American chestnut partnership in Norfolk County
Example of viable chestnut (Photo by CCC)
Written by Liv Monck-Whipp, conservation biology assistant
A new partnership between the Nature Conservancy of Canada (NCC) and the Canadian Chestnut Council (CCC) is helping endangered American chestnut trees in Norfolk County in Ontario.
Once plentiful, now at risk
The American chestnut has been identified as an endangered species in Ontario and throughout Canada. But this tree species was not always at risk of disappearing. Before 1900, American chestnut trees dominated the Carolinian forest, towering up to 35 metres and making up almost 40 percent of canopy cover. Chestnuts played an important role in sustaining small mammal populations, and were eaten by humans too. Wood from these giant trees was prized for furniture production, due to its straight grain and resistance to rotting.
By the late 1930s, however, American chestnuts had almost vanished from the forest, killed off by a fungal disease known as chestnut blight. The blight was introduced from Asia through imported nursery trees. It is estimated to have reduced American chestnut populations to only one percent of their former numbers.
A recently completed survey revealed that only 23 percent of these trees surveyed 10 years ago remain.
A natural partnership
CCC Volunteer with American chestnut on NCC Property in Norfolk County, ON (Photo by CCC)
CCC has been working for decades to preserve remaining blight resistant chestnut trees, and to establish new, genetically diverse populations of blight tolerant chestnuts in suitable locations. And now, NCC and CCC are investigating locations within NCC’s Norfolk County lands for fostering chestnut seedlings.
CCC’s Seed Colony project involves planting American chestnut seedlings in forest “nurseries,” where the plants can grow in a natural setting. By growing seedlings from a number of genetic sources, CCC works to preserve and increase the genetic diversity of current American chestnut populations. Colony sites must meet specific criteria to ensure they are suitable for raising young chestnuts – from avoiding alternative hosts of chestnut blight, to soil pH and composition.
Mature chestnut tree, leaf and an example of a non-viable nut (Photo by NCC)
The Breaking Isolation project seeks to help isolated chestnut trees reproduce by planting blight-free saplings nearby. American chestnut trees generally don’t self-pollinate, so mature trees that have survived the chestnut blight are unable to reproduce if they are too far from other mature chestnuts.
The Breaking Isolation project introduces reproductive partners to these trees by grafting chestnut saplings onto chestnut sprouts, and planting 10 within pollination range. The saplings respond from grafting by producing pollen within two years, far faster than a sapling would normally.
NCC is currently working with CCC to determine which chestnut trees on NCC properties would be good candidates for this program. CCC will be monitoring the saplings for three years after planting. The hope is that NCC’s isolated American chestnut trees will soon be able to produce a new generation of genetically diverse, blight-tolerant American chestnut.