Ash Forests After Emerald Ash Borers Destroy Them –

Ash Forests After Emerald Ash Borers Destroy Them –

The first thing you should know: The adult emerald ash borer is beautiful. Isolated in an artfully composed macro photo, its shimmering exoskeleton is breathtaking.

The second thing you should know: Unwittingly airlifted by humans into an environment from which it had been evolutionarily isolated, the emerald ash borer is simply following its God/Darwin-given imperative when it destroys the Northeastern ash forest.

The third thing you should know: The novel ecosystem that emerges from that destruction will not be a sterile lunar landscape. It will include many living things forming a deeply wonderful “nature.” Our descendants will walk through that landscape appreciating its non-human wonders even as some of them are aware of the role humans played in defining it.

The fourth thing you should know: Even so, something will have been lost.

This topic comes up every time I do a docent tour at the marsh. Much of the effort of restoring habitat is weeding out nonnative invasive plants. Remove the nonnative plants and you give the native plants a chance to survive. Help the native plants and you help the insects that co-evolved with them, and the insectivorous birds that co-evolved with the insects, and the parasites that live on all of them, and so on up and down and out through the multitude of layers that build up when life has a chance to operate in relatively stable conditions across evolutionary timescales.

A metaphor I’ve used to try to describe it is a piece of music. The organisms that co-evolve to form a natural community have built up over millions of years, gradually adding notes to a complex symphony that is rich and harmonious. Introducing a nonnative species in that setting is like bringing in a Jimi Hendrix solo in the middle of a Brahms concerto. It’s not that the Hendrix solo is bad. But it’s out of place, discordant. The other instruments can’t compete. The Hendrix solo gets louder, its amplification drowning out the gentle notes that had been providing its counterpoint. One by one, other instruments go quiet. Eventually the Hendrix solo may exhaust itself, continuing with the volume turned down. Things stabilize, and a new equilibrium is reached. But the overall musical landscape is poorer, less diverse, than it was before.

Over time it can build up again. The process of extinction and speciation continues. The emerald ash borer’s destruction of the ash forest is just one part of a much larger piece of music. There have been five great extinctions in the history of earth, and the fact that we’re currently engineering a sixth isn’t some huge tragedy, at least from a sufficiently detached perspective. It’s just the end of one movement, which will lead to the start of another, in which the music gradually swells as it plays toward its inevitable, much more distant, conclusion.

But on the much briefer timescale on which humans live their lives, it’s a loss.

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Tags: insects, extinction, insects that anonsally will never see, emerald ash borer, loss.

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