Mink River Estuary a landscape approach to protection

[From the U.S. Government Printing Office, www.gpo.gov]

Mink River Estuary: A Landscape Approach to Protection

1995

This project was made possible by a grant provided by the
Wisconsin Coastal Management Program in partnership with
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the Wisconsin Chapter of The Nature Conservancy.

Investigators:

Michael Grimm, Laura Hewitt, Brian Hotz, Kathy Kirk and Kimberlee Wright

GC
97
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1995

Project Background

The Mink River is unique freshwater estuary opening into Lake
Michigan and located at the tip of Wisconsin's Door Peninsula.
The near pristine integrity of the plant communities and the lack
of human disturbance in the wetland complex makes the Mink River
Estuary Reserve a natural area of regional significance. In the
early 1970's the Coastal Zone Management Program considered the
Mink to be one of the highest quality estuaries in the upper
Great Lakes.

The National Estuarine Sanctuary program explored conservation
actions and protections to apply to the Mink River Estuary and
for a variety of reasons was unable to pursue long term
conservation goals for the area. The Nature Conservancy was then
asked to assess the area for potential protection activities.
The Conservancy had a long history of private land protection in
Door County and was familiar to many local conservationists.
This history enabled the Conservancy to work cooperatively with
area landowners to find protection solutions'for the estuary.

The Coastal Zone Management Program's initial investment in the
area included funding a study by Forest Stearns and Janet Keough.
This report proved invaluable in helping the Conservancy
formulate early protection goals. [Stearns and Keough, 19821 The
Conservancy's land acquisition efforts began in the early 19701s.
The Conservancy currently owns and manages over 1600 acres in the
river corridor and surrounding uplands.

In the early 1970's the Conservancy's conservation goals for the
Mink River Estuary were largely concerned with water quality.
The largest threat to continued high water quality was potential
runoff from logging, agriculture and recreational development.
Today some of the threats to the wetland corridor that were of
concern in the early 1970's have been alleviated by Wisconsin's
exemplary wetland protection rules and regulations. In the early
days of the Mink River project, the permanent protection of the
lowland forest in the river corridor was a top protection
priority.

.The effort to protect the lowland forest has been successful with
a majority of the sensitive riparian areas owned and managed by
the Conservancy, with an additional 400 acres covered by
cooperative agreements with private landowners. Private
landowners in the watershed of the Mink River include many local
families with two or more generations of ties to the land. These
families have been the hallmark of,the Conservancy's protection
efforts in the Mink River Estuary.

Many long-standing families in the corridor sold land to the
Conservancy early on in the project to insure perpetual
protection of lands so carefully stewarded by their parents and
grandparents. The Conservancy was able to stabilize traditional

land use patterns in the corridor in light of rising taxes and
the increasing pressures associated with population growth and
in-migration.

According to Wisconsin Department of Administration population
projections for the Town of Liberty Grove, which includes most of
the watershed of the Mink River Estuary, the number of people in
the Town will increase by 50*-. by the early 21st Century. This
projected growth represents a potential threat of further
fragmentation of the landscape and significant changes in the
traditional land use patterns of the area. It is this
anticipated population growth that spurred the Conservancy into
considering the need for a broader look at the landscape
supporting the Mink River Estuary Reserve.

The abundant richness of the Mink River Estuary has coexisted
with the human community since European settlement in the mid-
18001s. The Conservancy's efforts have served to stabilize the
river corridor in light of a change in human patterns on the
landscape. This study, funded by the Wisconsin Coastal
Management Program, allowed the Conservancy to assess the larger
landscape which supports the biotic richness of the Mink River
Estuary and assess threats to supportive natural processes and to
develop strategies to cope with undesirable conversions in
traditional land use patterns.

Natural Area Protection - A Bl@ndinq of Theory and Practice

The Nature Conservancy owns and manages the largest system of
privately held nature reserves in the world. The Conservancy was
founded by scientists and has remained committed to designing
conservation action plans based on the best available
information. The Wisconsin Coastal Management Program shares
this approach as evidenced by its early sponsorship of the
Stearns and Keough report--the first study to systematically
observe and record the ecological processes supporting the biotic
diversity of the Mink River Estuary. The Conservancy's
conservation actions have been largely driven by the Stearns and
Keough study for over two decades.

In the past ten years a new discipline has emerged from the many
strands of science concerned with the understanding of ecological
processes and functions. The science of Landscape Ecology blends
scientific theory and practical, on-the-ground applications in an
effort to use the best available information to protect
biological diversity, while at the same time monitoring our
actions and measuring our effects on the landscape. The Nature
Conservancy is a leader world-wide in applying science-based,
direct action conservation strategies to protect the best
examples of natural diversity.

The Wisconsin Chapter's efforts in Door County are informed by
the Conservancy's systematic assessment of the biological
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diversity of the Great Lakes Basin. In 1994, The Nature
Conservancy developed a database of the rare, threatened and
endangered species and natural communities in the Basin. The
information was then entered into a Geographic Information System
which allowed the mapping of "hot spots" of biological diversity
in the Great Lakes. The Door Peninsula stood out as an area high
in concentrations of species of concern, including globally rare
species found only in the Basin. [The Nature Conservancy, 19941

The Wisconsin Chapter systematically reviews existing
conservation plans for its statewide network of privately-owned
natural areas in an effort to stay current with the best
available information regarding ecosystem-based conservation and
management. Mink River was deemed to be a high priority for
careful review based on the biological richness of the site and
the increasing threats from changing land use patterns. The
Wisconsin Chapter's approach to conservation is rooted in a rich
legacy of natural resource scholars and practitioners.

Wisconsin has long been a leader in practical applications of
ecosystem-based thinking. Aldo Leopold encouraged us to liken
ecosystem management to watch repair when he warned us not to
"throw away the parts." John Curtis furthered this legacy with
his classification of natural communities in The Vegetation of
Wisconsin. In defining the landscape in terms of the
associations based on soils, underlying substrate, climate and
vegetative cover, Curtis supplied a solid foundation for the
Wisconsin Department of Natural Resources State Natural Areas
program. The goal of the State Natural Areas program is to
protect representative examples of Wisconsin's native diversity
associated with the six distinct eco-regions of Wisconsin (Hole
and Germain, 19941 .

It is in this Wisconsin conservation tradition that the Wisconsin
Coastal Management and The Nature Conservancy have rooted their
conservation efforts. The Wisconsin Coastal Management Program's
support of the study of the natural and human communities that
make up the Mink River Estuary has allowed the Conservancy to
assess land use in the area and develop strategies to encourage
the continuation of those patterns that support the biotic and
cultural richness of the area.

Prolect Design
It is on the foundation of a dynamic, inter-disciplinary approach
that the Conservancy's ecosystem protection and management
strategies are formulated. By utilizing an inter-disciplinary
team, the Conservancy blends the best available scientific
theories with practical knowledge based in hands-on management of
natural areas. This approach is particularly suited to the Mink
River Estuary. The goal of the project was to carefully review
past protection efforts in light of the best available science
and make revisions in strategies that will best insure long-term
viability of critical natural features of the watershed.
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The first step in building a functional ecological model of the
Mink River Estuary was to review existing information and
identify gaps in that knowledge base. The. Mink River study team
collected information via a variety of avenues including review
of WI-DNR Bureau of Endangered Species records, individual
studies associated with the Mink, interviews with local
professional and amateur naturalists, literature searches on key
species and systems and field assessments of areas where existing
information was inadequate.

The study team then compiled and presented this data in a threats
analysis workshop. The list of key features gleaned from this
research formed the framework for the discussions of the
workshop.

The team incorporated the findings of the workshop into the
overall project, with particular emphasis on refining the
ecological boundaries of the study area. The threats analysis
was instrumental in determining conservation strategies and
priorities.

Another crucial element of the study was to include the community
in the process. Successful ecosystem protection efforts must
include the human community that depends on the landscape for
economic and cultural survival. The main activity in this regard
was a "neighbors" meeting held in the Liberty Grove Town Hall in
July 1995. All the landowners in the study area were invited, by
mail, to the forum to discuss the new approach to protecting the
Mink River Estuary watershed. This was a most valuable
interchange of information and concerns about the study area.
The Conservancy's actions in the area have long been informed by
the compelling conservation ethic of the local population. The
neighbors meeting was a continuation of this fruitful
partnership.

Finally, the team incorporated the scientific and sociological
findings into a final report including a map of ecological
boundaries, conservation strategies and a list of future needs.
The Threats Analysis Workshop was the key framework on which the
study results were based. A summary of that process is listed
below. A list-of sources relied upon throughout the study
follows the report.

Mink River Estuarv Threats Analysis Workshop
A workshop was held in July of 199S to review the ecological
boundary proposed by the Mink River study team and to assess the
level of threat(s) to the natural features of concern within that
boundary. The workshop was attended by a wide range of natural
resource professionals, including professors from the University
of Wisconsin system, Wisconsin Department of Natural
Resources(WI-DNR) researchers, local conservation organization
representatives and others with specialized knowledge of the Mink
River Estuary.
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The workshop followed a model the Conservancy has developed to
assess conservation objectives in key project areas. That model
applies a systematic approach to landscape-scale conservation
which considers five distinct avenues of inquiry including: the
natural systems and processes that support the natural feature(s)
of interest; the stresses to those systems; the sources of
stress, or threats; strategies to address protection of natural
systems by eliminating or mitigating sources of stress and
measures of success which monitor conservation actions and their
long term effectiveness for the protection of natural features of
concern.

Natural Systems The key natural systems were those identified as
integral to the viability of the natural features of concern
within the Mink River Estuary study area. The natural key
natural processes that tie the Mink River Estuary and the
surrounding landscape together are based in water.

The estuary itself is dependent on the fluctuation of water
levels that result from the seiche effect driven by the tidal
action of Lake Michigan. The changing water levels maintain the
diverse array of natural communities in a stable but ever-
changing pattern throughout the river corridor. The periodic
inundation of the expansive marshes in times of high water sets
back the successional displacement by woody shrubs. The varied
and expansive mix of natural communities provides habitat for
many different plants and animals.

The changing water levels are also integral to the mixing of the
nutrient-rich groundwater entering the system via a series of
discharge areas throughout the corridor and the water of Lake
Michigan. It is this mixing of waters that provides the
conditions necessary to maintain the productivity of the estuary.

Water may also be a key contributing factor supplying critical
nutrition to the vast stream of neo-tropical migrant birds
utilizing the Door Peninsula each spring and fall. Preliminary
results from a Nature Conservancy study in Michigan's Great Lakes
coastal areas suggests the warm, near-shore waters in spring
supply an abundant source of invertebrates to migrating birds.
The warm, near-shore waters provide an excellent habitat for many
species of insects which hatch out in consort with migrating
birds such as the many species of warblers to pass through Door
County each spring.

The coastal ribbon of boreal-like forest is also dependent on the
climatic conditions created by Lake Michigan. The mix of plant
species making up these coastal forests is similar to conditions
not found elsewhere in Wisconsin, with the exception of the Lake
Superior coastal area. Further studies are expected to confirm
anecdotal accounts of northern bird species, such as the Canada
warbler and others not common elsewhere in Wisconsin, utilizing
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the boreal-like forests which frost much of the shoreline.
Additionally, the coniferous strip of forest in the coastal areas
is believed to play a critical role for many species in spring
and fall migration when other food sources area scarce.

The gradient of natural communities from the bluffs of Ellison
Bay to the cobble beaches of Lake Michigan captures
representative examples of most of the features of the northern
Door Peninsula. The land gradually slopes fromthe northwest to
the east following the tilt of the Niagara escarpment. Cold air
drains from the uplands to the wetland areas moving moisture
across the landscape. A gradient of forest communities extends
from the lowland forest edging the wetland complex, through
northern mesic forest to the north and east, and then into the
northern dry--mesic forest at the northwestern corner of the Door
Peninsula. This continuum creates a variety of habitats for
plants and animals and allows for the opportunity to preserve
biodiversity and the natural processes necessary to maintain
viable populations of species. A corridor of contiguous forest
from the northern coast to the riverine wetlands allows for
better dispersal and seasonal movements of the inhabitants as
well as minimizing the risks of predation and competition from
edge species encouraged by a more fragmented landscape. The
pportunity to protect such a rich continuum of Great Lakes-
dependent natural communities is unavailable elsewhere on the
0

peninsula and no similar presentation is known elsewhere in the
Great Lakes.

The identification of these natural processes was instrument'al in
determining the adequacy of the initial ecological boundaries
proposed by the study team. Once the boundaries were agreed
upon, the next step was to assess the threats to the natural
processes and the sources of potential stresses to these systems.

Stresses and Sources of Stress The threats to the key natural
features used to define the study area boundaries are varied in
their sources. The section below will identify the most
significant stresses and their sources for each natural process
or*system considered critical to the viability of species and
natural communities of concern in the study area.

Hydrologic regimes, or the inputs and patterns of water movement
throughout the study area are susceptible to stress from a
variety of sources. Stabilization of water levels in Lake
Michigan would have a devastating effect on the diverse wetland
complex in the study area. Without the periodic flooding to keep
shrub invasion and other successional patterns in a dynamic
balance the system would become less diverse, or monotypical over
time. The fluctuating water levels result in a rich mosaic of
natural communities with an abundance of habitat niches to
support numerous species.

The protection of water quality in the system has been an
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important objective from the beginning. The introduction of
toxins into the system would effect the integrity of species
throughout the trophic chain. A federally endangered dragonfly,
the Hines Emerald or Somatochlorai hineana, has been documented
in the Mink River-corridor and would be greatly compromised by
reduced water quality.

Another threat to water quality is through increased
sedimentation. Sedimentation reduces water clarity and thus
reduces light available to aquatic vegetation and it loads an
excess of nutrients into the system. The early reserve design
sought to protect the lowland forest in the Mink River corridor
to act as a filter to trap toxics and sediments and keep them
from entering the estuary. The early design has proved to be
effective with regard to reducing the threats from increased
sedimentation and to a lesser extent, the introduction of toxins.

The quantity of water entering the system in the form of
groundwater is essential to the viability of the estuarine system
and the fen-like plant communities dependent on the nutrient-rich
discharge. The early reserve design did not adequately address
the protection of groundwater discharge by the omission of
protection aimed at critical recharge areas in the uplands
surrounding the Mink River Estuary. Although there has been no
formal groundwater mapping in the watershed, the topography and
location of discharge areas suggest key upland features in need
of protection. The most significant threat to water quantity in
the system is dense development in the uplands. Poorly placed
development may affect groundwater quantity in two ways. Removal
of vegetation and creation of impermeable surfaces in recharge
areas interferes with the system's capacity to capture surface
waters. Dense development may also pose a threat through the
mining of groundwater to supply well water to residential and
commercial developments. There are areas in southeast Wisconsin
where densely developed subdivisions have experienced decreased
quantities as additional wells are mining the aquifer.

Neo-tropical migrant birds are a key natural feature of the Door
Peninsula with from 500 to 1000 species documented in the Mink
River corridor in a given season. The largest threat to these
migrants lies in the fragmentation of habitat. The expansive
marshes of the Mink River and the continuous ribbons of forest
cover along the Green Bay shoreline in the northern part of the
study area Currently provide critical habitat for migratory
birds. Fragmentation of habitat due to increased subdivision and
development is a very real threat in light of the population
growth projected for the Town of Liberty Grove. Forestry
practices also may contribute to fragmentation of key areas.
Much of the forested shoreline in the study area is currently
supporting migratory bird habitat. Changes to these current land
use patterns are likely as the population grows and properties
change hands and are potentially subdivided and cleared for
development.
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The gradient of communities in the study area supports the entire
range of biological diversity that characterizes this ecosystem.
The areas of gradual blending or grading from one community type
to the next have been determined to be "hotspots" of diversity.
The gradually changing characteristics such a's moisture and
aspect provide opportunities for species survival in extreme
conditions such as times of drought. Fragmentation is the
largest threat to the biotic richness found along these landscape
gradients. The main source of fragmentation in the study area is
subdivision and development. Land conversion for agricultural
production, while historically a source of fragmentation, is not
a major threat in the study area. The trend appears to be moving
way from agricultural land uses toward residential subdivision
and development. The expected population growth will likely
accelerate fragmentation and reduce future options to maintain
connective corridors of gradually changing habitat types.

Strategies The boundary revision recommendations within this
report are founded on a blend of the best available science and a
realistic assessment of the likelihood for success of on-the-
ground conservation actions. The human community within the Mink
River ecosystem has coexisted in a largely compatible manner with
the elements of biological diversity. The challenge of this
project is to encourage the continuance of land use patterns that
protect and enhance important natural features while continuing
to provide the cultural and economic opportunities essential to
the well-being of the human community.

The Nature Conservancy has worked cooperatively with the people
of Liberty Grove throughout the history of this project to
protect important'natural features in a manner that also
facilitates the continuance of traditional land use patterns.
The Conservancy has utilized a variety of conservation tools to
achieve the goals of the project. Most familiar in the toolbox
is land acquisition. Acquisition remains an effective tool for
protecting core natural areas that area best left undisturbed,
but owning and managing all the land in the ecological boundary
is neither practical or necessary.

The application of particular strategies must be determined by
assessing the appropriate level of protection for the
conservation target and the needs of the people associated with
the land that supports the features of concern.

The strategies listed below are accompanied by examples of how
they might be employed. The individual strategies may have many
applications and aren't.limited to these examples.

Communication and Education The Town of Liberty Grove has a
tradition of valuing and protecting the natural resource base of
the community. The conservation ethic of the community is long-
standing. The Conservancy's success in this project is rooted in
the acceptance and support the community has for natural resource
conservation.

Historic land use patterns have been largely compatible with the
biological richness of the area. The Conservancy may be in a
position to provide linkages between local traditions and new
members of the community. Many new residents of the area have a
deep appreciation of the natural beauty of the area, but don't
have the benefit of the kind of knowledge and intuition developed
over generations of association with the land. The Conservancy
can "bridge the gap" by learning from the long-time residents and
providing information and local history to new members of the
community.

Migratory bird habitat along the shoreline of Green Bay in the
northern part of the study area is currently well provided for.
Although the area has a high degree of residential development,
the residents maintain the natural vegetation which supports
migratory birds. Although current land use is compatible with
the habitat requirements of migratory birds, there is no
assurance that this pattern will remain stable over time.

A series of materials and presentations designed to provide
information to landowners regarding the habitat requirements of
migratory birds may help to stabilize current conditions. The
assumption being that most people will make good decisions if
they have good information.

Conservation restrictions recorded with the deed of a given tract
of land can provide perpetual, legally binding protection
measures for land which is privately owned and managed. This
tool is suited to a wide range of conservation objectives but
works particularly well for families who would like to insure the
present condition of their land even after transfer of ownership
by sale or bequeath.

Conservation restrictions or easements can stabilize current land
use patterns and densities by limiting the subdivision of a given
parcel of land. There are several key properties within the
project area that area in close proximity with core natural
areas. The current densities may be compatible with the
conservation objectives for the natural areas nearby, but ten
dwellings on the same forty acre tract may not be. The
Conservancy has already purchased one property in the project
area and placed permanent restrictions on the deed which prohibit
further subdivision and resold the land. The new owner may
improve the existing dwelling but is prohibited from subdividing
the land. This same owner may sell or bequeath the property and
the restrictions, which are recorded with the deed, will apply to
all subsequent owners of the property.

The use of conservation easements and restrictions provides for'
private ownership and use of important land while also limiting
the density of development to current patterns.

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Voluntary cooperative agreements between private landowners and
The Nature Conservancy facilitate the sharing of information and
management advice for sensitive natural features. when a
landowner elects to become a member of the Conservancy's Registry
program they are entered into a computerized, conservation
database which allows the Conservancy to offer the latest
information regarding a particular species or natural feature.
For example, if a Registry participant has a population of rare
orchids on her land, the Conservancy can provide the landowner
with the most current information regarding the orchid. The
landowner has access to the best available information and at the
same time maintains complete control over her property. The
Conservancy does not hold a legal interest in the property and
does not have physical access without prior permission from the
landowner.

Success, how do we measure our progress in protecting biological
diversity? The Conservancy used to be able to measure success in
terms of dollars spent and acres acquired. Working at the
landscape scale renders this measure inadequate. The Mink River
Estuary Reserve is part of a working landscape that provides
spiritual and economic sustenance for a community. We can't own
it, so how do we measure success?

The ecological boundaries developed in this project are based on
a set of assumptions grounded in the latest and best scientific
theories. The science of ecosystem management and protection is
relatively new and many of the assumptions remain untested. The
challenges presented by accelerating development and the
resultant habitat loss will not take a day off while conservation
organizations conduct "further studies."

If we are to preserve the opportunties that currently exist on
the landscape to protect the natural processes and functions we
must often act quickly. The great challenge of ecosystem
analysis and protection is to build in research and monitoring
protocols that will test our assumptions and measure our success.

The Conservancy has worked in the Mink River Estuary for over two
decades. We discovered in the course of this study that we have
many more questions than answers with regard to the biota of the
study area. while we have a "fair amount of information regarding
the rarest of species within the project, we have very little
baseline data on the more common natural features.

One of the unexpected conservation objectives to come of this
study is the goal of developing scientifically valid protocols
for monitoring the biological diversity of the study area over
time. Projects such as these are the living laboratories where
ecosystem management principles will be applied and refined. It
is our responsibility to develop research and monitoring programs
that will measure our success against our stated conservation
objectives.
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Conclusion
The Wisconsin Coastal Management's support of this project
provided The Nature Conservancy with the resources necessary to
systematically assess the protection strategies for the Mink
River Estuary Reserve'and refine those strategies in keeping with
the best available conservation planning information.

Conservancy staff have been concerned about the accelerating rate
of change in local land use patterns for several years, but until
this time did not have the resources necessary to conduct a
thorough investigation incorporating the principles of landscape
ecology and ecosystem management.

The increasing pressures on the natural system.s supporting the
biological diversity found within the study area, we believe,
will continue to grow. The information collection and analysis
made possible by the support of the Wisconsin Coastal Management
Program will allow the Conservancy to preserve landscape
protection opportunities through the efficient application of
resources in the areas most threatened with irrevocable change.

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Mink River Estuary: A Landscape Approach to Protection
Ecotogicai Boundary Map

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