Melissa Stefun
Leaf Color and Urban Heat Islands
We are all most likely familiar with the phytochemicals Carotenes and Anthocyanins that color the red leaves in fall. Warm sunny days, with nighttime temperatures below 45 degrees Fahrenheit but above freezing, raise the level of red coloration. The timing of the color change depends on multiple factors, weather, latitude, elevation, and the local microclimate. In discussion, we have been talking about anthropogenic effects on the environment and specifically the urban heat island effect. I think that the urban heat island effect creates it's own microclimate, causing leaves to change color later in urban areas than in forest dominated. A group of researchers studying flowering rates of trees in urban settings found, that when compared to their forest counterparts, urban trees flowered significantly earlier in spring. I would extrapolate that it may be possible that trees take longer to drop their leaves due to urban warming as well. Thankfully, this probably does not alter their role in depositing nutrients. Leaves contain calcium and potassium, which the trees’ roots took up from the soil. Decaying leaves recycle the nutrients back into the top layers of the soil. The humus produced by the decaying leaves is also important for conserving water in the forest soil.
1. Lu, P., Yu, Q., Liu, J., & Lee, X. (2006). Advance of tree-flowering dates in response to urban climate change. Agricultural and Forest Meteorology, 138(1), 120-131.
2. University of Maine Extension Bulletin #7078
Leaf Color and Urban Heat Islands
We are all most likely familiar with the phytochemicals Carotenes and Anthocyanins that color the red leaves in fall. Warm sunny days, with nighttime temperatures below 45 degrees Fahrenheit but above freezing, raise the level of red coloration. The timing of the color change depends on multiple factors, weather, latitude, elevation, and the local microclimate. In discussion, we have been talking about anthropogenic effects on the environment and specifically the urban heat island effect. I think that the urban heat island effect creates it's own microclimate, causing leaves to change color later in urban areas than in forest dominated. A group of researchers studying flowering rates of trees in urban settings found, that when compared to their forest counterparts, urban trees flowered significantly earlier in spring. I would extrapolate that it may be possible that trees take longer to drop their leaves due to urban warming as well. Thankfully, this probably does not alter their role in depositing nutrients. Leaves contain calcium and potassium, which the trees’ roots took up from the soil. Decaying leaves recycle the nutrients back into the top layers of the soil. The humus produced by the decaying leaves is also important for conserving water in the forest soil.
1. Lu, P., Yu, Q., Liu, J., & Lee, X. (2006). Advance of tree-flowering dates in response to urban climate change. Agricultural and Forest Meteorology, 138(1), 120-131.
2. University of Maine Extension Bulletin #7078