||Inwood Marsh & Nature
Listed By Borough
Listed By Ecosystem
Bayside Acacia Cemetery
Central Park's North End
East River Oyster Beds
Fresh Creek Marshland
Harlem River Yards
Inwood Marsh & Nature Center
Manhattan Marsh Re-creation
Manhattan Maritime Holly Forest
Northern Manhattan Forests
Operation Renovo Gardens
Time Capsule NYC
West Harlem Marshlands
the only park on
names of features within and surrounding
the arrival of the first Dutch settlers in
most coastal areas of
now highly modified by human activity, the area surrounding the lagoon
Inwood’s remnant salt marsh fragments still represent enormous
potential. To the end of realizing some of this potential, this
project will focus on this small area within
The need for restoration of
noted above, extensive restoration efforts are ongoing at
The proposed restoration project will focus on restoring native flora and fauna to the area surrounding the Nature Center, including the upland lawns and pedestrian walkways on the peninsula containing the Nature Center, the eroding banks extending from this upland area into the lagoon, and the remnant salt marshes on the bank of the lagoon opposite to the Nature Center (Fig. 1.) Although it would not be feasible to recapture entirely native conditions in this area, as to do so would likely mean elimination of the Nature Center and the return of the land on which it now rests to marshland, tremendous potential does exist at this site to recapture some of the former ecological potential and native diversity of Inwood Park.
1. Proposed Restoration Sites near the
need for this restoration project is apparent from the highly modified
of the landscape, and its consequent diminished capacity to support
diversity. While the remnant salt marshes are made much of in
As the project would entail extensive construction and disruption of a visible, heavily used section of the park, it would be completed in several stages in order to allow visitation of the area throughout the construction period. Through whatever means possible construction activities would also be used as an opportunity to educate the public about restoration; interpretive signage and tours by park staff would be employed throughout the construction period.
most frontcountry portions of urban parks, the land surrounding the
Two grassy lawns surrounded by park
paved walkways are in the immediate area to the northwest of the
Fig. 2. Extensive bare soil areas currently in Native Plant Area 1.
require less water than turfgrasses. Grasses such as Pennsylvania sedge (Carex pensylvanica), and Sideoats grama (Bouteloua curtipendula) make excellent ground covers and produce seeds attractive to many native songbirds, and so would be ideally suited for planting throughout much of Native Plant Area 1. Native wildflowers such as Heart-leaved aster (Aster cordifolius) and Blue-stemmed goldenrod (Solidago caesia) produce showy flowers attractive to butterflies, and so would be ideal for planting around park benches for the enjoyment of park visitors (NRG).
successful establishment of newly planted vegetation, and to add to the
complexity and health of the restored system, effort should be made to
the continuous lawn that now extends across the upland areas
The irregular surfaces and varied vegetation of restored areas would render them less easily traversed by humans, and hence less subject to degradation by the high volume of foot traffic that impacts most parkland lawns. To preserve sufficient human access to accommodate the area’s high visitation levels and maintain its attractiveness to visitors, flagstone walkways would be installed leading to park benches and several stations along the shoreline. Current park benches would be retained, and their appeal enhanced with native flowering shrubs and wildflowers planted around them.
second portion of Phase I would endeavor to perform similar restoration
0.07 acre lawn area closer to the
Fig. 3. The vicinity of the
Phase II: North Lagoon salt marsh restoration
While restoration of the upland areas surrounding the Nature Center would have as its focus the re-creation of a native landscape for the enjoyment of human, lepidopteran, and avian park visitors, Phases II and III of the project would focus on restoring part of the native salt marsh that once extended to the south of the Nature Center’s current location for the sake of recapturing this ecosystem’s enormous productivity and ecosystem services.
more than 20-acre area now occupied by the
Although restoring Inwood’s salt marsh to its former extent would be impracticable, the restoration of even a small portion of this ecosystem could have profound impacts for the biotic communities of Inwood. The replacement of the rocky shoreline surrounding the lagoon with a salt marsh community of some extent would support insects and invertebrates, provide spawning habitat for fish and amphibians, and attract a diversity of avian species. A salt marsh ecosystem that more closely resembled the original salt marsh of Inwood would be a powerful educational tool for the park’s visitors, who come to Inwood for its natural character and would appreciate the opportunity to learn about its heritage.
northern bank of the lagoon would be the starting point for salt marsh
restoration activities, which would be conducted throughout with the
of both restoring the ecosystem and offering educational opportunities
visitors. Just beyond the fence separating Native Plant Area 1 from the
is a bank that is largely denuded of vegetation, its bare soil showing
exposed roots of sparse woody plants (Fig. 4). This bank offers an
demonstration site for salt marsh restoration, as its soil is
moist to support some of the high salt marsh species such as Juncus gerardi and Spartina patens
(Warren 1993) as well as perennial species such as
marsh elder (Iva frutescens)
characteristic of the transition zone from marsh to upland ecosystems
1994). This site’s proximity to the
Tidal marsh ecosystems are characterized by distinctive patterns of vegetation associated with small variations in elevation, with one or a small number of “low marsh” species occupying substrate that is subject to regular inundation and a greater diversity of “high marsh” species colonizing banks at greater elevations (Larkin et al. 2006). To provide a gradient suitable for growth of the full range of salt marsh species, and to extend the banks of the lagoon to allow for adaptation of vegetation to changing environmental conditions, 25-30 cubic yards of sand would be spread over the bank southwest of Native Plant Area 1. The eroding bank depicted in Fig. 4 and descending to the lagoon from the fence would be covered with dredged sand and graded to form a gradual slope, while an additional 10-15 cubic yards of sand would be used to raise the bottom of the lagoon to extend the area suitable for Spartina colonization.
Fig. 4. Bare, eroded soil on north bank of lagoon.
bank would then be planted with native salt marsh species, in
their tolerance for the salinity and inundation levels characteristic
elevation. In areas of low elevation, subject to regular inundation due
fluctuating tides of the
Phase III: South Lagoon salt marsh restoration
The south bank of the lagoon, now modified by the placement of large boulders and separated from a pedestrian walkway by a wrought-iron fence, was once a salt marsh that likely extended well into the area now occupied by the walkway and adjacent soccer fields. Although restoration of the entire extent of this former salt marsh would likely meet with resistance from the many users of the soccer fields and surrounding trails and walkways, the restoration of a portion of this extent would be feasible and also desirable from multiple standpoints.
Currently, the major remnants of Inwood’s celebrated salt marshes occupy a narrow strip along this south bank. The Spartina alterniflora occupying these patches is constrained from expansion onto land to its south by the considerable elevation of this land, which as noted above was filled to create the soccer fields and pedestrian walkway in the 1930s and early 1940s (See Figs. 5). The rocky substrate along the south bank of the lagoon also prevents the natural fluctuation of the salt marsh in response to changing tidal conditions, while the depth of the lagoon and likelihood of near-constant inundation prohibits the establishment of Spartina to the north of existing patches.
While future plans to repave or maintain the walkway in its current location might be reconsidered in light of the relative benefits of maintaining a 22-foot-wide pedestrian walkway and 4.5 acres of soccer fields as opposed to pushing back these features to make room for a more extensive and productive marshland community, these decisions will be left to future managers. At present, it is more feasible to extend the existing marsh into the lagoon by depositing sand on the south bank, grading it to provide habitat for suitable species, and elevating the bottom surface of the lagoon to provide more suitable habitat for colonization by salt marsh species.
Figs. 5. Pedestrian walkway and rocky substrate limiting extent of salt marsh on south bank of lagoon.
Roughly 10,000 cubic yards of sand would be sufficient to cover the extent of the south bank to a depth required for Spartina to establish and begin the slow process of growth, death, decay, and sediment accretion that results in a healthy salt marsh habitat that may support a vast array of invertebrate and other aquatic species. Sand will be deposited along the entire southwestern to southeastern perimeter of the lagoon fronting the pedestrian walkway (see Fig. 1), so as to create a gradual slope transitioning to upland areas as well as to fill in the edge of the lagoon to extend current suitable habitat for salt marsh species.
on the north bank, suitable species for planting would be selected from
existing remnant salt marsh patches in the area, from the
Considerations in successful salt marsh restoration
In order to succeed in capturing and maintaining desired ecological traits over the long term, a restoration project must take into account a number of considerations related to the restoration site and the species of focus. While the upland portions of this project, due to their proximity to the Nature Center and their design as a more managed system, may with ease be maintained over time by the continual addition of water, nutrients, or new plants and topsoil, ideally the salt marsh will be restored in such a way as to minimize the necessity of such inputs. The realization of this goal will require that restoration efforts during each of the project’s phases be undertaken with sensitivity to physical and ecological conditions prevailing at the restoration site, and genetic and population-level characteristics of restored plant species.
a. Genetic diversity
begin with, a sufficient level of genetic diversity among introduced
necessary to ensure flexibility of the population overall in responding
environmental changes and uncertainty (Falk et
al. 2006). To ensure this level of diversity, seeds for this
be chosen from a variety of sources such as the
addition, the location of
b. Metapopulation issues
Given a diverse genetic makeup of the founder salt marsh community and the potential for genetic exchange among individuals, attention must also be paid to establishing populations of a minimum size necessary for viability. Patches of introduced marsh plants must contain a minimum population size in order to withstand stochastic events and stressors that may emerge in the abiotic environment. Hence the budget (see below) should allow for seeding in excess of the number of propagules that are hoped to become established, to allow for the possibility that some sites will not succeed due to less than ideal conditions. As some areas are likely to become sources for the spread of salt marsh, and others are likely to fail to establish at least initially, budgetary allocations for seeding should reflect a range within which an exact amount will be determined through adaptive management.
In addition to ensuring that restoration sites contain a sufficient number of individuals, attention must also be paid to establishing a minimum number of suitable patches to ensure metapopulation persistence. Selecting a number of restoration patches on both banks of the lagoon will ensure exchange of genetic material among patches, particularly if sites for reintroduction are spatially arranged to allow for self-propagation (Falk et al. 2006). As the lagoon is a relatively small, enclosed area that is visited by many bird species, it is likely that any sites selected could rapidly spread to adjacent sites or sites across the lagoon.
c. Abiotic constraints
the lagoon’s historic occupancy by a salt marsh community suggests that
sheltered, sunny location offers ideal light and energy conditions for
reestablishment of a salt marsh community, some aspects of the abiotic
environment have changed since the time of the original salt marsh and
successful restoration project must take these aspects into account.
quality tests should be conducted in the lagoon to determine whether
availability or lack of availability may limit target species growth.
outflows into the
d. Topographic heterogeneity
The likelihood of success of a salt marsh community in this site could be further enhanced by the creation of surface variations in the process of adding and grading dredged sand on the banks of the lagoon. This project will be informed by other successful marsh restoration projects that have incorporated habitat heterogeneity into their design, as there is evidence that such efforts may further buffer restored systems from uncertainty and raise their likelihood of success (Larkin et al. 2006). Effort will be made to incorporate topographic heterogeneity into the design of salt marsh substrate, through the construction of rivulets and other small variations that mimic those that would be found in natural marshlands.
e. Climate change and ecosystem equilibrium
While the restoration of Inwood’s salt marsh offers clear benefits to the many human and nonhuman organisms that utilize Inwood Park, and it is likely that the salt marsh, once restored, would enjoy tremendous popularity among those who already enjoy Inwood’s many natural attractions, the nature of ecosystems is to change and there is no guarantee that the salt marsh would be the final resting state of the proposed restoration area. Indeed, it is unclear whether the historic salt marsh of Inwood represented a stable equilibrium or was a step along the successional pathway for this area. Especially in light of changing climate, managers concerned with restoration must be aware that target restoration states may not be equilibria (Suding and Gross 2006).
The benefit of this restoration project is that while restoring a state that existed in Inwood for decades or centuries in times past, it will also increase the flexibility of the system to respond to environmental change by increasing the permeability of the lagoon banks and extending the area available for salt marsh species to colonize. This renders the system more adaptable and resilient in the event that sea level change renders formerly occupied areas inhospitable. Particularly in times of rapid environmental change, systems that embody traits of flexibility and means of adapting to that change are far more likely to persist and continue to offer the diverse benefits of a functioning ecosystem.
f. Invasive species
The specter of changing climate and rising sea levels raises the possibility that conditions at the restoration site will shift so as to favor a different suite of species than those supported by the current environment. As noted by Millar and Brubaker (2006), restoration efforts are increasingly informed by the perspective that climate change may alter expected outcomes at a site, and lessen the degree of control managers have over its species composition.
the case of Inwood, a warming climate may favor the establishment of
salt marsh species. The main invasive salt marsh species in the
Salt marsh restoration in
a Spartina salt marsh along the banks
complete the transformation of the
portion of the project will refurbish
the decline of salt marsh ecosystems in
North River Sewage Treatment Plant, located on the
toilets are an element of ecological design that has been little
urban environments, largely due to the difficulty of finding
for the use of composted organic matter. The
As a final component of
While ambitious, a plan incorporating
systems and composting toilets as design components would be both
cost-effective at the
The Inwood Hill Park Native Vegetation Restoration and Nature Center Refurbishment Project will restore ecological functionality to a heavily used landscape that has great ecological and educational potential. The project will recapture some of the natural character, wildness and ecological diversity for which Inwood Hill Park is celebrated, and supplement restoration efforts that have to date neglected that portion of the park that is the most visible and has the greatest potential to support rare and valuable habitat and ecosystem services. With a modest investment of capital and effort, this project has the potential to transform what is already an oasis for humans and wildlife alike into a vibrant and unique ecosystem that supports abundant wildlife while offering an unequalled educational opportunity for human visitors.
Grand Total: Maximum** of $84,147.90 + $50/month in perpetuity
**Some of total costs expected to be offset by volunteer labor and the donation of marsh plants and seeds by universities, botanical gardens, and other participating institutions
Phase I: April-May 2007
1. April 2007: Tilling of soil in Native Plant Restoration Area 1, augmentation with topsoil and compost as needed
2. April 2007: Planting of native plants throughout Native Plant Restoration Area 1
3. April 2007: Installation of one interpretive sign along west edge of the area.
4. May 2007: Tilling of soil in Native Plant Restoration Area 1, augmentation with topsoil and compost as needed
5. May 2007: Planting of native plants throughout Native Plant Restoration Area 1
Installation of two interpretive signs, one along walkway to
Phase II: June 2007
1. June 2007: Deposition of sand on short stretch of north bank of lagoon
2. June 2007: Grading of substrate to appropriate marsh elevations
3. June 2007: Installation of interpretive sign near park bench overlooking lagoon
4. June 2007: Seeding of four or more native salt marsh species on newly created bank
Phase III: June-October 2007
1. late June-July 2007: Deposition of sand along much of lagoon’s south bank
2. July 2007: Grading of substrate to appropriate marsh elevations
3. July-August 2007: Seeding of four or more native salt marsh species on newly created bank
Phase IV: September 2007
2007: Installation of gray-water system in
2. September 2007: Installation of irrigation system to direct gray water to drought-intolerant plants
2007: Installation of composting toilets in men’s and women’s restrooms
4. September 2007: Installation of interpretive sign explaining the benefits and use of composting toilets
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