How Does Fire Effect the Ecosystem?
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Disturbance
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Ironically, the stability of ecosystems relies on disturbance. Natural disturbances like fire and wind shaped environments, and in turn, influenced the wildlife that would inhabit an ecosystem. Some ecosystems like pine forests and tall-grass prairie fail to survive in the absence of fire. Fire suppression in pine forests can make the ecosystem less resilient when fire does occur.
Fire and Plant Nutrition
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Fire is a re-generator of nutrients. Nutrients locked up in plant biomass or living mass are returned to the soil and recycled. Fire stimulates the growth of nitrogen-fixing legumes such as clover. These plants are able to use atmospheric nitrogen and return it to the soil, thus improving its health. A resurge of plant growth soon follows.
Frequent fire has had direct effects on the nutritional quality of available forage that have then influenced the grazing patterns of herbivores. The interactive effects of fire and plant eaters have been a major determinant of species' richness and diversity. Fire on native prairie is a frequent event. The highly-combustible nature of the grasses allows for easy ignition and rapid spread of fire. In addition, the lack of woody vegetation makes for a relatively cool and minimally-destructive fire.
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Prairie Management
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Lighting is the primary cause of fire. Native Americans used fire extensively for wildlife management of bison herds and during times of war. While they recognized and exploited the benefits of fire, Americans today have been trying to control this natural phenomenon for the past 50 years, perhaps to the demise of the prairie.
Big bluestem is a common prairie grass that is well-adapted to the sometimes arid conditions. Long, underground roots stems protect the life of the plant and ensure availability of water. Without these extensive root networks, non-native species such as Timothy are weakened from the effects of fire. Consequently, the dominance of prairie grasses is ensured by enhancing the competitive edge.
Forest Management
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Pine forests are similarly adapted. Pre-settlement forests also experience frequent fires. A hot ground fire removes forest floor litter, allowing the sun to warm the soil temperature. For some plants, a higher temperature is needed for seeds to sprout, thus regenerating the vegetation. Some trees such as Jack pine are able to reproduce when fire temperatures reach levels that can force open their tightly-clutched cones.
There is a risk to the ecosystem if fires are suppressed. Biomass, whether it is in the prairie or in a forest, can build up to greater levels. Fire will occur at some point due to lightning. Fires in these areas are hotter, more destructive fires that can kill plant life above and below ground to a point where recovery may take decades. These fires are harder to control and are more likely to become wildfires.
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