FIre’s Role in the Environment
Since pre-history, fire has played an important role in the environment. The study of fire’s effects on the environment is called fire ecology. Fire ecology focuses on the origins of wild land fire and its relationships to the environment around it. Wild land fire is any fire burning in a natural environment. Fire is a natural process, and its factors are plants, animals, fire history, fire regime, and fire’s effects. Studies show that environments develop a dependence on fire based on its recurrence and benefits. Although most people see fire in a negative manner, there are more benefits than disadvantages of fire.
In order to understand fire’s role in the ecosystem, there has to be a basic understanding of fire. Humans have caused about 90 percent of fires in the last ten years (Pacific Biodiversity Institute). This includes fires that have been caused by sparks, cigarettes, campfires, and also arson. The remaining ten percent of fires have been caused naturally through lightning. Next, fires influence the composition of a forest. When a fire comes through an ecosystem, depending on the regime, it can leave different vegetation types dead and some unharmed (Frissel). The third important key in understanding fire is understanding fire regimes. Fire regimes can be defined as the nature of a fire and it’s effects on an ecosystem (Smith).
Moreover, there are three main fire regimes. Understory fires are not lethal nor do they significantly change an environment. Also, 80 percent of above ground vegetation survives in an understory fire (Smith). Next, there are the stand-replacement fires. These fires kill most above ground vegetation, consuming at least 80 percent of it (Smith). The final fire regime is that of mixed-severity fires. These are known for ranging on a wide scale of consumption of vegetation. Another term for this is selective mortality. Fire regimes also vary in frequency, season, size, and effects. Over long periods of time, a general pattern occurs in fires. Fires are highly variable, therefore descriptions of regimes are broad (Smith). Finally, fire regimes can be influenced by the land a fire occurs on, wind, and the areas history of fire (Pacific Biodiversity Institute).
Because fire is a natural process, many species and plants rely on fire, counting on it for growth, regeneration, and evolution (Pacific Biodiversity Institute). With regular occurrence, fire reduces the build up of fuel for fires, lowering the chance of a large wild land fire. Also, fire speeds up growth by creating an open, clean seedbed for vegetation. It also makes more nutrients useful by removing harmful plants and plants that are not indigenous to that area. Fire has played a role in the ecosystem as long as there has been vegetation (Brown). It is known today through deposits of charcoal that fire has been around for a long time. Based on the surrounding environment, fires can occur in different intervals. Climate and vegetation play major roles in the recurrence of fire. For example, southern pine ecosystems can expect natural fires every two to five years while an alpine tundra ecosystem only has natural fires every 500 to 1000 years (Brown).
Fire has different effects on different organisms. Fire can affect vegetation’s composition, structure, and function. Usually, these effects are easier to see in short-term fire interval areas (Weise). With regular occurrence, trees must build up a resistance to fires. The taller a tree gets, the more resistant it becomes to mortality during the event of a fire. This occurs because the bark thickens and the tree’s stem’s diameters increase as well. This theory works conversely with smaller trees. They tend to develop much less resistance to fires than larger, taller trees (Brown). Fire plays an important part in the ecological process as well. It does so by changing the microclimate, increasing the range of soil temperature, changing the nutrients in soil, regenerating vegetation, succeeding new vegetation patterns, changing plant growth rates, altering wildlife habitats and the activity of animals, and changing the water storage capacity and pattern of runoff (Brown).
In the occasion of regular fire occurrence, plants change in structure, composition, and their reactions to changing temperatures. While fire can cause plants to die, it can also cause plants to respond positively to changing climates. In some cases, fire has even become dependent on fire due to long term exposure (Brown). Not only does fire rapidly increase the positive response of plants to changing climate, but fire also can change the overall climate of a region. This can affect vegetation’s physical make up along with its life cycle. Fire can change an environment’s climate through radiation, humidity, precipitation, temperature, and wind (Brown). All vegetation in an environment has to to with the climate around it. As a climate changes, so does the vegetation in that area.
One of the negative effects of fire is plant mortality. Wether or not a plant is killed by fire depends on the heat of the fire. A lower temperature fire, normally an understory regime, will take longer to kill a plant. But, a stand-replacement fire will take significantly less time to kill vegetation. Just like any other organism, vegetation is more susceptible to damage when growing (Brown). Although these plants die, it is not always a negative effect. Post-fire sprouting can be very beneficial to an ecosystem. Structures on plants such as sprouts and buds are there before a fire occurs. However, these are almost always destroyed during a fire. Also present pre-fire are growth hormones. When buds are destroyed, a higher level of growth hormones is released and this allows plants to sprout faster and healthier (Brown).
Fire also has an effect on both large and small animals. However, a low percentage of animals are killed during a fire. Temperatures of at least 145 degrees Fahrenheit are lethal to smaller animals and this temperature does not vary greatly for larger animals. Most fires do have the potential to kill animals (Smith, 17). The animals that are normally mortally wounded by fires are those without much mobility. Large animals are rarely, but sometimes killed by fires. When it comes to mammals, survival depends almost entirely on mobility. Most find safety in a shelter or underground. A larger animal such as an elk will be less likely to panic in the case of a fire (Smith, 18). A bird’s survival in a fire depends on its age and the severity of the fire. Adult birds have a low mortality rate, while young birds are more likely to die because of the high level of nest destruction in fires (Smith, 18). A reptile or amphibian will have a low mortality rate regardless of their low mobility. This is because their habitats are less likely to burn (Smith, 20).
Fire can make a difference in animal populations as well. There is a direct correlation in fire density and animal population. There are long term and short term changes due to fires, such as without fire, oak trees will eventually become to tall and dense, negatively effecting the blue jay population (Smith, 25). When it comes to immigration and emigration, many animals are attracted to fire. The main reason for this immigration is food resources (Smith, 21). Most mammals occasionally immigrate to find food and shelter and different species can move into burned areas. Large animals usually move to burned areas for food sources and they sometimes move because of familiarity with the area pre-fire (Smith, 23). Few species of birds are attracted to burning areas. The most common types of birds that are attracted to burned areas are scavengers and predators (Smith, 22). However, lots of animals emigrate because of the lack of their particular food or resource needed for survival. Large mammals relying on plants for food must leave that area when fires kill off all of their food resources. Elk, caribou, and deer usually leave when understory vegetation is completely consumed (Smith, 21). Finally, birds leave areas that have been exposed to fires in order to avoid injury. But, others come to an area to take advantage of the altered habitat (Smith, 21).
In today’s world, the environment must be taken care of by humans. An ecological approach for resource stewardship and managing forests is called ecosystem management. In order to keep the world healthy and functional, humans must sustain resources for the future. Some ecosystems are naturally managed through fire (Weise, 139). Because fire can be dangerous to humans, there are certain techniques used to suppress fire. Silvicultural thinning is a controversial, and sometimes unsuccessful method used to suppress fires. This thinning method basically is carried out by logging small-diameter trees (Pacific Biodiversity Institute). Thinning is a controversial topic because it is not ecologically sound nor does it always benefit an environment in the case of a fire. Studies have shown that silvicultural thinning can lead to drier forests and higher winds.
In conclusion, the benefits of fire significantly outweigh the disadvantages. Fire accelerates the growth of plants and, over time, can lead to healthier animal populations. Very seldom is fire recognized as a good thing. As a society, people must see that even though fire can be damaging to an urban setting, it is incredibly helpful to an entire forests ecology. Animals benefit greatly through food and resources being made easier to obtain, and plants benefit through amplified sprouting. In order to thrive, many environments rely on fire. All in all, the societal outlook on fire does not reflect the truth, and fire is a great service to the environment.