Nitrogen availability and plant community structure on a restored gravel pit four years after restoration

The purpose of ecological restoration is to help accelerate the recovery of a disturbed ecosystem that may not recover on its own.  Restoration does not just begin or end with replacing historic vegetation. It requires the reestablishment of an entire ecosystem on a comparable if not equivalent pre-disturbed successional trajectory. Thus, acquiring a total picture of ecosystem recovery, post-restoration, is important for ascertaining restoration success. Given that belowground function is a major driving force for shaping aboveground structure, studying soil dynamics is just as important as measuring plant community. This is especially true for the oligotrophic soils of the New Jersey Pinelands (NJP), where mechanical disturbances leave the landscape void of vegetation for decades. In order to determine the efficacy of a revegetation strategy in the NJP, we conducted a comprehensive evaluation of both ecosystem structure and function on a restored gravel pit. Four years after restoration we assessed belowground function by measuring soil nitrogen availability on the restored site and compared it to a naturally recovering reference site. We found a seasonal influence in both soil ammonium and soil nitrate concentrations (p<0.05) but only nitrate differed among sites. Unavailable nitrogen (microbial biomass nitrogen) also varied seasonally (p<0.05) but there was no difference between the restored and reference sites. Bray-Curtis similarity between the sites was 0.70. Based on the evaluation of aboveground structure and belowground function, it appears the restored gravel pit is recovering in a comparable manner to that of a naturally recovering site in the NJP.