Planting seedlings: Part 2
Previously, I covered the opportunities and limitations imposed by soils in regards to planting tree seedlings. Here, I will cover tree species choice within the context of browse by white-tailed deer, planting methods, and protecting seedlings.
Many forests lack natural levels of complexity, hampering their ability to adapt to stressors, provide for biodiversity, and meet some ownership goals. Past management activities, invasive plants, and deer herbivory are major reasons forests are not complex. By eating tree seedlings, for instance, deer fundamentally shape a forest by determining which tree species make it to the canopy and successfully reproduce. In doing so, deer alter the composition (species mix) and structure (arrangement of vegetation) of forests. Forest restoration efforts can therefore focus on species that should be in a forest, but are not.
Very few species of native trees are free from deer browse. Eastern white pine, red pine, jack pine, white and black spruce, balsam fir, ironwood, American beech, and black and white ash usually do fine without protection. Key word: usually. In most instances, all other tree species are browsed readily: eastern hemlock, northern white-cedar, all birches, all oaks, all maples, all cherries, etc.
How to plant?
Trees prioritize their growth. As seedlings, energy is first spent in root establishment for the uptake and transport of water and nutrients, storage of energy, and stability from wind. Next, trees exhibit phototropism; they grow toward the light to facilitate photosynthesis. Finally, trees put on diameter growth. It may take a decade or more until a young tree (sapling) really starts to grow in diameter.
Because of these characteristics one can manipulate patterns of tree growth by seedling planting density. Conifer plantations are planted tightly (7’x7′ or less) so that developing saplings/trees grow tall in an attempt to reach sunlight coming only from above. Wider seedling spacing (10′ x 10′ or more) allow saplings/trees to obtain sunlight from above and the sides, thereby producing a shorter, “bushy” tree. These types of trees may function better for windbreaks or visual screens.
Most plantings can be done by hand using a planting bar. No digging is done. Instead, the soil is pushed aside at a depth of 8″ or so, the seedling placed into the ground so all roots are vertical and not “J-rooted”, and the hole closed. Make sure roots have room to grow. Wet weather is good planting weather.
While many landowners like seedlings that come encased in a soil medium (plugs), these can be problematic: they are costly, the seedlings often have roots that struggle spreading, soil diseases can be moved around, and studies have been shown deer can sense the increased nutrient loads and browse them more readily. Conversely, while bare root seedlings may be intimidating, their long roots can be trimmed to 8″ for easier planting if need be.
How to protect?
In forest openings created by timber harvests, the best planting areas are amongst the downed woody debris. While also important for biodiversity and soil development, woody debris can form a barrier to deer. Conversely, for the serious planter, one could institute the fencing of an entire forest stand with 8′ fencing. After 5-10 years, the fencing is pulled and placed elsewhere. This practice is relatively common in Pennsylvania, for instance, and protects natural regeneration. Perhaps in future years this may be a more common activity in northeastern Lower Michigan and an activity for which agency cost-share provides assistance?
Until then, tree tubes and fencing of individually planted stems will be required. Tree tubes can protect a seedling until it becomes an 8′ sapling and then free from deer browse. Tree tubes can be very effective for most single stemmed, deciduous species, especially when planted in an area without direct sunlight. In areas exposed to full sunlight, tree tubes can cause seedlings to wilt. Fencing, along with bark guards to protect the main stem from rodents, are often used in combination for fruit trees.
For more site-specific advice, see professionals with your Conservation District, the Natural Resources Conservation Service, or a consulting forester.
Greg Corace is the forest and wildlife ecologist for the Alpena-Montmorency Conservation District. For more information, including assistance with forest planning and management, email Greg: firstname.lastname@example.org.