Thursday, April 11, 2019

The Rubrum Conundrum

Red maple stump sprouts (D. Jackson)

Over the vast many years that I have been interacting with our region’s forest practitioners and enthusiasts, I have observed that many of us harbor a profound and deep emotional relationship to particular tree species. These emotions run the gamut from effusive adoration to downright animosity. Some species are almost unanimous in the passions that they invoke; from the pleasing attributes of the stately white oak to the displeasing attributes of the noxious tree-of-heaven.

Some species are subtler, and our sentiments are derived by how we personally value specific qualities. Sweetgum is a good example. If you are a birder you may love to see this tree prevail on your land because it can be an important avian food source; providing seeds during fall and winter and attracting many species of Lepidoptera during the spring and summer. Sweetgum does not provide a quality food source for most game species, however, so a sweetgum dominated landscape may cause ire to landowners looking to attract game. Sweetgum’s brilliant autumn foliage is aesthetically pleasing for folks but at the same time its nefariously spiked seedpods are potential hazards to partially clad feet. We are complex organisms, so our emotions about a species may not be so fixed.  Black locust…anyone? How about American beech?

The tree that I seem to have the most complicated relationship with is the ubiquitous red maple (Acer rubrum). Red maple, by far, is the most abundant and widely distributed tree species in the entire eastern North America with a native range from Newfoundland to Florida. In our Chesapeake region, according to US Forest Service Forest Inventory Analysis (FIA) data, it is three times more abundant than the second most numerous species, loblolly pine. You probably don’t need FIA data to tell you that red maple grows almost everywhere. You can find it growing along dry ridges of our mountains all the way down to the poorly drained edges of our tidal wetlands and throughout our urban and suburban areas. It is a super generalist in its resources needs and therefore can be found in a variety of soil types, climates and elevations.

Red maple, despite its abundance today, is estimated to only have comprised 5% of the forest area in North America when Europeans first arrived and, although still widely distributed geographically at that time, they were mainly found in riparian areas, thusly earning the name swamp maple by early settlers. Red maple has increased exponentially on the landscape for a variety of reasons beyond its ability to tolerate a wide range of site conditions and climates. They can produce flowers in as little four years and are prolific seeders, often producing bumper crops every two years. These seeds, which are produced early in the spring, germinate soon after hitting the ground, and new seedlings take advantage of a longer growing season.

Red maple regeneration following a harvest (D. Jackson)
Both natural and anthropogenic disturbances over the years has created gaps in our forests and given red maple an opportunity to spread into new sites.1 Suppressing fire from the landscape too has aided the success of red maple establishment and proliferation, especially in our oak dominated forests. The thinner barked maples are highly susceptible to even low grade surface fire. Red maple’s proliferation throughout eastern forests is changing the ecology of our forests now and for the foreseeable future and displacing tree species that often have higher ecological and economic value.
Now, I am not trying put all this ecological discord on the red maple. We humans are, obviously, the cause of the drastic changes to our forests (development, high grading, invasive species, air pollution, deer, etc.). Therefore, I remain conflicted about my perceptions of red maple, the tree. To be honest, it is an awesome tree with attributes we all can value. Red maple is one of the first deciduous trees to break dormancy during winter. Think about the long winter we endured this year and what a joy it was to see the crimson buds of the red maple swelling early in a canopy of gray stupor. Red maple flowers are set soon after bud break and typically before it unfurls its leaves. Although these flowers are generally wind pollinated, they provide a vital early food source for various pollinators like bees.

Red maple trees are also tapped for maple syrup production. Sugar maple, obviously, is the gold standard in maple syrup production due to the higher sugar content in its sap, but red maple ultimately supplements the amount of syrup being produced each year. It may play a more prominent role in the industry as species shift and sugar maple becomes less abundant in our region.

Red maple is a viable wood product as well. Although its value pales in comparison to other hardwoods in our region like oaks and black cherry, red maple is readily harvested as sawtimber and pulpwood and used to make such things as furniture and cabinets. Maple, including red, is a tone wood and is often used by North American luthiers in the production of guitars, mandolins and other fine stringed instruments.

Due to its ability to thrive on various sites, red maple is valuable tree to incorporate in forest restoration and riparian buffer plantings. There will probably be several people reading this that are wondering why on earth would I want to plant more red maple when I just emphasized that their numbers are already exploding. I know – great question. Remember, I am conflicted here. We do incorporate a high diversity of trees in our plantings, especially oaks. Sometimes on certain sites we just need to get trees established quickly to reduce competition, and well, as mentioned earlier, red maple is really good at doing that. It is reassuring to see trees growing out of five-foot shelters after just one growing season.

This has been my arboreal confession concerning a common and valued tree in our Chesapeake forests. We all know trees provide us all benefits, but our woodlands are not static and will change whether we plan for it or not. The science of silviculture and its forestry practices were developed out of our need to sustain our woodlands, propagate them and enhance the myriad of values they provide. It is important (and fun) to learn about the attributes of trees. You may discover appreciations or connections you never realized you had.
Reprinted with permission.
By Craig Highfield, Director of Chesapeake Forests for the Alliance for the Chesapeake Bay

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