Restoration of Hydrastis canadensis:: Experimental test of a disturbance hypothesis after two growing seasons

This paper tests the hypothesis that disturbance simulation is beneficial for restoration of Hydrastis canadensis (goldenseal) 2 years after a disturbance event. This takes into account possible delay in resource allocation to reproduction. At five deciduous woodland sites in Ontario, Canada, three disturbance simulation treatments, fertilization, soil turnover, fertilization + soil turnover, and a control were randomly applied to experimental blocks in 1999. Seeds and mature rhizomes were transplanted into each treatment plot. Seed production and seedlings were recorded in 2001. Transplants were measured and flowers and fruit recorded in 2000 and 2001. Soil turnover and fertilization + soil turnover significantly increased the production of flowers and fruit in the second year after disturbance, contrasting with lack of significance in the first year. The effect on plant size was opposite, with significantly increased cover in the first year but not the second. Soil turnover + fertilization significantly increased seed production. The disturbance treatments did not have a significant effect on number or presence of seedlings possibly due to extraordinary drought conditions. Consideration of second-year results strongly suggests that (1) substrate disturbance, in addition to canopy gaps, is an important factor in woodland herb ecology; (2) certain woodland herbs may be rare due to lack of specific disturbances which were more prevalent in the past; and (3) mature woodlands may require management, involving disturbance simulation, for the protection and restoration of certain rare woodland flora.