Director's Note
Welcome to our new seasonal newsletter! The Minnesota Phenology Network and the Backyard Phenology project have teamed up to provide a forum to share all things phenological. Each quarter starting on the winter solstice 2017 we’ll bring subscribers a mix of essays, stories, research updates, upcoming events, and resources. We’ll also provide a list of phenophases (events in plant and animal life cycles) to watch out for during the quarter. We are excited to start this journey will all of you and invite you to contribute to future editions.
Although we call this newsletter “First Sightings” I want to start with a story about last sightings. Over the last few months, I’ve been getting a lot of questions about this year’s fall colors. The most common is “Why didn’t my leaves turn color, they are still green and frozen on the branches?" Leaf colors change as a tree goes into dormancy in preparation for winter. It involves the breakdown of nutrient-rich compounds in the leaf and their movement into the stem and roots for storage over winter. How do plants know when to do this? They use three signals: temperature, length of daylight and soil moisture.
So what happened this year? Like in past years, we had warm weather late into fall. In addition, we had an very wet October. Then, in late October (on Halloween in the Twin Cities), temperatures dropped below freezing overnight and we had below freezing nighttime temperatures for almost two weeks. Thus, warm and wet October weather kept leaves healthy and functional late in the season and then when it got cold it stayed cold long enough to kill the leaves before they went through their normal dormancy process. In short, they got caught with their leaves on! In the long run, this shouldn’t hurt the trees unless it starts happening every year.
Today is the shortest day the year, the start of astronomical winter. Tomorrow, the sun will begin it’s return. Though days will slowly lengthen, we have several months where many of the plants and animals will lay in dormancy, waiting for the cues to tell them that spring has arrived. At the same time, some, like the great horned owl, will begin their life cycles. Keep you senses open and enjoy winter phenology as we await the overwhelming sounds, scents and first sightings of spring.
Rebecca Montgomery
Associate Professor of Forest Resources
Founder of the Minnesota Phenology Network
mnphenology@gmail.com
|
