Beetles and Monoculture

by Natasha Chart

categories: Biodiversity, Climate, International

Published June 30, 2009 @ 07:39PM PT

Julian Siddle of the BBC doesn't seem aware that a pine beetle infestation has already spread to the United States, devastating forests all the way into southern California, but nonetheless provided some interesting reporting on how Canada is addressing the pine beetle decimation of their forests and the environmental circumstances shaping their thinking on the matter:

... Cold winters usually kill off the beetle larvae, but the region has been warmer than usual in recent years.

... Without interference from man, mature lodge pole pine would be regularly destroyed by forest fires. But, [Staffan Lindgren, professor of entomology at the University of Northern British Columbia,] explained, the species has evolved to use fire to aid regeneration.

... The damage caused by the beetle, combined with the downturn in the demand for wood due to the global recession, has brought about a rethink on forest policy in British Columbia.

Mixed forests, rather than monocultures, are now seen as healthier both for the trees and other plant and animal life - even though a lack of uniformity makes them more difficult to harvest. ...

First, warming temperatures have helped pests proliferate. Not only would a sufficiently cold winter kill more beetles off, but as we've covered before, insect life cycles are governed by what are called degree days. That is, they need a certain minimum heat input within their tolerable range before they can progress to the next stage of their life or reproduce. It's a fascinating biological clock mechanism that allows them to be very responsive to limiting environmental constraints.

Second, the natural cycle of ecosystem renewal and regeneration has been disrupted without adequate replacement. Having spread ourselves out so widely, and having such rigorous fire supression knowledge, we left the trees without a means to clear out the competition and literal dead wood so that new, healthy seedlings could periodically get a decent chance to establish themselves.

Third, human ecosystem management techniques have decreased biodiversity. If even one pest organism can take advantage of a fatal flaw in the dominant species, the monoculture ecosystem can collapse.

Making ecosystems work properly is hard. We don't always understand all the necessary inputs and interactions.

Though we do know of a few surefire ways to break an ecosystem, some of which we might be directly or indirectly responsible for. Global warming and the monoculture are our fault, and these stressors give an opportunistic organism like the pine beetle the chance to take over and do its worst.

In this case, it's why the western portion of North America is increasingly covered in large stands of dead kindling. In the case of our artificial agricultural ecosystems, it's why when a pest develops resistance to whatever method we're using to combat it, it can devastate food production across a wide region.

Hard to create, easier to destroy. It's going to be true of any complex system, and certainly the living systems we depend on for life support. Though we can learn to interact positively with our environment, we tamper at our peril.

(Photo credit: tomsaint11 on Flickr.)