55, May/June 2004
Fire Ecology II
In this issue of the Arid Lands Newsletter we continue to consider the role of fire in Earth's arid regions, this time with more emphasis on developing trends in fire effects, fire regimes and fire management. First, we turn to Africa, with an article by Winston Trollope and Lynne Trollope (University of Fort Hare, South Africa) on the use of prescribed burning for wildlife management in African grasslands and savannas. In its description of three such burning systems, the article touches on two particular points that increasingly affect the development of fire management policies around the world:
Of the three systems described in this article, the range condition burning system is recommended as most effective. This system bases its use of prescribed fire on the local vegetation's condition and known response to fire effects. The article provides detailed recommendations for applying all three systems described; while specific to Africa, these recommendations may also be useful to land managers in other savanna/grassland areas where large herbivores are a significant element in the landscape.
Next, using the Mojave National Preserve of the southwestern U.S. as their focus, Matt Brooks and colleagues (U.S. Geological Survey) outline a relatively low-cost method for using existing vegetation and slope data to develop fuel and fire hazard maps for desert ecosystems. Such maps are an important tool for land managers, allowing them to anticipate where the danger of undesirable fires is greatest and thus to take steps to prevent these fires entirely or to reduce their negative impacts when they do occur. As the authors point out, maps of this type do not currently exist for many arid regions in North America (or elsewhere). This is because fires in these regions have historically been infrequent: the native desert vegetation simply does not support them. This "fire immunity" is now disappearing due to an increasing number of human-caused fires and a growing prevalence of fine fuels in the shape of invasive alien grasses.
That this latter factor is of increasing concern was borne out by several presentations attended by the ALN editor at the 2002 Ecological Society of America/Society for Ecological Restoration (ESA/SER) joint meetings in Tucson, Arizona. In one talk, for example, Dave Richardson of the University of Cape Town, South Africa, addressed the key role of "transformer species" in changing fire regimes (1). These are invasive species that can change the character or condition of a given ecosystem over a substantial portion of that ecosystem's area; the most damaging transformer species are those that change the nature of the very disturbance regime (i.e. fire) that gave them a foothold in the first place.
At the same meetings, Alberto Burquez of the National Autonomous University of Mexico, Hermosillo, provided an example of this kind of species in his presentation on the growing impact of buffel grass (Cenchrus ciliaris) on the Sonoran Desert of southwestern North America (2). Buffel grass, native to Africa, spreads easily, is highly resistant to grazing pressure, and is considered desirable forage for cattle. Consequently, it has been widely planted particularly in the Mexican portion of the Sonoran Desert, where cattle ranching is an important economic activity. Unfortunately, when buffel grass is not grazed, it burns, with devastating effect on the native, non-fire-adapted, desert vegetation. Dr. Burquez stated that, if not checked, this grass could potentially invade the entire Sonoran Desert, transforming it from diverse desert to monocultural grassland, with huge loss of biodiversity. Socioeconomic factors greatly increase the complexity of the problem: a key factor driving the spread of buffel grass in the state of Sonora is a shift within Mexico from communal to private land ownership and from a subsistence to a market-based economy. This shift is being promoted by Mexican government policy. Quite understandably, when the land is privatized, people want to clear it and plant buffel grass so they can raise beef to sell to the U.S. market. This example clearly shows that successful fire management policy must take socioeconomic as well as ecological factors into account.
More and more, in fact, local community involvement is being recognized as crucial to successful fire management policy, particularly in rural areas. In the U.S., one response has been the development of the national Firewise Program and its implementation on a state-by-state basis. In the third article of this issue, Alix Rogstad (Cooperative Extension Service, University of Arizona) provides an overview of this program, its genesis, and its particular development within the State of Arizona. She begins with a brief, cogent overview of the past hundred years of fire management policy in the U.S.: an aggressive policy of fire suppression that, together with land use changes, has led to an excessive and dangerous buildup of fuels on the landscape. At the same time, urban expansion and the growing desire of many urban dwellers to live "closer to nature" has led to growing numbers of homes and businesses being located in what used to be rural, wildland areas. Such areas have come to be known as the wildland-urban interface (WUI). The explosion of WUI settlements has had the effect of exposing vastly greater populations to the possibility of wildfires and straining local firefighting capabilities to their utmost. In response, U.S. federal agencies with firefighting responsibilities developed the Firewise Program, with the overall goal of teaching WUI residents how to keep their property fire-ready so that firefighters can deploy their resources as effectively as possible during wildfires. Within Arizona, the program has been in effect for almost two years and is already bearing encouraging fruit.
Next, Rick DeIaco, head of Ruidoso Forestry, presents a case study from Ruidoso, New Mexico, detailing the evolution of that community's forest health and community fire management plan. The initial impetus for Ruidoso's fire management plan came in the 1990s, from a local citizen's group working together with the New Mexico Division of Forestry; by 2000, these grass-roots efforts had led to the establishment of the Ruidoso Wildland Urban Interface Group and the development of an overall forest health and wildfire prevention plan for the Ruidoso WUI. This plan emphasizes maintenance of forest health as the cornerstone of successful fire management. Since 2002, the Ruidoso Community Forest Management Plan has incorporated basic concepts, guidelines and resources developed through the Firewise Program. Throughout the process, getting the entire community involved in developing and implementing the plan has been crucial to its success. Another factor in the plan's success has been its ability to create economic opportunities for local businesses based on the need to maintain forest health.
That community involvement is crucial to rural fire management is also evident in the next article, which chronicles the development of a community-based fire management plan in Bukombe District, located in the Shinyanga region of northwestern Tanzania. As author Edwin Nssoko (head of Fire Protection, HASHI Project) relates, this is an area which was covered by miombo woodlands, dominated by leguminous species, until about the 1920s, when large areas were deforested in an attempt to control tsetse flies and other pests as well as to clear land for commercial crops. Unfortunately, the deforestation caused land degradation whose effects still persist. Since 1986, the HASHI Project has worked with local populations to halt and reverse this degradation, while also improving local economic conditions and promoting biodiversity. Within this context, local communities have also developed fire management plans that draw on local knowledge and traditional land use practices, strengthen community self-organizing skills, and provide local employment. Results of the program are encouraging, but increased security of land tenure, improved collection of fire-related data, and establishment of a nationwide fire policy would further enhance fire management activities within the district and the nation as a whole.
Finally, Stephen Pyne of Arizona State University discusses the fire ecology of industrial combustion: what he has called "third fire" (where "first fire" is fire caused by natural causes such as lightning and "second fire" is human-caused open fire in the landscape.) As Pyne points out, these three kinds of fire now compete with each other, and understanding "How they do so may be the most fundamental three-body problem in fire scholarship."
It is in fact this concept of "third fire" that comes full circle and explains why fire is of concern even in the most hyper-arid environments. While such environments may never be subject to the direct ravages of wildfire, they most certainly can be subject to the long-range, long-term effects of biomass burning, whether living or fossilized. The effects of industrial, fossil-fuel burning are of course increasingly recognized in the overall impacts of greenhouse gases and global warming. The burning of fossil fuels is one of the major factors in rising concentrations of greenhouse gases in the atmosphere and it is increasingly recognized that biomass burning, such as that from agricultural field burning or even cooking fires, also releases significant quantities of carbon to the atmosphere. Global warming in turn may cause feedback loops that promote the spread of invasive species and change local and regional fire regimes, perhaps irrevocably. Furthermore, greenhouse gases are not the only byproducts of combustion that affect climate at local and regional scales; other aerosols emitted during burning can also have wide ranging effects such as changing rainfall patterns in areas far downwind from where the aerosols were emitted (3). Perhaps even more ominous, recent regional climate models suggest that black carbon aerosol emissions from both living and fossil biomass burning in India and China may be contributing to a tendency towards increased summer floods in southern China and increased drought in northern China (4).
In sum, humans and fire are inextricably linked, and the large-scale effects of fire can be felt even where living wildfires may never be present. But, until now, most fire research has focused on single aspects of fire, such as its effects on vegetation cover, or the effects of land use change on fire regimes. It is imperative that fire research move beyond this fragmented focus to a more integrated approach if we are to arrive at a thorough understanding of fire's character and processes, and to be able to moderate these processes so that their effects are more benign. As Pyne states, "It is worth an attempt."
(1) Richardson, Dave. Impacts of invasive alien species on fire regimes. Paper presented at the joint ESA/SER Annual Meetings, Tucson, Arizona, August 4-9, 2002. (Back to text)
(2) Burquez, Alberto. Effects of buffel grass invasion on Sonoran Desert plant communities. Paper presented at the joint ESA/SER 2002 Annual Meetings, Tucson, Arizona, August 4-9, 2002. (Back to text)
(3) See, for example: Rosenfeld, D. Smoke and desert dust stifle rainfall, contribute to drought and desertification. Arid Lands Newsletter 49, May/June 2001. http://ag.arizona.edu/oals/ALN/aln49/rosenfeld.html. (Back to text)
(4) See, for example: Menon, S., J. Hansen, L. Nazarenko, Y. Luo. 2002. Climate effects of black carbon aerosols in China and India. Science 297:2250-2253. (Back to text)
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