Castanea dentata: The American Chestnut
The American Chestnut (Castanea dentata) was once very common within the forests of the eastern U.S and extreme Southern Ontario. However, a fungal blight has spread like wildfire through our forests, and the Chestnut has all but disappeared.
At one-time, the 'iron-tough' wood of the chesnut was the most economically important timber in eastern forests, producing quality lumber with little shrinkage and good resistance to rot, water and shock. American Chestnut was used for everything from houses and furniture, to railway ties and telephone poles. To wildlife, the seeds of the Chestnut were a dietary staple.
Based on the principles of conservation biology, we recognize the importance of this species to forest ecology and genetic diversity. In appreciating the intrinsic value of this beautiful tree, Friends of the Rouge Watershed (FRW) have planted several dozen American Chestnuts, attempting to establish a healthy population in the Rouge Park, an area which is isolated from the areas affected by the blight.
History and Importance
Two Asian tree species, Castanea mollisma and Castanea crenata, were planted at the turn of the century around the Bronx Zoo in New York. As beautiful as these exotic species were, they brought with them the chestnut blight Cryphonectria parasitica, a virulent, parasitic fungus. Transmitted by insects, wind, rain, birds and mammals, the chestnut blight spread rapidly. It infects cracks and wounds in the bark, creating sunken cankers that girdle the stem and kill the tree.
American Chestnut was the most economically
important timber species in eastern forests
Almost all of our North American Chestnut trees have died since the introduction of Cryphonectria parasitica. Prior to the introduction of chestnut blight, trees reached heights of greater than 35 metres and 100+ cm in diameter with an average life span of over 300 years (Farrar, 1996). They now seldom reach heights of 10 metres. They have survived only because their stumps sprout prolifically, a trait that enabled their persistence in spite of the chestnut blight.
Most of the species that relied on the American chestnut for food were generalists. The deer, rodents, insects and bird species that traditionally made Chestnuts a large component of their diet, now browse other nuts such as acorns, walnuts, beech nuts, hickory nuts. Oaks have replaced the Chestnut over much of its former range, which may have mitigated the harmful effect of losing so many American Chestnuts.
Grouse benefit from a consistent and nutritious diet of chestnuts, preparing the birds for long, cold winter months. Black bears and deer gorged themselves on the nuts as well. Gray squirrels were in far greater number due to the bounty of mature chestnut, oak, walnut, hickory and beech nuts.
The American Chestnut, which was a favoured food of the extinct Passenger Pigeon, is now in real danger of becoming extinct itself. The last of the Passenger Pigeons died in 1914 in the Cincinnati Zoo, where she remains gracelessly perched to this day, stuffed and glassy-eyed. (Bruce Carly, 1999). We do not want to see the American Chestnut follow the path of the Passenger Pigeon.
Regenerating cleared areas with American Chestnut
American chestnut is a member of the family Fagaceae that also includes Quercus (Oaks), Fagus (Beech), and Castanea (Chestnuts). It prefers to grow on easterly facing, xeric (relatively dry) slopes, favouring sandy soils, but will grow in clay or loam and on sites with low fertility. (ACCF, 1998) American Chestnut productivity can be limited in alkaline environments (lime based soils), preferring a pH of 4.3 - 6.4. The ideal seedbed is an undisturbed forest floor with humus and mineral soil, sufficient to cover and protect the seedlings.
Planting seeds will result in excellent first year growth. Seeds should be planted in October, so that the taproot begins to grow in early spring and the stress caused by transplantation is avoided. The planting hole should contain a mixture of humus and mineral soil (50/50). (ACCF, 2000).
Transplanting Planting holes should be 1 foot wide and three feet deep, to accommodate American chestnut's extensive taproot, generally the same length as the seedling. The taproot should be kept approximately 5 cm from the bottom of the hole. After transplanting, the tree should be watered and the soil compressed to remove any air pockets around the root system. (ACCF, 2000)
American Chestnut Seedlings
Protection of your trees
Wire tree shelters are useful for the protection of seedlings from hungry neighbours. Extra precaution can also be used to protect these valuable trees. A bag of human hair attached nearby or to the shelter will deter deer from eating the seedlings. Fishing line fences have also been successful. Deer, which are frightened when they run into the fence, learn to avoid the area.
From competition Mulch can be used as a ‘weed' controlling device, and helps to protect the tree from drought and excessive heat. Care should be taken with the use of mulch because microorganisms that decay organic matter can extract nitrogen from the soil, creating poor growing conditions for the seedlings. If the seedlings display nitrogen deficiency symptoms such as pale yellowing of the foliage, steps should be taken to remove the mulch or to add supplement nitrogen (Land Owner Resource Guide, 1999).
The silvicultural methods used to regenerate tolerant hardwoods (uniform shelterwood and selection) help to control competing vegetation through continuous crown cover (Anderson, 1990).
Where can you find American Chestnut?
Written by Paul Heydon, Friends of the Rouge Watershed