My inquiry question is: “How should government funding be used for the prevention of wildfires?” I’m currently researching what kind of impact wildfires have on different aspects of the environment so I can get a better idea of how I think government funding should be used based on that, and other factors that I will later research in the next cycle.
In my last round of research, I researched both the negative and positive effects wildfires can have on the vegetation and wildlife. This week, I will be looking into the impact wildfires have on the soil and surrounding water.
- The soils in forests are rich in nutrients from decaying forest debris (1, 2, 3). They contain several natural features that support innumerable life forms and organic activities (2, 3). Wildfires may kill helpful soil microorganisms that have the role of breaking down the soil and encouraging soil microbial activities (2). The extreme temperatures wildfires bring to these soils can potentially destroy the nutritive and organic value of the soil almost entirely (1, 2, 3).
- The impact that wildfires have on the soil depends on how much heat is transferred to the ground of the burning area. However, it’s not necessarily the high-intensity fires that have the most amount of impact on the soil. In fact, sometimes high-intensity fires will move fast through the tree canopies and have a smaller impact on the soil compared to low-intensity fires that burn close to the ground for a longer amount of time. Therefore, rather than looking at the intensity of the wildfire, it would be more useful to look at the severity of the burn in order to determine the impact on the soil. The severity of the fire explains the effects that the fire has on different elements of the ecosystem, including the physical, chemical and biological properties (4). If any of the properties are disturbed, it can affect the nutrients in the soil (1, 2, 3, 4), cause soil erosion (1, 4, 5, 6), or change how much water the soil is able to retain (4).
- There was a study done that looked at how the soil organic matter content, composition and nutrients changed after a fire in 1999 in a boreal ecosystem in Alaska. What they found is that a year after the wildfire, burned soils had 1071 to 1040 g/m^2 less carbon than soils that weren’t burned. Burned soils also had less nitrogen, more calcium, and almost the same amount of potassium, magnesium and phosphoric stocks. Burned surface soils tended to contain higher concentrations of non-combustible elements like calcium, potassium, magnesium and phosphorus. The chemistry of the deeper layers of soil in both burned and unburned areas were similar, which suggests that the immediate effects of the fire were restricted to the surface soil horizon (7).
- The reason why the amount of carbon in the soil after the fire is significant is because soil organic carbon is linked to soil fertility. It’s a part of the natural carbon cycle, and Earth’s soils have nearly twice as much carbon than what is found in the atmosphere and vegetation. Organic material is made by plants using the carbon dioxide from the air and water. Plants and animals die and are decomposed and recycled, returning to the soil where minerals are released, while carbon dioxide is released into the air. Larger amounts of soil organic carbon is beneficial because it helps diminish climate change by reducing the amount in the atmosphere, and it improves soil fertility and health (8).
- The elements found in the soil are also important because they are soil macronutrients, and it is crucial for plant growth and nutrition is needed in large amounts. They impact productivity of the site and vegetation dynamics. In plants, nitrogen has the function of proteins and amino acids, phosphorus serves as nucleic acids, and potassium is a catalyst and ion transport (9).
- Due to fewer trees and plants after a wildfire (4, 10), rain cannot be trapped and soaked into the ground as much. As a result, there is a higher surface runoff and increased erosion which raises water quantity yet lowers the quality of the water (5, 9, 10, 11).
- Wildfires may cause several substances to be released from the soil and into drinking water sources, causing contamination. Significant changes that may occur in source water quality after a wildfire can have effects on water treatment processes. Examples of these changes are enhanced mobilization of nutrients, sediments and dissolved organic carbon (DOC), which can affect the capability of drinking water utilities to make water that meets Environmental Protection Agency (EPA) standards. Based on studies done at the University of Colorado, up to a point, when the soil becomes warmer, more compounds containing carbon and nitrogen are released from the soils. Generally characterized as DOC, these compounds may react with chemicals used to purify water and hence be turned into disinfection byproducts (DBP’s), and you don’t want that in drinking water. However, they were surprised to find out that as they increased the severity of the wildfire, the quantity of DOC the soil released decreased, so you could also actually end up with more sediments in the source waters (12).
- Excessive precipitation and/or snowmelt in addition to fewer trees may contribute to flooding and mudslides. The impact these floods can have after a wildfire can be made worse by debris flows containing lots of soil, rocks and trees from an area affected by a wildfire (10).
- Moreover, if it rains after a wildfire, the ash and soot created by the wildfire may be flushed through a watershed. Sediment can alter the structure and function of a stream, the long-term effects of the fire and sediment depending on the characteristics of the watershed (lakes, rivers), the severity and reoccurrence of rainfall after the fire. Headwater reaches will go through erosion and may become unstable, whereas more flat downstream reaches will gain sediment and the fine material can clog it (10).
That’s it for this week! Next I will be doing my metamorphosis for this cycle, then after that, I plan to research how wildfires might pollute the air, and if wildfires may be linked to climate change. Any suggestions, comments or websites are welcome. Thanks!