Volume 142, Issue 3, March 2009, Pages 500–508
Changes in the flora of Thoreau’s Concord
Abstract
To
determine the effectiveness of conservation efforts, scientists and
land managers must evaluate the ability of conservation areas to protect
biological diversity. The historic town of Concord, Massachusetts, home
of the philosopher and naturalist Henry David Thoreau, provides a
unique opportunity to examine how well conservation areas preserve
biodiversity in a suburban landscape. About 35% of total land area in
the town has been protected, and botanists, including Thoreau, have
surveyed plants in Concord five times over the last 170 years. We spent 5
years (2003–2007) re-surveying a subset of Concord’s flora for species
presence and abundance. Of the species seen by Thoreau in the mid-19th
century in Concord, we could not locate 27%, and an additional 36%
persist in one or two populations where they are vulnerable to local
extinction. Most species losses appear to have occurred in the past
three to four decades. Certain groups, such as orchids, have shown
particularly severe losses. More native species are declining in
abundance than are increasing. Non-native species represent an
increasing percentage of the flora, with many increasing in abundance.
The flora has experienced a net loss of species over the past four
decades, with 82 species gained and 236 species missing. Because many
species are rare on a local scale, persisting as one or two small
populations, local extinctions will likely continue in coming decades.
Habitat management, primarily to prevent tree establishment, appears to
have allowed many rare species of open habitats to persist and recover.
Active management of existing sites will likely be the key to protecting
the species diversity of the Concord flora and maintaining the living
connection to the writings of Thoreau.
Keywords
- Concord, Massachusetts;
- Flora;
- Henry David Thoreau;
- Local extinction;
- Population declines;
- Species composition;
- Suburban landscape
- Corresponding author: Tel.: +1 617 353 2454.
- 1
- Present address: USA National Phenology Network, 1955 East 6th Street, Tucson, Arizona 85721, USA; The Wildlife Society, 5410 Grosvenor Lane, Bethesda, MD 20814-2144, USA.
