Issue 9 - Science You Can Use!
If You're Ready to Restore Oaks to Your Forest, Check Out OAKUS
Wouldn't it be great to know how many trees you need to plant to get just one successful tree for your site conditions? Would planting larger diameter seedlings pay off in the end? How much of a difference will controlling competing vegetation really make? If you're ready to underplant oaks but still have questions, the Oak Understory Success Program (OAKUS), can help provide answers.
A collaborative effort of the Southern and Northern Research Stations, OAKUS allows you to evaluate alternative oak planting and restoration strategies by predicting the future success of various treatment options based on your forest site quality (site index) and other environmental variables. The probability of seedling success is based on the results of an 11-year study conducted by Martin Spetich, research forester with the SRS upland hardwoods unit. Spetich found that the probability of success is most impacted by the percent of shelterwood stocking (canopy cover), the control of competing woody vegetation, and the initial diameter of the seedlings.
The likely success of a planted tree, or dominance probability, was determined using a logistic model that integrated the combined effects of the environmental and management variables. Perhaps more significant to resource managers, Spetich found that the reciprocal of this value could be used to determine the number of trees to plant to achieve the desired future stocking level (the number of successful planted oaks per acre).
To take maximum advantage of your investment and meet your management goals, take a look at OAKUS before you underplant. A CD containing the OAKUS program, instructions and examples, as well as a summary of the research is available. To order copies, contact Pearley Simmons at 828-257- 4830 or firstname.lastname@example.org. -LM
How to Start Regenerating Oak 10 Acres at a Time
Callie Schweitzer encourages private landowners to come out to the demonstrations set up on State land in Jackson County, AL. If you like what you see on the 75-percent retention plot where researchers are experimenting with overstory treatments, here’s what you can do:
- Take everything out of the midstory except the oaks.
- Don’t create any gaps in the canopy.
- To kill midstory trees, make one hack in the stem for every 3 inches of diameter and spray one small squirt of Roundup™ in the cut.
- Remember, don’t kill your midstory oaks!
- Do this little by little all summer long; by the end of the summer, you can have 10 acres treated and give your oak seedlings a chance to make it into the midstory.
New Method to Predict Acorn Crop Sizes
The annual production of acorns in a forest ecosystem directly impacts the regeneration of oak species—as well as the reproduction, survival, and body condition of many wildlife species. Black bears, wild turkeys, ruffed grouse, white-tailed deer, and several small mammals all depend on acorns for food. It’s no wonder that State and Federal resource agencies make such a tremendous effort each year to estimate the size of acorn crops, or hard mast production.
Estimates are made using one of several hard mast index methods (HMI) that have been developed by researchers to rate acorn crops on a relative scale. HMIs effectively track patterns of acorn production because they allow for comparisons of crop sizes among years and areas, given the same method is used. Because different agencies use different HMIs, it’s difficult to compare acorn crop production among States and regions.
HMIs can also be labor intensive and time consuming. There has long been a need to simplify HMI methods and coordinate them regionally, in this case, among the Eastern States.
A Faster, Simpler Method
SRS research ecologist Cathryn Greenberg and Gordon Warburton, wildlife biologist with the North Carolina Wildlife Resources Commission, have developed a faster, simpler method to estimate acorn crop sizes based on their finding that the proportion of trees bearing acorns alone is a successful predictor of HMIs. Their method, based on 21 years of data from visual acorn surveys, produced similar index values to those generated using the Whitehead HMI method. This similarity allows for continuity between the historic HMI data collected by States and the new Greenberg and Warburton method. If adopted by State and Federal agencies as a standard stand alone index of acorn production, the new method would allow acorn data to be compared and tracked across the Eastern United States. —LM
For more information:
Cathryn Greenberg at 828–667–5261, x118 or email@example.com.