Ecosystem restoration typically involves restoring a self-organizing process, like fire regime or hydroperiod, in order to produce a historic pattern with minimal cost. In many cases, however, the ‘degraded’ system is under new pressures from exotic species, climate change, increased nutrients, etc. and process restoration may have unexpected results under the new conditions. Increasingly, the process itself cannot even be restored and we are left with what can only be considered a novel ecosystem. In some cases we continue to strive for a historic pattern without the process, an approach Mitsch and Wilson (1996) compare to gardening. We use a study from a central Florida Lake to illustrate such an approach, where a combination of exotic species, altered hydrologies, and excess nutrients was countered with bulldozers and herbicide. By implementing a draw-down and mechanically removing millions of cubic meters of organic material from the littoral zone, managers hoped to restore the historically oligotrophic vegetation communities to a eutrophic system. We repeatedly collected vegetation biomass and densities from 186 sample locations twice annually for two years prior and four years after the restoration to monitor the success of the project.
Results/Conclusions
Four years after the restoration project we found significant expansion of a submersed vegetation community in the treated plots, while most control plots had reverted to dense, tussock forming vegetation similar to pre-restoration. However, at shallow depths the treatment was less effective and recovery was much quicker. These results suggest that without continued herbicide applications the treated areas would have returned to pre-treatment levels in as little as four years, and there was little impact to the shallowest communities. In cases like these where historic processes are no longer restorable or new factors alter their impacts, we must decide whether to set novel restoration targets or continue our gardening at an increasing cost.
