Red Spruce Restoration
The study of how, or if, a species is genetically adapted to its environment is called genecology. USDA Forest Service plant physiologists Kurt Johnsen and John Butnor, with biological scientist Chris Maier, are conducting genecology and molecular genetic studies across the range of red spruce (Picea rubens) in a cooperative study with Steve Keller of the University of Vermont.
The range of red spruce stretches from eastern Canada to the Appalachian Mountains in North Carolina. The tree is commonly found in Maine, Vermont, and New York, with small, isolated populations in Ontario and Pennsylvania.
In the Southern Appalachians, it was a dominant species at higher elevations until the early 20th century when it was severely logged followed by numerous fires on the slash left behind. The high quality wood was used for building aircrafts during World War I. As a result, only five percent of its original magnitude occurs in isolated populations across the Southern Appalachian mountain.
The genecology study hopes to show whether red spruce is a generalist or a specialist. A generalist species can grow and survive across many environments. A specialist is a species that adapts to its particular environment – which means that planting adapted genotypes on a specific site is important.
If red spruce is a specialist, then planting trees derived from seed from the proper elevation is important in restoration efforts. This study will also test how well genotypes grow at higher elevations – information that may be important for adapting to warmer environments in the future.
The experiment includes study sites in Burlington, Vermont; Frostburg, Maryland; and Asheville, North Carolina. Seeds from 300 trees (open-pollinated families) across the range were collected by hand picking, a pole clip, or with a specialized slingshot to reach cones from the biggest trees. Seedlings were grown in Vermont and then planted in raised beds at each site using identical soils (shipped to each site).
Seedlings are being grown under 50 percent sunlight, because red spruce is adapted to shady conditions. The team is also measuring weather conditions at and around the experiment sites, including temperature, relative humidity, and light levels.
The scientists are measuring important adaptive traits – when a tree starts growing in the spring and stops growing in the fall, total height growth, as well as physiological traits. All seedlings will be harvested to quantify total biomass and how biomass is partitioned among leaves, stems, and for the Southern Appalachian study, roots.
A population study on red spruce in the Southern Appalachians is embedded within the larger cooperative study. The researchers collected seeds from 60 trees on Mount Mitchell, North Carolina and Clingmans Dome in the Great Smoky Mountains Nation Park, Tennessee. The seeds were collected along elevation gradients of 3300 to 6000 feet and from different parents in different geographic locations. Individual trees were measured and their GPS coordinates documented. Seedlings grown from these seeds were planted in the raised beds as described above.
In the Southern Appalachians, restoration efforts are underway to increase the presence of red spruce in the region. The Southern Appalachian Spruce Restoration Initiative (SASRI) is made up of government, universities, non-governmental organizations, and private citizens including SRS and the Pisgah National Forest in North Carolina. Johnsen is a member of the SASRI steering committee.
A key partner is the Southern Highlands Reserve; they grow seedlings for restoration efforts and lead the field planting. Currently seed for these restoration efforts are selected from random seed collections. However, it may be important to plant populations at sites with the proper seed collections to achieve good survival and growth rates.
The study results will help resource managers restore red spruce in the correct locations with the correct seed sources.
Read a preliminary study on red spruce in the Southern Appalachians.
For more information, email Kurt Johnsen at kurt.johnsen@usda.gov