Structure Condition Services Stressors
Mercury is a persistent bioaccumulative toxin, which means that it stays in the environment for a long time, cycling through air, water, and soil. Mercury can be deposited by wet and dry deposition, and is assimilated into plants and soils. It accumulates in organisms, leading to damage with long-term consequences1. Elevated mercury can cause reductions in growth and reproduction, and increases the rate of wildlife mortality. Here, we quantify the annual amount of mercury deposited at an air quality site in Underhill, Vermont. Annual scores are computed as the difference between the target concentration of 0 µg/m2 and the maximum (the maximum value in record + 10% of the range).
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 target and maximum (scaled 1-5)
|Directionality of scores||
Lower values in the data are better.
|Minimum value used in scoring||
|Maximum value used in scoring||
Data maximum + 10% of range
Data on mercury deposition (µg/m2) were accessed from the National Atmospheric Deposition Program (NADP) Mercury Deposition Network (MDN) for sites at Underhill, Vermont1. Annual values are computed from weekly samples collected at the site. We set the target for mercury deposition to zero2. The annual score was computed as the difference between the target concentration of 0 µg/m2 and upper scoring bounds (maximum value in the data plus 10% of the range). This difference was then scaled between 1-5.
Acid rain harms forests and other ecosystems by damaging leaves and leaching nutrients.
The length of the growing season varies from year to year, but large or persistent changes can be problematic to forests.
Ozone can cause many negative impacts to forests by reducing regeneration, productivity, and species diversity.
Mercury is a toxin that persists in the environment for long periods by cycling back and forth between the air, water, soil and organisms - resulting in long-term, negative effects to forest ecosystems.
Warmer winter minimum temperatures can allow for non-native species to proliferate, while at the same time stressing native forest trees.
Higher maximum summer temperatures can stress forests, reducing productivity and health.
Changes to precipitation can alter the water balance in Vermont’s forests, causing either drought or deluge.
Snow insulates the soil and tree roots from cold temperatures and provides water when it melts.
Climate change will continue to result in more extreme weather events, which can stress forests beyond what they are accustomed.
Lack of sufficient precipitation can cause both immediate and long-term stress to trees.
As native trees are not adapted to defending themselves from non-native, invasive insects and diseases, widespread damage and mortality can result.