Using Photo Points to Monitor Plant Community Change
Plant communities are changing all the time. These changes are often very subtle and can be undetected by the casual observer. However, from a management perspective, detecting change is very important. Depending on management goals, change can be positive or negative. Monitoring change can help a land manager evaluate specific land management practices such as herbicide use, livestock grazing and prescribed burning. Monitoring change can also assist in planning future management strategies.
How does a land manager monitor change in a plant community? One of the simplest methods is to use photo points. This method consists of taking photographs from permanently marked locations, known as photo points, to monitor visual change in the plant community over time. Photo point locations should incorporate areas with a large field of view, as well as areas of particular interest such as a recently burned pasture. Photo points should be permanently marked because they will be used year after year. T-posts, corner posts and specific trees are just a few objects that can be used to mark photo points. A handheld GPS unit can be used to mark locations that do not or cannot have permanent physical markers. The appropriate number of locations will be different for each property and determined by the needs of the land manager.
After choosing locations, determine a schedule of future photography. Attempt to take the photographs at the same times each year. Most land managers would benefit from photographs taken once per winter, spring, summer and fall. Photographs taken over these periods will provide a complete "picture" of the annual change in a given plant community. Additionally, attempt to take the photographs in the same direction and at the same time of day. The four cardinal directions north, south, east and west are commonly used.
Monitoring annual change can reveal short-term clues about long-term problems. For example, an increase in cool-season grasses in an area managed for warm-season grasses would be cause for concern. Photo points can facilitate recognition of this trend and actions to reverse it can be implemented. A positive example would be evaluating the control of eastern red cedar encroachment with the use of prescribed burning. Eastern red cedars less than 4 feet tall are easily controlled with prescribed burning. Many land managers do not notice this silent intruder until it is too late; however, this evergreen is easily seen when compared to dormant vegetation during the winter months.