A Northwest Regional Land Cover Classification

Jason Karl, Philip Tanimoto, and Shannon Mann

Conservation Imaging, Inc.

March 15, 1999

This regional land cover classification combines the most recent Gap
Analysis Project Land Cover products from the states of Idaho, Oregon
and Washington, into a common, hierarchical scheme.

When cross-walking any two, different land cover classifications, loss
of thematic detail occurs. We have approached this task in a manner that
retains a high degree of thematic detail and provides a hierarchical
scheme that can be expanded or collapsed to meet user needs. We have
also tried to meet existing data needs of the Environmental Protection
Agency, Region 10.

Cassidy et al. (1996) created the first Northwest Regional Vegetation
Classification using the Gap Analysis Land Cover products from Idaho,
Oregon and Washington. However, this classification was neither
hierarchical nor ordered according to major life form (i.e.,
urban/developed, non-forested, forested, water, riparian, non-vegetated,
alpine, snow). Since that classification was produced, Idaho and Oregon
have completed new, more detailed land cover classifications. These
reasons prompted the creation of this new Northwest Regional Land Cover
Classification.

Our land cover classification uses the most current data available from
Idaho, Oregon and Washington as of March, 1999. The Idaho Land Cover
Classification (unpublished data, available at
www.wildlife.uidaho.edu/idgap.htm) was compiled from the Land Cover of
Western Montana and Northern Idaho (Redmond et al. 1997) and the
Idaho/Western Wyoming Landcover Classification (Homer 1998). Both
sources resulted from hybrid, supervised and classifications of Landsat
Thematic Mapper (TM) imagery. The Idaho Land Cover Classification
recognizes 80 land cover types with a 30m^2^ cell size and 2 hectare
minimum mapping unit (mmu).

The Northwest Habitat Institute (1998) created the Oregon GAP Analysis
Vegetation product from Landsat TM imagery. It recognizes 72 land cover
types at a 100ha mmu using 25m^2^ grid cells. The Land Cover of
Washington State (Cassidy 1997) was interpreted from Landsat TM imagery
and digitized on-screen. The vector coverage was rasterized with a cell
size of 25m^2^ and a 100 ha mmu for upland land cover types and a 40 ha
mmu for wetlands and riparian areas.

Washington's land cover classification used a system of ecoregions,
zones and cover classes to describe each delineated polygon instead of a
single code set for describing land cover types across the state. This
resulted in a detailed, yet complex classification scheme. For this
project, we relied on the scheme provided in the Northwest Regional
Vegetation Classification (Cassidy et al.1996), which we used to
cross-walk the Washington Land Cover into a scheme compatible with those
of Idaho and Oregon.

876 polygon text descriptors from the Washington data set were assigned
to their most appropriate crosswalk classes. These assignments are
provided in the file, wa_recl.xls. In addition to this, the info item
"WA_PRIMARY" is provided in the Value Attribute Table for the user's
reference. PRIMARY is a three-digit, hierarchical code developed by
Cassidy 1997 (see "PRIM" Appendix A) which does not bear a one-to-one
relationship with the crosswalk code. Rather, it describes major cover
types and various defining characteristics which refine the polygons and
regions they describe.

Our new Northwest Regional Land Cover Classification is hierarchical and
ordered by major life form (Appendix B). This classification is founded
upon a 4-digit code whereby each digit describes a part of the land
cover type. The first digit describes the major life form (e.g., Urban,
Non-forested, Forested, etc.). The second digit breaks a major life form
into distinct sub-forms (e.g. Forest is divided into Deciduous Forest,
Coniferous Forest and Mixed Forest). The third digit further divides the
sub-forms into categories (e.g. Deciduous Forest is divided into Xeric
Deciduous and Mesic Deciduous). Finally the fourth digit completes the
land cover type, which corresponds generally to floristic composition.
The number 0 is always reserved to mean that there are no further
divisions of that type. For example, water is coded as 5000 because
there was no attempt to discriminate between streams, rivers or lakes.
In this system, there are up to 9 possible complete cover types within
each unique 3-digit category (for example, "coastal coniferous forest",
421, can contain only 4211 through 4219). The addition of a 5^th^ digit
to the codes would allow recognition of 99 cover types in each 3-digit
category. However, a 5^th^ digit was not necessary for this
classification; and therefore, was not added.

Land cover classes from each of the three states' classifications were
cross-walked into the Northwest Regional Land Cover Classification based
on the dominant species composition described for each cover type
(Appendix B). For the coniferous forest categories (4200 series), a
Mixed Coniferous Forest category was created for each forest category
(4^th^ digit is 9). Any state-level coniferous forest type with more
than 1 principal dominant species was assigned to a mixed coniferous
forest cover type.

We adopted the Lambert Conic Conformal projection used by Cassidy (1997)
for this project. All data were resampled to 30-meter pixels using a
nearest neighbor algorithm within the PROJECT sub-routine of Arc/Info.
The Oregon Gap Analysis Vegetation grid was changed from NAD83 (and
spheroid Global Reference System 1980) to NAD27 (spheroid Clarke 1866)
using the NADCON datum conversion program. No attempt was made to change
the minimum mapping units provided in the original state products.

**References:**

Cassidy, K.M. 1997. Land cover of Washington State: description and
management. Volume 1 in Cassidy, K.M., Grue, C.E., Smith, M.R., and K.M.
Dvornich. eds. Washington State Gap Analysis Project Final Report.
Washington Cooperative Fish and Wildlife Research Unit, University of
Washington, Seattle. 260pp.

Cassidy, K.M., Csuti, B. and M. Murray. 1996. Regional vegetation
classification: Idaho, Washington, Oregon. Idaho Cooperative Fish and
Wildlife Research Unit, University of Idaho, Moscow.

Homer, C.G. 1998. Idaho/western Wyoming landcover classification report
and metadata. Department of Geography and Earth Resources. Utah State
University. Logan, UT 84322-9635.

Northwest Habitat Institute. 1998. Oregon GAP analysis vegetation.
Midcontinent Ecological Science Center, U.S. Geological Survey, Fort
Collins, Colorado.

Redmond, R.L. 1997. Mapping existing vegetation and land cover across
western Montana and Northern Idaho. Wildlife Spatial Analysis Lab.
Montana Cooperative Fish and Wildlife Research Unit. University of
Montana, Missoula, MT 59812.

**Appendix A: Polygon classification system of Cassidy (1997).**

**PRIM (Primary)**

PRIM is the land cover that occupies the greatest surface area of the
polygon. SECO, if necessary, is the land cover that occupies the second
greatest surface area of the polygon. TERT, if necessary, is the land
cover that occupies the third greatest surface area of the polygon. PRIM
SECO, and TERT are all identified by a 3‑digit code.

**The first digit of the cover code indicates one of 9 Level I
categories. A Level 1 category was always assigned: I‑‑‑ Bare ground 2‑‑
Developed 3‑‑ Agriculture 4‑‑ Open Water 5‑‑ Wetlands, riparian 6‑‑
Non‑forested 7‑‑ Hardwood forest 8‑‑ Mixed hardwood/conifer forest 9‑‑
Conifer forest**

**The second and third digits each indicate Level 2 categories within
the Level 1 categories. Digit 2 is Attribute A and digit 3 is Attribute
B. Attributes A and B are independent of one another and, if the
attribute could not be confidently assigned or the cover had multiple
(mixed) attributes, the attribute was assigned a 0.**

> **1‑‑ Bare ground (\<10% vegetation cover; excludes water, fallow
> fields, pavement, etc.) General type (Attribute A) 0‑ Unknown/mixed I
> ‑ Rocky ground 2‑ Ice/snow 3‑ Sand**
>
> **Form (Attribute B)**
>
> **‑0 Unknown/mixed**
>
> **‑ 1 Cliffs**
>
> **Sample combinations used:**
>
> **110 Bare rocky/stony ground**
>
> **111 Bare cliffs**
>
> **120 Ice/snow**
>
> **130 Sand (to date, always beach sand)**

**2‑‑ Developed**

**Level of development (Attribute A)**

**0‑ Unknown/mixed levels**

**I‑ High density (\>60% of surface covered by pavement, structures,
etc.)**

**2‑ Medium density (30‑60% surface development)**

**3‑ Low density (10‑30% surface development)**

**3‑‑ Agriculture**

**Irrigation status (Attribute A)**

**0‑ Unknown or a combination of irrigation types**

**1‑ Irrigated**

**2‑ Non‑irrigated**

**Type of development (Attribute B)**

**‑0 All types**

**‑1 Primarily residential**

**‑2 Primarily business/industrial**

**‑3 Mining operations**

**‑4 Roads**

**‑5 Predominant cover is mowed grass (golf courses, sports fields,
airports)**

**‑6 Predominant cover is planted trees among mowed understory (wooded
city**

**parks)**

**Sample combinations:**

> **231 Low density residential (e.g., suburban housing w/large lots)**
>
> **212 High density business/industrial (e.g., core Seattle downtown
> area)**

**Crop type (Attribute B)**

**‑0 Unknown or a mix of crop types**

**‑1 Maintained pasture (i.e., seeded, mowed, hayed, etc.)**

**‑2 Herbaceous row crops**

**‑3 Orchards/vineyards**

**‑4 Soil Conservation Reserve fields (usually Crested Wheatgrass)**

**Sample combinations:**

> **312 Irrigated row crops**
>
> **320 Non‑irrigated crops of unknown type or a mix of types**

**4‑‑ Open water**

**Fresh or salt water (Attribute A)**

**0‑ Variety of salinity levels**

**1‑ Freshwater**

**2‑ Saltwater**

**3‑ Brackish water**

> **Water body type (Attribute B)**
>
> **‑0 Mix of types (usually combination of rivers and lakes)**
>
> **‑1 Lakes (including shoreline)**
>
> **‑2 Municipal ponds**
>
> **‑3 Channeled scabland and steppe kettle ponds**
>
> **‑4 Fish hatcheries**
>
> **‑5 Large rivers**
>
> **‑7 Irrigation canals**
>
> **‑8 Irrigation ponds**
>
> **Sample combinations:**
>
> **411 Freshwater lakes, including shorelines**
>
> **415 Rivers large enough to have visible open water at our
> resolution**
>
> **420 Ocean**
>
> **430 Brackish water (always the mouths of large rivers)**

**5‑‑ Wetlands**

**Water flow type (Attribute A)**

**0‑ Mixed or unknown type**

**1 ‑ Estuarine marsh**

**2‑ Freshwater marsh**

**3‑ Riparian**

**4‑ Vernal pools or small ponds (interchangeable with 413)**

**5‑ Beach/ocean shoreline**

> **Vegetation physiognomy**
>
> **‑0 Mixed or unknown dominant vegetation form**
>
> **‑1 Sparse emergent, submerged, or floating**
>
> **‑2 Herb, shrub dominated**
>
> **‑3 Hardwood dominated**
>
> **‑4 Conifer dominated**
>
> **Sample code combinations:**
>
> **512 Estuarine marshes, usually grassy**
>
> **523 Freshwater marsh, dominated by hardwood trees**
>
> **530 Riparian vegetation, variety of communities**

**[Water/wetland notes:]{.underline} The distinction between open water
and wetlands is not sharp. The wetland category \"riparian,\" for
example, refers to the vegetation along a river and the open water
category \"river\" refers to the open surface water of a river. In
practice, a narrow river would be labeled \"riparian\" with the polygon
including the shoreline vegetation and the open river, while a wide (\>
50 m across) river in a polygon would be labeled with the open water
category \"river\" but would include at least part of riparian
vegetation on the shore. Thus the distinction between open water and
wetland is often a quantitative difference in the proportion of open
water to emergent vegetation, rather than a qualitative categorical
difference.**

**6‑‑ Non‑forested**

**Seral stage or disturbance status (Attribute A)**

**0‑ Unknown or a mix of sera\] types**

**1 ‑ Disturbed by logging, burning, or heavy grazing**

**2‑ Undisturbed or climax type**

> **Vegetation physiognomy (Attribute B)**
>
> **‑0 Combination of types or type unknown**
>
> **‑1 Sparse vegetation (10‑30% cover)**
>
> **‑2 Grass or forb dominated (\<10% shrub or tree cover)**
>
> **‑3 Shrub savanna or mix herbs and shrub patches (shrub cover 10‑25%;
> tree**
>
> **cover \<10%)**
>
> **‑4 Shrub dominated (shrub cover \>25%; tree cover \<10%)**
>
> **‑5 Tree savanna (tree cover 10‑25%)**
>
> **Sample combinations:**
>
> **613 In a forest zone, usually a logged or burned area regrown to a
> mix of herbs and shrubs; in a steppe zone, usually indicates a shrub
> savanna dominated by exotics due to heavy grazing**
>
> **605 Tree savanna, disturbance status unknown**
>
> **620 A variety of apparently natural communities (i.e., no sign of
> recent logging, bums, heavy grazing); often used to designate a mix of
> alpine/subalpine meadows, parklands, and shrub fields.**

**7‑‑ Hardwood forest (overstory generally \> 75% hardwood) 8‑‑ Mixed
hardwood/conifer forest 9‑‑ Conifer forest (overstory generally \>75
%conifers) Seral stage (Attribute A; same for all forest classes) 0‑ Mix
of seral (i.e., successional) stages or seral stage unknown 6‑ Early
seral 7‑ Mid seral 8‑ Late seral**

**Canopy closure (Attribute B; same for all forest classes)**

**‑0 Mixed closure, patchy closure, or closure unknown**

**‑1 Open canopy (25‑60% overstory cover)**

**‑2 Closed canopy (generally \>60% overstory cover)**

> **Sample code combinations**
>
> **962 Early seral, closed canopy, predominantly conifer forest**
>
> **860 Early seral, mixed forest, with patchy closure (e.g., tree
> stands mixed with shrubby regrowth) or a mix of closed and open
> stands.**
>
> **901 Conifer forest, open canopy, unknown seral stage.**

**[Forest]{.underline} note 1: Conifer forest is the most common forest
type in Washington State. Hardwood and mixed forests are often (but not
always) an early seral stage in a succession that eventually leads to
conifer domination. Thus, a mid‑ or late‑seral hardwood forest is, in
many cases, something of a contradiction. If these terms are applied to
hardwood forest, they are generally meant to indicate that the hardwoods
are probably large and mature.**

**[Forest]{.underline} note 2: Seral stage is most easily determined
when canopies close early and evenly and when the terrain is not too
rugged. Under those conditions, the evenness of the top of the tree
canopy is roughly correlated to sera\] stage. In dry forests, forests on
uneven terrain, or forests on deeply shadowed slopes, seral stage was
either not labeled (e.g., 901, 902 classes) or is unreliable unless the
satellite data were supplemented by other sources of information. Most
east‑side forest classes were not labeled with seral stage because they
are relatively dry with uneven canopy closure. High elevation forest
types, which are often on rugged terrain, tended to be labeled as late
seral unless there was some obvious sign of recent logging or fire.**

**[Forest note]{.underline} 3: Seral stage and tree size. We initially
used a classification that substituted tree size for seral stage, but
that type of system is difficult to apply across large elevation
gradients, and forest size classes are exceedingly difficult to
determine with satellite data. In forests at low elevations on moderate
terrain, \"early seral\" corresponds roughly to sapling and pole‑sized
trees; \"mid seral\" to large pole and small saw timber; and \"late
seral\" to large saw timber and \"old growth.\" However, at high
elevations, late‑seral forest may consist of short, stunted, pole‑sized
subalpine trees. Additionally, \"tree\" generally applies to plants
taller than 5 meters. Thus a Douglas‑fir plantation of 2‑meter
seedlings, if classified correctly, would be labeled 614 (a
non‑forested, disturbed shrub land) rather than a forest. However, some
latitude was applied to subalpine forests, where trees hundreds of years
old are often less than 5 meters; if classified correctly, these stands
would be labeled forests.**

**Appendix B: Northwest Regional Land Cover Classification**

**1000 *Urban/Developed***

**2000 *Agricultural***

**3000 *Vegetated: Non-forested***

> **3100 Grasslands**
>
> **3110** *Grasslands*
>
> **3120** *Subalpine Meadows*
>
> **3130** Wet Meadow
>
> **3200 Upland Shrublands**
>
> **3300 Xeric Shrublands**
>
> **3301** Big Sagebrush
>
> **3302** Other Sagebrush
>
> **3303** Salt-desert Shrub
>
> **3304** Bitterbrush
>
> **3305** Mountain Mahogany
>
> **3306** Rabbitbrush

**4000 *Vegetated: Forested***

> **4100 Deciduous Forest**
>
> **4110** *Xeric Deciduous Forest*
>
> **4120** *Mesic Deciduous Forest*
>
> **4200 Coniferous Forest**
>
> **4210** *Coastal Coniferous Forest*
>
> **4211** Sitka Spruce
>
> **4213** Lodgepole Pine
>
> **4219** Mixed Coastal Forest
>
> **4220** *Xeric Coniferous Forest*
>
> **4221** Ponderosa Pine
>
> **4222** Jeffry Pine
>
> **4223** Douglas-fir
>
> **4224** Pinyon
>
> **4225** Western Juniper
>
> **4226** Utah Juniper
>
> **4227** Limber Pine
>
> **4229** Mixed Xeric Forest
>
> **4230** *Mesic Coniferous Forest*
>
> **4231** Lodgepole Pine
>
> **4232** Grand Fir
>
> **4233** Douglas-fir
>
> **4234** Englemann Spruce
>
> **4235** Western Red Cedar
>
> **4236** Western Hemlock
>
> **4237** Western Larch
>
> **4239** Mixed Mesic Coniferous Forest
>
> **4240** *Subalpine Coniferous Forest*
>
> **4241** Subalpine-fir
>
> **4242** Whitebark Pine
>
> **4243** Mountain Hemlock
>
> **4244** Pacific Silver Fir
>
> **4249** Mixed Subalpine Coniferous Forest
>
> **4300 Mixed Deciduous/Coniferous Forest**
>
> **4310** *Xeric Mixed Forest*
>
> **4320** *Mesic Mixed Forest*

**Appendix A: Continued**

**5000 *Water***

**6000 *Riparian/Wetland***

> **6100 Forested Riparian**
>
> **6110** *Coniferous Forested Riparian*
>
> **6120** *Deciduous Forested Riparian*
>
> **6130** *Mixed Coniferous/Deciduous Riparian*
>
> **6200 Non-forested Riparian**
>
> **6210** *Shrub Dominated Riparian*
>
> **6220** *Graminoid/Forb Dominated Riparian*
>
> **6300 Estuarine Marsh**

**7000 *Non-Vegetated***

> **7100 Exposed Rock**
>
> **7200 Sand**
>
> **7300 Lava**
>
> **7400 Tidal Flat**

**8000 *Alpine***

> **8100 Alpine Meadows**

**9000 *Permanent Ice and Snow***

**9800 Cloud**

**9900 Cloud Shadow**

\\

**Appendix C: Crosswalk of State Land Cover Codes into Northwest
Regional Land Cover Classification. Washington crosswalk is provided in
wa_recls.xls.**

  ------------ ----------------------------- -----------------------------
  **NWRLC      **Idaho Codes**               **Oregon Codes**
  Code**                                     

  **1000**     1000-1102                     124

  **2000**     2000                          125

  **3110**     3101-3103, 3106-3110          103, 112, 121

  **3120**     3104                          105, 110, 114

  **3130**     3105                          114

  **3200**     3201-3203                     85, 87, 89

  **3301**     3305-3307                     91, 96

  **3302**     3308, 3309, 3315, 3316        93

  **3303**     3310                          95, 122

  **3304**     3304                          97

  **3305**     3301                          90

  **3306**     3312                          NM

  **4110**     NM                            75

  **4120**     4101-4103                     63, 64, 66, 72, 77

  **4211**     NM                            NM

  **4213**     NM                            46

  **4219**     NM                            32, 37, 43

  **4221**     4206                          54

  **4222**     NM                            42

  **4223**     4212                          56

  **4224**     4232                          NM

  **4225**     4231                          61

  **4226**     4230                          NM

  **4227**     4205                          NM

  **4229**     4216, 4222                    40, 41, 58, 59, 106

  **4231**     4202                          44

  **4232**     4207                          NM

  **4233**     NM                            NM

  **4234**     4201                          NM

  **4235**     4210                          NM

  **4236**     4211                          NM

  **4237**     4215                          NM

  **4239**     4221, 4223, 4225-4229         34, 35, 49, 50, 52

  **4241**     4208, 4217                    NM

  **4242**     4219                          NM

  **4243**     NM                            33

  **4244**     NM                            NM

  **4249**     4218, 4220                    39, 45

  **4310**     NM                            53,57

  **4320**     4301                          51, 67

  **5000**     5000                          130

  **6110**     6101                          NM

  **6120**     6102                          65, 68, 135, 200

  **6130**     6103, 6104                    NM

  **6210**     6202, 6203                    136, 201

  **6220**     6201, 6301-6304               138, 203

  **6300**     NM                            137, 202

  **7100**     7300, 7800, 7900              NM

  **7200**     7201, 7202, 7302              113, 128

  **7300**     7300                          127

  **7400**     NM                            126

  **8100**     8100                          NM

  **9000**     9000                          129
  ------------ ----------------------------- -----------------------------

**\* NM** = Not Mapped