Like quite a few area residents, my family moved to “Greater Middleburg” from the city. We came from a world of human-designed lawns and landscaping. Little did we know how much we had to learn about living in the country!
Our new home included a narrow, wooded area filled with brambles, vines, young trees of various types, rotting hay bales, the remnants of an old fence line, and a line of 80-year-old maple trees interspersed with mature wild cherry trees which had grown up along the fence line. The gorgeous, mature maples had sweeping branches and trunks far too wide to wrap our arms around. We learned that the cherries produced lovely flowers and edible fruit during our first spring on the property. We loved the maples and cherries and dreamed of reading books, walking, and riding our horses under the spreading branches of these stately trees. There was just one problem – that mess of brambles, vines, hay bales, and wire surrounding the trees.
We looked enviously at our neighbor’s park-like yard that featured mature, spreading trees surrounded by neatly trimmed lawn. My husband hired a crew of workers, pointed toward our neighbor’s property, and asked the crew to “make our yard look like theirs.” The crew arrived with chain saws and a small skid-steer and proceeded to remove everything except the mature trees. We planted grass around the trees and looked at our newly cleaned-up and landscaped tree line with great satisfaction. Little did we know that our clean-up would damage the very trees we loved. The first tree in the tree line fell within two years of the clean-up. Within ten years, a number of our trees, along with many of the trees we admired in our neighbor’s yard, broke off and had to be cut down, were uprooted in storms or died of disease.
As we drove around the area, we noted that we were not the only ones losing mature trees. As more and more people turned woodlots and old fence lines into lawns, pastures, fields, and developments, more and more stately oaks, locusts, and other mature trees succumbed to storms and disease. It seemed that the larger and more beautiful the tree, the faster it broke or fell.
Despite noticing this trend, we could not explain it. Nor did we know what to do differently to preserve the mature trees we loved. After one of last year’s storms broke yet another maple in our tree line, our landscaper suggested we talk with Horticulturalist and Certified Arborist Philip Klene of Shade Tree Farm about a replacement. The tree was going to need to fit with our now almost 100-year-old maples, so it needed size. The new tree could not be a two-inch-thick stack of a tree from a local garden center.
Shade Tree Farm provides landscaping companies and individuals with trees and shrubs grown outdoors in fields that back up to the Blue Ridge Mountains near Upperville. As Horticulturalist Erica Klene showed us, the farm’s trees and shrubs are much larger, more substantial, and more accustomed to our climate than most garden centers’ small, greenhouse-grown trees.
After studying our tree line, Philip explained that four bad things often happen when a tree is surrounded by grass and separated from other trees. First, grass and trees are not actually compatible. Each wants to reproduce more of its kind, so trees produce biochemicals that are toxic to grass, and grass produces biochemicals that are toxic to trees. When a mature tree is surrounded by grass, the result is a stressed tree (and vice versa, which is why it is often difficult to get grass to grow well under trees). Second, especially with zero-turn lawnmowers, the grass gets mowed by a relatively heavy lawnmower which compacts the soil under the tree, making it even harder for the feeder roots to gather the water and nutrients the tree needs. While trees have taproots that run deep into the ground, most of the trees’ water and nutrition come from feeder roots that grow in the top layer of soil – the same place the grass grows. Third, in order to mow the lawn and keep the yard looking neat, our landscaping team and we remove sticks, leaves, petals, and seeds/nuts/fruit dropped by the trees. In natural settings, all of these items fall to the ground and decay in the area around the trees, nourishing the trees. Removing these items robs the trees of the nourishment they need. Fourth, the water around the tree runs off a mowed grass lawn faster than it does when a tree is surrounded by understory trees, shrubs, other leafy plants, or a natural forest floor. The combination of toxic biochemicals in the grass, root compaction from mowing, removing natural deadfall that decays to nourish the trees, and more rapid water run-off produces thirsty, undernourished, stressed trees that are more likely to succumb to disease or the strong winds of a storm.
We landscaped each mature tree into an island to add insult to injury when we had the tree line cleared. Each mature tree was separated from other trees and surrounded by grass. We disrupted the mycorrhizal fungi web that serviced each tree in the process. As Philip explained, the mycorrhizal fungi web serves as each tree’s cellphone and Internet provider, electric utility, and water and sewer system. Trees and grass both tap into mycorrhizal fungi webs, but the web that trees tap into is different from the web grasses tap into. Landscaping our mature trees into islands was like confining senior citizens in nursing homes to their rooms during the pandemic. Just as the senior citizens suffered from loneliness and sometimes hopelessness, the trees suffered from being cut off from the exchange of water and nutrients with other trees. When you add the stress of a local climate that is now significantly warmer than when these large, mature trees grew up, it is no wonder we and others in the area keep losing our most mature and stately trees.
The good news is that there are ways to preserve and protect our mature trees. According to the Kleines, the most important action is to reduce the stress on the mature trees. The goal is to give the trees back the resilience to stand up to changing weather, storms, and disease. The first step in reducing stress is to remove the grass around mature trees. Ideally, any grass surrounding each tree would begin just outside the tree’s dripline. The drip line is the outermost reach of the tree’s branches. After a rain, trees move rainwater to the ends of their branches, where it drops to the ground. Opening the dripline allows water to better seep into the ground, reach the tree’s feeder roots and nourish the tree after a rain. For large trees with sweeping branches like our mature maples, the dripline extends many feet from the base of the tree in all directions. We are still trying to figure out how to remove enough grass to open the dripline for our trees.
Ideally, the area where the grass has been removed would be allowed to collect fallen leaves or needles, fallen branches, seeds, nuts, spent flowers, and the like produced by the tree. This deadfall would then be allowed to decay to nourish the tree. As an alternative, the grass-less area can be covered with leaf mulch in the spring and fall. Mycorrhizal fungi will grow in the decomposing deadfall or mulch to service the tree.
Providing company for mature trees using other trees or related plants also helps make the tree more resilient. If the tree is native, younger native trees of the same species and native understory trees, shrubs, and perennials help mimic nature and provide resilience. The appropriate “friends” for the tree depend on the tree’s size, location, and native habitat. Had we cleared the tree line properly, we would have left the non-invasive understory trees and as many other native plants as possible rather than taking the area to bare earth. These understory trees and plants were likely already linked to the large, mature trees through the existing mycorrhizal fungi web. Leaving as much of the existing web in place as possible would have reduced the stress on the trees both during the clearing process and for years afterward. Horticulturalists like the Kleines and landscape designers specializing in natives like John Magee of Magee Design in Middleburg can help create a plan to improve the resilience of existing trees or safely landscape existing treed areas in ways that highlight the mature, specimen trees without harming them.
Like the almost century-old maples in our yard, many large, mature trees took decades, and sometimes centuries, to grow. They are irreplaceable. As my family proved, it is easy to inadvertently use landscaping techniques that stress these gorgeous, majestic, and well-loved trees. Thankfully, it is also possible to landscape without harming the trees and improve the situation for trees that have already been landscaped into islands surrounded by grass or lawn.
We worked with John Magee to create mulched beds around our mature maples and cherry trees and to introduce native plants into the beds. Shade Tree farm provided younger, replacement trees for the trees we lost over the years to help keep all of the trees connected. We are also introducing understory trees at various places to help create a rich mycorrhizal network to nourish our mature trees. Hopefully, our new knowledge and care will allow us to help the mature trees we love become more resilient and continue to keep the birds, squirrels, fireflies, and us happy for years to come.