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P rotecting the Forests of the Chesapeake Watershed: Use Best Tools …. John Scrivani Resource Information April 16, 2007 Update. Methodology Update. Bring forward the five layers developed for Version 1.0 Streams, shorelines, and floodplain forests and forested wetlands - PowerPoint PPT Presentation
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Protecting the Forests of the Chesapeake Watershed:Use Best Tools …
John ScrivaniResource Information
April 16, 2007 Update
Methodology Update Bring forward the five layers developed for Version 1.0
Streams, shorelines, and floodplain forests and forested wetlands Forests in headwaters and on steep slopes Forest protecting drinking water supplies Large contiguous blocks of forest; and Sustainable, managed working forests
Add layers representing habitat integrity at the landscape scale (12-digit hydrologic units)
Index of Terrestrial Habitat Integrity Modified Index of Biotic Integrity (Aquatic systems from INSTAR)
Compute forest conservation value via weighted overlay with 60% weight on habitat integrity
Methodology Update
For comparison, compute forest conservation value for current conserved lands
Compute layer of forest conversion rates from Phase 1 FIA data
Compute weighted overlay of forest conservation value and forest conversion rates to identify higher value lands under higher threat of conversion
Streams, shorelines, floodplain forests and forested wetlands
National Hydrography Dataset (NHD) 1:100K
Buffered to 500m
Refined by NWI, NLCD
Headwaters and steep slopes National
Watershed Boundary Dataset (NWBD) 1:24K (DCR)
Divides buffered to 1km
Ranked by % slope
Forests protecting drinking water supplies
Surface water source protection areas (VDH)
Zones 1 & 2
Large contiguous blocks of forest
VANLA (DCR)
Managed working forests
Index of Terrestrial Habitat IntegrityComposite of four layers:
The Natural Cover Index (INC) is based on the proportion of a watershed that is represented by natural vegetation
The River-Stream Corridor Integrity Index (IRSCI) is the
proportion of the river-stream corridor that is covered by natural vegetation
The Habitat Fragmentation/Road Index (IHF) addresses
habitat fragmentation by roads and reflects degradation of water quality, and terrestrial and aquatic ecosystems from associated development
The Imperviousness Index (IP) is the proportion of a
watershed that is identified as impervious cover
Figure 1. Natural Cover Index (INC)0.86 - 1.00
0.72 - 0.85
0.56 - 0.71
0.36 - 0.55
0.04 - 0.35
Figure 2. River-Stream Corridor Integrity Index (IRSCI)0.86 - 1.00
0.72 - 0.85
0.56 - 0.71
0.36 - 0.55
0.04 - 0.35
0.25 - 0.39
0.17 - 0.24
0.10 - 0.16
0.06 - 0.09
0.04 - 0.05
0.00 - 0.03
Figure 3. Habitat Fragmentation/Road Index (IHF)
Figure 4. Imperviousness Index (IP) 26.10 - 42.15
16.80 - 26.09
10.64 - 16.79
6.27 - 10.63
3.07 - 6.26
1.43 - 3.06
0.55 - 1.42
0.00 - 0.54
Figure 5. Index of Terrestrial Habitat Integrity (ITHI )91 - 100
81 - 90
71 - 80
61 - 70
51 - 60
41 - 50
31 - 40
21 - 30
11 - 20
0 - 10
< 0
Figure 6. Modified Index of Biotic Integrity (mIBI ) 21 - 24
17 - 20
15 - 16
13 - 14
11 - 12
8 - 10
Overlay Model - Forest Conservation Value
After an initial equal-weighting overlay it was deciding to set the relative weights:
• 30% Modified Index of Biotic Integrity (mIBI)• 30% Index of Terrestrial Habitat Integrity (ITHI )• 20% large forest blocks • 5% Streams, shorelines, floodplains and forest wetlands • 5% headwaters and steep slopes• 5% drinking water source protection areas • 5% managed working forests
The resulting values ranged from 1 to 10.
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Figure 7. Forest Conservation Value
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Figure 8. Forest Conservation Value of Non-conserved Lands
Cumulative Acres of Forest by Decreasing Conservation Value Score
Score Acres Cumulative Acres
10 3,019 3,019
9 284,393 287,412
8 1,531,436 1,818,847
7 2,390,522 4,209,369
6 1,138,582 5,347,951
5 256,895 5,604,846
4 53,921 5,658,767
3 13,312 5,672,079
2 81 5,672,160
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Figure 9. Forest Conservation Value with Threat of Forest Conversion
Acreage Distribution of Forest Conservation Value Scores weighted with Conversion Threat.
Score Acres Cumulative Acres
11 2,790 2,790
10 15,198 17,988
9 17,447 35,436
8 50,180 85,615
7 97,349 182,964
6 2,137,013 2,319,977
5 2,187,282 4,507,259
4 1,120,239 5,627,498
3 38,685 5,666,183
2 5,887 5,672,070
Thank you !10
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