Cogs in the Works of Ecosystem Resilience

SP-03 Forest Health in a Changing world.

Severe outbreaks of mountain pine beetle can throw a cog in forest ecosystems. Photo courtesy of Bugwood.org
Severe outbreaks of mountain pine beetle can throw a cog in forest ecosystems. Photo courtesy of Bugwood.org

A cog in the works usually means interference at the least, possibly irreparable damage to a system. From time to time, certain factors (cogs) affect natural systems, influencing their capacities to regenerate or adapt to changes following natural or even human-induced disturbances.

Speakers in the plenary session explored the different hindrances to ecosystem resilience in the face of cogs, using case studies from several regions of the world. Basically, resilience was defined as the capacity of a particular system to recover from large-scale disturbance such as catastrophic fire events, floods, and other occurrences.

Most systems have inherent capacity to be resilient without human intervention, but when certain tipping points are exceeded, this capacity becomes severely compromised, and the system can become susceptible to degradation.

In an example from Chile, the speaker explored the capacity to determine the tipping points that take a forest ecosystem to a point where recovery from a disturbance (such as excessive harvesting) is virtually impossible.

Based on various simulations, they concluded that this seemingly gargantuan task was indeed achievable, specifically that 65 square meters (or below) of harvest within a 1000 ha plot of forest could be used as a sustainable metric that signifies no degradation. Harvests beyond that level could send the system reeling toward a tipping point after which recovery might be unattainable.

Examples from North American boreal forests indicated other, perhaps more serious, cogs plaguing forest ecosystems. Outbreaks of insect pests and diseases are becoming a nightmare to ecosystem managers and the scientific community alike.

Today managers grapple with plagues such as mountain pine beetle, southern pine beetle, gypsy moth, laurel wilt disease, and sudden oak death, to name a few. These and others continue to inflict enormous damage to already fragile forest ecosystems, sometimes at very large spatial scales.

Climate change exacerbates outbreaks of forest pests and diseases. Predictions show that the geographical ranges of some insect pests continue to increase, and some are better able to survive summers and harsh winters as a result of temperature changes.

Mike Wingfield from South Africa talked passionately about yet another cog in the sustainable management of forests presented by the growing international trade and transfer of live plants, which moves insect pests and potentially harmful forest pathogens across the world. While he alluded to the fact that there might be no known way to practically address this issue, he expressed optimism that collaborative research and market mechanisms can eventually provide ways to confront the negative effects of international trade as it relates to live plant transfers.

Despite these seemingly negative implications for forest management, all is not gloom. Forests, like many other ecosystems can exist in different states, and so does their management. The “protection” forests in Japan (as presented by Kimiko Okabe), for example, continue to provide many ecosystem services as long as natural forest cover is maintained.

The session scientists expressed confidence that with collaborative planning, commitment to research and funding, the cogs they described can be just that: cogs. With persistence they can be overcome, or their impacts can be minimized over time, paving the way for the sustainable management of precious forest resource in a rapidly changing world.

Written by: Humphrey Kalibo

 

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