Population Monitoring

A population is a group of individuals of the same species that have the ability to genetically interact and inhabit a defined geographic area.

Population monitoring involves consistent and repeated observations to detect, measure, assess, evaluate and draw conclusions as to how species and ecosystems are changing through time and space.

Monitoring is a key component of rare plant conservation, required under several federal acts, for endangered, threatened, and rare species. Population monitoring is coupled with developed objected and management methods and is useful in determining success of implemented management practices.

Flowering stems of the Schweinitz's sunflower counted during population monitoring.

Qualitative Data Monitoring

FoPC Staff Olivia counting flowering stems of Schweinitz's sunflower.

Presence or Absence: Documenting weather or not the species is still found on site.
Estimate population size: Using one aspect of the population to estimate overall condition (counting reproductive or large individuals).
Estimate population condition: Documenting observations such as signs of herbivory, disease, percentage in different life cycle stages, etc.
Vigor indicators: Plant height, number of flowers, number of leaves, diameter of rosettes, etc.

Demographic Monitoring

Assessment of changes in population throughout the lifecycle; measures germination and mortality rates, growth, size, density, and distribution.

Population Modeling and Viability analysis: Mapping individual plants and marking all stages of the plant life cycle to construct a model for future population viability assessment.
Single age/stage class investigation: Measuring a few stages of the lifecycle such as seedling survival or longevity of adults.
Demographic structure: A measurement taking at one time to assess the distribution of individuals in age or stage classes(seedlings, juveniles, non-reproductive adults, reproductive, and old/dying).

Schweinitz's sunflower. Photo by PCP Staff.

Habitat and Protected Area Monitoring

Detection or measurement of changes in focus habitat through repeated observations and recordings of the specific ecosystem from a previous status.

Best done with a standard field sheet and quantitative assessments.
Assess for associated vegetation, exotics, and disturbances.

For more detailed information on methods for population monitoring check out this technical reference.

What to Bring into the Field

Clipboard
Standardized guidelines and recording sheets
Pencil
Rite in the Rain notebook or paper
Eye lens
Plant ID reference
Ruler

Yearly monitoring of liatris involves counting rosettes, height, and number of flowering stems. Photo by PCP Staff.

Reporting

For proper reporting include an executive summary, maps, photos, monitoring methodology, standards and equipment used, parameters monitored, location, frequency and intensity of monitoring, date, time, and duration.

For more information on monitoring and reporting check out this link.

Sources and Resources

Chapter 13: Monitoring of Areas and Species/Populations to Assess Effectiveness of Conservation/Management Actions

Elzinga, L. Caryl; Salzer, W. Daniel; Willoughy, W. John. Measuring & Monitoring Plant Populations. BLM Technical Reference 1730-1.

Vitt, Pati; Tienes, Melissa; Skogen, Kriss; Havens, Kayri. Optimal Monitoring of Rare Plant Populations II: Data Collection and Analysis. USDA Forest Service.