Stewardship Analysis Project - Delaware Methodolgy
This project is funded by a USFS grant to analyze the potential for forest stewardship
throughout the State. Twelve common stewardship criteria (layers) were weighted and
combined to produce areas of high, medium, and low stewardship potential. The 12
common data layers are briefly explained below. All data is presented in UTM Zone 18
Coordinates (NAD 1983 meters).
Public Water- DNREC recharge potential layer was queried to find areas of good and
excellent recharge potential. This shapefile was then converted to a 30m raster and then
reclassified to have public water with a value of 1 and all other areas equal to 0.
Forested Wetlands – National Wetlands Inventory (NWI) data was queried for all
forested wetlands. The vector data was then rasterized and then reclassified to show
forested wetlands with a value of 1 and all other areas equal to 0.
Slope – Slope layer was created from DEMs for each county from the UD Spatlab. Slope
was derived for each of the three DEMs by using the slope tool in model builder. Then
each county slope raster was combined using the mosaic tool to produce a statewide slope
raster. Some of the statewide layer extends beyond the landmass of DE so it was
converted to vector and intersected with the region of DE shapefile. This layer was then
converted back to raster and then all areas that had slope 5% or greater were extracted.
The final layer is a raster reclassified to show areas of slope greater than 5% with a value
of 1. All other areas had a value of 0.
Priority Watersheds – This data layer shows watersheds of concern based on EPA’s
TMDL requirements. The shapefile was converted to raster and reclassified to show all
priority watersheds to have a value of one. All other areas had a value of 0.
Riparian Buffers- 100 ft riparian buffers were created on all NHD data throughout DE
with the buffer tool. All rivers, streams, creeks, and water bodies were buffered. The
vector was then merged and converted to raster, the final layer showing all riparian
buffers with a value of 1 and all other areas with a value of 0.
Threatened & Endangered Species- Natural Heritage Data was obtained in vector
format. This was then converted to a 30m raster. All areas of T & E had a value of 1,
other areas a value of 0.
Forest Patches- The forest patch layer was created by querying the 2002 Delaware Land
use layer for shrub/brush (320), deciduous forest (410), evergreen forest (420), mixed
forest (430), and wetlands (600). In the creation of land use layer forested wetlands and
tidal marsh wetlands are lumped together. This creates a problem as forests do no grow
on tidal marsh. To correct the problem, tidal areas were extracted from NWI data and
unioned with the query from the 02LU data. The areas in common were then deleted
from the shapefile. The next step was to make sure that all roads and railroads that
separated forest patches on the ground did indeed separate the patches in the shapefile.
All roads from the DelDot centerline shapefile for each county and all railroads from
USGS railroad layer were buffered 50 ft as this is the average distance from the roads
edge to the edge of the forest. The buffer layer and forest layer were unioned and the
common areas were deleted from the shapefile. This produced a vector layer with true
forest patches. Next the multipart features were converted to single part and then
dissolved to prepare patches for acre calculation. A field was added and populated with
acreage of each patch. All patches greater or equal to 10 acres were extracted and then
were converted to raster and reclassified to show all patches 10 acres or greater to have a
value of 1 and all other areas to have a value of 0.
Proximity to Public Land- Tax parcel data for each county was queried for any parcels
that were owned by public entities. These features were buffered to one-quarter mile and
then converted to raster. The layer was reclassed to show all areas that meet the criteria as
one all other areas equal to 0.
Wildfire Risk- This is a preliminary data set that was taken from a map of the MidAtlantic Compact that shows areas of Delaware with “High” and “Very High” fire risk.
All areas were reclassed to show all areas as 1.
Developing Areas- This layer was derived from US Census data from 1990 and 2000.
The change in households per square mile of census blocks was determined with the
raster calculator. From this raster all cells with 0-20 more households were extracted. The
final raster was reclassified to show developing areas a 1 and all other areas as 0.
Private Forest- This layer was created from the shapefile of all forests queried from the
DE 2002 Land Use Layer. This shapefile was converted to raster and reclassified to show
all forested areas to have a value of 1 and all other areas to have a value of 0. This
reclassified raster was then added with the analysis mask to produce only areas of
privately owned forest.
Forest Health- This layer consists of all areas of forest that are susceptible to infestation
of Gypsy Moth. The 02 DE Land Use Layer was queried for all deciduous and mixed
forests in the state. These were then dissolved and converted to raster format. The raster
was then reclassified to show all cells that meet the criteria for the layer as 1 and all other
as 0.
Green Infrastructure- This layer indicates areas of importance according to the
Governor’s Liveable Delaware Program. The vector data obtained was converted to a 1/0
30m raster.
Analysis Mask- This layer was created in Model Builder to exclude from the analysis all
urban, open water, and publicly owned areas. First the DE 02 LU layer was queried for
all urban areas as noted:
airports (114)
commercial (120)
highways/roads/access rds (141)
industrial (130)
junk/salvage yards (123)
marinas/port facilities (146)
mixed urban or built up land (160)
transportation/communication (140)
mobile home parks (114)
multi family dwellings (112)
other commercial (129)
other transportation (149)
other built-up land (170)
parking lots (142)
railroads (143)
retail sales/wholesale (121)
single family dwelling (111)
vehicle related (122)
warehouse/storage (125)
A vector layer was created for surface water by querying all streams and water bodies
from the NHD dataset. This layer was then converted to raster. A vector layer containing
all publicly owned tax parcels was also converted to raster. The urban, surface water, and
public rasters were then combined using the mosaic tool. The resultant raster was then
reclassified to show urban, surface water, and public land as No Data while all other
areas are equal to 0. Cells classified as No Data tell ArcGis to exclude them from
calculations.
Private Forest Mask- The final private forest raster layer was reclassified to show
private forests with a value of 0 and all other areas set to No Data. When combined with
the High-Med.-Low overlay this produced a raster that shows areas of private forest with
high, medium, and low stewardship potential.
Non-forest – Non-Developed Mask- The NFND mask was created by taking the private
forest raster layer and inverting the values or reclassifying it to show all private forests as
No Data and all other areas equal to 1. The result was a raster that shows all areas other
than private forests. This layer was added to the analysis mask to mask out all urban,
open water, and public lands. The result was the NFND raster layer that shows all areas
that are privately owned that are not forested or developed. The NFND layer was then
reclassified to show that all NFND areas equal to 0 and all other areas set to No Data.
This reclassified NFND layer was then added to the High-Med-Low Overlay. The result
was a raster that shows the stewardship potential of Non-forest – Non-developed lands.
Overlay Model- The final twelve common data layers were weighted using an interval
scale scheme. Eight staff foresters within the Delaware Forest Service were asked to rank
each layer from 0 to 2 in increments of 0.25. Zero being lowest importance and 2 being
the greatest importance. The weights were then averaged and then expressed as a percent.
In raster calculator, each of the twelve data layers were first multiplied by their respective
weight and then added together to produce a continuous grid composite. The continuous
grid needs to be converted to a discrete grid to show definitive areas of potential. So, the
continuous grid was multiplied by 10,000 to preserve data in the conversion process. The
resultant raster was then converted to integer data with the Int tool. This discrete data was
then reclassified to three classes of natural breaks to show High-Med-Low areas of
stewardship.
Weighting Scheme Results
Factor/ Layer
Slope
Forest Patches
Proximity to Public Land
Wildfire Assesment
Developing Areas
Riparian Buffers
Private Forested Land
Forested Wetlands
Public Water- recharge potential
Forest Pests
Threatened & Endangered
Species
Priority Watersheds
Green Infrastructure
Decimal Increments of 0.25 in a range of 0-2
0.25
0.5 0.75 0.25
0.5 0.5
0 0.25
2
2 1.25
0.5
1.5 1.5
1 1.25
2
1 1.25
1
1.5 1.5 0.75 1.75
0.25
1
1
1.5 1.25
1 0.25
1
1.5
0.5
1.5 1.75
1.5
2 1.75 0.75
1.5 1.25
2
2
1.5
2 1.25 1.75
2 1.75
1
1.5 1.75
2
1.5
1.5
1.5
1.5
1.5 1.75
1.5
2
1.5 1.25
1.5 1.25 1.25 1.75 1.25 1.5 1.75
2
1
1
1
1 1.75
1 1.75 0.75
0.5
1.5
1.25
1
1.5
1
0.25
0.75
0.5
1.25
1.25
1
1.5
1.75
1
1.5
1.5
1
1.5
1.75
1
2
1.5
0
Mean Weight
0.4
1.4
1.3
0.9
1.4
1.7
1.6
1.6
1.5
1.2
As a %
2%
8%
8%
6%
9%
10%
10%
10%
9%
7%
Rel.
Weight
0.0229
0.0838
0.0819
0.0552
0.0857
0.1010
0.0990
0.0952
0.0933
0.0705
1.2
1.4
0.8
16.4
7%
9%
5%
100%
0.0724
0.0876
0.0514
1.0000
Project Stats
HML Overlay Composite
Low Potential
Medium Potential
High Potential
Forest
Low Potential
Meduim Potential
High Potential
Area (sq. meters)
1758300000
982940000
712230000
Area (acres)
434499.6101
242897.7118
176001.625
total
853398.9469
Area (sq. meters)
28986300
497980000
697670000
Area (acres)
7162.905105
123057.5646
172403.6529
total
Non-Forest Non-Developed
Low Potential
Medium Potential
High Potential
Area (sq. meters)
1729200000
484830000
14544000
total
Acres in Stewardship Plan Raster = 27,850
% of Total
51%
28%
21%
% of Total
2%
41%
57%
302624.1226
Area (acres)
427308.6081
119808.0225
3594.018273
550710.6489
% of Total
78%
22%
1%