There is much effort going into reforesting the Arboretum here at Carleton, and a couple different methods to achieve the goal of increased woodland. One (very obvious) approach is to simply plant more trees. Every year the incoming students plant many trees in the Arb. However, this is very labor intensive, what with the planting itself and all the work it takes to keep the trees alive and safe from deer and other animals that would otherwise eat the trees. The other method of reforestation in the Arb is simply to let areas naturally increase tree growth, with no human intervention. This method doesn’t necessitate any human labor, but it does require trees to “take the initiative” to spread to different areas in the Arb.
Of course, individual trees cannot actually move, but species can spread (branch out) over the course of generations. Like many common sayings, “the apple doesn’t fall far from the tree” is not entirely accurate. In many cases, trees manage to move great distances from one generation to the next. Different species have many different strategies for achieving this movement. Many trees, such as the Black Cherry Trees and Walnut Trees found in the Arboretum, use fruits or nuts to move. In these instances, birds or other animals eat or grab the fruits or nuts from the tree, or ground around the tree, and then move on (as animals tend to do). Eventually, the seeds or nuts are dropped far from where they started, and begin to grow there. Other species of trees rely on the wind for their movement. One common example of a tree found in the Arboretum that utilizes wind power is the Silver Maple, which has samaras (commonly called helicopters or whirlybirds) that catch the breeze as they fall and are whisked away, and later spin down to the ground in a far-off location. Other trees, like Trembling Aspens, have seeds in cotton-like puffballs attached to dangling catkins, which float away from their parent trees on gusts of wind, thereby enabling the species to spread.