Softening Riverside Park:
Restoration of a tidal salt marsh
on Manhattan’s West Side

Ferdie Yau

 

Abstract

Rapid urbanization in New York City has converted almost all of the wetlands in Manhattan to urban-industrial uses.  This has led to a general decline in the health of the NY/NJ Harbor Estuary.  A proposal to restore and create tidal salt marsh to the West Harlem Waterfront is made using a biodiversity ecosystem functioning approach.  The tidal salt marsh restoration project will enhance the multiple-use capabilities of the West Harlem Waterfront while restoring important ecosystem services, such as flood control, to benefit the community.

 

Introduction

 

Tidal salt marshes are important ecosystems that occur in the intertidal zone along the shorelines of estuaries, bays and tidal rivers (Broome et al. 1988).  Wetland habitats were once thought to have very little value ecologically or economically which led to the widespread conversion of these valuable estuarine systems to agricultural, urban, commercial, and recreational uses.  In the last century alone, it is estimated that 75% of the historical wetlands in the NY/NJ Harbor Estuary have been lost to development projects (NY/NJ Harbor Estuary Program 1996).  The only remaining salt marsh habitat in Manhattan are a few patchy stands in Inwood Hill Park (NYC Department of Parks and Recreation 2006). 

 

The value of salt marshes has been recognized and has slowed the loss of wetlands.  Increasing attention has focused on restoring and maintaining healthy and productive ecosystems in the NY/NJ Estuary (NY/NJ Harbor Estuary Program 1996).  All too often in the past, decision-makers have separated developmental goals and environmental goals.  In New York City, the pressure to support economic development has brought about rapid draining and filling of wetlands in favor of urban and industrial uses.  However, to achieve sustainable development, the integration of social and environmental goals is essential (Weinstein and Reed 2005). 

 

Tidal salt marshes provide ecosystem functions and services that are vital to a healthy and productive estuarine system.  These areas consist primarily of grasses, sedges, rushes and other vegetation which are periodically flooded by tidal forces (Broome et al. 1988).  Marshes convert energy from the sun into primary production (Broome et al. 1988) and are among the most prolific ecosystems in the world in this aspect (Montalto et al. 2006).  As transitional zones between uplands and estuaries, marshes recycle nutrients, stabilize shorelines, filter pollutants, and provide important habitat for valuable fishery species and other wildlife (Broome et al. 1988, Montalto et al. 2006).

 

This proposal will attempt to restore a significant area along Riverside Park in West Harlem, New York City to tidal salt marsh habitat.  The design will incorporate multiple use functions that will encourage public interaction with the waterfront, stimulate economy, enhance social and ecological resilience to disturbance, create habitat for wildlife, create a unique environmental education opportunity and improve the quality of life for the surrounding community.  The shoreline of West Harlem between West 116^th Street and West 133^rd Street, which currently consists of riprap, will be dramatically softened to create tidal salt marsh habitat.  Restoration of salt marsh will have several ecological benefits for the area including stabilization of the shore line, protection against floods from storm surges, filtering pollutants before they enter the Hudson, and provide habitat for wildlife.

 

History of Riverside Park

 

Ecological history of West Harlem Waterfront, Riverside Park

 

During the last glacial period which ended about 14,000 years before present, the area we now know as Manhattan was covered by the Wisconsin Glacier (USGS 2003).  When the interglacial period set in and the climate warmed, the recession of the glaciers helped shape and form the geology and natural features of the region (USGS 2003). An analysis of a British Headquarters Map from 1782 (Figure 1) shows that the upper Westside of Manhattan consisted of a diverse topography of hills, valleys, rivers, streams, and wetlands (Eric Sanderson unpublished data).  As human settlement completely transformed the landscape of the region, virtually all of the wetlands, rivers, and streams were filled and many hills were leveled.  Although much of the land has changed, evidence of the glaciers can still be seen by the presence of large erratics (USGS 2003).  One of the features formed by the receding glacier is the low hills along what is presently Riverside Drive.  These hills will later have an important role in shaping the design and construction of Riverside Park during the 1870s. 

 

Sanderson (2003) combined detailed geographic models along with historical records and maps and natural history surveys to reconstruct the ecology of Manhattan when Henry Hudson first sailed the Hudson River in 1609.  The reconstructed map of the upper Westside shows that the landscape was substantially influenced by the Hudson River with several large river mouths and a tidal wetland near the shoreline at what is now West 124^th and 125^th Streets (Figure 2).  Hydrologic processes strongly influenced by tides from the Hudson River strongly suggest that this wetland was most likely a tidal salt marsh (Figure 2) similar to others that historically dominated the NY/NJ Harbor Estuary.  In the last century, rapid urbanization of the New York City area has led to a 75% loss of historical wetlands in the NY/NJ Harbor Estuary (NY/NJ Harbor Estuary Program 1996).  The U.S. Fish and Wildlife Service estimated that only about 20% (or 6270 ha) of the historical tidal wetlands existed within a 40 km radius of Central Park, Manhattan in 1997 (Montalto and Steenhuis 2004, USFWS Coastal Ecosystem Program 1997).

 

Figure 2.  Reconstructed map of the upper Westside showing rivers, streams, and wetlands (patchy blue area).  A tidal salt marsh most likely occurred near the shoreline at 125^th Street (top right corner of map).  Courtesy of Eric Sanderson, Wildlife Conservation Society.

 

 

Creation of Riverside Park

In the 1840s, the Upper Westside of Manhattan was largely a rural landscape until the Hudson River Railroad was constructed in 1846, establishing the first freight rail link between Manhattan and Albany (Cromley 1984).  The first proposal to build a park in the area came from Central Park Commissioner William Martin in 1865 as a way to make the upper Westside a more attractive neighborhood to potential residents (Cromley 1984).  Land was acquired in 1866 to be the future site of Riverside Park and Riverside Drive.  The conceptual plan was prepared by Frederick Law Olmsted in 1873, which incorporated the existing landscape into the design of Riverside Drive and created a winding road around the gentle hills of the Upper Westside (Cromley 1984).  Calvert Vaux and Samuel Parsons designed the layout of the park from 72^nd Street to 125^th Street from 1875 to 1910 (Riverside Park Fund 2005).  It is interesting to note that recreational uses of the waterfront were not seriously considered until the 1890s (Cromley 1984). 

 

In the early 1900s, the park expanded northward to 158^th Street (Riverside Park Fund 2005).  The first attempt to limit pollution from the railroad into the Hudson River was made by the purchase of land between the railroad tracks and the Hudson River in 1894 (Cromley 1984).  Riverside Park underwent another growth phase in 1937 under the leadership of Robert Moses as Commissioner of Parks for New York City (Riverside Park Fund 2005).  During his administration, the roof over the railroad was completed, shaping Riverside Park as it occurs today (Cromley 1984). 

 

West Harlem Waterfront

Despite the expansion of the park to 158^th Street, very valuable waterfront property between St. Claire Place (around 125^th Street) and 133^rd Street was used for commercial purposes until recently.  In 1998, community-led efforts to develop the Harlem Piers began to seriously consider the area primarily for recreational uses (WEACT 2000).  The area was formerly used as a parking lot for the Fairway wholesale/retail food market.  In 2004, the schematic design for the West Harlem Waterfront project was completed (for details, see www.nycedc.com/westharlem).  The project will stimulate the economy and encourage recreational uses of the waterfront and Hudson River (NYC EDC 2004) for a neighborhood that has largely been neglected in the past.

 

West Harlem Waterfront: Current problems

 

Flooding Hazard

The West Harlem Waterfront is situated in a former river valley that ran down what is now known as 125^th Street.  The low elevation of this area makes it vulnerable to flooding from major storms such as hurricanes.  A map depicting hurricane evacuation zones created by the Office of Emergency Management (2006) indicates that the shoreline from 125^th Street to 158^th Street is vulnerable to flooding from a Category 2 hurricane or higher, while areas further inland from 125^th Street to 133^rd Street is vulnerable to storm surge flooding from a Category 3 hurricane or higher (Figure 3).  Although major hurricanes in New York are rare, the density of the human population makes it an area vulnerable to a natural disaster.  Over 35,000 people or 12,700 households live in the surrounding area of West Harlem (WEACT 2000).  The destructive power of Hurricane Katrina in 2005 to the city of New Orleans and surrounding areas should serve as an example of the disaster that can happen to a coastal area that has lost most of its wetlands as natural barriers against storm surges. 

 

Figure 3.  A close-up view of West Harlem from Office of Emergency Management New York City Hurricane Evacuation Zones (From: Office of Emergency Management. 2006. New York City hurricane evacuation zones. Available at:  http://www.nyc.gov/html/oem/html/ready/hurricane_guide.shtml. Accessed December 2006).  Yellow area indicates storm surge flooding from a moderate (Category 2 and higher) hurricane.  Green area indicates storm surge flooding from a major (Category 3 & 4) hurricane making landfall just south of New York City.

 

 

Habitat loss

As with most areas of Manhattan, the West Harlem Waterfront is dominated by human use and virtually no natural habitat remains.  The current use of the land has minimal potential for wildlife habitat, which is evident from the lack of biodiversity observed in the region.

 

Pollution

Urbanization has transformed the natural landscape of the area into one of concrete and asphalt.  The heavy vehicular traffic and proximity of the streets, especially the Henry Hudson Parkway, to the Hudson River creates runoff pollution into the river during storms.  Toxic chemicals that enter the Hudson River through runoff pollution have contributed to fish and shellfish consumption advisories (NY/NJ Harbor Estuary Plan 1996).  Furthermore, the North River Treatment Plant, located on the Hudson River from 137^th to 145^th Street, discharges untreated sewage directly into the Hudson River when heavy rains overload the plant’s capacity to treat wastewater.  This adds organic waste into the Hudson River and can have negative effects on aquatic wildlife by altering the biochemical properties of the river.

 

Vision for West Harlem Waterfront: bringing back the tidal salt marsh

 

A plan to address the environmental issues at the West Harlem Waterfront is proposed here.  Urbanization has contributed to the increase in pollution, reduced open spaces, restricted access to the shoreline (NY/NJ Harbor Estuary Plan 1996), and increased the vulnerability of the West Harlem community to flood risk.  The creation/restoration of a tidal salt marsh habitat along the West Harlem Waterfront can restore several ecosystem services and increase resilience to natural and human disturbances in the community.  The proposal is intended to incorporate the elements of the current West Harlem Waterfront restoration plan and will serve to enhance the interface of the river and land by increasing the multiple-use capabilities of the waterfront.  Urban-industrial societies that have developed in former estuary areas can benefit from wetlands.  Tidal salt marshes provide benefits such as public access to the waterfront and outdoor activities, a maritime cultural history, aesthetics, recreational fishing, and wildlife sanctuaries (Weinstein and Reed 2005).  This proposal will use a biodiversity ecosystem functioning approach (Naeem 2006) to restoring salt marsh habitat.  Ecosystem functions and services provided by wetlands include flood control (Weinstein and Reed 2005), primary production, important wildlife and breeding habitat, support of diverse food webs, nutrient cycling (Montalto et al. 2006, NYS DEC 2000), exchange of sediments and organic matter, pollutant filtering, and shoreline stabilization (Montalto et al. 2006).

 

Sanderson’s (2003) reconstruction of the ecological history of the island of Manhattan is useful because it provides a reasonable reference to plan restoration projects for land that has been completely transformed by human use for centuries.  Weinstein and Reed (2005) argue that it is not realistic for restoration projects to aspire to historic baselines as a goal in highly urban areas such as Manhattan.  An alternative to this approach is to focus restoration around selected ecosystem services and functions in highly urban areas (Roe and van Eeton 2001).  This proposal considers the historic and natural features of the landscape in the restoration design and attempts to restore ecosystem health as well as social and ecological resilience to disturbance.  It is intended to serve as a pilot project for similar salt marsh restoration projects in Manhattan in the future.

 

Figure 4.  View of West Harlem Waterfront in November 2006 from St. Claire Place looking north.

 

Construction of tidal salt marsh

The construction of 0.3 ha of tidal salt marsh habitat is proposed to soften and stabilize the shoreline along West Harlem from 116^th Street to 133^rd Street. The shoreline is currently dominated by concrete and riprap (figure 4).  Figure 5 depicts the extent of the area for the proposed restoration from 116^th Street to 133^rd Street.  The salt marsh will complement the current West Harlem Waterfront project by increasing wildlife habitat (figure 6) while preserving the original design. 

 

Figure 5.  Area bordered by red indicates the general area for the proposed site of tidal salt marsh restoration/creation.  Map courtesy of Google Earth, accessed December 2006.

 

Coastal marshes along shorelines of tidal rivers occur in the intertidal zone of moderate to low energy (Broome et al. 1988).  Landfill will be used to create land for the salt marsh off the shoreline of West Harlem Waterfront.  One of the challenges to constructing a salt marsh in this site is the tidal flow and ebb of the Hudson River which can generate strong currents in the river.  A way to overcome this problem is to create narrow areas of high marsh as jetties to partially enclose the site to strong currents and essentially creating an estuary that is still influenced by tidal regimes but protected from strong currents.  Sand can be used as landfill and it is estimated that about 4500 cubic yards of sand will be needed to create 0.3 ha of land for the salt marsh.  Dredging material can be used in addition to sand if it is available.  Softening the shoreline will also require removal of some of the riprap.  It may not be necessary to remove all of the riprap as some of the large rocks can potentially be used as landfill and covered up with sand.

 

Figure 6.  West Harlem Waterfront Schematic plans as of November 2006 (From: New York Economic Development Corporation. 2004. West Harlem Waterfront: St. Clair Place to 135^th Street. Available at: http://www.nycedc.com/westharlem).  The red line (not part of the original design) was drawn in to indicate the approximate area for tidal salt marsh restoration/creation.  Note that the salt marsh will continue to 116^th Street.

 

Slope

Broome et al. (1988) recommends that gentle slopes of 1 to 3% are preferred for tidal salt marsh restoration.  Gentle slopes can dissipate wave energy over a comparatively wider area and also allows a greater area of marsh.  However, slopes must be sufficient for appropriate surface drainage to prevent ponding and subsequent increases in salinity due to evaporation (Broome et al. 1988).  Some areas of slope may exceed 3% in order to a mixture of high and low marsh areas. 

 

Hydrology

It is essential that the appropriate hydrologic processes of the site be used as drivers of the tidal salt marsh restoration.  The wetland hydroperiod, or flooding regime, is responsible for the evolution, structure and function of wetlands (Montalto and Steenhuis 2004).  Other than slope, the hydraulic properties of the marsh substrate determines the rate at which pore water drains out of the marsh, which in turn, influences the oxidation state of the marsh substrate (Montalto et al. 2006).  These drainage patterns of the substrate influence the chemical properties of the soil and pore water, microbial and vegetative communities supported, rates of erosion, and sediment exchange (Montalto et al. 2006).  Hydrologic processes to aim for include an 11 to 9 hour daily inundation zone for the low marsh and a 7 to 4 hour inundation zone for the high marsh (NYS DEC 2000), with the water table always within 10 cm of the marsh surface for the low marsh (Montalto et al. 2006). 

 

Tidal ranges are important to consider as well in determining the zonation of the marsh.  While tidal range could not be measured at West Harlem Waterfront, a tidal range of 1.3 meters was reported at The Battery (NYS DEC 2000).  In general, intertidal mudflats are unvegetated areas which are only exposed during low tide, low marsh is submerged at high tide but exposed at low tide, and high marsh is only periodically flooded by spring and flood tides (NYS DEC 2000).  Each zone will differ in the amount and type of plant species present, which is largely determined by the tidal regime (NYS DEC 2000).  In addition, the highly invasive wetland plant Phragmites can be limited in sites that are frequently flooded (Warren et al. 2002).

 

The presence and absence of channels can influence how water drains from areas where the topography is relatively flat or away from the edge of the river (NYS DEC 2000).  Artificial channels can be dug if it is found that certain areas are ponding at an undesired level, however it is recommended that channels be allowed to form by natural processes unless increased salinity in the substrate from ponding and evaporation becomes prohibitive for biological communities.

 

Vegetation

Tidal salt marshes are typically divided into three zones: mudflats, low marsh, and high marsh.  Mudflats do not hold any rooted vegetation, but are often dominated by micro- and macroalgae, which are important for bacterial communities (NYS DEC 2000).  The inundation period for mudflats is too long for rooted plants to survive. 

 

In the low marsh, Spartina alterniflora is the dominant angiosperm of regularly flooded salt marshes (NYS DEC 2000).  This species will be intensively planted as plugs with a mixture of equal parts sand, top soil and peat moss included.  Seeding is not recommended at this site since it is only effective in sites with low wave energies (Broome et al. 1988).  The plugs can be grown in greenhouses using seeds from other natural marshes in the NY/NJ Harbor Estuary.  This can insure that the plants will come from a genetic reservoir that is adapted to the environmental conditions of the region.  Seeds of S. alterniflora should be harvested as closer as possible to maturity or just prior to shattering (Broome et al. 1988).  It is recommended that S. alterniflora plugs be planted 0.5 meters apart.  This planting density has resulted in successful standing vegetative cover in relatively high energy sites (Broome et al. 1986).  Other species in the low marsh will be allowed to colonize naturally.  These species include rockweed Fucus vesiculosus, green algae Enteromorpha spp., and sea lettuce Salicornia europaea.  While Phragmites may become invasive in the high marsh, an appropriate flooding regime in the low marsh should inhibit colonization by Phragmites.

 

In the high marsh, a mixture of S. alterniflora and S. patens will be planted at 0.5 meters apart as above.  Spikegrass Distichlis spicata will be planted in lower densities among S. alterniflora and S. patens in the high marsh.  Other species, such as switchgrass Panicum virgatum, sea-lavender Limonium caroliniamum, saltmarsh plantain Plantago maritime, and seaside gerardia Agalinis maritime, will be allowed to colonize naturally as well.  Constant monitoring of plants in the high marsh will be essential to prevent the invasion of Phragmites, which prefers relatively drier sites to colonize (NYS DEC 2000, Warren et al. 2002).

 

It is estimated that about 20,000 plugs of S. alterniflora will be needed for effective restoration of 0.3 ha of salt marsh.  This estimate also includes additional plants to compensate for early mortality of the transplants.  The sandy substrate of the marsh provides very few nutrients for the initial establishment of plants (Broome 1988).  Therefore, slow-release fertilizers will be used in the low marsh to help the vegetation establish itself.  Planting will occur in the late winter or early spring to allow for a full growing season before the onset of winter.

 

Macroinvertebrates

Macroinvertebrates such as snails Melampus, isopods Philoscia, and amphipods Orchestia tend to return within 5 years, which is relatively early in the restoration process (Warren et al. 2002).  Other macroinvertebrates important to salt marshes are ribbed mussel Geukensia demissa and fiddler crabs Uca spp. These organisms generally feed on organic matter and invertebrates, but are themselves food for many birds and fish (NYS DEC 2000).  Thus, it will be important to monitor the presence of macroinvertebrates since they will attract species from higher trophic levels such as fish and birds.

 

Fish

Many fish are dependent on salt marshes for at least part of their life cycle.  Fish such as mummichog Fudulus heteroclitus, striped killifish F. majalis, and sheepshead minnow Cyprinodon variegates live in salt marshes for most of their lives (NYS DEC 2000).  Other fish, such as Atlantic silversides, use salt marshes as breeding habitat; while winter flounder Pleuronectes americanus, tautog Tautoga onitis, sea bass Centropristes striata, alewife Alosa pseudoharengus, menhaden Brevoortia tyrannus, bluefish Pomatomus saltatrix, mullet Mugil cephalus, sand lance Ammodytes americanus, and striped bass Morone saxatilis all use salt marshes as nursery habitat (NYS DEC 2000).  Typical fish species assemblages return relatively quickly after restoration, but the time it takes for the abundance of particular species to compare to reference systems may take over 10 years (Warren et al. 2002).

 

Birds

A Spartina-dominated tidal salt marsh has been demonstrated to attract more bird species and a higher number of state-listed species than Phragmites-dominated marsh (Benoit and Askins 1979).  In the early stages of restoration, marsh generalists such as song sparrows Melospiza and red-winged blackbirds Agelaius phoeniceus may be expected to be relatively more abundant than marsh specialists.  However, in 10 to 15 years after restoration of Spartina-dominated salt marsh, it can be expected that marsh specialists such as the salt marsh sharp-tailed sparrow Ammodramus caudacatus and seaside sparrow Ammodramus maritimus will increase their use of the salt marsh while the generalists will decline (Warren et al. 2002).  Other birds that may return to the area as a result of salt marsh restoration are long-legged waders such as herons and egrets (family Ardeidae). 

 

Benefits of tidal salt marsh restoration at the West Harlem Waterfront

 

Flood protection

As the constructed salt marsh becomes a self-sustaining ecosystem dominated by dense stands of Spartina along the West Harlem Waterfront, the community will benefit from the flood protection against storm surges that the marsh will provide (NYS DEC 2000).  The risk for flood damage in this community is high due to the vulnerability of the area and the dense human population.  This is the same deadly combination of factors that led to the unprecedented natural disaster of Hurricane Katrina in 2005.  The increased protection against storm surges by itself is enough justification for the creation of tidal salt marsh habitat along the West Harlem Waterfront.

 

Primary productivity

Being among the most productive ecosystems in the world in terms of primary production (Montalto et al. 2006), tidal salt marshes support complex food webs.  Their production promotes populations of finfish, shellfish, crustaceans, and birds (NYS DEC 2000). 

 

Pollutant control

Stormwater runoff from roads directly contributes to pollution of the Hudson River.  The heavily-used Henry Hudson Highway is located along the shoreline of the Westside of Manhattan.  Creation of the tidal salt marsh along the West Harlem Waterfront can be a first step in addressing the issue of non-point source pollution from Manhattan’s streets into the Hudson River.

 

Wildlife habitat

The restoration of tidal salt marsh will provide critical habitat for invertebrates, fish, and birds (NYS DEC 2000).  While the primary production of salt marshes can support food webs, the physical structure of the marsh becomes important nesting and nursery habitat for birds and fish, respectively (Warren et al. 2002).  This will increase the biodiversity of the area and restore some trophic interactions that had disappeared centuries ago.

 

Multiple-use facility

This proposal is meant to complement the on-going West Harlem Waterfront project that already includes several uses for the area including a walkway, bicycle path, boat pier, future building site, open areas for passive recreation, recreational fishing, a woodland, and a kayak float (NYC EDC 2004).  The salt marsh can provide bird watching and nature enjoyment activities.  The proposed building can house an environmental education center that can take advantage of the unique opportunity that the creation of the salt marsh will provide.  The environmental education center can educate the community about restoration and urban ecology, connect people to the cultural and natural history of the Hudson River, and promote a more environmentally responsible lifestyle.  The project will stimulate economy by attracting businesses and people to the area.

 

Timetable

The estimated timetable for the tidal salt marsh restoration project from start to finish is estimated to be 2 to 3 years, but continued monitoring and management of the site will be a long-term commitment.  It is unclear how long it takes for a constructed slat marsh to approximate functions of a natural salt marsh, but recent studies have indicated that key functions in constructed and restored salt marshes may take 10 to 30 years to reach a level comparable to natural salt marshes (Morgan and Short 2002, Warren et al. 2002).  Thus, even after the marsh is planted, continued monitoring and management is necessary to track the trajectory of the functional development of the marsh.  The following is a general timetable for the tidal salt marsh restoration:

 

Year 1

Collection of seeds and growing seeds in greenhouse in preparation for planting.  Adding landfill along the West Harlem Waterfront shoreline to become the structural base of the salt marsh.

 

Year 2

Planting Spartina spp. plugs in intertidal zone.

 

Year 3

Replanting of bare areas (if necessary).

 

Beyond year 3

 Monitoring of site and using adaptive management approach.

 

Budget

 

Product/service             Quantity                                   Price

Labor                                       2000 person-hrs @ $35/hr       $70,000

Sand (landfill)                           4500 yd³ @ $3/yd³                  $13,500

Plants                                       20,000 plants @ $1/plant         $20,000

Fertilizer                                   0.3 ha @ $2000/ha                  $600

Travel                                                                                       $5000

Contractor                                3 years                                     $90,000

Overhead                                                                                 $80,000

Total                                                                                        $279,100

 

Summary

The widespread loss of wetlands in Manhattan has not only resulted in a general decline in ecosystem health, but it has left some areas of Manhattan particularly vulnerable to natural disturbances such as floods.  The West Harlem Waterfront has been selected as a possible site for tidal salt marsh restoration.  Creation of a tidal salt marsh along the shoreline of West Harlem may serve to protect the community against storm surges as well as restore other ecosystem services important to urban societies.  This project is intended to be a pilot project and may serve as an example for further salt marsh restoration in Manhattan.

 

References

 

Benoit, L. K. and R. A. Askins. 1999. Impact of the spread of Phragmites on the distribution of birds in Connecticut tidal marshes. Wetlands 19: 194-208.

Broome, S. W., E. D. Seneca, and W. W. Woodhouse, Jr. 1986. Long-term growth and development of transplants of the salt marsh grass Spartina alterniflora. Estuaries 9: 63-74.

Broome, S. W., E. D. Seneca, and W. W. Woodhouse, Jr. 1988. Tidal salt marsh restoration. Aquatic Botany 32: 1-22.

Cromley, E. 1984. Riverside Park and issues of historic preservation. The Journal of the Society of Architectural Historians 43(3): 238-249.

Montalto, F. A. and T. S. Steenhuis. 2004. The link between hydrology and restoration of tidal marshes in the New York/New Jersey Estuary. Wetlands 24(2): 414-425.

Montalto, F. A., T. S. Steenhuis, and J.-Yves Parlange. 2006. The hydrology of Piermont Marsh, a reference for tidal marsh restoration in the Hudson River Estuary, New York. Journal of Hydrology 316: 108-128.

Morgan, P. A. and F. T. Short. 2002. Using functional trajectories to track constructed salt marsh development in the Great Bay Estuary, Maine/New Hampshire, U.S.A. Restoration Ecology 10(3): 461-473.

Naeem, S. 2006. Biodiversity and ecosystem functioning in restored ecosystems: Extracting principles for a synthetic perspective. In Foundations of Restoration Ecology, ed. D.A. Falk, M.A. Palmer, and J.B. Zeller, 210-237. Washington, D.C., Island Press.

New York City Department of Parks and Recreation. 2006. Forever wild: Inwood Hill Shorakapok Preserve. Accessed November 2006 at: http://nycgovparks.org/sub_about/parks_divisions/nrg/forever_wild/site.php?FWID=38.

New York Economic Development Corporation. 2004. West Harlem Waterfront: St. Clair Place to 135^th Street. Available at: http://www.nycedc.com/westharlem. Accessed November 2006.

New York/New Jersey Harbor Estuary Program. 1996. New York-New Jersey Harbor Estuary program final comprehensive conservation and management plan. New York, NY. Available at: http://www.harborestuary.org/mgmt.htm. Accessed November 2006.

New York State Department of Environmental Conservation. 2000. Salt marsh restoration and monitoring guidelines. Available at: http://www.dec.state.ny.us/website/dfwmr/marine/saltmarsh.pdf. Accessed November 2006.

Office of Emergency Management. 2006. New York City hurricane evacuation zones. Available at:  http://www.nyc.gov/html/oem/html/ready/hurricane_guide.shtml. Accessed December 2006.

Riverside Park Fund. 2005. Riverside Park. Available at: http://www.riversideparkfund.org/ThePark.htm. Accessed October 10, 2006.

Roe, E. and M. van Eeton. 2001. Threshold-based resource management: a framework for comprehensive ecosystem management. Ecological Applications 27: 195-214.

Sanderson, E. 2003. The Mannahatta project. Wildlife Conservation Society. Available at http://www.wcs.org/sw-high_tech_tools/landscapeecology/mannahatta. Accessed November 2006.

United States Fish and Wildlife Service, Coastal Ecosystem Program. 1997. Significant habitats and habitat complexes of the New York Bight Watershed. (Computer CD). Charlestown, RI, USA.

United States Geological Survey. 2003. Quaternary geology of the New York City Region. Available at: http://3dparks.wr.usgs.gov/nyc/morraines/quaternary.htm. Accessed November 2006.

Warren, R. S., P. E. Fell, R. Rozsa, A. H. Brawley, A. C. Orsted, E. T. Olson, V., Swamy, and W. A. Niering. 2002. Salt marsh restoration in Connecticut: 20 years of science and management. Restoration Ecology 10(3): 497-513.

Weinstein, M. P. and D. J. Reed. 2005. Sustainable coastal development: The dual mandate and a recommendation for “Commerce Managed Areas”. Restoration Ecology 13(1): 174-182.

West Harlem Environmental Action, Inc. (WEACT). 2000. Harlem on the river planning document. Available at: http://www.weact.org/hotr/planning_document.html.  Accessed November 2006.

APPENDIX

 

 

Figure 1.  British Headquarters Map 1782 of the upper Westside of Manhattan (courtesy of Eric Sanderson, Wildlife Conservation Society).  Modern New York City streets are overlaid on the map.  The winding red line is Riverside Drive.  A river valley set against the northern edge of Morningside Heights is clearly shown where 125^th Street runs today. Map will be put online at a later date.