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How does this triple-digit heat affect our tree canopy?

As the triple-digit temperatures continue, we all look for ways to stay cool. Have you ever wondered how this extreme heat impacts the trees in our urban forest?

Heat can have both direct and indirect impacts on trees, and its effects can vary depending on the species, climate, and intensity of the heat. Some ways in which heat can impact trees are as follows:

  • High temperatures can increase the rate of evaporation from tree leaves, leading to excessive water loss and drying out of foliage. This can cause leaf wilting, scorching, and ultimately, leaf drop. Severe or prolonged heat can lead to desiccation stress, especially if the tree is not receiving sufficient water through its roots.
  • Heat stress can affect the process of photosynthesis in trees. Excessive heat can damage the chlorophyll pigments responsible for capturing sunlight and converting it into energy. This can result in reduced photosynthetic activity, decreased growth, and diminished overall health.
  • Heat affects not only the aboveground parts of trees but also their root systems. High temperatures can increase soil temperature, leading to heat stress on roots. When roots are subjected to extreme heat, they may become damaged or die off. This can disrupt the tree’s ability to absorb water and nutrients, resulting in further stress and potential decline.
  • Heat-stressed trees may become more vulnerable to insect pests and diseases. Weakened trees have reduced defenses and are less capable of fighting off attacks. Insects like bark beetles, which can infest and damage trees, often thrive in warm and dry conditions.
  • Heat stress can impact a tree’s growth and reproduction. It may cause stunted or distorted growth, reduced flower production, and lower seed or fruit yields. Extreme heat can also affect the timing of phenological events, such as leaf emergence, flowering, and fruit ripening.
  • Prolonged exposure to high temperatures and heat stress can have cumulative effects on trees over time. Chronic heat stress can weaken trees, making them more susceptible to other environmental stresses like drought, storms, or diseases. In some cases, repeated heat stress events can lead to tree mortality.

To learn more please check out this article “Heat Stress in Urban Trees” from the PennState Extension at the College of Agricultural Sciences at Pennsylvania State University to learn more. With the continued deforestation throughout Bexar County due to development, extreme weather events, and drought, expanding and preserving our tree canopy is more important now than ever before. To learn how to help your trees survive the predicted hotter and drier summer than normal, please check out this video from the Texas Forest Service: Tree Watering Tips – How to Properly Water your Trees. To learn more about any water restrictions in your area, please visit the SAWS Drought Restriction & Watering Rules or the Bexar County Water Control and Improvement District websites for more information. We can all do our part to be a responsible part of the solution. Thank you for all you do!

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