Most of the forestland in our area is classified as the oak-hickory type, meaning that over 50% of the trees in the forest are some species of oak or hickory. Unfortunately, these species are not growing back into woodlands on many of the better sites. This could have a negative impact on certain wildlife species such as deer and turkey, which use the acorns and nuts (called “mast”) for food.
The oak-hickories are losing their grip on these sites primarily because of their medium shade tolerance. If an oak-hickory forest is never cut, they will gradually die and be replaced by younger trees that are able to grow under the shade of larger trees until the larger ones die out. Red maple and beech are two examples of very shade tolerant trees. Most of our trees start to decline in health around 100-150 years of age.
If you go to the other extreme and cut all of the trees in a harvest, then you open the stand up to full sunlight and trees that can’t take any shade (called shade intolerant) tend to grow better and will push out the oak-hickory. Shade intolerant species include yellow poplar, cedar, and pines of all sorts.
Now this doesn’t mean we are going to lose all of our oak-hickory forests. On dryer, less rich sites they seem to be able to hold their own despite how they are cut or treated. This would include south and west facing slopes and sites furthest away from water such as upper slopes and ridge tops. These areas produce slow tree growth, but oaks and hickories can regenerate there.
To keep oaks and hickories on the better sites (east and north facing slopes, and lower slopes, you need to create shade conditions that young seedlings and sapling prefer and can become established. You need medium sunlight, so a method called a sheltered cut has often been recommended for regenerating oak-hickory.
This method involves thinning out trees to open up the forest floor to some sunlight, not too much, not too little. It’s tricky, and involves a partial harvest where trees here and there are cut, and undesirable trees are felled or deadened. Around 10 years later, after the baby oak-hickories are around 4-6 feet tall, you cut the remaining big trees to give full sunlight to the babies.
It’s not easy, but oak-hickory forests are important for valuable timber and wildlife habitat, so we need to hand on to them if we can. For more information this or any forestry subject, contact your local state forestry office.