Shining Tree Woods

How Best to Manage

by Irene Fedun

Shining Tree Woods, a parcel of old-growth forest acquired in August 1994 by the North American Native Plant Society (then the Canadian Wildflower Society), has survived, some may even say thrived, on our benign neglect.

Shining Tree Woods (STW) is named for the cucumber trees (Magnolia acuminata) that occur in this magnificent forest in Norfolk County, Ontario. Indigenous tribes referred to this, Canada's only magnolia, as the "shining tree" due to the sheen on its leaves.

At the northern limit of its range in the southernmost parts of Ontario, the nationally and provincially endangered cucumber tree, or cucumber magnolia, grows in rich soils on moist sites. At STW it shares the undulating topography with red maple (Acer rubrum), white ash (Fraxinus americana), yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), eastern hemlock (Tsuga canadensis) and tulip tree (Liriodendron tulipifera). The rich diversity of tree species, complemented by a flourishing understorey of spring ephemerals and almost no invasion of exotics such as garlic mustard (Alliaria officinalis) or purging buckthorn (Rhamnus cathartica), ensures a healthy forest ecosystem.

So the question arises: should anything at all be done at Shining Tree Woods? Grif Cunningham, who leads the NANPS Land Management Committee, visited the property twice in fall 2003 with fern/tree propagator Richard Woolger to collect cucumber magnolia seeds and determine a plan of action (or inaction) for STW. They found that Nature was "functioning in a wonderfully reproductive way without our help". Their recommendations were: erect a sign signifying NANPS ownership of the property and the rationale behind it, develop a system for demarcating the property's boundaries, establish excellent relations with the neighbours and appoint a local botanist to help manage the land. They also suggested planting some cucumber magnolias in appropriate places such as the former tobacco/corn field, which comprises about half of the 50-acre property owned by NANPS.

Magnolia acuminata is at the source of the debate about STW. At last count there were 23 mature cucumber trees six to 51 centimetres (2.5 to 20 inches) diameter at breast height. One tree has its top broken off, one was struck by lightning and two have interior decay at ground level, according to biologist Mark Bacro who lives within walking distance of the woods. Two young trees were knocked over by another falling tree and several saplings are covered in grape vines.

Although the majority of the mature cucumber magnolias are healthy, Mark has seen little regeneration of that species over the past five years. He has found a few young trees but no seedlings and only two saplings approximately 30 centimetres (one foot) high. Mark's recommended strategy is to free up two or three small clearings by taking down a couple of large trees, pulling the strangling grape vines off the emerging cucumber trees and removing some brush, before planting out a few Magnolia acuminata saplings.

Dr. John Ambrose, the former curator of the University of Guelph Arboretum, who has worked with Carolinian species for almost 30 years, sees no need to kick-start the growing of cucumber trees. John notes that there is already a higher concentration of Magnolia acuminata in this forest than in most of its habitats. He believes that natural regeneration will work just fine as birds and other animals eat the fruit, then defecate the seeds, enabling the old fields to transition into forest with healthy new cucumber magnolias popping up among other species.

"Rather than be in a rush to plant cucumber tree seeds/seedlings or cut openings in the forest, we should encourage the establishment of new and expanding habitat in the old fields such as a matrix of pioneer forest species and meadow openings into which the cucumber magnolias and other special species of this forest will colonize when the conditions are right," says John.

"Processes are a bigger concern here, that is to say, ensuring sufficient habitat for the seed dispersers and a functioning watershed. We too often think of just planting trees without knowing if that is the right solution to the unexplored problems that exist on a site," he adds. John suggests working with adjacent landowners to create wilderness corridors by planting windbreaks on farmland and helping regenerate native vegetation on stream banks, thereby improving water quality.

Mark has had discussions with the previous landowner who says that the field was never leveled out for farming, although Grif points out that any activity using a tractor would result in some loss of the microtopography i.e. the holes and hillocks created by natural processes such as falling trees. In the 11 years since the land was farmed, exciting new growth has appeared in the old field. Sugar maple, white ash, red cedar (Juniperus virginiana) and sumacs (Rhus spp.) are among the woody plants that have taken hold. Wet pockets around the perimeter of the field harbour young black gums (Nyssa sylvatica), poplars (Populus spp.), dogwoods (Cornus spp.) and - to everyone's amazement - tulip trees. Should the field then be left to regenerate on its own? Should we plant cucumber magnolia trees in appropriate locations or artificially create pits and mounds?

Although Mark is in favour of minimal management of the woodland to accelerate the growth of cucumber trees and other native tree species (he is fearful that a great windstorm or other natural calamity could take out several prime trees) he believes that bringing a bulldozer into the field to dig pits would be counterproductive. Many of the young trees would be damaged in the process.

Mathis Natvik, the author of "Pits and Mounds" (Blazing Star, spring 2003), believes the bulldozer technique (employed at Clear Creek Forest in Chatham-Kent, Ontario to create the craters and resultant hills that are the hallmark of an old-growth woodland) could be used to good effect at STW. He suggests using a smaller backhoe and working in the lower areas of the fields to minimize damage to newly sprouted trees and other vegetation. Although the soil is sandy and, therefore, less likely to hold water into the summer the way clay would, the artificially created pits will become pockets of organic mulch as leaves and other debris settle in them. These pockets will retain rain and meltwater longer than the fast-draining sand of the field, and will host future ferns and other moisture-lovers. They may even nurture young cucumber trees.

Mathis adds that digging pits is critical in sandy soils which typically lose most of their organic material through farming. "A lot of earth work has occurred on farm fields to get them smooth and I feel one of the most important issues in restoring fields is to rough them up again, getting them back to their natural state," says Mathis.

A major part of this process is the removal or blocking of drainage tiles used for farming. Spring meltwater, which would otherwise soak into the soil, slowly being absorbed by the native vegetation over the spring and summer, is drawn off through the tiles and sent coursing down ditches into a local lake or large watercourse. This allows the farmer to get in earlier to plough and seed his fields, which would otherwise be too wet to work. But the practice has serious environmental consequences, changing both the ecology of major bodies of water and the soil conditions for local plant life.

From conversations with a neighbouring farmer, Mark has learned that there is at least one row of tiles in the STW field (possibly extending into the forest). This information will also be on record with the municipality as stipulated by the Ontario Drainage Act. Mathis notes that it would be worthwhile to consult the drainage map, determine the location of the tile runs and sever the ends. The field would then revert to its natural drainage patterns and ephemeral ponds would form providing habitat for wildlife and plants.

After the field has been returned to a semblance of its natural state, Mathis recommends planting a few Magnolia acuminata (grown from nursery stock with seed gathered at STW) across the lower areas close to constructed pits. Red osier dogwoods (Cornus stolonifera) have taken residence in those areas, an indication that the water table is close to the surface there.

Mathis believes it is necessary to plant a young stand of cucumber trees in the field since "the greater landscape around STW does not have a large enough matrix of young and old forest to be able to depend solely on natural regeneration of Magnolia acuminata", something the pre-settlement woods had in great abundance. Mathis predicts that succession will push STW into a beech/maple stand as old cucumber magnolia trees die out, until a disturbance in the canopy creates the sunny opening that magnolias need as seedlings.

Former NANPS president Tom Atkinson agrees. The unpredictability of natural disasters - lightning strikes or violent storms that rip trees out by the roots and open up the forest floor - argues in favour of human intervention. As Mathis says, Shining Tree Woods is much too small to host the greater landscape processes - in a landscape dominated by corn, soybeans and tobacco - that would give M. acuminata the necessary opportunities to regenerate successfully.

Although John agrees that the site conditions need to be restored, he is less convinced that planting is necessary. John concludes: "If we restore the altered physical conditions to their previous diversity we will set in motion the natural regeneration of a diverse forest - sometimes amazingly quickly - and perhaps including cucumber trees. Watching the species and structural diversity of the new forest develop over the next 10 years will be very instructive. If no cucumber magnolia seedlings appear, and decline is noted in the mature populations, planting should be considered."

Mark would prefer to act sooner. He reminds us that Magnolia acuminata is an endangered species and this woodland is one of the few remaining places in southern Ontario where it continues to grow in a viable forest community. Why not take this opportunity to jump-start the regeneration of these trees and ensure that a good number survive and thrive?

It remains for the NANPS board to decide what's to be done. In the meantime, NANPS members eagerly await the fall excursion to this beautiful woodland, while Grif and Richard keep busy, lovingly tending their "shining tree" seedlings.