In these early April days you have probably noticed every excursion in The Arb accompanied by lots of wind. April is the windiest month in Minnesota, with a daily average of 11.8 mph winds this year (www.startribune.com). At the forefront of these windy conditions is the volatility and gradient of the temperature. Air moves from a region of high pressure to one of low pressure, the difference due to unequal heating of the atmosphere. There is still very cold air in the poles and warm air around the equator which leaves Minnesota in a transition zone.
Walking on the paths in the Arb there is the lingering noise of the leafless trees rustling with the breeze. Wind is important for trees in forests, like the restored forest habitat in the Arb. Root systems tend to form more structural root mass when exposed to persistent prevailing winds from one direction. The tree’s adaptive growth in response to wind movement enhances the rigidity of the soil-root plate, helping to counteract the increasing vulnerability to windthrow as it grows taller (woodlandsteward.squarespace.com). Wind also increases the amount of pollen in the air and the distance tree seeds can be blown. These are of great ecological importance for perpetuation of the tree species in the Arb. Nearly all conifers, or cone bearing seed plants, rely on wind pollination, as do some hardwood trees including Oaks (Quercus sp.) and American Elms (Ulmus americana). Consistent wind is very important for the trees and plants in the Arb and is representative of this transition zone, not just weather-wise, but also as the winterized Arb starts to get ready for a green spring.
- Isabelle Connolly ’27, for the Cole Student Naturalists
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