THE POLLINATOR STUDY
Benefits of a Real Christmas Tree
One of the virtues of using a real farm-grown Christmas tree is the benefits to the environment. In western North Carolina, Fraser fir Christmas tree growers maintain living groundcovers around their trees. This has many benefits to tree production such as reducing erosion and lowering soil temperatures which allows for better root growth and nutrient up-take. But the environmental benefits are just as important.
For every Fraser fir Christmas tree that is cut, there is 25 square feet of green space for wildlife for all the years that tree is being grown. But some of the most important wildlife are the smallest — the insects and particularly pollinators and insect predators. Though important through the growing season, they are not active in the late fall when trees are being cut and are not found on the cut Christmas trees that are marketed.
Currently, a study is being conducted by the North Carolina Cooperative Extension in six Fraser fir farms to determine the impact of groundcovers on biodiversity, pollinators, and the natural enemies of insect pests. Personnel involved in the study include Jill Sidebottom, Area Extension Specialist for mountain conifer integrate pest management; Meghan Baker, Watauga County Agricultural Agent; Travis Birdsell, Ashe County Agricultural Agent; Brad Edwards, Area IPM Technician; Teresa Herman, Alleghany County Extension Agent, Jerry Moody, Avery County Extension Director; and Jeff Vance, Mitchell County Extension Director. Growers who are involved in the project include Bryan Davis, Wiley Gimlin, Ewing Harmon, Dan McKinney, Mike Shatley, and Jack Wiseman.
The following summarizes observations made from these fields through the summer and fall of 2012.
How the Pollinator Study is Being Conducted
Pollinators aren't important in the production of Christmas trees which are harvested before they reach reproductive maturity. Even then, Fraser fir is wind pollinated. But, pollinators are quite important to the environment and the production of food.
The groundcovers that Fraser fir growers maintain around their trees bring in many butterflies, bumblebees and honeybees. But pollinators aren't the only insects of importance. Insect predators (insects that eat other insects) and parasitoids (insects that complete part of their life cycle inside of their insect host) are important in controlling many Fraser fir pests. Providing a suitable habitat for these in the field helps growers to continue to reduce pesticide use.
To learn how pollinators and other important insects are utilizing Christmas tree fields, a study was started in July 2012. Click here for details about how the pollinator study is being conducted.
Fields of Flowers
Have you ever heard the expression, you can't see the forest for the trees? That might be true when you see a Christmas tree field. After all, what you see is row after row of trees that are sheared to look alike. It must be a monoculture. Nothing could be further from the truth.
What's important to the environment is what is growing around the trees and in field borders. The plants growing in groundcovers are being cataloged in the six Fraser fir farms as part of the pollinator study. So far, more than 75 different species of plants have been identified with 21 to 37 different species at each farm. From July through October of 2012, up to 13 different species of plants were found blooming in these fields at any given time. Many of these, like clover and goldenrod, are important sources of pollen and nectar. Others, such as milkweed, are also important habitat for pollinators that are on the decline such as Monarch butterflies.
Honeybees, Bumblebees, and Things that go Buzz
Honeybees, bumblebees, and other native pollinators are in decline in the US. When Christmas tree growers switched from killing all the groundcovers around their trees to maintaining a living groundcover, people started noticing these returning to tree fields. Through the summer and fall, honeybees, bumblebees, wasps and yellow jackets were all observed at the six study sites. Click here for more details of the occurrence of these pollinators in Christmas tree fields.
Some of the loveliest pollinators are butterflies. Many butterflies are commonly seen in Christmas tree fields. Others were not as common. Click here for details of the butterflies observed in Christmas tree fields during the pollinator study.
Many predators of Fraser fir pests such as lacewings, lady beetles, and hover flies also depend on pollen and nectar sources at some point during their life cycle. These predators are more commonly found in the spring, but many were observed during the summer and fall study period. Click here for details of the predators observed in the pollinator study.
How Growers Can Create Habitat for Pollinators
Christmas tree growers have the unique opportunity of creating habitat for pollinators as well as increase the natural predators that give them free pest control. Managing field roads and borders for flowering weeds appears to greatly increase biodiversity in the field. These bring in many beneficial predators as well.