Part 1: New Approaches to Monitoring Populations and Communities

DeCoster, James; Norris, Jodi; Swan, Megan

In an effort to implement long-term monitoring of upland vegetation and soils in National Park Service units across the southern Colorado Plateau, the Southern Colorado Plateau Network began establishing plots in key ecosystems in a number of parks in 2007. Annual variation in species abundance, driven in part by changes in precipitation, was expected, particularly in drier ecosystem. To capture this variation, we chose to establish a subset of plots in each targeted ecosystem and sample those plots for three or more consecutive years. This strategy allows for examination of temporal and spatial variation, which will aid in developing revisit designs that maximize our ability to capture changes in community composition and structure over time. However, by extending our baseline sampling over multiple years, a number of other unexpected factors came into play and caused additional variation to the baseline conditions. These included human disturbances, such as the implementation of a landscape restoration project, and natural disturbances, such as wildfires. In addition, over this time period we detected vegetation changes beyond interannual precipitation-mediated fluctuations. These included an increase in nonnative species abundance and native shrub die-off. Temporal variability necessitates defining baseline conditions over multiple years, but directional change and disturbance during that time period may interfere with the definition of the baseline.