Title: Head of the Plains Nantucket Shadbush (Amelanchier nantucketensis) Response to Prescribed Fire Management, Final Report 2014
Author: Kelly Omand
Abstract: Until 2011, Nantucket shadbush was listed as a species of “Special Concern” in Massachusetts, under the Massachusetts Endangered Species Act. While it is still considered uncommon throughout much of its range, recent surveys have led to the removal of its “Special Concern” status. However it still remains ranked “1” for rarity in the northeast, and the island of Nantucket is likely home to some of the largest and healthiest populations.
Nantucket shadbush is a low-growing deciduous, clonal shrub. It propagates itself mainly by sending up new stems from the root stock, rather than by producing seed. It typically blooms in May-early June, producing cream colored flowers which are smaller and less showy than many other shadbush species. The unassuming flowers distinguish this shadbush from its close relatives—its pollen is often born along the petals’ edges, rather than on anthers, which is a very rare plant trait in the plant.
Observations by ecologists and land managers indicated that this low growing shrub responds well to periodic disturbances that reduce the height of competing vegetation, such as brush-cutting or prescribed fire. As a result, NCF’s Science and Stewardship staff designed this long-term research project (2005-2011) at the Head of the Plains property to assess the effects of prescribed fire on this unusual and rare clonal shrub.
In order to better understand the response of Nantucket shadbush to prescribed fire, we monitored patches over time, following prescribed burns. Results of this study suggest that the primary immediate benefit of fire to Nantucket shadbush is vigorous re-sprouting. All burned patches survived fire and many produced numerous root and stump sprouts in the first year following the prescribed burn. Our research indicates that Nantucket shadbush tolerates both spring and fall burns, and requires a relatively long time frame for recovery (4-5 years).
While this species appears to flourish under current conditions on Nantucket, changes in management, such as reduced fire or brush-cutting, could lead to rapid declines in available habitat. Erosion of shoreline areas, development, or changes in climate could further affect populations. Management decisions on Nantucket should take into account the fact that this species is very uncommon elsewhere in the region, and that the Island’s early successional grasslands and heathlands are core habitat for this species. Based on the regrowth trajectory we observed in this study, care should be taken to choose an appropriate interval for management (every 4-5 years). Finally, this unusual shrub is linked to particular guilds of native bees. Given recent concerns about declines in native pollinators, particularly native bees, it is possible that although Nantucket shadbush itself has been removed from Special Concern status, it may be very important for these often understudied groups of insects.