'Recovered' Forests Still Suffer From the Past

Sixty years ago the cropland that once dominated the South Carolina longleaf pine woodlands was finally left untilled. Now, the woodlands appear to have recovered to their former glory, showing little evidence that they were once ever wide and empty fields. However, while it may not be obvious, local plant and animal life seems to still know what happened to their home not too long ago.

That's at least according to a new study published in the Journal of Animal Ecology, which details how grasshoppers are a strong indicator of how well forests have recovered from an agricultural past.

"Ecologically, grasshoppers are at the heart of the food chain," researcher Philip Hahn explained in a recent statement. "They eat the plants and then they're eaten by others: other insects, reptiles, birds."

Building on past research that shows post-agricultural sites have poorer-quality soil and differences in the types of plant species that grow back, Hahn and his colleagues surveyed the plants, soil quality and grasshoppers found at 36 study sites in South Carolina.

 Interestingly, despite 60 long years of recovery time for the longleaf pine woodlands, the forests still do not resemble untouched forests when compared.

According to the study, the woodlands that had never been cleared for farming in the region were found to boast more grasshoppers, plant types, and other fauna. There was also a clear link between these populations - a pattern that should be evident in developed ecosystems and their food chains. However, in the "recovered" forests, this correlation wasn't nearly as clear, and there were far fewer grasshoppers.

According to study co-author John Orrock, this raises important questions about nature's ability to recover from human impact.

"Why has what we did so long ago lasted? Why hasn't nature recovered?" he asks.

"It challenges what we know," Orrock added. "If it's true that the past influences ecological relationships in ways that we can't predict, then all bets are off."

This work actually reflects a past study, which found that the drastic changes forests are undergoing in the Northern Hemisphere may have less to do with climate change, and a lot more to do with the fact that they are still recovering from a state of "disequilibrium" caused by past agricultural influences.

"We thought most bad things could be undone in a decade," Orrock said. "The good news is, at least we know where we are and it's a start. We know business as usual might not work."

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