Twigs in the Garden

posted by Caitlin McDonough MacKenzie

Greetings from Maine!

From the summit of Cadillac Mountain, the view is a water-colored wash of new greens over a grey and brown landscape. Leaves are just beginning to unfurl from their buds on beech trees, maples, birches, and alders. In the understory, Canada mayflower leaves crowd under tangles of blueberry and huckleberry stems, while last year’s tough, dark green sheep’s laurel and cinquefoil leaves provide a contrast to this spring’s delicate new buds and intricately folded new leaves.

My fieldwork here in Acadia National Park records variations in spring phenology. For example, the lowbush blueberries at the base of Cadillac are leafing out about a week ahead of the lowbush blueberries on the summit. Last fall I worked with volunteers to establish three common gardens on Cadillac — at the base, middle, and summit of the mountain. This study explores the relative effects of environment and genetic differences among populations on the spring phenology of reciprocal transplants. The transplant gardens provide a kind of natural warming experiment: transplants from the summit will experience a milder climate in the mid- and low-elevation gardens, no heated cables or infrared lamps required. This spring, I have begun monitoring the lowbush blueberry, sheep’s laurel, and three-toothed cinquefoil in the gardens as they leaf out and flower. Will the genetics of source population determine leaf out date or will the microclimates at each garden drive spring phenology for these transplants? We’ll see…

Lowbush blueberry and Sheep's laurel twigs on April 28th — the day they were cut!

To compliment these transplants, we added a new version of the Primack lab’s signature twig-cutting experiments to the gardens. It was a hard winter up in Acadia, and we were worried that our new transplants might experience high rates of mortality. A twig-cutting experiment might bolster our chances of getting data from the gardens. So, in late April I cut twigs from low bush blueberry and sheep’s laurel plants growing adjacent (but not in!) to the gardens. Instead of reciprocal transplants, I created a reciprocal twig-exchange from the base, mid-elevation, and summit sites; at each garden, a set of popsicle molds filled with water and tagged twigs from the three elevations was established. These miniature twig-gardens are monitored alongside the transplant garden. As the twigs begin to leaf out, the same question remains: will the genetics of source population determine leaf out date or will the microclimates at each garden drive spring phenology for these twigs? We’ll see…

Lowbush blueberry twigs on May 26th — leafing out at the low elevation garden!