An entomologist and his ecologist daughter have outlined the dramatic changes that have occurred over the past half-century in the forests of White Oak Canyon in the Shenandoah National Park due to a canker fungus.
In their paper published on the open-access site PLOS ONE, Richard Karban with the University of California-Davis, and Claire Karban with the University of Colorado, Boulder, describe how the forest looks today compared to the late 1970s as a means of highlighting the impact that fungal infections can have on a forest environment.
As the Karbans note, in the 1920s, researchers conducted a survey of the forest at White Oak Canyon—they noted that chestnuts and oaks were the dominant canopy trees there. Later, in 1950, botanist and ecologist Lucy Braun described the tree composition of the forest in her book “Deciduous Forests of Eastern North America”; she, too, noted the dominance of oak and chestnut trees.
In 1977, Richard Karban surveyed the forest and found it very much like Braun had described it. But when he returned to the forest in 2021, this time with his daughter, he was surprised to find that fundamental changes had occurred. The pair soon learned from prior research that the fungus Cryphonectria parasitica—a canker fungus—was primarily responsible for the changes. It had killed almost all the chestnut trees.
The researchers noted that the forest appeared to be responding slowly—instead of oaks taking over to become the only dominant large tree in the forest, smaller trees, such as birch, had begun to fill in the gaps. The researchers noted that not all traces of the chestnut tree had vanished—there still remained trees that had reverted to shrub form.
The researchers plan to continue study of the forest, hoping to better understand why it has been so slow to respond to the relatively sudden disappearance of a dominant tree species. They also plan to document other changes, such as the increase in the deer population, as an increase in brush has led to a larger food supply. They also wonder if the absence of large fires in the forest is due to the change in canopy trees.
More information:
Richard Karban et al, Floristic changes following the chestnut blight may be delayed for decades, PLOS ONE (2024). DOI: 10.1371/journal.pone.0306748
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Documenting the impact of a fungal outbreak on a forest over half a century (2024, October 8)
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