By Drs. Robert & Sonia Vogl
President and Vice President,
Illinois Renewable Energy Association
It’s spring – time to start thinking seriously about gardening. Casual thinking began the week after Christmas with the arrival of colorful, tempting garden catalogs. Cold hardy vegetables will be planted during March; delicate ones in April and May.
Last week, dinner guests perked up our meal with a salad of mixed greens they had just picked. They make good use of their hoop house growing and enjoying fresh vegetables throughout the year. The simple plastic covered structure functions as an unheated greenhouse.
We’ve eaten fresh greens from our hoop house in past winters, but this year, our schedule was interrupted by a high wind that tore the plastic cover off in pieces. After replacing it, weeds were removed, leaving a clean, bare spot to seed. Next week, we’ll plant fresh greens and still enjoy them earlier than from the outdoor garden.
The meal was a fine finish to a busy week. With a small crew, we helped burn most of the prairie at Sand Ridge, owned by the Prairie Preservation Society of Ogle County. Sites, generally burned every other year, begin growing soon after the fire, which is done to enrich the soil and retard the growth of invasive woody plants. Burning every other year reduces the amount of carbon released to the atmosphere. Even restoration leaves a carbon footprint.
The week before, we burned our own prairie plot and are burning parts of our woodland. Species diversity has flourished at Sand Ridge and our property. We usually burn the woodland first to avoid damaging early spring flora, but our schedule has been thrown off by early blooming dates. Climate change has speeded up the onset of spring, which for years remained fairly stable. We maintained records for a while, but lost track of them. One memorable blooming date is that of violets. When we were young, they could be expected by Mother’s Day; now they appear nearly a month earlier. But not all plants are equally affected. Bloodroot came into bloom this past week; dutchman’s breeches are about to. According to Swink & Wilhelm’s 1994 edition of Plants of the Chicago Region, both are right on schedule.
A friend who is a restoration director for a forest preserve observed that first blooms are moving earlier in the year. Although they keep no actual records, the general consensus of land managers is that they think phenomena are moving up by a week or two.
Aldo Leopold collected data in Sauk County, Wisconsin, between 1936 and 1947. His daughter, Nina Leopold Bradley, collected data from the same county between 1976 and 1998, both studies spanning a total of 61 years. “The record includes 74 phenophases, focusing especially on arrival dates for migratory birds and dates of first bloom of spring flowers.” Biological data were correlated with the date of ice melt in Lake Mendota. The mean change was 0.12 day per year earlier. Significant changes occurred for forest phlox and baptisia as well as for eastern phoebe and rose breasted grosbeak. Some changes were not significant.
We are considering maintaining phenological data once again. Others may also want to do it, as changing biological timing can be an indicator of climate change.