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MassGIS Data: Prime Forest Land

January 2013

These layers were created using primarily the NRCS/MassGIS Soils data; the basic procedure was to classify potentially forested land into nine different categories based on potential average timber productivity.

Download this layer (Zipped Shapefile ArcGIS 10 layer file):
Statewide (305 MB), or regionally:
Northeast (Essex, Middlesex Norfolk, Suffolk; 91 MB)
Southeast (Barnstable, Bristol, Plymouth, Dukes, Nantucket; 121 MB) 
Central (Worcester; 78 MB)
West (Berkshire, Franklin, Hampden, Hampshire; 115 MB)

Smaller geographic areas may be downloaded in OLIVER
Sample of Prime Forest Land

The project “Soil Productivity Mapping for Use in Forest Management” is a digital representation of work done previously in the Department of Natural Resources Conservation at the University of Massachusetts at Amherst. GIS data created for this project followed (where possible) the protocol established in UMass Research Bulletin #705 – Prime Forest Land Classification for Forest Productivity in Massachusetts.

Using primarily the NRCS/MassGIS Soils data, the basic procedure was to classify potentially forested land into nine different categories based on potential average timber productivity of white pine and red oak “…per acre per year at culmination of mean annual increment. Site index values are at age 50.” Other data sets were used to refine this classification, including aspect, land cover, riparian, slope position, wetlands, hydrologic soil association and unique areas.

With the January 2013 update the dataset is complete statewide.

The layer is named PRIMEFOREST_POLY.


The categories of potentially forested land are:
    Cubic Volume Site Index
    ft3/ac m3/ha ft m
WHITE PINE        
1 Prime 1 >155 >10.9 >70 >21
2 Prime 2 120-154 8.4–10.8 60–69 >18-<21
3 Prime 3 85-119 6.0-8.3 50-59 >15-<18
3W Prime 3 Wet 85-119 6.0-8.3 50-59 >15-<18
S Statewide Importance 65-84 4.6-5.9 45-49 >14-<15
SW Statewide Importance Wet 65-84 4.6-5.9 45-49 >14-<15
L Local Importance <65 <4.6 <45 <14
LW Local Importance Wet <65 <4.6 <45 <14
UW Unique Wet N/A N/A N/A N/A
1 Prime 1 >55 >3.9 >65 >20
2 Prime 2 45-54 3.2–3.8 60–64 >18-<20
3 Prime 3 40-44 2.8-3.1 55-59 >17-<18
3W Prime 3 Wet 40-44 2.8-3.1 55-59 >17-<18
S Statewide Importance 35-39 2.5-2.7 50-54 >15-<17
SW Statewide Importance Wet 35-39 2.5-2.7 50-54 >15-<17
L Local Importance <35 <2.7 <50 <15
LW Local Importance Wet <35 <2.7 <50 <15
UW Unique Wet N/A N/A N/A N/A

In order to assign one of these values (1, 2, 3, 3W, S, SW, L, LW and UW), the process required the use of the following digital data:

  1. Soils data produced by the Natural Resources Conservation Service (NRCS) (downloaded from MassGIS)

  2. Topographic data (slope, aspect and slope position derived from DTM point elevation data downloaded from MassGIS) to create a hydrologically accurate surface grid

  3. data were used to assign a “W” modifier to the classification (from the MA Department of Environmental Protection Wetlands Conservancy Program, downloaded from MassGIS)

  4. Land use – land cover data produced by Resource Mapping at UMass to determine forested, potentially forested and non-forested areas as of 1999

  5. Riparian corridor data (downloaded from MassGIS) (note: no longer distributed by MassGIS)

  6. Unique vegetated communities (in this case Atlantic White Cedar wetlands, downloaded from MassGIS)

There was a minimum mapping unit of 5 acres for the project initially but when the project was recreated digitally, there was a minimum mapping unit of 0.5 acres. Potentially forested land included all land currently forested as well as abandoned farmland and unimproved pastures. A master list of soil associations was developed based on the timber productivity values listed above. There are 269 different soil associations in Massachusetts, 163 (60.6%) are hard wired into a defined category while 106 (39.4%) can go one category higher or lower. For these soil associations that are between prime forest categories AND on forested or open land, we would use slope, slope position, aspect, and riparian corridors to bump the classification up or down one category using NRCS “Hydrologic Groups” and this ancillary data. The rules developed for this process state:

aspect: if droughty soil on south facing slope, move down one category, all others move up, if wet soil on south facing slope, move up one category, all others move down
slope position: if droughty soil on bottom of slope, move up one category, all else down one category, if wet soil on bottom of slope, move down one category, all else up one category


The most important field in the database for this data is in the “PRIME” column. This classifies each polygon into one of the following categories (see timber productivity values above):
1   Prime 1   (These first
 four are
2   Prime 2  
3   Prime 3  
3W   Prime 3 Wetland  
S   Statewide Importance    
SW   Statewide Importance Wetland    
L   Local Importance    
LW   Local Importance Wetland    
UW   Unique Wetland (Atlantic White Cedar)    
NON-FOREST   Not Forested    
The other item in the layer's polygon attribute table is ACRES, which stores the acreage of each polygon.


Questions can be directed to:
David W. Goodwin, Assistant Program Manager
DCR, Bureau of Forestry, Management Forestry Program
40 Cold Storage Drive
Amherst, MA  01004
413 545-5748

Last Updated 2/26/2013


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