Structure Condition Services Stressors
Hardwood regeneration tells us the future composition of the forests dominated by species such as maple and oak. While assessments of mature trees provide information about the current condition of Vermont’s forests, the density of seedlings give details about the likely hardwood composition in the future. Hardwood regeneration is a measure of the density of seedlings (classified as less than 1" in diameter and 12” tall) per acre, inventoried annually on Forest Inventory and Analysis (FIA) plot data1. Here, a dominant component of the northern hardwood forest, and an ecologically and economically important species, sugar maple (Acer saccharum), was used as a proxy for all hardwood species regeneration. These sugar maple regeneration estimates are from maple-beech-birch forests where we would expect to find sugar maple seedlings. A high score means that there is a high density of seedlings, measured as the count of seedlings per acre, each year.
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.
Distance between 0 and max (scaled 1-5) using a 5-year moving window
Data maximum + 10% of the range
|Directionality of scores||
Higher values in the data are better
|Minimum value used in scoring||
|Maximum value used in scoring||
Data maximum + 10% of the range
We used sugar maple (Acer saccharum) seedling counts per acre in maple-beech-birch forests estimated from USFS Forest Inventory and Analysis (FIA) Program Phase 2 subplots. Seedling data were collected using an FIA-established query in EVALIDator;>1 (“0045 Number of live seedlings (less than 1 inch d.b.h./d.r.c.), in seedlings, on forest land”) filtered by sugar maple (“and seedling.spcd = 318”) and grouped by forest type. Per FIA protocol, plots were reassessed every 5 years until 2014 (i.e. data reported for 2007 used 2003, 2004, 2005, 2006 and 2007), and then every 7 years after that;>2. Estimates are calculated by scaling the seedling data to represent the maple-beech-birch forests of Vermont. The target for this dataset was set to the maximum value plus 10% of the range. The current year is scored for where it falls between zero and the target, scaled to be between 1 and 5.
Forest cover is the percent of the state of Vermont with tree cover.
Regeneration of sugar maple seedlings provides information about the future of Vermont's hardwood forests.
Regeneration of red spruce seedlings provides information about the future of Vermont's softwood forests.
Forests with greater stand complexity have trees in a range of sizes and as a result, may be more productive and resilient to stress.
Forest patch sizes provides information on the average size of contiguous forest blocks.
Forest connectivity is a measure of the linkages among Vermont's forests.
With greater diversity in tree species, forests can support more biodiversity, exhibit higher resilience to stress, and store more carbon.
Across the landscape, having a range of forest stand ages provides diversity, varied habitat conditions, and resilience to stressors.