Could massive elms ever come back?

American Elm on Old South Street, Northampton, MA (October 2019). Photo: Msact, CC BY-SA 4.0via Wikimedia Commons

For over a thousand years in eastern North America, anyone who wanted to build a house or replace a roof, or maybe just needed a few storage bins, a canoe and a snow shovel , knew where to shop. In what is now southeastern Canada and the northeastern United States, the American elm (American ulmus) was a veritable Home Depot for many First Nations peoples.

Although elm trees are still present in our forests, Dutch elm disease, which has the appropriate acronym “DED”, is now killing them before they reach maturity. This fungal pathogen from Asia appeared in Western Europe shortly after World War I and by 1930 had migrated to the United States. It took a few years to discover Canada and arrive there in 1946. The spores of the disease are spread by two bark beetles, one native and the other introduced.

As the DED fungus spreads, it clogs the xylem tubes that bring water and nutrients to the leaves. Where elm trees grow crowded, as was the case in many cities and towns until the 1970s, DED also spreads by root grafting. This is how entire streets lined with elms have become bare in a few years. A few trees show some degree of natural resistance, but all native elms eventually succumb.

Before the arrival of the DED, these fast-growing trees reached their greatest proportions in the rich floodplains of eastern North America, where they reached 100 feet tall, their trunks are said to be over nine feet in diameter. . Elm trees tend to lose their lower branches early in life and usually have upright, vase-like forms.

This stretch of knotless bark on the lower trunks of tall elms was ideal for the roofs and walls of longhouses at the time. Prodigious leaves of elm bark were peeled in spring and early summer, then anchored flat to bake in the sun. When dry, a sheet of elm bark is equivalent to plywood.

Covering a longhouse was an impressive feat, as some of them are known to be over 150 feet long. Elm was also used to surround smaller dwellings and outbuildings. In fact, elm was perfect for making items as diverse as canoes, trays, snow shovels, ladles, grain scoops, baskets, and containers of all sizes.

Fresh elm bark feels like thick, damp leather and can be worked in the same way. It can be folded, sewn, squeezed, cut or tied into a range of useful items. Once dry, roof panels, utensils, containers and other useful objects become rock hard and retain their intended shape, even if re-exposed to moisture.

The Haudenosaunee (Iroquois) in particular used elm “plywood” extensively. Once the sheets of bark were laid flat, holes were easily punched with something sharp like a hawthorn, or drilled with a bow drill bit, along the edges while the bark was still malleable . Within days, the sections were ready to attach to the log frame of a longhouse that could house dozens of families.

As accomplished agronomists, the Haudenosaunee stored huge amounts of grain in each of their towns. European colonizers such as Jacques-René de Denonville, Governor General of New France (1685-1689), wrote of their astonishment at finding tens of thousands of bushels of corn in giant elm bark bins and cradles in the Haudenosaunee villages they cheerfully burned to the ground.

I was told that the Haudenosaunee made mostly elm bark canoes because paper birch trees were not as abundant in most of their territory as in the north. Being heavier than birchbark boats, elm canoes were not carried, but used locally for travel on lakes and rivers.

Between late spring and mid-summer, elm bark can be removed with no more effort than peeling a banana. True, this “peel” is heavier, but it is easily lifted from the trunk of the tree. Elm bark shrinks as it dries, but unlike the “skin” of many other species, it does not split easily. Not only is fresh elm bark easy to work with, it’s fun to the point of being addictive. Ever since an Abenaki friend taught me how to make elm rattles, spoons and baskets over thirty years ago, I’ve tried to spot a small elm tree or even a branch to peel every spring.

Small to medium sized elms can be found throughout their native range, from Nova Scotia to northern Florida. At higher elevations, where soil type rather than climate often limits where elms can grow, isolated stands of elms may see less frequent cycles of DED infestation. These stands often grow for decades, growing quite large before perishing.

Some of the largest old elms in North America are found in places such as New York’s Central Park and on the campus of Penn State University. These elders exist through a regimen of systemic fungicide injections and insecticidal sprays. In fact, Penn State cleans its campus for a few days each year so helicopters can spray its elm trees.

Chinese and Siberian elms are highly resistant to DED, but none come close in size or shape to American elms. Since 1983, the Elm Research Institute in Keene, New Hampshire has been promoting “American freedom elms”, some of which have resistance to DED, but are not immune. Hybrids between Chinese and American elms have good resistance, but they still cannot fill the shoes, so to speak, with American ulmus.

Although it is still a long way off, we will one day again have massive elms like those whose bark once covered longhouses. It’s a show I would love to see.

ISA certified arborist Paul Hetzler tries not to bark at the wrong tree.

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