Spring coming too early?
Across much of Pennsylvania, it has been a different winter. It has been a winter of little snow and scarce cold weather. Some will recall it as a great winter; others might wonder what it means, especially to our woodlands.
As February came to a close, there are signs of spring. For sure spring garden flowers - crocus, daffodils, grape hyacinth - are pushing up. The careful observer will also note some tree buds swelling early. Red maple flower buds have been creating a red cast in forest canopies for a couple of weeks. Aspen flowers are expanding and will soon be opening. Flower buds on these and other trees have only one chance each spring. Unlike leaf buds, there are no "reserve flower buds" available to replace them.
Many Pennsylvania wildlife species depend on forest mast or "forest food." It is not easy to understand all the interactions that lead to good mast years. There are many questions. For example, how did last summer's weather affect flower bud sets? Will our woodland flowers come on too early this spring and be lost to a sudden cold snap? It is difficult to predict this spring's weather and what will happen to this year's forest mast crop. It is worrisome.
In normal winters, a combination of temperatures and increasing sunlight initiate the emergence of spring flowers. It is a somewhat delicate balance. This winter's warmer temperatures and brighter days are, apparently, accelerating flower bud expansion and we're seeing earlier emergence. Maybe too early - March can be a mishmash of weather.
Among our state's important mast producing trees are oaks - both the red and white oak groups. Consider first the red oaks. In 2009 and 2010, we had above average acorn set in the state's red oak woodlands; last year there were few acorns produced. Red oaks take two years to produce an acorn. Branches broken from red oak trees in the early snowfall in October 2011 suggest that acorn production in this oak group will be spotty in 2012 as there were few acorns set in spring 2011. And, if we lose this year's flowers there might be poor yields in 2013 as well.
White oak acorns mature in a single growing season. The flowers that will emerge this spring will produce acorns this fall. Wildlife generally prefers white oak acorns - they are somewhat less bitter. Will the winter's weather push white oak flowers to emerge early? If it does, and a late spring cold snap occurs, will we have another major mast group fail to produce fruit?
Of course, all of this is speculative. As they say, everyone talks about the weather, but nobody does anything about it. This will certainly be the case as this winter turns to spring. We'll have to wait and see how the weather and leaf and flower sets play out. Understanding what's going on in your forest now gives you an idea of the choices you may have later in tending your woods.
Woodlands are an intricate system. They offer many lessons to learn and are fascinating to observe. Give pause to consider woodlands' meaning and impact on our lives and the plant and animal communities we care about.
To learn more about tree flowers and mast production, visit http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm, Silvics of North American Trees published by the US Forest Service. This is a rather technical book, but fun to explore.
The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management. For a list of free publications, call 800-234-9473 (toll free), send an email to RNRext@psu.edu, or write to Forest Stewardship Program, Forest Resources Extension, The Pennsylvania State University, 416 Forest Resources Building, University Park, PA 16802. The Pennsylvania Bureau of Forestry and USDA Forest Service, in Partnership with Penn State's Forest Resource Extension, sponsor the Forest Stewardship Program in Pennsylvania.