Structure Condition Services Stressors
The diversity of forest-dwelling birds provides a sense of how well Vermont's forests support bird habitat, food sources, and reproductive success. Further, trees rely on birds for flower pollination, seed dispersal, and pest control1. Examining annual bird counts of forest-dwelling bird species can provide an indication of the quality of the forest habitat in supporting wildlife. Here, forest bird species abundance is assessed using a Living Planet Index (LP1)2. The Living Planet Index gives a sense of how this bird diversity is sustaining over time. A high score means that diversity is high.
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 maximum and minimum (scaled 1-5)
Data maximum + 10% of range
|Directionality of scores||
Higher values in the data are better.
|Minimum value used in scoring||
Data minimum - 10% of range
|Maximum value used in scoring||
Data maximum + 10% of range
Data on forest bird counts by species were collected by Vermont Center for Ecostudies1 at forested locations throughout Vermont beginning in 1989, with a more complete survey of the selected sites in 1990. From these data, we computed a Living Planet Index (LPI) 2. We used a beta package for R, rlpi3, to compute the LPI for all bird species. We used equal weighting among species and no sub-groupings. Only those Forest Bird Monitoring sites with a complete record were included: Bear Swamp, Concord Woods, Dorset Bat Cave, Galick Preserve, Maypond, Moosebog, Pease Mountain, Roy Mt WMA, Sandbar WMA, Sugar Hollow, The Cape, and Underhill State Park. Living Planet Index ranges from zero to two. We computed the index and set the target to 1, and the current year is scored as the difference between the target and the current year value, scaled to be between 1 and 5.
Timber harvested from Vermont's forests provide jobs and income to the state, and support the maintenance of forest land.
Aquatic species that live in forested streams provide an assessment of the health of the surrounding forest.
The ability of forests to support big game species for hunting indicates healthy forest habitat.
The amount of carbon stored by forests helps offset rising atmospheric carbon dioxide concentrations.
Maple syrup production is an iconic staple of Vermont's landscape and is reliant on the continued health of maple trees.
The number of people using Vermont's forests for camping and hiking provides a measure of the value of our forests for recreational uses.
The number and diversity of bird species that live and use forested habitats provides a sense of the quality of Vermont's forestlands for a variety of species.