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July 29-230-Trish Long

6 Aufrufe

Veröffentlicht am

2019 SWCS International Annual Conference
July 28-31, 2019
Pittsburgh, Pennsylvania

Veröffentlicht in: Umweltschutz
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July 29-230-Trish Long

  1. 1. Using a Land-use Change Analysis to Inform Wetlands Protections in New Jersey Trish Long / July 2019 USDA-NRCS
  2. 2. Wetland conversions in New Jersey Questions: • How many acres of wetlands in NJ were converted to agricultural uses since 1985? • Where are these conversions occurring? The Problem
  3. 3. I. Background II. Analysis III. Results IV. Conclusions and Next Steps Outline
  4. 4. Background Wetlands - defined by hydric soils, vegetation, and hydrology – perceived as "wasted space" and were converted to other uses – “By 1984, over half (54%) of all the wetlands in the United States were drained or filled for development or agriculture.“ Converted wetlands – wetlands that have been drained, dredged, filled or leveled or where woody vegetation has been removed Agricultural wetlands - cultivated lands that are modified former wetland areas, and which still exhibit evidence of soil saturation https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/wetlands/
  5. 5. Background Increased awareness of the environmental benefits associated with wetlands prompted Congress to enact the Wetland Conservation Compliance Provisions of the Farm Bill in 1985. – Farmers who drain, clear trees, fill, or otherwise manipulate wetlands so that they can be cropped, may lose eligibility for USDA programs. – Before doing any alteration to a wet area, including clearing trees or maintenance of existing drainage, farmers should contact NRCS for a wetland determination. The Wetland Compliance provisions are the only laws that afford protection to many wetland types.
  6. 6. Where in the world is New Jersey?
  7. 7. ~7,700 square miles or ~5,000,000 acres 21 counties New York Philadelphia • The most densely populated state in the country • The Garden State • Ranks 8th for nursery and horticultural sales • Vegetable farming • Horses
  8. 8. Analysis Original question: What is the extent and location of wetlands conversions to agricultural uses since 1985? Available Datasets New Jersey’s Land Use/Land Cover datasets • 1986 Land Use/Land Cover • 1995/97 update • 2002 update • 2007 update • 2012 update • 2015 update Original question, revised, due to available datasets: “…between 1986 and 2012” Note: The wetlands described here were photo-interpreted. They are not on-the-ground delineations.
  9. 9. Analysis NJ’s Land Use/Land Cover Data – Modified Anderson Classification System 1000 Urban 2000 Agriculture 2140 Agricultural wetlands (modified) 3000 Range 4000 Forest 5000 Water 6000 Wetlands 7000 Barren
  10. 10. Land Use Change in NJ 1986 - 2012 New Jersey ~5,000,000 acres Units = acres 1986 2012 Change 1000Urban 1,252,138 1,573,836 321,698 2000Agriculture 818,592 618,246 (200,347) 4000Forest 1,614,891 1,527,740 (87,152) 5000Water 248,052 1,067,097 819,045 6000Wetlands 940,442 900,380 (40,062) 7000Barren 71,646 55,341 (16,305) 8000Managed Wetlands 7,988 n/a Grand Total 4,955,736 5,744,652 796,879
  11. 11. Land Use Change in NJ 1986 – 2012
  12. 12. What is the extent and location of wetland conversions to agricultural uses between 1986 and 2012?
  13. 13. Step 1 Select all “ModAg” polygons from the 2012 dataset 69,450 acres
  14. 14. Step 2 Intersect the 2012 Ag Wetlands with the 1986 Land Use/Land Cover layer to create a new layer that shows the prior land use for the 2012 Ag Wetland polygons.
  15. 15. Step 3 Select the 1986 wetlands from the output of Step 2 New layer that shows wetlands that were converted to ag uses between 1986 and 2012.
  16. 16. Results 9,492 acres of wetlands were converted to ag uses 8,842 polygons • sizes ranged from very tiny (slivers) to 53 acres • average polygon size: ~1 acre
  17. 17. Summary of Results 1) Types of wetlands that were converted 2) Summary of conversions by field office 3) Visual examples for staff training purposes
  18. 18. 1) Types of Wetlands that were Converted LAND_USE LABEL GISACRES FREQUENCY average acreage 6240HERBACEOUS WETLANDS 3,450.93 1,831 1.8 6210DECIDUOUS WOODED WETLANDS 2,234.12 3,851 0.5 6231DECIDUOUS SCRUB/SHRUB WETLANDS 1,472.83 1,474 0.9 6232CONIFEROUS SCRUB/SHRUB WETLANDS 383.13 71 5.3 6220CONIFEROUS WOODED WETLANDS 186.07 225 0.8 6252MIXED FORESTED WETLANDS (CONIFEROUS DOM.) 181.61 249 0.7 6251MIXED FORESTED WETLANDS (DECIDUOUS DOM.) 161.10 330 0.4 6233MIXED SCRUB/SHRUB WETLANDS (DECIDUOUS DOM.) 160.79 147 1.0 6234MIXED SCRUB/SHRUB WETLANDS (CONIFEROUS DOM.) 83.32 86 0.9 6221ATLANTIC WHITE CEDAR WETLANDS 77.43 51 1.5 6110SALINE MARSHES 23.79 30 0.7 6120FRESHWATER TIDAL MARSHES 8.04 24 0.3
  19. 19. 2) Summary by Field Office acres of wetlands converted to ag wetlands by 2012 total acres of wetlands in 1986 % of wetlands converted Hackettstown (7 counties) 1,660.51 119,904.48 1.4% Frenchtown (3 counties) 1,001.31 52,459.99 1.9% Freehold (3 counties) 1,825.65 122,809.79 1.5% Columbus (3 counties) 2,781.14 257,896.30 1.1% Woodstown (2 counties) 1,029.24 88,756.00 1.2% Vineland (3 counties) 1,194.75 253,893.74 0.5% Total 9,492.58 895,720.30 1.1%
  20. 20. 3) Visual Examples New Jersey Aerial Imagery Datasets / Orthophotography • 2012 imagery • corresponds to the 2012 Land Use/Land Cover layer • 1986 imagery • not available • 1995 imagery • earliest, readily available and usable aerial photography available statewide
  21. 21. 53 acres 1986 1995
  22. 22. Limitations • Without 1986 imagery, we cannot verify the original land cover classification. • This study can only be used to verify conversions that happened since 1995. • The following slides show examples of verified conversions since 1995.
  23. 23. Example 1. Camden County Deciduous Wooded Wetland 1.8 acres 2012 1995
  24. 24. Example 2. Burlington County Deciduous Scrub/Shrub Wetland 20 acres 2012 1995
  25. 25. Example 3. Cumberland County Deciduous Scrub/Shrub Wetland 1 acre 2012 1995
  26. 26. Example 4. Ocean County Coniferous Wooded Wetland .8 acres 2012 1995
  27. 27. Example 5. Burlington County Mixed Forested (Coniferous Dom.) Wetland 6 acres 2012 1995
  28. 28. Final Question Of the 9,492 acres of wetlands that were converted to ag between 1986 and 2012, how many acres were on lands that NRCS has worked on? Use GIS to overlay final results with Common Land Unit layer. Result: 81% (7,668 acres)
  29. 29. Conclusions  ~9,000 acres of wetland conversions to ag uses may have occurred in NJ since 1986.  This may be an overestimate. Next Steps  Present this information to field office staff to raise awareness of the issue.  Consider using imagery from 1980s to verify original land use classification and accuracy of results presented here.  USDA-NHAP scans from the 1980s  Not georeferenced, not statewide, not readily available  But we are in the process of having the 1980s imagery processed so that we can use it in the future.
  30. 30. Questions? Trish Long GIS Specialist trish.long@usda.gov USDA-Natural Resources Conservation Service 220 Davidson Ave Somerset, NJ 08873 732-537-6064 www.nj.nrcs.usda.gov

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