Just outside my window this morning…
When I first moved to the mountains almost 40 years ago I was entranced by the beautiful Northern White Cedars that seemed to grow in such abundance here. On my property I have a number of these magnificent bell shaped trees with their fan-like fronds and clusters of budded green or brown cones that are found on the newer growth in spring and fall. Since I have water all around me and I noted their penchant for moisture I thought I might have ideal habitat for them to thrive.
One year my neighbor planted a whole row of majestic cedars in front of his mother’s house, and over a period of many years I have had the pleasure of watching the saplings become large healthy trees providing shelter for many birds. During the winter the deer continue to browse on the lower branches of the cedar, a favorite winter forage plant not just for deer but also for moose and rabbits.
After a number of years I began to notice that I no longer saw cedar seedlings popping up around fallen logs around the “mother” trees. Why weren’t the trees producing offspring? At that point I asked my neighbor if I could dig up two small trees of his and I planted these two around the house. The one closest to the house survived browsing deer; the other did not. It was a while before I made the connection between the increasing deer population and the lack of cedar seedlings. I also unwittingly contributed to this problem by feeding deer on this property, something I will certainly not be doing in the future.
The beautiful cedar I planted in my yard next to the house was totally destroyed by deer the first winter I spent in New Mexico. Last year I planted and protected a new cedar seedling in my garden but it was deliberately crushed by a rock that someone pulled out of my stone wall. Fortunately, I have a pictorial record of this egregious act so it won’t happen again.
This spring I have been on the lookout for young cedar seedlings elsewhere and finding few. I have also been talking with my neighbor about this problem. He believes that the exploding deer population is responsible for decimating the seedlings and that we are losing these trees for good. Wise in the ways of the forest, I take his words seriously especially since my own observations match his, and as a naturalist, learning from observation is what I have learned to trust.
After doing some preliminary research on cedars I discovered that indeed, the inflated deer populations are now considered the primary threat to the life of all Northern white cedars. Apparently these trees are threatened by deer in every state they grow in from Maine to Michigan.
New world cedars are not to be confused with the old world cedars of Lebanon; the latter are “true” cedars. Ours come from the Cypress family. To confuse matters further our cedars and junipers are related; the difference between the two is that new world cedars have cones; junipers have berries.
What follows is some research on the Northern White cedar:
The literature clearly indicates that cedar prefers organic matter where the pH is neutral to basic (pH 6.0 – 8.0) and where rates of organic matter decomposition are relatively rapid. As soon as water stagnates soils become highly acidic. Chemistry and waterflow are therefore critical factors that affect cedar survival and growth.
Cedar dominated forests develop where the groundwater contains relatively high concentrations of oxygen and essential nutrients and where it moves laterally through the soil. These conditions result in finely decomposed organic matter and a high pH, both characteristics of a good cedar soil. Lateral movement of oxygen and nutrient laden water through the soil may be why cedar swamps typically occur as bands in wetlands and along lakes and streams.
Typically, cedar is found growing in association with other lowland conifer and hardwood tree species. Tamarack, balsam fir, white and black spruce and hemlock are common evergreen companions. Hardwoods like maple, black ash birch and pine are good examples of the latter.
In lowlands Cedar is typically found in small, relatively pure patches. These seem to occur in areas where the water table is at or very near the surface and is moving, such as the edge of a low ridge or along a small stream.
A common denominator in upland cedar habitats is a rich basic mineral soil with a high pH. Cedar forests are more or less confined in the uplands to soils with free calcium carbonate close to the surface.
Another common observation is that upland cedar forests invade open areas: old fields, clear-cuts, sand dunes, and limestone bluffs. These situations are, apparently, the only ones where seedling establishment is clearly the mechanism of stand regeneration.
There is evidence of genetic differentiation between upland and lowland populations. In programs of artificial regeneration, consideration should be given to the fact that local ecotypes could exist. Lowland vs. upland seed should be used to reforest the appropriate habitat.
Northern white cedar is a dependable seed producer. It bears good seed crops every 3 to 5 years, with light to medium crops in the intervening years.
However, seed viability is low, although seed production is relatively consistent year to year. Seed dispersal by wind starts in September with the majority of seed falling during autumn. Some seed is dispersed during winter. Most seed is dispersed within 50 meters of the mother tree.
Seedlings can establish on bare organic and mineral substrates, moss and downed logs in various stages of decay.
Establishment is numerically greatest on logs, but sources point out that the numbers of seedlings are not necessarily related to cedar survival because of deer browsing. It is generally agreed that an estimated 99% of the initial seedlings died by the thirteenth year.
Light in the forest understory doesn’t seem to be a factor regulating seedling establishment according to the literature. I question this statement because the few seedlings I have found seem to have access to some light, either in the morning or late afternoon during the summer, and more light off season. As I have mentioned previously, seedling establishment is definitely positively related to soil PH.
All the sources I consulted concur: The lack of seedlings and saplings in lowlands is due to browsing by the white-tailed deer. Cedar dominated lowland swamps are critical winter habitat for these animals. Small cedars die when more than 15 to20% of the foliage is removed annually. Seedlings often grow very slowly; it can take 20 years for a seedling to reach 1 meter in height. Because cedar grows slowly, seedlings are exposed to browsing pressure for a relatively long time. The only successful reports of sexual reproduction come from uplands and lowlands that are not utilized by deer.
Cedar can and often does reproduce by layering or tree tipping. Branch layering where a branch of the parent stem transforms into a stem is the predominant type of vegetative reproduction. The presence of thick sphagnum moss facilitates the formation of new roots and branch layering. Trees can also be blown over and the lateral branches then become main stems. Vegetative reproduction via layering and blow – down appear to be major pathways for successful regeneration in the lowlands.
The notion that cedar typically occurs in the understory and eventually replaces other trees is a myth that should be eliminated. Cedar almost never grows taller any other tree simply because it grows so slowly. Cedars are capable of living a long time – up to about 500 years or more (one cedar in Ontario was dated to 900 years). Because these trees occur in the lower portion of the canopy and can live a long time a myth developed around the idea that cedar is very tolerant when it is not, at least not today.
Researchers suggest that today’s cedar swamps are very similar to those that existed in the same locations more than 150 years ago. Wind – throw is extremely common in cedar swamps and is a major form of natural disturbance. Completely and partially uprooted trees abound. When trees tip only partially, lateral branches assume dominance and the resulting trees are unusually shaped.
Today, most blow-downs encourage spruce, fir, and hardwood regeneration, or the gaps are colonized by hardwoods and conifers Some cedar reproduction still occurs in open plaes, especially when trees are only partially uprooted and lateral branches remain beyond the reach of deer. But because there is little chance for natural reproduction to grow above the browse – line, cedar does not generally regenerate in areas that are disturbed by wind. Thus, the primary mode of natural regeneration has been eliminated by the white-tailed deer.
Another young friend of mine who is so knowledgeable about trees (and also loves cedar) that I asked him to read this article made a critical observation. He notes that in his experience most trees have a particular strength that compliments their weaknesses and wonders what quality a cedar might have (or develop) that might help them deal with deer predation. We discussed the fact that cedars produced oils that made them more attractive to deer during the winter (also true for junipers). And I wonder if one cedar strategy for long – term cedar survival might be to stop producing the chemical that deer find so tasty during the winter months…
For anyone who loves trees, especially our native cedar there are two things we can do to help address our current cedar losses. The first is to plant and be prepared to care for cedar seedlings long term providing them with adequate deer protection.
The second more unlikely possibility might be to contact the Maine Inland Fisheries and Wildlife folks with a request for help with this issue, even though this organization is heavily invested in maintaining an inflated deer population for hunting.
Cedar has been a valuable tree that has been used by people for millennia beginning with the Native peoples of this country. The Wabanaki named the cedar the ‘Tree of Life’ and used it to make rope, clothing, baskets canoes, poles, fences, and totem poles (west coast – red cedar). Today, in the east these trees are still used to build fence posts etc. because of their durability and natural resistance to insect damage and decay. Burning cedar during the winter, a practice I have engaged in for years, purifies the air because of the Pinenes that are present, and the intoxicating scent of the dried fronds is reason enough to gather a bough or two in the fall to dry…
I think we have taken our native cedars for granted as I once did. Surely, we need to intervene on behalf of these trees giving nature time to make necessary adjustments or we might lose them forever.