The Tragic Fall of the American Chestnut

Before the Fall

Imagine you went back in time 200 years. You view massive forests as far as you can see. The forest has some oaks, conifers, and other familiar trees; but you also see hundreds of a tree you don’t recognize. They are bigger than all the trees around and outnumber all the others. The trees have long saw-toothed-shaped leaves. Little do you know you are seeing the mighty American chestnut (Castanea dentata).

The chestnut once was the most dominant canopy tree in all the eastern United States. 1 of every 4 trees in the United States was a chestnut. When this tree was at full strength it was the main choice of wood for North America’s first colonizers. The wood had rot-resistant properties and straight grain strength which made it the perfect choice for fences and log houses. Not only that, but it also grew exceptionally fast. The tree averaged a 3-foot growth per season and would grow up to 100 feet tall.

The chestnut was instrumental in early livestock feeding. The nut produced was high in essential nutrients and fats. Farmers would either haul in hundreds of pounds of nuts to feed livestock, or more commonly would let cattle and pigs forage in chestnut-dominated forests. Sadly, this tree which survived ice ages and all other environmental changes over millions of years would become functionally extinct in only 40.

The Fall

In 1904 this mighty tree faced a threat that would forever change the forest landscape. From South Asia, a deadly fungus called the Chestnut Blight (Cryphonectria parasitica) was accidentally imported. The fungus was first noticed in New York but soon spread through the trees’ entire range in the Eastern U.S.

The fungus spreads in almost every way imaginable. Short ranged the wind and rain easily spread the spores, and long-range the spores get carried by insects and birds. Once the spores spread the fungus enters the tree through wounds and then starts growing under the bark.

The symptoms start as orange cankers up and down the tree. The cankers start to kill the tree limbs which spreads to the leaves causing them to shrivel and die. Soon the fungus causes the tree to completely collapse back to its roots. The chestnut can regrow back from the roots, but the new sprouts immediately die back to the ground as the blight takes over. This cycle has given the chestnut the classification of functionally extinct. This classification means the species has no impact anymore on its ecosystems.

It is estimated that from 1904 through 1944 over 4 billion chestnut trees were killed. This completely devastated the logging economy by causing billions of dollars in lost profits. When this happened, the industry overreacted and further devastated the chestnut’s chances of survival. The plan to stop the blight was to cut all chestnuts with any symptoms to prevent spread. Little did they know they weren’t preventing the spread but were killing off trees that might have resistance to the blight. If they had not cut down all infected trees a resistant variant had a possibility of emerging and repopulating. The situation is not completely without hope.

Can It Rise Again?

Can the American chestnut ever rise to the same heights? This is a complicated question with the answer more than likely being no. In its absence, other tree species have taken their place in the canopies. The most common now is the Black Oak (Quercus velutina). Just because it won’t be where it once was does not mean it can never make a return.

There have been many conservation efforts trying to restore the tree to its once wide range. The most effective way to do this is by genetically engineering the tree. The American chestnut is harmed by the blight, but the Asian chestnut is resistant to it. Using these scientists started to combine the two tree species, and what they discovered was that by having a genetic mix of 97% American and 3% Asian the tree becomes resistant to the blight. This combination leaves the species almost completely pure, but with a fighting chance. As these efforts to spread the new engineered American chestnut continues one day you might look in the forest and see this wonderful tree again.