THE POLLINATOR STUDY:
Documenting Biodiversity
Details of Pollinator Study
Study objectives. The pollinator study was started in July 2012 by Dr. Jill R. Sidebottom with North Carolina State University, and will continue through June 2013. It is being funded in part through a grant from the North Carolina Christmas Tree Association.
The objectives of the study are to:
- Document the diversity of plants in groundcovers and field borders in Fraser fir Christmas tree fields and observe when these are flowering. Why is this important? It's the flowering plants that will bring in the pollinators and many of the predators.
- Observe when pollinators are actively foraging with particular interest in honeybees and bumblebees.
- Learn how natural predators are utilizing flowers in groundcovers.
Farm selection. Six farms were chosen in five Christmas tree producing counties — Alleghany, Ashe, Avery, Mitchell, and Watauga based on interest by the grower and the presence of mature groundcovers. A 1/2 acre block of trees was selected at each farm. Trees at the different farms ranged from 4 to 7 feet. Some blocks were fully stocked and others had had trees harvested from them.
The Christmas tree growers were told to keep their production practices the same. That way a range of field conditions could be followed. Groundcover management varied between the different farms. Though all relied on Roundup for their primary weed control, they varied as to when applications were made and at what rate. Growers were asked to keep track of their production practices to determine how different factors ended up affecting pollinators.
Photographs of the six field sites.
Groundcover biodiversity
Cataloging plants in groundcovers. The first step was to determine what plants were in each block. Plant identifications were made during an initial field visit by walking through the trees. However, each time the field was subsequently visited, any new plants that were observed were added to the list. This will continue through June 2013.
Documenting flowering. Every 2 to 3 weeks, the fields are visited and the plants that are flowering noted. In addition, an estimate is given for each plant species that is in flower as to the percentage of the area around the trees that is occupied by flowering individuals. This varied greatly through time. Some plants like white clover might make up 90% or more of the groundcover, but may only be actively flowering in a small portion of that or not flowering at all. Since some plants are tall and others short, the percentage sometimes exceeded 100%.
Observing pollinators
During each field visit, any pollinator that is observed is noted. In addition, pollinators in groundcovers were sampled with a sweep net with three samples collected on each observation date. In each of three samples, the net is swept through the groundcover 20 times while walking through the field or along field roads. Field borders were not included in these samples, though observations of pollinators, especially butterflies, were made here as well. The insects that were caught were emptied into a plastic bag which was frozen. After several days, any pollinators or predators important to Christmas tree pests were placed in alcohol for subsequent identification.
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