This past weekend in Vermont was seriously cold on Friday followed by a chilly and snowy Saturday which was then taken over by warmth and pouring rain early Sunday morning. Now, we are back on track with highs around 10oF. Vermont’s weather could not make up its mind over the past few days - leaving me quite sad about the loss of snow at the ski areas. After this weekend’s weird weather patterns, I have been thinking about climate change and wondering how it will affect our urban forests and if urban forests have an impact on climate change.
Predictions of climate change are increases in temperature, storm severity, and air pollution, and soil habitat alterations. Warmer winters will increase evaporation and reduce snowpack resulting in a decrease in summertime soil moisture and an increase in drought. Drought decreases tree productivity and increases stress on trees leaving them more vulnerable to pests. The loss of canopy from the decline in tree health and mortality will increase the urban heat island effect leading to even more temperature increases and exacerbate temperature induced stress on urban trees. The increase in storm severity including flooding, high winds, and icing, on top of other stressors, will leave our trees vulnerable.
Long-term effects of climate change include changes in tree species range and forest composition, and in the distribution of tree pests that could have also impact species composition. Species habitat range is projected to increase for 47 species and decrease for 31 species in the northeast. This habitat change could have considerable economic impacts in Vermont if the sugar maple range decreases as predicted.
While there seems to be a lot of negative impacts of climate change on our urban forests, there are many positive effects that our urban trees have on the sources and effects of climate change. Urban trees can help to mitigate stormwater runoff and the urban heat island effect while mitigating energy use by shading decreasing need for cooling systems.
Over that last two years, the Vermont Urban & Community Forestry Program conducted public urban tree inventories in 26 towns. Data analysis indicates that these trees sequester 985.47 tons of carbon a year, that is equal to the emissions of 100,558 gallons of gasoline and to the emissions of 201 vehicles. This analysis only includes 16,000 publicly owned trees in 26 towns. Imagine if we expanded the analysis to the estimated 11 million urban trees in Vermont. Although it may not seem like much, it is a reminder that every urban tree is making a difference, no matter how small it may seem now.
Things are going to change for trees in the future, but we can be proactive. This will include planning for a shift in species and increases in threats from pests and storms. Many places are creating climate change adaptation plans, which include tree selection plans. Tree selection and management will be crucial in ensuring we have diverse, healthy, well adapted, and resilient urban forests. Although I have had a hard time accepting all of the changes eventually coming our way, I feel better when I know that there are things that we can still do about it.
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