written by Karen Colson and Jason Karl
Description and Uses
Photo points are permanent general view photographs (landscape or feature photographs) which provide a qualitative record for documenting and evaluating vegetation changes over time. Photo points are useful for detecting large changes in vegetation structure and for visually documenting measured changes. They are retaken from the same location and filling the same frame each time, allowing for a consistent comparison of changes between years.
Photo points are typically used in combination with other monitoring methods and are regularly used as a standard part of monitoring for documenting:
- Study Site Location
- Transects and Macroplots
- Landscape Changes
- Habitat Conditions
- Population Conditions
Advantages and Limitations
Photo points are a great visual technique for document landscape changes. However, in shrub ecosystems it can sometimes be difficult to see small changes over time. In many instances this method may require taking the photographs at the same time each year to avoid seasonal fluctuations when comparing photos. Because it is a qualitative technique, comparing photographs requires personal interpretation.
- USFS Photo Point Monitoring Handbook (Hall 2002).
- Monitoring Manual for Grasslands, Shrublands, and Savanna Ecosystems (Herrick et al. 2009).
- Measuring and Monitoring Plant Populations (Elzinga et al. 2001).
Technical and Application References
- Todd (1982), Rogers et al. (1984), and Brewer and Berrier (1984) provide overviews and suggestions for establishing and using photopoints.
- Turner, R. M. 1990. Long-Term Vegetation Change at a Fully Protected Sonoran Desert Site. Ecology 71(2): 464-477.
- Sharp, L. A., K. Sanders, et al. 1990. Forty Years of Change in a Shadscale Stand in Idaho. Rangelands 12(6): 313-328.
- Hart, R.H. and W. A. Laycock. 1996. Repeat photography on range and forest lands in the western united states. Journal of Rangeland Management. 49:60-67.
photo_plots_-_visual_record: Photo plots are also photographs that are retaken from the same spot and filling the same frame each time the photograph is repeated, however they are photographs taken of a defined small area (a plot) and are taken from a specific height, unlike photo points which are taken at a larger, landscape scale.