Linn County Master Gardener
A favorite topic of conversation lately has been the prolonged Winter. How long will it continue to snow? When is Spring coming? When will the trees and shrubs, which usually start to flower in February, bloom?
Changes in ocean and wind currents have created uncomfortable weather patterns – for us, for plants, insects, birds and other animals. Some of us remember heavy snow in March, a blizzard in June, and other memorable weather anomalies in past decades, but not temperatures so low for so long.
Temperatures are key to signs of Spring. The science of phenology studies periodic events in biological lifecycles and how they are influenced by seasonal and annual changes in climate. First and last leaves and flowers, first migratory appearance of birds, development cycles of insects, egg-laying of chickens and frogs, and other phenomena or recurring natural happenings have been observed for centuries.
The data is collected worldwide but varies by microclimates. With unpredictable temperatures it is a guessing game for us to predict when the events will occur. The plants, insects and animals are pre-programmed for response to temperatures, but it seems they are as confused as the rest of us.
Some pollinating insects may appear before or after the fruit trees blossom, and some birds may arrive before or after the insects are available as a food source. Some plants, insects and birds will travel to places better suited for their cycles as they adapt and throw the whole system out of sync.
If we search https://extension.oregonstate.edu/catalog for “phenology” we get publication EM9305 Vegetable Degree-Day Models, An Introduction for Farmers and Gardeners. Researchers are exploring the relationship between temperatures and plant development in crops. By tracking and calculating daily and accumulated temperature minimums and maximums and observing plant development during a growing season.
The current formula for “Degree Days” is ((Tmin+Tmax)/2)-Tbase=degree days. The Tbase reflects a crop’s lower temperature threshold. Plants shut down when temperatures are too low or too high for growth, important information as winters get colder and summers get hotter in our area.
Calculated models are published for broccoli, cucumbers, snap beans, sweet corn, sweet peppers, tomatoes, and summer annual weeds. The models can be used to schedule planting and harvest more accurately than seed catalogs and packages because they account for local real weather conditions. Little research is readily available on phenological calculations for ornamental trees and shrubs.
Where can we explore more information about phenology? Of course, there are many videos on YouTube, some more entertaining than others.
USA National Phenology Network (usanpn.org) recognizes that insect emergence is timed with leaf appearance on host plants, and birds nest so eggs hatch when insects are available for feeding. They are gathering citizen observations to track patterns and changes.
Nature’s Network is a project of USA NPN, with child educational activities and reporting charts to share observations.
Project Budburst at http://neoninc,org/budburst was created to share observations of plant phenophases.
North American Bird Phenology Program at USGS Patuxent Wildlife Research Center (PWRC) has a citizen science program to digitize bird phenology records. It can be reached at www.usgs.gov/eesc.
