Unfortunately, determining which oak trees are the best acorn producers on your property can be difficult. In fact, most managers skip this process and rely on tree size, form, and spacing to determine which trees will be harvested from a stand. This approach is legitimate if your only goal is to improve timber quality of oaks. It is the wrong approach for a serious deer manager interested in improving acorn production. Thinning oak stands, without first identifying the best acorn producers, can reduce acorn production as often as it increases it.
Currently, the only way to distinguish good acorn producers from poor producers is by monitoring acorn production of individual trees. The following describes a visual survey technique that I've found simple to conduct and effective at identifying good acorn producers.
An acorn survey technique
In this survey, you count the average number of acorns produced by each tree and rank acorn production as either Excellent, Good, Fair, or Poor (Table 1) . Trees ranked as Excellent or Good producers are marked as the best producers in the stand for the year of the survey. The survey is conducted once each year and should be conducted for three years prior to a timber harvest that thins the oak stand. A three-year survey is best because it enables you to identify between 85-100 percent of the best acorn producers in your stand. If you can't devote the time to a three-year survey, a one- or two-year survey is better than nothing. However, surveys conducted for less than three years can miss ¼ to ½ of the excellent producers in the stand. Remember, the best producers may not produce acorns every year, nor may they be the best producers every year they produce a crop.
Conducting the Survey
The best time to conduct the survey is between the second and last week in August; during this time, acorns are developed enough to been seen from the ground and acorn predators won't have eaten your entire crop. Surveys don't need to be conducted in consecutive years, but at least one survey should occur during an abundant crop year. An abundant crop year is one where nearly all trees produce at least some acorns and most trees have clusters of acorns distributed throughout their crowns. Ideally, the survey should be conducted by the same person(s) each year to allow for a consistent survey between years.
To conduct the survey, all you will need is Table 1 of this article, a good pair of binoculars, and a way to mark your trees. I've found that a bright-colored spray paint, found in any hardware store, is a cheap, convenient way for temporarily marking trees. The paint is quick to use, easy to see, it can't break like plastic flagging, and it won't damage your trees. Also, this paint usually fades from view within three years, so it will last long enough for your survey, but won't be permanent.
Start your survey at the first oak in the stand. Identify if it is a "White Oak" or "Red Oak." Next, look at the top ½ of the tree and use your binoculars to estimate the average number of acorns growing within 24" of each branch tip. Notice that acorns on "White Oaks" occur near the tips of the branches (Fig. 2) and that acorns from "Red Oaks" occur on last year's growth (Fig. 3).
Use Table 1 of this article to determine if acorn production of that tree is Excellent, Good, Fair or Poor. If you determine it is "Excellent" or "Good," mark the tree with the spray paint. If it is "Fair" or "Poor," the tree remains unmarked. Move on to the next tree and continue the survey. Once you get going, the process of counting acorns and marking trees will take about 45 to 60 seconds per tree.
How to mark your trees
When you mark an "Excellent" or "Good" tree I suggest using a dot of paint placed about chest-high on the tree. I mark each tree with a total of four dots, one dot on each "side" of the tree. This allows me to see marked trees regardless of the angle at which I approach them. I make the paint dots just large enough for me to see from a distance. To help you keep track of which trees you have surveyed in the stand, you can place a small dot of paint near ground level on "Fair" and "Poor" quality trees; any tree without marks at chest-height is a candidate for removal from the stand.
Conduct the survey the exact same way each year. Ranking acorn production of all oaks in the stand and marking "Excellent" and "Good" producers for that year. Use a different color paint for each year of the survey to keep track of which trees were consistent producers, and which year each tree produced a good acorn crop.
I've identified the best acorn producers - Now what?
In the next article, I'll explain what you can do to encourage the trees you've identified, to produce abundant acorn crops on a regular basis.
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