Patterns and processes of recovery in and around an Indiana limestone quarry

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Patterns and processes of recovery in and around
an Indiana limestone quarry Vanessa L. Artman,
Dana A. Dudle Bryan Helm, David Pope, and Aaron
Randolph Department of Biology, DePauw
University, Greencastle IN 46135
Results The three forest habitats differ
significantly in forest structure, vegetation
composition, and breeding bird communities.
These differences are surprising given the
relative proximity of the sites. Furthermore, the
forest composition of several of the sites is
unusual for eastern deciduous forests. The
history of human activity at the sites may
provide a partial explanation for these
differences.
Introduction In October 2003, DePauw University
acquired a 192-ha nature park, intended for the
various purposes of habitat conservation,
education, and recreation. The land comprises
several habitats, including deciduous forest, old
fields, wetlands, a river, and several freshwater
ponds, but the central feature of the land is a
large limestone quarry that was abandoned 30
years ago. Each of these habitats has been
significantly affected by human activity, through
logging, mining, construction and some areas are
highly disturbed. Some central questions of
restoration ecology Is the ecosystem recovering
on its own? Or is human intervention appropriate
and/or necessary to promote recovery? If
intervention is necessary, what kind? form the
core of our discussions about how DePauw should
use and manage this resource. Here, we present
our baseline data describing the present state of
breeding bird and forest tree communities at
several sites in the park, and our preliminary
plans for further research and management at the
site.
Discussion Cerulean warblers occurred only at
the QS site and not the other sites (Table 1).
Widespread population declines of Cerulean
Warblers have been occurred throughout the
region, and this species is being considered for
federal protection. Cerulean Warblers are
patchily distributed within suitable habitat
throughout the region, and their presence at QS
attests to the importance of maintaining this
habitat within its existing condition. Indigo
Buntings were also common at the QS site, nesting
in the dense shrub cover. This species usually
occurs in early-successional habitats such as
open meadows or edge habitats, but its presence
in closed-canopy presents interesting questions
about fitness consequences of habitat selection
in different environments. Acadian Flycatchers
occur only in forest-interior habitat. They were
common at all three sites (Table 1) with fairly
high levels of breeding productivity (Table 2).
Their nests tend to be in predictable and
accessible locations, usually situated at the
ends of long branches extending over stream
drainages. Wood Thrushes were common only at
QH and were almost absent from the other sites
(Table 1). The differences in forest structure
and composition between the sites dont
necessarily explain these results because Wood
Thrushes are usually common and uniformly
distributed throughout suitable habitat, but
their unusual spatial distribution at the sites
merits closer attention.
Figure 1. Study areas at DePauw University
Figure 3. Forest understory composition at the
three study sites. Native shrubs dominate the
understory at the ARB but the regeneration layer
lacks oaks and hickories. An invasive shrub
forms the bulk of the understory at the quarry
sites, but the dense shrub cover provides nesting
habitat for songbirds such as Indigo Buntings and
Northern Cardinals.
Figure 2. Forest tree composition at the three
study sites. Forest composition at the ARB is
typical of eastern deciduous forests. At QH and
QS, forests have unusually high proportions of
elm and cherry, and lack oaks and hickory,
signature species of this region.
Table 1. Number of bird territories at each
site, 2004. All three sites support a variety of
songbird species, but some differences in
breeding populations across sites, despite their
proximity, suggest intriguing avenues for future
work on a subset of these species.
Acadian Flycatcher
Cerulean Warbler
Study Sites We chose three forested sites to
collect baseline data on bird and plant
communities the Arboretum (ARB), Quarry South
(QS), and Quarry Hillside (QH) (Figure 1).
Forest habitat at the sites has been relatively
undisturbed in recent history. However, habitat
quality is limited by extensive forest
fragmentation, with the surrounding landscape
comprised of a mix of rural and suburban
development. Adjacent land is used for athletic
fields, four-wheel-drive roads, powerline
rights-of-way, open meadows, and an abandoned
limestone quarry. Methods We measured
vegetation and habitat characteristics at ten
randomly located plots in each site following
BBIRD protocol. Within a 5-m-radius subplot, we
estimated leaf litter depth, estimated percent
cover of understory vegetation (and counted the number of shrubs and saplings (8.0 cm dbh) by species and size class. Within an
11.3-m-radius subplot, we counted the number of
trees and snags ( 8.0 cm dbh) by species and
size class. We censused bird populations using
the territory-mapping method. Each site was
surveyed four times between mid-May and the end
of June, between the hours of 5 and 10 a.m.
During each survey, we recorded locations of
singing and calling birds. Clusters of
observations over multiple visits were used to
identify territories, and then to estimate
population sizes. We searched for and monitored
nests at the sites following BBIRD protocol.
Nests were monitored every 3 to 5 days to
determine their fate. We estimated daily nest
survival rates using the Mayfield method.
Wood Thrush
Indigo Bunting

• Implications
• The forest at QS, QH, and ARB provides valuable
  habitat for a variety of songbirds, several of
  which are of significant conservation concern.
  We recommend that forest management practices
  proceed with caution throughout the natural areas
  to maintain the existing integrity of the
  communities.
• The sites provide an array of opportunities for
  research and coursework in ecology. We are
  excited about the opportunity for multiple
  long-term experiments at common sites, using an
  interdisciplinary approach to address questions
  such as
• What abiotic and biotic factors contribute to
  the unusual forest composition at the sites?
• How does food availability differ, given
  variation in distribution of masting trees
  (oaks, hickories, walnuts) between the sites?
• How do we minimize spread of invasive plant
  species without reducing available songbird
  habitat?
• What is the recent history of the sites and how
  has human land use affected the biological
  communities?

Table 2. Nesting success for two species of
forest birds at the sites
Figure 3. Size distribution of trees and cover
of leaf litter at three sites. Different letters
above the bars indicate significant differences
between sites (1-way ANOVA with Tukey tests,
p
at the quarry sites, and has more extensive
litter however, leaf litter at all three sites
is less extensive than in typical eastern
deciduous forests. Leaf litter decomposition
rates may vary at the sites, which would impact
communities of soil invertebrates, and thus,
birds.
Acknowledgments We thank DePauw University for
funding this research. This research would not
have been possible without the foresight of
Hansen Aggregates and the many hours of dedicated
fieldwork by our student co-authors.