 3 8 2 0.0
AZBURN 2 1 2 8 3 0.0
AZBURN 2 1 2 0 1 0.0
AZBURN 2 1 2 4 1 0.0
AZBURN 2 1 3 0 10 0.0
AZBURN 2 1 2 0 1 0.0
AZBURN 2 1 3 2 1 0.0
AZBURN 2 1 2 4 1 0.0
AZBURN 2 1 3 2 1 0.0
AZBURN 2 1 3 2 1 0.0
AZBURN 2 1 2 2 1 0.0
AZBURN 2 1 2 0 2 0.0
AZBURN 2 1 2 4 1 0.0
AZBURN 2 1 2 9 1 0.0
AZBURN 2 1 3 8 4 0.0
AZBURN 2 1 9 0 0 8.0

ASPEN.EXE is a windows-based executable program for PC's that will summarize regeneration survey data for aspen that was collected using the format and codes described above. This program will run on WINDOWS 95, 98, and 2000 (IT WON'T RUN ON THE FOREST SERVICE IBM SERVERS!). Follow the instructions on the CD or web site where the program was downloaded to install the program. We suggest creating a shortcut on the desktop to run the program. Once the data has been entered into an Excel spreadsheet, double click on the shortcut icon to run the program.

Read the program's instructions carefully. You will be asked to click on the file tab,browse to your Excel file directory and select it. The data spreadsheet will appear in the program window. Enter the plot radius and select an acre or hectare summary (note if you collected data in English units and want a per hectare summary, convert the plot radius in feet to meters and enter that value before selecting the hectare summary) Click on the reports tab at the top of the program window to see the summary report. If out of range data, or other problems are encountered, an error message will appear referring to the error.

To correct it, close the program before returning to Excel to correct the data. Possible errors include:
1. Out of range values for size or damage codes
2. Alphabetic characters in a numeric field
3. Data columns in the wrong order

The summarized data can be viewed in the report window, printed, or saved to an output file you specify by clicking the appropriate tab in the report window. After viewing the report window, click the graph tab to view bar graphs of summarized data.

A spreadsheet output file is also available so data summaries can be manipulated for further for further analysis For example spreadsheet statistics can be applied to these columns to obtain variance, standard errors, etc of the sample.

As with all freeware, this program and the data presented here come with absolutely no guarantee. We recommend checking the results of the first and last plots in a data file by hand to make sure everything worked correctly. We'll be happy to entertain questions and comments. Contact us at: E-mail: or

Disclaimers | Freedom of Information Act (FOIA) | Privacy Notice | Website Questions