Fire, to we humans, is a paradox. It is both friend and foe
We need fire, yet it can destroy us. In Nature, fire is a positive force. Fire is an important part of forest and grassland ecology. It is a force in Nature that provides new and restored connections. Paradoxically, the destructive nature of fire is its great strength. Fire is a transformational force that Nature requires in order to bring health to ecosystems. This lesson was learned by humans only in recent times.
Forest fires have the following benefits:
- Clear out dead branches and leaves
- Some plants seeds only germinate after a fire
- New growth is low to the ground and accessible to animals for food
- Dead trees are removed
- The burned areas are suitable for new species of animals
- Minerals are returned to the soil. When the fire burns the organic material in the forest, nutrient rich ash is left behind. When the first rain comes, the nutrients in the ash dissolve into the soil for the new plants to use. This process is called nutrient recycling. These nutrients left in the soil are a good source of food for the young plants that will begin to grow back.
Campaigns in the United States have historically molded public opinion to believe that wildfires are always harmful to Nature. This view is based on the erroneous belief that ecosystems progress toward an equilibrium and that any disturbance, such as fire, disrupts the harmony of nature. More recent ecological research has shown, however, that fire is an integral component in the function and biodiversity of many natural habitats, and that the organisms within these communities have adapted to withstand, and even to exploit, natural wildfire. More generally, fire is now regarded as a ‘natural disturbance’, similar to flooding, wind-storms, and landslides, that has driven the evolution of species and controls the characteristics of ecosystems.
Fire prevention and suppression in forests and grasslands was started to protect the timber and cattle industries as well as human property. It was also believed that by suppressing fires, man ensured a healthy future for the forest or grassland. But, these ideas were proven to be wrong. Fire suppression was misunderstood. The effect of human fire suppression over many years resulted in a high density of trees and ground cover in forests and grasslands. In turn, this high density caused far more destructive fires when they did occur.
Science that has revealed important and intricate connections between fire and Nature’s ecosystems
However, the benefits of occasional fires became understood. Fire ecology is a recent science that is devoted to the study of fire in forests and grasslands. It is a science that has revealed important and intricate connections in Nature within forest and grassland ecosystems. One consideration has been the connection of humans. While humanity demands protection from fire damage, forests and grasslands need fire. One way to balance these seemingly opposite needs is to employ human initiated controlled burning. There is not yet a consensus on the wisdom of this approach to balancing the needs of man with the needs of other ecosystems. The key, of course, is to understand the effects of any action on the vital connections that sustain healthy ecosystems.
As homes are built closer and closer to national parks, grasslands, and forests, fire suppression becomes an important issue for the citizens of the region. All of the agencies involved have tried to balance fire suppression with fire management, frequently with controlled fires
As scientists gathered more information on the effects of fire on forest and grassland ecosystems, they learned that fire exclusion might not be a healthy choice for forests and grasslands. Today it is known that fire exclusion causes thick vegetation and large amounts of dead fallen materials. The heavy vegetation and dead material increase the fuel quantity on the forest floor and may cause fires to ignite more easily. When a fire does begin on the thickly covered floor, the blaze burns at a much higher intensity causing more damage to the forest ecosystem. Not only does fire exclusion cause an accumulation of thick vegetation on the forest floor, but also causes an increased density of smaller trees. When fire does occur, these small trees guide the raging fire from the forest floor to the crown of the older trees causing a crown fire. Instead of burning slowly and low to the ground, fires burned hot and high in the crowns of the trees and travel quickly from tree to tree, These fires are more difficult to contain once started.
Fires, both natural and human-caused, are important in maintaining grasslands. Ancient hunting peoples set regular fires to maintain and extend grasslands, and prevent fire-intolerant trees and shrubs from taking over. Grasses are able to survive fires because they grow from the bottom instead of the top. The occasional fires common in grasslands keep the number of trees and shrubs there low. Grass fires destroys trees and saplings because most of their mass is above ground and therefore vulnerable to fire. But grasses have most of their mass below ground, which helps them survive in periods of rainfall. Fires thereby remove species that compete with grasses for resources. Another benefit of fires is that they burn away the layer of dead grass that accumulates during the year, converting it to valuable nutrients. The nutrients act as fertilizer, giving grasslands a deep fertile soil held in place by grass roots. Heat from fires also aids the germination of many grass seeds.
Many ecosystems, particularly prairie,savanna, chaparral and conifer forests have evolved with fire as a natural and necessary contributor to habitat vitality and renewal. Many plant species in naturally fire-affected environments require fire to germinate, to establish, or to reproduce, or all three. Fire suppression not only eliminates these species, but also the animals that depend upon them. Finally, fire suppression can lead to the build-up of inflammable debris and the creation of less frequent but much larger and destructive wildfires.
So why not just let things burn?
The fact is that fire is inconvenient to the human race. Fire can cause structure loss. This begs the question regarding the balance between human needs and the needs of Nature.
This essay has focused on fire from the perspective of Nature. Marcia Penner Freedman, a resident of a forest in California where fire is a regular companion, gives us some human perspective in her article in the Fresno Bee “We Choose To Live With Certainty Of Fire”
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