Weather, climate change and the urban forest
The weather in Pittsburgh is never consistent. From Snowmageden to the Polar Vortex, our winters over the last six years have provided us with a new vocabulary. While summer weather hasn’t provided any new words, it has been just as unpredictable: from summers where we had to do virtually no watering of trees to summers where we couldn’t water all of them, we’ve had some drastically different climates. Weather is the state of the atmosphere at a specific place and time, and climate is the weather conditions in an area in general or over a long period.
The warm winter this year caused Director of Urban Forestry Matt Erb’s Crocus vernus “Pickwick” to flower March 8. While plenty of data and statisics are recorded daily to provide weather and climate analysis, quantifying the impact a changing climate has on plants is more difficult. For example, a seasoned gardener may notice that their Brussels sprouts didn’t grow one year due to poor weather or that their figs failed to ripen due to a shorter growing season. Some gardeners even keep journals noting flower or harvest times.
The practice of tracking seasonal natural phenomena is known as phenology. By making observations of the natural world around us (especially plants) and recording this data in a database, the impacts of climate change on plants can be studied.
Over the last four years. Matt has used his smart phone to take photos of the first Crocus flowers that bloom in his garden. In 2013, it was March 29. In 2014, March 31. In 2015, flowers bloomed April 1. This year, they bloomed three weeks early on March 8. While there is typically a week difference between blooms on the sunny side of his garden vs. the shady side, the difference this year was only two days. These flowering times also closely relate to the flowering of Matt’s Cornelian cherry dogwood (Cornus mas). Another observation of 2016 is that no honey bees have been present on these flowers, which may or may not be tied to the early blooms but certainly illustrates the potential impacts of climate change and the whole ecosystem.
While Matt’s casual backyard observations show this year is an anomaly, overall flowering times are becoming earlier. Longterm phenological data has shown many flowering plants that Henry David Thoreau observed at Walden Pond are flowering approximately three weeks earlier today than in Thoreau’s time. Phenology can also be used to record observations of insects, mammals and other living creatures, helping to paint a larger picture of how the timing of nature and climate is changing and what impact that may have on the larger ecosystem.
To learn more about phenology in your backyard, visit the USA National Phenology Network.