Arbor Day

Tim Iverson

(4/2017) April is colloquially known for its showers that bring May flowers. April also plays host to Arbor Day. Nationally it is observed as the last Friday of April. Arbor Day is the civic holiday reserved for planting and celebrating trees, and all they do for us. They do, in fact, do quite a bit for us ranging from the all important oxygen creation to lesser known climate regulation. Our forests are classified as primarily eastern, or temperate, deciduous forests. This forest type occurs in areas with mild winters and warm, humid summers. Our deciduous forests are also associated with their vividly ephemeral color displays in autumn.

In broad general terms trees are broken down into two main categories: coniferous and deciduous. Coniferous trees have needles and produce cones. Deciduous trees have broad leaves which die off in cooler temperatures in a process called abscission. Deciduous means "to die off," which is where the name comes from, and this usually coincides with winter and cooler temperatures. Abscission happens when leaves stop producing chlorophyll and green pigmentation. During the summer the broad leaves are essential for survival, but in the winter those leaves become a lethal liability. The leaves are a costly source of water loss and consumption, and during the winter months water is hard to come by. To prepare for the change in seasons deciduous trees will shed their leaves. Conifer needles have less surface area and retain water better than leaves because of a waxy coating and smaller pores, which can allow for year round photosynthesis.

Our deciduous forests are dominated by oaks, maples, tulip poplars, hickories, and beech trees. Formerly, the American Chestnut also called these forests home. Due to an unprecedented disease arriving in the early 20th century they’re all but extinct. Many of these trees, including the chestnut, were huge economic drivers throughout the region. Many of these forests were culled for agriculture, settlements, and industry. Both Catoctin Mountain Park and Cunningham Falls State Park were clear cut several times over the course of the early settlement of the region well into the early 1900’s to fuel an iron furnace operation in Thurmont, MD. Most of what currently occupies the Catoctin mountains is considered a second-growth forest. By and large, it is mostly less than 100 years old and was largely replanted through efforts of the Civilian Conservation Corp and Works Progress Administration in 1936 during the creation of the Catoctin Recreational Demonstration Area, the forerunner of both parks.

The forests of Catoctin are relatively new second-growth forests, as are much of eastern deciduous forests. The National Park Service estimates that there are 0.1% original old growth forests left on the east coast. When defining an old-growth forest it doesn’t necessarily mean the trees are old, though it often does. What is generally meant is more about characteristics displayed between the two. Second-growth forests usually contain trees that are less than 100 - 200 years old. The canopies and floors of old-growth forests are very complex. They exhibit several layers of understory growth, large old trees, standing dead trees called snags, canopy openings where dead trees have fallen, and lots of large dead wood on the floors that become habitats and food for other forest inhabitants. Second-growth forests exhibit little or none of these examples. Given enough time and proper management they will eventually become an old-growth forest.

Whether their old or second-growth forests they still provide the same services. Chiefly among them is the creation of oxygen. Just as we breathe in oxygen and exhale carbon, trees respirate too. Trees consume sunlight, water, and carbon dioxide (as well as other gases) to create sugars and oxygen in a process called photosynthesis. The oxygen they don’t consume during this process is exhaled back out into the world. By absorbing carbon dioxide (CO ) during photosynthesis trees store carbon both above and below ground.

As greenhouse gases accumulate in the atmosphere spurring climate change this can become a vital tool for us. The US Forest Service estimates that American forests store up to 750 million metric tons of CO each year, which is about 10% of the country’s carbon emissions. Carbon sequestration is a process where CO is removed from the atmosphere and stored for an extended period of time. The carbon is stored within the leaves, stems, roots, and body of a tree.

Because trees live for so long this banks the carbon potentially for hundreds of years. Additionally, products made from wood will still contain the carbon stored within extending the sequestration period until that product either decomposes or is burned. Scientists and policy makers are trying to figure out if we can harness this ability of trees to slow or reverse climate change. By not deforesting and reforesting areas we can potentially bank excess CO for some time. Utilizing carbon sequestration may not be the solution to the climate change problem, but it may buy us some time.

Forests can help forestall long-term climate change, but they also help to regulate local climates and weather patterns too. Globally, vegetative cover accounts for about 20-30% of total land. Within forests or areas of vegetative cover plants release water vapor and absorb and emit energy used to drive weather. Forests create their own micro-climates with leaves through transpiration, or evaporative cooling, which reduces the humidity and temperature in the surrounding area. As water vapor is evaporated back into the air it condenses into clouds and eventually rain.

Forests are important brokers in the water cycle. Many forests are apart of regional watersheds. A watershed is an area of land that absorbs snow and rain as it drains into rivers, streams, and lakes. Forests help keep these bodies of water clean by providing natural filtration systems through vegetative cover that promotes healthy soils and by preventing soil erosion. As water filters through a forest it may be consumed by trees and plants and later released through groundwater aquifers purifying it in the process.

The first American Arbor Day was proposed by a well-known Nebraskan journalist, J. Sterling Morton, in 1872. It was observed in Nebraska on April 10, 1872 and soon caught on across the country in metropolitan areas and other states. The Nebraska Board of Agriculture held a competition among organizations and localities offering prizes for those who planted the most trees. It’s estimated that about one million trees were planted that first American Arbor Day. It’s alleged that, while Morton was always a prominent environmental advocate, he initially proposed the idea because he was homesick for the trees of his native Michigan. The very first Arbor Day type holiday occurred as early as 1594 in a small Spanish town. American Arbor Day is nationally observed on the last Friday in April, but some states observe the holiday earlier or later depending upon local seasonal conditions best for planting. The idea is now truly global as tree planting festivals or holidays occur in at least 44 different countries.

Whether it is to beautify your community, to reduce energy costs by shading your homes, for their carbon sequestration ability, or any of the other positive effects trees contribute consider joining others around the nation by planting trees within your yards and communities.