The National Wildlife Federation defines natural disturbance as any event that causes a disruption to the current state of an ecosystem. Disturbances can be localizedonly impacting a small patch of landor they can affect an entire forest or wetland. The results of a disturbance can be shortlived or longterm. Sometimes it takes a few months for an ecosystem to bounce back, and other times it can take decades.
The federation delineates several types of natural disturbance: fire, flood, wind, disease, severe storms, insect swarms, volcanic activity, drought, longterm freezing and earthquake.
This Refuge Update looks at some of those disturbances and how U.S. Fish and Wildlife Service employees manage for them at national wildlife refuges.
John Schmerfeld, the Refuge Systems climate change coordinator, knows about disturbance.
One of our biggest challenges is overcoming uncertainty about extreme events, random natural events. We dont have the ability to predict floods or fires or droughts or hurricanes with any great certainty. But we can plan for them generically, he says, by incorporating extremeevent adaptation measures
Specifically, Schmerfeld would like to see the Refuge System factor disturbance resiliency into decisions about:
- placement of facilitiesso were not building in a floodplain, for instance, or on shifting barrier island sands.
- placement of wetlands, impoundments, canals and other water control structures that can be vulnerable to disturbance.
- land acquisition. Are we going to purchase lands that the models show are going to be underwater in 10 or 15 years? he asks. Or should we think critically about buying a little bit farther in, a bit higher?
- placement and design of roads regarding interaction with water. Can culverts be included to allow water (and wildlife) passage? Can roads be built for the 500year flood instead of the 100year flood?
We dont really have the luxury not to think critically about this, Schmerfeld says.
He cites two important sources of information that can help: the Refuge System Inventory and Monitoring program and the Department of Defense Strategic Environmental Research and Development Program (SERDP).
The I&M program, which was established three years ago and is based in Fort Collins, CO, is gathering data about disturbance trends.
SERDP, a wellfunded program, might point the way for the Refuge System. SERDP is modeling extreme disturbance events and incorporating those models into longterm planning at military bases, especially coastal installations. What Id like to do is try to piggyback on that science, Schmerfeld says.
This Refuge Update focuses on naturaland not humandisturbance, but Schmerfeld says its difficult to decouple the two.
When we think about landscapescale planning, he says, one of the prime drivers is human development and landuse change. Those are significant drivers that you have a difficult time decoupling from natural disturbance. Those things become additive and synergistic in mostly bad ways.
Schmerfeld points out a sometimesoverlooked aspect of disturbance. All of these eventsflooding, hurricanesmake our job managing invasive species more difficult. When disturbance comes and upsets an ecosystem that is intact, oftentimes it creates opportunities for invasives to gain footholds.
And, he says, climate change exacerbates pretty much every stressor we have on the [Refuge] System, including natural disturbances.
Regardless of the disturbance(s) in question, Schmerfeld suggests proactive planning is the key: Im hopeful that managers feel like they have the leverage and the support to make innovative decisions that are based on the best science we have, the best data we have at hand.