Forest Stewardship Spatial Analysis Project
New York Methodology
Project Summary:
The Forest Stewardship Spatial Analysis Project (SAP) is designed to determine
stewardship potential on private land throughout New York State. Using a raster-based
GIS analysis, 30-meter by 30-meter grid cells were assigned values based on 12
environmental parameters to determine their individual stewardship potentials.
The 12 parameters used by New York State were divided into two sections: Resource
Threat Factors and Resource Potential Factors.
Resource Threat Factors:
- Development Risk
- Forest Health
Resource Potential Factors:
- Private Forest Land
- Forest Patch Size
- Riparian Corridors
- Public Water Supply
- Priority Watersheds
- Threatened and Endangered Species
- Wetlands
- Proximity to Publicly Owned Lands
- Conservation Easements
- Slope
This list differs from the list offered by the pilot states in that a Fire Risk assessment
layer is not included. The reason for this is simply that the data necessary for the creation
of this layer was not available at the time of production. During the weighting of the
layers (described below) the Fire Risk layer was almost unanimously ranked as the least
important and, as a result, its inclusion would not have had a significant effect on the
raster cell values. If fire risk data becomes available, it will be factored into the SAP at
some future time, based on its weight and rank recorded here.
Due to the large amount of land involved, a layer defining Conservation Easement lands
was included in the analysis. Conservation Easement presence was determined to be a
Resource Potential Factor, and the layer given the same rank as the Proximity to Publicly
Owned Lands layer.
1
Layer Creation:
Raster layers created for the purpose of this analysis were 30-meter grid cells, defined by
the extent of the Digital Elevation Model used to create the Slope layer. While the Slope
layer was created first, layer descriptions here will be presented in order of decreasing
importance as defined by the DEC Service Foresters of New York State.
Private Forest Lands:
The Private Forest Lands data layer was
created using both the Forest Patch and
Proximity to Publicly Owned Lands data
layers. The Forest Patch layer was created
using 30-meter resolution LANDSAT 5
imagery and included the Deciduous
Forest, Coniferous Forest, Mixed Forest,
Shrub-land and Woody Wetlands land
cover classes. A buffered road layer was
erased from the Forested Areas identified
by the LAND-SAT imagery and,
subsequently, all forest patches smaller
than 5 acres in area were deleted.
An unbuffered version of the Proximity to
Publicly Owned Lands data layer,
described below, was also erased from this
Forest Patch layer, resulting in a layer
composed of forested areas, greater than 5
acres in size, not occurring on publicly
owned lands. Five acres was chosen as the
threshold due to the fact that this is the
minimum size for participation in the New
York State Forest Stewardship Program.
This layer was then rasterized to the same
30 m grid as the slope layer and assigned a
value of 1429. This data layer is shown at
right, with Private Forest areas shown in
yellow.
2
Forest Patch Size:
Forest cover used in this analysis was
extracted from LANDSAT 5 imagery
collected from the 1990 - 1993 period, with
classification based upon a 30 meter pixel
size. Five classifications were used to
create a forest layer: Deciduous Forest,
Coniferous Forest, Mixed Forest, Shrubland and Woody Wetlands. The road data
used in this layer were from a 2005 roads
dataset constructed from high resolution
ortho-imagery. Roads were buffered based
upon their intrusive significance to the
landscape, with the buffer areas
corresponding to the cleared rights-of-way.
Interstate roads were buffered by a total of
300 feet, state and county roads by 66 feet.
The buffered road layer was erased from
the forest cover layer to yield a raster data
set which approximated actual forested
land cover in the State, and forested
polygons which were less than 5 acres in
area were deleted.
This layer was then rasterized to the same
30-meter grid as the slope layer and
assigned a value of 1169. The data layer is
shown at right, with Forest Patches greater
than 5 acres in area shown in green.
3
Forest Health:
The Forest Health Dataset was created by
the Bureau of Private Land Services, Forest
Health and Protection Section, NYS DEC
Division of Lands and Forests. Point
classes were created to represent damage
discovered during aerial analysis, later
confirmed by ground-checks. The point
classes from the 2004 and 2005 surveys
were unioned and then buffered to a
distance of 5 miles. These features were
then rasterized to the same 30 meter grid as
the slope layer.
It was decided early in this project that
priority would lie with the protection of
healthy forests, in contrast to the
rehabilitation of unhealthy or at-risk
forests. As a result, this raster layer had to
be reclassified to an inverse of itself. An
analysis mask derived from the New York
State boundary shapefile available from the
Department of Environmental
Conservation GIS data archive was used to
prevent extraneous information, and the
features showing forest damage were
assigned a value of zero. All other features
were assigned the determined ranking
value of 1147. Areas which are considered
not-at-risk are shown at right in purple. It
should be noted that in Map 5: Resource
Threats, the original forest health dataset,
giving value to damaged forests, was used
to show areas of potential health threats.
4
Developing Areas:
Using a unioned dataset created from 1990
and 2000 census tract data, housing units
per square kilometer by census tract were
determined for both 1990 and 2000 census
tract polygons. Due to inconsistencies in
the boundaries of the tracts, tract polygons
which showed a value of zero in either field
were removed from the dataset. This
enabled the elimination of most of the
sliver polygons caused by boundary
digitization irregularities. For the
remaining tract polygons, a field was
created in the attribute table showing the
change in number of housing units per
kilometer over the ten year period.
Borrowing from the methodology of the
state of Indiana, polygons with greater than
64 housing units per square mile (24.7
units/square kilometer) in either 1990 or
2000 were removed from the dataset.
These areas are considered too urban to
support stewardship. Areas which showed
an increase of 8 or more housing units per
square kilometer between 1990 and 2000
were also selected and removed from
consideration. Finally, census tracts which
had their center within the boundary of any
polygon classified as a “City” boundary in
the New York State Towns, Villages, and
Cities dataset were also removed.
The resulting shapefile, shown at right in
blue, contained all of the areas which were
considered to have a low risk of
development and, therefore, an increased
potential for stewardship. This dataset was
rasterized to the same 30-meter grid as the
slope layer and given a weight of 1017. It
should be noted that for Map 5:
Development Risks, the inverse of this
raster was used to identify areas with an
increased development risk.
5
Riparian Corridors:
Riparian zones were identified by creating
a 100 meter buffer around 1:24,000
hydrologic data developed jointly by the
Department’s Division of Water and the
U.S. Geological Survey. The buffered
features included perennial streams, and
surface (ponded) waters greater than 4047
square meters, or one acre, in size. Ponded
waters less than 1 acre were not included
due to the fact that they generally do not
connect to a drainage network, and
proximity disturbance close to a ponded
shoreline would have minimal effects on
downstream water quality.
It should be noted that all cells from the
EPA Multi-Resolution Land Characteristics
data layer which were identified as water
were later masked out of the final data set.
As a result, many of the water features
were removed from consideration, while
the buffers remained. The Riparian
Corridor data layer shown at right in dark
blue represents the data before the
application of the analysis mask. This
layer has been rasterized to the same 30meter grid as the slope layer and given a
value of 996.
6
Public Water Supply:
The NYS Department of Health maintains
a statewide database of Public Water
Supply sources serving a population of 25
or more residents. Coordinate locations in
the database yield point locations for
sources which include springs, wells,
intakes from rivers or reservoirs, and
infiltration galleries. All wells and springs
were assigned a protective disturbance
buffer of 50 meters. Reservoirs and lakes
which contain intakes were selected from
1:24K hydrology and buffered to 312
meters. This distance was selected as the
statewide reservoir/surface water buffer,
which corresponds to the 1000 foot
reservoir disturbance protection zone
recognized in the NYC Watershed. Intakes
on rivers were buffered as points, also to
the 312 meter distance.
The final assembled drinking water layer,
shown at right in red, consists of buffered
wells, buffered springs, buffered river
intakes, and buffered reservoirs/surface
waters. This layer was rasterized to the
same 30-meter grid as the slope layer and
assigned a value of 974.
7
Priority Watersheds:
The Priority Watershed data was obtained
from The Nature Conservancy, in Albany,
NY. The data layer was created by
factoring in a number of influences,
including population density, road density,
protected lands, dam density, natural land
cover, and interior forest cover.
Watersheds were broken down into 11digit Hydrologic Unit Code areas, and
ranked in increasing quality from 1 to 10.
From this dataset, ranks 7, 8, 9, and 10
were kept as the Priority Watersheds for
this project. This breakdown allowed for
the inclusion of roughly 25% of the area of
New York State.
These areas were exported and rasterized to
a 30-meter grid identical to that of the grid
used in the slope layer. This grid was
assigned a weight of 866. Areas
considered to be priority watersheds are
show at right in blue.
8
Threatened and Endangered Species:
The New York State Natural Heritage
Program element occurrences dataset was
used from the Department’s GIS data
archive. These data are contained in four
themes: all points, all boundaries, filtered
points, and filtered boundaries. Each theme
contains features which represent element
occurrences, as recorded in the New York
Natural Heritage Program's Biodiversity
Databases. Element occurrences are
documented, including observed locations
of rare plants, rare animals, rare or
significant ecological communities, and
multi-species animal concentration areas.
The EO Rank field is coded for the status
and relative quality or viability of the
element occurrence. Values selected out for
use were: A - excellent, B - good, C - fair
and D - poor. EO Ranking values not
included in the study were: E - extant with
insufficient information to rank A-D, F failed to find during most recent survey,
based on a limited search; possibly still
present, H - historical with no recent
information; unknown whether is still
present. X - extirpated; determined to be
no longer present, and ? - unknown.
The polygons were not altered, but the
points were buffered by 2640 feet. The
layer was then clipped to the boundary of
New York State found in the data archive,
as many of the buffered features crossed
over the state boundary. The Threatened
and Endangered Species layer was
rasterized to the same 30-meter grid as the
slope layer, and is shown at right in brown.
The value assigned to this layer was 844.
9
Wetlands:
A combination of three wetlands datasets
were used to create a comprehensive
statewide dataset. The National Wetlands
Inventory Dataset, updated most recently in
December 2004, covers almost 75% of the
area of New York State. The New York
State Regulatory Wetlands Data are based
on official New York State freshwater
wetlands maps as described in Article 240301 of the Environmental Conservation
Law. This layer was used to ensure that no
parts of the state were overlooked, as it
contains statewide wetland information.
Finally, the New York State Adirondack
Park Agency cover type wetlands were
used to supplement these data.
These data were unioned together, to
ensure comprehensive inclusion of
wetlands throughout New York State. The
resulting layer, shown at right in bluegreen, was rasterized to the same 30 meter
grid as the slope layer and assigned a value
of 823.
10
Proximity to Publicly Owned Lands:
The Public Lands data layer was assembled
from a variety of datasets and includes:
Lands managed by the New York State
Department of Environmental
Conservation for forest, wildlife, preserve
or unique purposes, State Parks managed
by the Office of Parks Recreation and
Historic Preservation, military lands
including Fort Drum, West Point, and other
lands managed by NYS Office of Military
and Naval Affairs, Federal lands managed
by the Department of Agriculture and the
Department of the Interior, lands managed
by local governments, including town and
county parks, and areas included in New
York City watershed protection.
All of the lands included in these categories
were merged together into a single layer
and buffered to a distance of 2640 feet.
This buffered layer, shown at right in
lavender, was rasterized to the same 30meter grid as the slope layer and assigned a
value of 368. It should be noted that the
pre-buffered version of this dataset was
also used to create the analysis mask used
in this study.
11
Conservation Easements:
When it was determined that New York
State would be unable to include a Fire
Risk layer into the Stewardship Potential
Spatial Analysis Project, the decision was
made to include an additional data layer
unique to the state. New York State has a
large number of Conservation Easements,
currently including more than 360,000
acres of land. As this land is not publicly
owned, it remains eligible for stewardship.
It is expected that this will be an especially
dynamic layer in the project, and regular
updates will be required to maintain the
accuracy of the information contained here.
The Conservation Easement layer, shown
at right in orange, was rasterized to the
same 30-meter grid as the slope layer. As
this data layer was not included in the
original ranking structure sent to regional
foresters, it was decided that this layer
would be assigned a value identical to that
of the Proximity to Publicly Owned Land
data layer, 368.
12
Slope:
The slope layer was created using the
Surface Analysis – Slope function of the
Spatial Analyst toolbar. Slope was
determined in terms of percentage rather
than degrees. Borrowing from the
methodology of the state of Missouri, it
was determined that areas with a
topographic slope greater than 40% would
be removed from the layer due to problems
with accessibility for timber harvesting
equipment.
The slope layer was created using a 30meter statewide digital elevation model.
The average slope percent was determined
for each 30 meter cell, and those slopes
classified as 0-40% were isolated. Cells
displaying slopes in this range are shown at
the right in green. At this scale, it is barely
possible to see the cells in the Catskill and
Adirondack Parks which have been
removed from the analysis. The value
assigned to the slope layer is 346.
Wildfire Risk:
The final layer intended for inclusion in the
SAP was a layer showing risk of wildfire;
however, at this time this data is
unavailable. Fortunately, this layer was
ranked almost unanimously last in
importance and as a result would have been
given a weight of 22. It is likely that when
this data becomes available, the SAP will
be updated to include it.
13
Statistical Ranking Methodology:
In order to rank the 12 data layers used in this study, a list was sent to New York State
Service Foresters. Foresters were instructed to assign numerical ranks to the parameters
in order of decreasing importance. The results of this survey were as follows:
Reg
3
Reg
4
Reg
5
Reg
6
Reg
7
Reg
8
Reg
9
7
11
10
8
9
10
12
9.5714
2.4286
0.0368
10
6
3
2
9
2
6
2
4.2857
7.7143
0.1169
2
9
9
7
3
10
1
5
6.2857
5.7143
0.0866
7
8
10
9
1
5
2
4
5.5714
6.4286
0.0974
6
11
8
6
11
11
11
10
9.7143
2.2857
0.346
11
5
4
5
5
4
8
7
5.4286
6.5714
0.0996
5
10
5
3
7
6
7
8
6.5714
5.4286
0.0823
9
Forest Health
Private Forest
Lands
Developing
Areas
2
7
8
4
3
4
3
4.4286
7.5714
0.1147
3
1
1
1
10
1
3
1
2.5714
9.4286
0.1429
1
3
2
11
2
8
5
6
5.2857
6.7143
0.1017
4
T & E Species
4
6
4
6
7
9
9
6.4286
5.5714
0.0844
8
12
12
12
12
12
12
11
11.8571
0.1429
0.0022
12
Parameter
Prox. To Pub.
Land
Forest Patch
Size
Priority
Watershed
Public Water
Supply
Slope
Riparian Areas
Wetlands
Fire Risk
Average
Inverse
Decimal
Rank
Ranking
Following the example of the state of Missouri, the averages of the ranking values were
subtracted from 12, in order to obtain inverse ranks. Each inverse rank was divided by
the total of all inverse ranks, in order to obtain a decimal rank directly proportional to the
value of the assigned numerical ranks.
In order to conform to the ESRI convention of assigning integer values to reclassified
raster data, each of the values in the “decimal rank” column were multiplied by 10^4. In
addition, the Conservation Easement layer (assigned a rank of 10 and decimal rank of
.0368) was not included in this original ranking. Due to this, and the removal of the Fire
Risk data layer, highest attainable rank is 10,347, not 10,000 as originally intended. Only
28 total cells in the analysis exhibit the maximum value.
The raster layers were all reclassified to exhibit either the value of their decimal ranking
* 10^4, or zero in all cells. These binary layers were summed using the Raster Calculator
to create the master SAP layer.
14
Analysis Mask:
An analysis mask was created using the EPA Multi-Resolution Land Characteristics
dataset, which breaks land cover down into 16 classes: Barren - Bare Rock and Sand;
Barren - Quarries, Strip Mines, Gravel Pits; Barren – Transitional; Deciduous Forest;
Emergent Wetlands; Evergreen Forest; High Intensity Commercial/Industrial; High
Intensity Residential; Low Intensity Residential; Mixed Forest; Parks, Lawns, Golf
Courses; Pasture/Hay; Row Crops; Uncoded; Water; and Woody Wetlands.
The High Intensity Commercial/Industrial, High and Low Intensity Residential, and
Water classes were recoded to a value of “NoData,” while other classes were recoded to a
value of “1.” While the MRLC dataset was already based on a 30-meter grid cell system,
during this reclassification the extent of the new Urban/Water raster was reset to that of
the Slope layer to ensure exact cell overlay. The unbuffered Proximity to Publicly
Owned Lands layer was also recoded to an inverse raster, with grid cells corresponding to
publicly owned lands displaying a value of “No Data,” and all other cells falling within
New York State coded to a value of “1.” Using the “Extract by Mask” tool in the Spatial
Analyst Toolbar, the Urban/Water layer was masked out of the inverse Public Lands
layer, and the result was a master Analysis Mask, with Urban areas, Water, Publicly
Owned Lands, and out-of-state cells coded to “No Data,” and all other cells coded to a
value of “1.”
SAP Data Layer Classification:
Areas determined to be part of the analysis mask were removed from the master SAP
data layer using the same “Extract by Mask” tool. Once the areas being considered for
stewardship were isolated, the master SAP layer was reclassified into 3 classes using the
Jenks Natural Breaks method. The numerical breakdown of the classes is as follows:
Low Stewardship Potential: 0-3549 (37,698,071 cells)
Medium Stewardship Potential: 3550-5541 (41,004,913 cells)
High Stewardship Potential: 5542-10347 (29,419,568 cells)
Of the area being considered in the analysis, 34.87% is considered to have Low
Stewardship Potential, 37.92% is considered to have Medium Stewardship Potential, and
27.21% is considered to have High Stewardship Potential.
Forest/Non-forest Classification:
The MRLC data layer was used to create two additional mask layers: Forested Areas and
Non-forested Areas. Classes included in the Forest mask were: Deciduous Forest,
Evergreen Forest, Mixed Forest, and Woody Wetlands. All other MRLC classes were
included in the Non-Forest mask. The masks were applied to the final SAP layer in order
to determine the area values and percentages of High, Medium, and Low Stewardship
lands falling on each of these classes of land cover.
15
Map Products:
1. Potential for Forest Stewardship Program Benefits
The Potential for Forest Stewardship Program Benefits map contains the master SAP
layer, converted from a 30-meter raster to a non-generalized shapefile in order to ensure
proper viewing at small scales. Shapefile format also facilitates the calculation of area
values, shown below. The legend entry, “Analysis Mask,” has been changed to, “Areas
without Stewardship Potential.”
Stewardship
Potential
Low
Medium
High
Total:
Forest
Acres
1,649,081
8,142,532
6,305,318
16,096,931
Stewardship Capable Lands
Non-Forest
Total
% of total
forest
Acres
% of total
non-for
Acres
% of total
10.2%
50.6%
39.2%
6,731,200
972,860
234,652
7,938,712
84.8%
12.3%
2.9%
8,380,281
9,115,392
6,539,970
24,035,643
34.9%
37.9%
27.2%
16
Map 2: Potential for Forest Stewardship Program Benefits and Existing
Stewardship Plans
Currently, this map is identical to Map 1: Potential for Stewardship Program Benefits,
aside from the inclusion of an additional table and legend entry. This is due to the fact
that at the time of writing, the existing forest stewardship plans have yet to be collected.
Once this data becomes available, it will be shown as a layer of polygon features,
symbolized in black.
17
Map 3: Forest Stewardship Potential on Private Forest Lands* and Existing
Stewardship Potential
In Map 3: Forest Stewardship Potential on Private Forest Lands* and Existing
Stewardship Potential, all New York State lands determined to be non-forested have
been masked out of the master SAP layer. Areas which were part of the original Analysis
Mask are shown in white, while areas masked out due to land cover are shown in grey.
The table, shown below, takes into consideration only those lands determined to be
forested. At the time of writing, existing forest stewardship data had not been compiled.
When this data layer is completed, it will be symbolized using black polygon features, as
shown in the legend.
Private Forest Lands
Stewardship Potential
Low
Medium
High
Total:
Acres
Capable of 1,649,081 8,142,532 6,305,318 16,096,931
Stewardship:
Stewardship #,###,### #,###,### #,###,###
Plan (acres):
Stew. Plan vs.
Acres Capable of
##%
##%
##%
Stewardship (%):
#,###,###
##%
18
Map 4: Resource Richness
Map 4: Resource Richness displays a separate analysis performed using only those data
layers which were defined as resource potential factors at the beginning of the analysis.
These layers include Private Forest Lands, Forest Patches, Proximity to Publicly Owned
Lands, Wetlands, Riparian Areas, Public Water Supply, Threatened and Endangered
Species, Slope, Priority Watersheds, and Conservation Easements. The same weight
values for each layer were used in this analysis, creating a maximum possible value of
8,183. Using Jenks Natural Breaks classification method, the breakdown of classes in
this analysis was: Low Resource Richness 1-1970, Medium Resource Richness 19714026, and High Resource Richness 4027-8183. Cells with a value of zero in this layer
were removed and are symbolized in grey; however, they were few enough that they are
not visible at the scale of this map.
19
Map 5: Resource Threats
Map 5: Resource Threats contains information from the Forest Health and
Development Risk data layers. When the information becomes available, this analysis
may be updated to include information from the Fire Risk layer. In order to stay within
the parameters of this map, the areas displayed as Low are areas which were classified as
a development risk, areas displayed as Medium are areas which were classified as a forest
health risk, and areas displayed as high were identified as risk areas in both layers.
Quantitatively, Low threat areas had a cell value of 1017, Medium threat areas had a cell
value of 1147, and High threat areas had a cell value of 2164.
20
Map 6: Forest Stewardship Potential on Non-forested – Non-developed* Lands and
Existing Stewardship Plans
To create the data layer shown in Map 6: Forest Stewardship Potential on Nonforested – Non-developed* Lands and Existing Stewardship Plans, the following
classes were extracted from the 30-meter EPA Multi-Resolution Land Characteristics:
Barren; Bare Rock and Sand, Barren; Quarries, Strip Mines, Gravel Pits, Barren;
Transitional, Emergent Wetlands, Parks, Lawns, and Golf Courses, Pasture/Hay, and
Row Crops. During this process, the cells were formatted to the same output extent as
the rest of the data layers. This new raster was applied to the master SAP layer as an
analysis mask, and the result is shown above. When the existing stewardship plans are
collected, they will be symbolized on this map in black.
Non-Forest – Non-Developed
Lands Stewardship Potential
Low
Medium
High
Areas Capable of
Stewardship:
Stewardship
Plan (acres):
Stew. Plan vs. Acres
Capable of
Stewardship(%):
Total:
6,731,200
972,860
234,652
7,938,712
#,###,###
#,###,###
#,###,###
#,###,###
##%
##%
##%
##%
21
Map 7: Potential for Forest Stewardship Program Benefits - New York City
Watershed Region
This map offers a closer view of the stewardship potential within the area defined as the
New York City Watershed. Due to the high percentage of New York State owned lands
within the Catskill Park area; these have been broken down by type and symbolized
separately.
New York City Watershed – Stewardship Capable Lands
Stewardship
Potential
Forest
Acres
Low
Medium
High
Total:
46,621
348,630
349,345
744, 596
% of
Total For.
6.3%
46.8%
46.9%
Non-Forest
% of Total
Acres
Non-For.
73,027
61.7%
33,462
28.3%
11,794
10.0%
118,283
Total
Acres
% of Total
119,648
382,092
361,139
862,879
13.9%
44.3%
41.8%
22