USDA Forest Service National Headquarters   National Forest Health Monitoring Program Natural Resource Ecology Laboratory at Colorado State University


Forest Health Monitoring Vegetation Indicator Pilot

Florence Petterson - FHM Audit (140 kb)Sampling Species Diversity (143 kb)On the Job Hazards (60 kb)Florence Petterson and Kelly Rimar - Project Leaders & Susan Will-Wolfe - Lichen Specialist (59 kb)



The Forest Health Monitoring (FHM) program is a national program that makes an annual evaluation of the condition, changes, and trends in health of forest ecosystems in the United States.  The evaluation of health is based on the sustainable forest management criteria stated in the Santiago Agreement (Stolte 1997).  The principle ecological criteria in this agreement are productivity, diversity, vitality, conservation of soil and water, and carbon cycling.  This pilot project is intended to test vegetation indicators (i.e., understory diversity and general vegetation structure) that will provide data to better evaluate diversity, vitality, conservation of soil, and carbon cycling in the Nation’s forests.   The variables collected in this field pilot also provide information to evaluate the suitability of forest stands as habitat for wildlife.FHM 2000 Study Map (80 kb)

The current FHM methods for evaluating understory plant diversity were modified for two reasons: the total area sampled was too small (12 m2, twelve 1 m2 quadrats), and the single-scale approach was inadequate to evaluate plant diversity in patchy and heterogeneous habitats (i.e., most habitats on Earth) (Figure 2).  Using multi-scale vegetation plots in forests and rangelands from Colorado to Minnesota, Stohlgren et al. (1995, 1997a, 1998a) found that ten 1 m2 subplots captured only 40% to 50% of the plant species in a 0.1 ha area.  Half the exotic species in rangelands were missed with a series of 1m2 quadrats (Stohlgren et al. 1998a).  The twelve 1m2 quadrats historically used in the FHM program probably captured even fewer native and exotic plant species in forested sites due to the patchy distributions of understory plants in canopy gaps. The single-scale, 1m2 quadrats would gather very incomplete data on plant diversity and exotic species primarily because most plant species are locally rare (>50% of the species have <1% foliar cover) and because plants are never randomly distributed on the plot or landscape (an underlying assumption of systematic sampling) (Stohlgren et al. 1998a).

FHM Plot LayoutFHM Subplot LayoutWe modified the USDA Forest Service Forest Health Monitoring (FHM) sampling method to better monitor native and exotic plant diversity in the Nation’s forests, beginning in Colorado, Michigan, Oregon, Washington and Virginia.  Single-scale small quadrat techniques were augmented with larger-scale surveys in each plot to record the number and cover of native and exotic species in two height classes.   Data showed that 69% of the forest plots had been invaded by at least one exotic species.  Areas of high native diversity were most heavily invaded.  Exotic species richness was significantly, positively correlated to native species richness (r+ 0.38, P < 0.001) and the cover of exotic species was significantly, positively correlated to exotic species richness (r = 0.64, P < 0.001). The Vegetation Indicator Pilot continues into 2001 with the addition of Pennsylvania, Delaware, and Wyoming crews.  Some streamlining and fine-tuning was done to the methods this year based on last year’s results.   We are currently working with Chuck Liff and Brian Cordova who provide information management support, to design and implement the data apparatus necessary for quick and efficient data crunching in the future.  This year’s electronic data files will be sent directly from the field to the database for rapid initial data summary and analysis. 

FHM data will allow for detailed analysis of local, regional, and national patterns of plant diversity.  For Example, analysis of variance of plots in Colorado showed that rangeland habitats had significantly greater cover of exotic species compared to woodland or timber habitats.  The cover of native plants did not differ significantly on grazed and ungrazed sites in ponderosa pine and pinyon-juniper plots.  However, the cover of exotic plants was significantly greater on ungrazed sites.  Early detection of exotic plant species was significantly enhanced with the new modified FHM multi-scale vegetation sampling design.  Because hot-spots of native plant diversity are being heavily invaded by exotic plant species, managers of National Forests and rangelands face a formidable challenge.  This national network of plant diversity monitoring is an important first step in assessing the extent of exotic species invasion at large spatial scales.  The Pilot is scheduled to go national in the year 2001.


Principal Investigator:

                                    Dr. Dan Binkley

Affiliation:      Colorado State University

                  A116 Natural & Environmental Sciences Building

                       Colorado State University

                        Fort Collins, CO 80523


Co Investigator:       Dr. Thomas J. Stohlgren

Affiliation:     Midcontinent Ecological Science Center

                 Biological Resources Division

                      United States Geological Survey

Address:      Natural Resource Ecology Laboratory

                 Colorado State University

         Fort Collins, CO 80523-1499


USDA Forest Service Contact:

                                    Ken Stolte

Affiliation:      Southern Research Station

Address:       Forestry Sciences Laboratory

3041 Cornwallis Road

P.O. Box 12254

Research Triangle Park, NC 27709


Local Forest Service Contact:

                                     Merrill Kaufmann

240 West Prospect St.

Fort Collins, CO 80526-2098




Stohlgren, T. J., M. B. Falkner, and L. D. Schell. 1995. A modified-Whittaker nested vegetation sampling method. Vegetatio 117:113-121.

Stohlgren, T. J., G. W. Chong, M. A. Kalkhan, and L. D. Schell. 1997a. Rapid assessment of plant diversity patterns: A methodology for landscapes. Ecological Monitoring and Assessment (In Press).

Stohlgren, T.J., G.W. Chong, M.A. Kalkhan, and L.D. Schell. 1997b. Multiscale sampling of plant diversity:  effects of minimum mapping unit size. Ecological Applications 7:1064-1074.

Stohlgren, T. J., M. B. Coughenour, G. W. Chong, D. Binkley, M. Kalkhan, L. D. Schell, D. Buckley, and J. Berry. 1997c. Landscape analysis of plant diversity.   Landscape Ecology 12: 155-170.

Stohlgren, T.J.,  D. Binkley, G.W. Chong, M.A. Kalkhan, L.D. Schell, K.A. Bull, Y. Otsuki, G. Newman, M. Bashkin, and Y. Son. 1998a.  Invasion of hot spots of native plant diversity by exotic plant species. Ecology (In press).

Stohlgren, T.J., K.A. Bull and, Y. Otsuki.  1998b. Comparison of rangeland sampling techniques in the central grasslands. Journal of Range Management 51:164-172 March 1998.



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last updated 14 September 2000