Fire is a complicated and controversial issue:

•  It can cause incredible damage, destroying homes, contributing to climate change and threatening human lives and health. The U.S. spent well over $1 billion fighting fire last year.

• But regular fires are also essential to maintaining habitats for many plants and animals around the world, such as those that inhabit the vast prairies of South Dakota and Minnesota, as well as pine forests of the American West and Mexico. 

That’s why The Nature Conservancy started conducting prescribed burns on many of its preserves beginning about 40 years ago. In order to better understand fire in modern life and in conservation, we talked to Ayn Shlisky, director of the Conservancy’s Global Fire Initiative.

Nature.org: I’ve heard that 2007 is forecast to be a bad fire season in the United States. Why is the number of fires increasing?

Ayn Shlisky: There are a variety of reasons. The vast majority of fires in the United States and most other countries are started by people. As populations increase and move farther into wild lands, the opportunity for people to start fires — either intentionally or accidentally — increases.

There’s also the fact that, in the United States, we’ve excluded fires from areas where they occur naturally for about a century, allowing vegetation to build up. That suppression makes these habitats more susceptible to larger and more intense fires when they do occur.

Climate change may also be a factor, since increasing temperatures and changes in rainfall and lightning patterns can increase the length and intensity of fire seasons.

Nature.org: Wildfires cause a lot of destruction every year across the United States. So shouldn’t we stop wildfires from burning?

Ayn Shlisky: Putting out wildfires — what we call “suppression” -- is often necessary to protect human life, property, and species and habitats that are unable to withstand fire.

But it’s also important to recognize that in many places, fire plays an integral role in maintaining ecosystems. Almost all U.S. ecosystems — forests, woodlands, shrublands and grasslands — developed over long periods with fire at some frequency and, hence, are fire-dependent.

Stopping fire from burning in some of these habitats over decades has damaged environmental health, affecting species such as the endangered Karner Blue butterfly, which needs fire to maintain the prairies where it lives. Without fire, shrubs and trees can invade prairies, eventually converting them into shrublands and forests.

Similarly, excluding fires from “woodland” habitats that naturally experienced frequent but low-intensity fire can produce unnaturally dense thickets that are eventually destroyed rather than rejuvenated by fire. Such unnatural fires leave behind sediment that can contaminate fresh water — and they can also be harder to control, posing a greater threat to fire fighters, communities and property. Fire exclusion contributed to the damaging wildfires that affected Southern California in 2003. More than 750,000 acres burned, claiming 24 lives, causing over 200 injuries and leaving more than 3,000 families homeless. The economic cost was more than $2.5 billion.

Clearly, even in fire-dependent habitats, we can’t let all fires burn because they can pose a threat to local communities. But we can let some wildfires burn under closely monitored conditions, and in many places, careful prescribed burning can be used to maintain fire’s ecological role while also protecting livelihoods from uncontrollable wildfires.

Nature.org: Is  starting prescribed fires inherently very dangerous?

Ayn Shlisky: There is no doubt that lighting fires brings with it an inherent level of risk. But trying to keep fire out of habitats that are naturally predisposed to burn can also pose ecological and social risks.

To maintain environmental health, the Conservancy burns about 100,000 acres of our own land every year and assists in prescribed burning on over 150,000 acres each year on the lands of our partners. We have more than 100 fire-trained staff in more than 35 states that meet or exceed the U.S. federal fire management standards, and our record of success in implementing safe prescribed burning is one of the nation’s best.

Successful prescribed burning programs have helped maintain and restore pine and oak forests in Arkansas, longleaf pine forests in Florida, Georgia and the Carolinas, grasslands across the Great Plains and several other types of habitat. The Conservancy is also rapidly expanding the on-the-ground fire management capacity of staff and partners in Latin America and the Caribbean.

Since prescribed burning occurs under carefully planned, pre-determined conditions, it is often less risky to carry out a prescribed burn than to wait for the inevitable incidence of a natural fire — which may occur when weather conditions make it difficult to control. 

Nature.org: How can you balance the importance of fire in maintaining landscapes with the risks posed to communities who live there?

Ayn Shlisky: Any approach to managing the role of fire must weigh all the potential positive and negative impacts to both people and the environment. The Conservancy has developed an approach called Integrated Fire Management, which provides a framework for evaluating the social, economic and ecological impacts of fire and helps people generate practical solutions to managing fire-related threats to nature.

For example, in Chiapas, Mexico, the Conservancy and partners are working with two rural communities in La Sepultura Biosphere Reserve, where frequent fires started by the communities to clear land for farming were damaging forest resources. Today these communities have fire management plans that specify where and how frequently fires are allowed to burn — and they are even using controlled fires to promote regeneration in some of their fire-dependent pine forests.

Nature.org: How does the issue of fire in the United States compare to other countries around the world?

Ayn Shlisky: The fire issues we face in the United States are not unique. More than one-half of the world’s terrestrial habitats are fire-dependent. And fire is behaving differently today globally than at any other time in human history.

The Conservancy has recently led a piece of research which demonstrates that fire has been altered significantly from its natural frequency and pattern in over 60 percent of lands assessed around the world. For example, habitats that are unable to withstand burning — such as wet tropical rainforests — are being decimated as a result of human-caused fires. As in the United States, human actions (including urban development, agriculture and fire suppression) are some of the main causes. And these issues are being further complicated by factors such as climate change and non native plant invasions.

Bottom line: Fire is a serious conservation issue both in the United States and around the world. The Conservancy is working to help governments, landowners and communities develop solutions that restore the natural balance of fire in landscapes to benefit both people and nature.

Nature picture credits (top to bottom, left to right): Photo © Ron Myers/TNC (prescribed burn Arizona); Photo © G Bailey/TNC (Ayn Shlisky); Jim Brandenburg/Minden Pictures (Jack Pine Seedling).