Structure Condition Services Stressors
Snow cover in the winter months insulates the soil, retaining both heat and moisture. Less snow can lead to deeper and more persistent soil freezing, resulting in increased tree roots mortality and changes in soil nutrient dynamics1,2,3. Also, the melting of snow in late winter can provide a steady supply of water to trees when they are preparing for bud break. Here, snow cover is defined as the number of days with snow cover greater than 1” in depth for Vermont. As trees are adapted to the conditions they have experienced, deviations in snow pack from the long-term mean (both above and below) could be problematic to forests. Therefore, annual snow cover scores are computed as the change from the long-term mean.
Snow cover is decreasing, as winter temperatures warm and less precipitation falls as snow, and the snow that does fall is melting during warm-ups and not accumulating. This lower snow cover leads to earlier spring melt and dryer summer soils. This can lead to drought and a longer wildfire season.
NOAA, Northeast Regional Climate Center at Cornell University (2020)
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 away from long-term mean (scaled 1-5)
|Directionality of scores||
No change from the long-term mean is better.
|Minimum value used in scoring||
Data minimum - 10% of range
|Maximum value used in scoring||
Data maximum + 10% of range
The total annual number of days with snow cover >1 inch in Vermont were collected from NOAA National Centers for Environmental Information1. We set the target for the dataset as the mean duration of snow cover from 1961-1990 which is used as the baseline normal for climate comparisons by the Intergovernmental Panel on Climate Change (IPCC). The current year is scored for where it falls between the target and the upper scoring bounds (maximum value in the dataset) or the lower scoring bounds (minimum value in the dataset), scaled to be between 1 and 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.