The importance of long-term observational data sets as records of ecosystem responses to climatic variation and directional change continues to increase. Ecologists and land managers use such records to ask questions about how ecosystems responded to past climatic variation and perturbations, in order to understand mechanisms behind increase/decline of species of interest, and to inform predictions about future scenarios.

Sampling using chart quadrats was a common method in the early 20th century as a means to track availability of perennial grasses and other species as forage for liveestock.  At the Jomada Experimental Range in southern New Mexico, chart quadrat sampling began in 1915 and continues through the present, with permanent quadrat locations being resampled approximately every 5 years. Using this detailed record we can not only investigate trends in grass cover, but also track variation in other plant community properties (e.g. species richness, species tumover, abundance distributions) as the system experienced severe droughts, variation in quantity and timing of yearly precipitation, and an overall trend of shrub encroachment  over the past 100  years.

Like many desert rangelands in the southwest, cover of perennial grasses such as black grama (Bouteloua eriopoda) has declined dramatically since the early 1900s. In recent samples, there is some evidence that cover of B. eriopoda has increased slightly on the quadrats where it has remained, likely the result of new recruits rather than existing individuals increasing in size. We also found that while species richness has remained fairly constant during the past 20 years, rates of tumover were also high, with rates of 50% tumover on average during each 5-year sampling interval. These results contribute to the broader picture of ecosystem dynamics at the Jomada Experimental Range, and demonstrate the value of long-term consistent sampling initiatives.