Latest Score:

2/5

in 2016

score trend is flat over time
Weight: 12%

Mean forest patch size is a measure of the average size of forest blocks throughout Vermont. When large forest blocks are subdivided during development, the average forest patch size decreases. As we fragment or divide large areas of forest, we reduce the ecological value they provide. Smaller forest patches limit the flow of seeds, animals, and nutrients1 and can make forests more vulnerable to damage or infestation by non-native pests or plants. Both the ecosystem services (such as recreational opportunities, moderation of fluctuating temperatures, and water filtration) and timber-based economic viability of these smaller patches are reduced. Here, we use landcover classification data from satellite imagery to assess the average size of forest patches in Vermont using FragStats software2. A high score means that mean forest patch size is not changing from year to year.

1 Sorenson, E and J Osborne. 2014. Vermont habitat blocks and habitat connectivity: an analysis using geographic information systems. Available at: http://www.vtfishandwildlife.com/UserFiles/Servers/Server_73079/File/Conserve/Vermont_Habitat_Blocks_and_Habitat_Connectivity.pdf
2 McGarigal, K., SA Cushman, and E Ene. 2012. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical and Continuous Maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. Available at the following web site: http://www.umass.edu/landeco/research/fragstats/fragstats.html

-- Expert interpretation for Mean Forest Patch Size is not available--

The score is calculated using a target value and the historical range of the the entire long-term dataset. The higher the score, the closer this year's value is to the target.

Once the score is computed for each year, the trend in scores over time is calculated. If the trend is significantly positive or negative, the long-term trend is marked as increasing or decreasing respectively.

Component Description
Scored as

Distance between minimum and target (scaled between 1 and 5)

Target value

Long-term mean

Directionality of scores

No change from the long-term mean is better

Minimum value used in scoring

Data minimum - 10% of the range

Maximum value used in scoring

Data maximum + 10% of the range

Using the National Land Cover Database (NLCD)1, we mapped forest cover (41 Deciduous Forest, 42 Evergreen Forest, 43 Mixed Forest, and 90 Woody Wetlands) at 30 meter resolution. The NLCD begins in 2001 from the reprocessed release in 2019. We used FragStats2 to compute the mean size of forest patches. We used the 8 cell neighborhood rule with a ‘no sampling’ strategy. We selected all Area-Edge Class metrics for computation. We set the target for this dataset to be the long-term mean. The current year is scored for where it falls between target and either the lower scoring bounds (dataset minimum minus 10% of the range) or the upper scoring bounds (dataset maximum plus 10% of the range) and the target when values are above the target, scaled to be between 1 and 5.

1US Geological Survey. 2019. National Land Cover Database. Available at: https://www.mrlc.gov/data
2 McGarigal, K., SA Cushman, and E Ene. 2012. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical and Continuous Maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. Available at the following web site: http://www.umass.edu/landeco/research/fragstats/fragstats.html

STRUCTURE INDICATORS