We are exploring vegetation and soil resource patterns after oil and gas development in the Piceance Basin in western Colorado. Disturbed areas are generally characterized by a loss in heterogeneity in vegetation and soil structure and function. We chose eight abandoned well pads and two reference sites to compare soil and vegetation characteristics. All sites are located in Rio Blanco County, Colorado. The most recently abandoned site had only just had the topsoil replaced in the spring prior to sampling, while the oldest site was abandoned in 1967. At each site, we sampled a 9m x 12m plot. We randomly located a point in each of 48 1.5m x 1.5m grid areas. We also randomly located 4 subplots of 2m x 2m, and sampled 16 random locations within each subplot. We sampled a total of 112 points in each plot. Soil organic carbon, nitrate and ammonium, pH, conductivity and gravimetric water content were determined for each sample.
Geostatistical analyses of soil organic carbon indicate less heterogeneity in the disturbed sites in comparison to the two reference sites. With the exception of the recently recontoured site, the range of maximum minus minimum soil organic carbon is linearly correlated with the age of abandonment and was lower than the two reference sites. These results suggest that even 40 years after abandonment, soil heterogeneity levels have not recovered. Attempting to instill heterogeneity at the time of reclamation may aid in the reclamation of these sites.