Ecological succession is a predictable set of changes within the plant community following a disturbance event. This concept is frequently used in forest ecology, however it is not commonly used on grassland ecology. Succession can be considered a metric of community recovery following disturbance. Federal land management agencies have been collecting vegetation line-point intercept data for decades. District and Area office archives are full of valuable data. However, researchers struggle to draw conclusions from such noisy data, which is leading the agencies to consider discarding those records and losing information obtained from years of field data collection. We suggest a method based on ecological successional stages to evaluate long term trend according to the change of climax functional group. On this study we analyze the point intercept data from 3 sites that are part of different studies in Montana: 1) the Gardiner Basin, 2) the National Bison Range, and 3) the Upper Gallatin Range. We grouped all the climax species summing the frequencies. We then compared the individual species trend against the climax functional group trend.
Results/Conclusions
At Gardiner Basin we had climax data only from 2 years (1978 and 2015). The trend visualization was straight forward: Agropyron smithii and Pseudoroegneria spicata increased and Artemisia tridentata declined. On the National Bison Range Festuca scabrella, Festuca idahoensis and Pseudoroegneria spicata showed the same trend, increasing from 1968 to 1990 then decreasing in 2010 with Stipa columbiana appering in the records in 2010. The results of the Upper Gallatin Range assessments done in 1958, 1962, 1968, 1976 and 2013 showed that the 4 climax species accounted for less than 4% of the total vegetation with multiple trends during the study period. Festuca idahoensis on the other hand was at least 6% of the total with a unique pattern. Because of its dominance it shaped the climax trend. The results of Upper Gallatin Range study demonstrated how hard it is to depict ecological trend within a complex vegetation community. Long term trends however became clearer when grouping climax species into functional groups. The results achieved on this study suggest that the data collected by the agencies are a valuable and useful resource and should be kept and not discarded.