NYC Tidal Marsh Assessment: Condition, Vulnerability and …conference.ifas.ufl.edu/NCER2016/presentations/42_1620... · 2016-04-27 · NYC Tidal Marsh Assessment: Condition, Vulnerability

NYC Tidal Marsh Assessment: Condition, Vulnerability and Restoration OpportunitiesChristopher Haight1, Marit Larson1, Rebecca Swadek1, Ellen K. Hartig1, Nicole Maher2, Stephen Lloyd2, Lauren Alleman2, and Helen M. Forgione3

NYC Parks - Natural Resources Group 1

The Nature Conservancy2

Natural Areas Conservancy 3

NCERApril 20, 2016

Why Urban Coastal Wetlands

• Coastal wetlands are a critical part of a livable NYCo resilient Park assetso aesthetic, recreational and educational valueo ecosystem services (fisheries, bird communities, water quality)

• Coastal wetlands are at risk

• Planning, management and restoration can help protect our wetland assets for the future

Historic NYC Wetland Extent

Current NYC Tidal Wetlands

Project Goals

• Assess current marsh condition

• Evaluate vulnerability (SLR)

• Identify opportunities for protection, conservation & restoration

Prioritize restoration & protection opportunities

Ecological Assessment at 25 salt marshes

Long Island Sound

Staten Island

Jamaica Bay

Desktop AnalysisoHistoric Loss

AnalysisoSLAMM

Rapid Ecological AssessmentsoMidTRAMoMarsh-wide

assessments

7

Marsh area

% Development in buffer

Species richness

Total cover

Low marsh soil strength

Breeding bird count

Bare soil cover

Pool expansion

Ditch density

Identify key ecological attributes of marsh condition for which there are measurable indicator variables:

Percent high marsh

Marsh area

Edge density

Waterward loss

Potential gain from migration

Potential loss by SLR

Identify key measurable indicators of vulnerability available from SLAMM outputs, field and desktop assessments

Idlewild Park, Queens, NYSalt marsh

Recently lost salt marsh

Sea Level Affecting Marshes Model (SLAMM)

10

Likelihood of Coastal Marsh 2080sIdlewild Park

Example – Saw Mill Creek Marsh, Staten Island

-2 -1 0 1 2 3

Marsh Area

Native Species Richness

Low Marsh Soil Strength

Bare Peat Coverage

Ditch Density

Z-Score

Condition

-5 -4 -3 -2 -1 0 1 2

Marsh Area

Potential Marsh Loss to SLR

Potential Gain from Migration

Trend in Waterward Marsh Loss

Edge Density

Percent High Marsh

Total Score

Z-Score

Vulnerability

Alley Creek Inner

Alley Creek Outer

Hutchinson Inner

Hutchinson Outer

Pelham Bay Cove

Pugsley Creek Marsh

Turtle Cove

Udall's Cove Marsh

Westchester Creek

Four Sparrow

Fresh Creek MarshIdlewild Marsh Inner

Idlewild Marsh Outer

Spring CreekArlington Marsh

Fresh Kills Marsh

Lemon Creek Inner

Lemon Creek Outer

Neck Creek Inner

Neck Creek Outer

Richmond Creek

Saw Mill Creek InnerSaw Mill Creek Outer

W. T. Davis Inner

W. T. Davis Outer

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

-1.5 -1 -0.5 0 0.5 1 1.5 2

Bronx/Queens

Jamaica Bay

Staten Island

Higher condition/Lower Vulnerability Higher condition/Higher Vulnerability

Lower condition/Higher VulnerabilityLower condition/Lower Vulnerability

Marsh Condition vs. Vulnerability

Long Island Sound

Marsh Area and Shape Explain Trends in Condition and Vulnerability Variables

R2 = 0.70

R2 = -0.89

Short/Mid-Term: Increase viability of existing marsh sites Remove fill and re-establish hydrology Remove debris and revegetate• Increase elevation of drowning marsh surface• Restore shore edge of marsh where eroded

Long Term: Assure sustainability of marsh ecosystems• Secure adjacent parcels where marsh can

migrate• Remove hard surfaces that impede marsh

migration

Identify and prioritize strategies for restoration

Actions Threats Targets

Long Term Viability & Function of NYC

Saltmarshes in

Study Area

Obstacles to Marsh Migration

Acquisition/Transfer

Restore Flooded Developed lands

Reduced Capacity for Vertical GrowthElevation

Enhancement

Erosion and Decreased Size

Rebuild Marsh Edge

Opportunities for Restoration / Conservation

Current Marsh Future Marsh with SLR

Ownership across 25 NYC Marsh complexes

Acquisition/ Transfer

36 ac

838 ac

63 ac

Future new marsh acres in Study Area

0

10

20

30

40

50

60

Acre

s

Private

City/State/Federal

NYC Parks

Acquisition of advancement zones

Restore Flooded Developed lands

Action prioritized by area of opportunity

Elevation Enhancement

Action prioritized by % low marsh and future marsh loss in SLAMM

Rebuild Marsh Edge

Action prioritized by acres, width and % of recent marsh lost and future marsh loss in SLAMM

Are these a better long-term investment?

Is there anything we can do to save marshes that are highly vulnerable to begin with?

Watershed / Water-body Considerations

-1-0.8-0.6-0.4-0.2

00.20.40.60.8

1

BQ JB SI

JB LIS SI

Focus on watershed – specific needs• SI = Acquire and transfer

parcels

• JB = Restore elevation

• LIS = Address Edge Extension uncertainty

Appropriate strategy depends on goals, landscape context, time horizon, and socioeconomic factors

• Preserve existing marsh ecosystems and marsh migration zones for future – explore acquisition and easement strategies

• Prioritize high condition / low vulnerability marshes through best management practices and these 4 conservation strategies as neededo Address uncertainty - study shoreline retreat, sediment

supply, and wave energyo Consider size and shape - conserve and restore to reduce

fragmentation for long term health and viability

• Consider socio-economic or ecosystem services when pursuing opportunities for low condition / high vulnerability marshes

• Consider a watershed approach to conserving wetlands in addition to site by site restoration projects.

Next Steps

NYC Parks - Natural Resources GroupChristopher HaightMarit LarsonRebecca SwadekEllen K. Hartig

Natural Areas Conservancy Helen M. Forgione

The Nature ConservancyNicole MaherStephen LloydLauren Alleman

Funding from U.S. EPA Region 2, Wetlands Protection Program Development Grant

Kathleen Drake