Often I notice folks asking which type of hard/soft mast trees (e.g., oaks or pears) will produce mast (acorns) in the fewest number of years. While many factors can/will influence how soon trees begin to fruit and the quantity of fruit produced; in general the larger the tree the sooner it may produce greater amounts of mast. And what is above ground is somewhat dependent on what's underground (the root mass and structure), In an earlier post I shared info from a MN organization discussing how to prepare trees for the winter.
They said ....
"Roots do not become dormant in the winter as quickly as stems, branches and buds, and roots are less hardy than stems. Roots of most trees and shrubs that grow in Minnesota are killed at temperatures at or below 0 to +10°F. These plants survive in Minnesota because soil temperatures normally are much higher than air temperatures and because
soil cools down much more slowly than air temperature.
Many factors influence soil temperature. Moist soil holds more heat than dry soil, so frost penetration will be deeper and soil temperatures colder for sandy or dry (drought) soils. Snow cover and
mulch act as insulators and keep soil temperatures higher. With newly planted trees, cracks in the planting hole backfill will allow cold air to penetrate into the root zone, reducing fall root growth or killing newly formed roots.
To encourage fall root growth and to reduce root injury, mulch new trees and shrubs with 6 to 8 inches of wood chips or straw. If the fall has been dry, water heavily before the ground freezes to reduce frost penetration. Check new plantings for cracks in the soil and fill them with soil." (
all emphasis added)
I suspect that when the soil temperature remains above 40-degrees tree roots will continue to grow. Much of the Midwest will see 40-50 degree temperatures by this weekend.
If the ground above the root zone of your trees had been covered/insulated by 8 inches of quality mulch (straw/wood chips) the soil should be warm enough for growth in spite of the fact that some pretty cold air has been experienced over the past 7-10 days. If you are concerned about rodent damage (mice,voles,etc), place landscaping fabric covered with pea gravel as many have suggested.....THEN mulch with straw bricks (a bale of straw left out in the weather for a year or 2 can be sliced off in sections as bricks .. see attached photo / straw has matted and could be replenished) or wood mulch. This technique will require a little more effort at the time of initial planting; however, the improved growth potential should occur for several years after planting. Add timely watering and adequate fertilizer, and you will boost/accelerate the growth rate of your mast trees. Sorry for the long post.

A better photo ...
