Competition With Fire

Plant-Plant Interactions With Fire

In this blog I will be discussing the interactions between plants and fire. Aldo Leopold is considered to be the godfather of conservation and has left a major impact on the wildlife techniques that we use today. Leopold had five wildlife management techniques. These techniques were an axe, cow, plow, match, and a gun.  Aldo Leopold once said, “Fire has always been part and parcel of the evolutionary background of our present species in many regions.” Prescribed fires are commonly used to promote plant growth and set back succession. Wildfires are fires that are burning out of containment and can have various intensities. While some people view fire as a detrimental thing to the environment, it can be very beneficial. For example, the Great Smoky Mountain wildfire destroyed many homes and businesses but it could result in the betterment of some of the ecosystems that were burned. Many plant species rely on fire for their existence. These plants have many adaptations that help them survive these fires. A few of these adaptations include serotinous cones and thick bark. Fires also clear debris from the soil’s surface allowing for seeds to be in contact with bare mineral soil. Fire can have a major impact on the environment in many ways. If you have never seen an area that has recently been burned, then you are in for a treat. What was once a place that was not anesthetically pleasing and covered in plant litter becomes a magnificent field of green plants emerging from the ground. Fire impacts plant-plant interactions by allowing more sunlight to reach the ground and by decreasing competition.

Many plant species have different light tolerance. Some species may be shade intolerant while others may be shade tolerant. It is up to the management objectives to determine what species composition that they want. If an early successional/shade intolerant ecosystem is desired, then prescribed fire can be a very useful tool to achieve those conditions. According to the Oxford Dictionary, competition refers to the “negative effects caused by the presence of neighbors, usually by reducing the availability of resources.” Plants generally need water, light, phosphorus, and nitrogen to survive. If plants don’t have these resources or other plants are using up most of those resources, then those plants will most likely die off. One of the most important factors that control plant communities is competition (Bond et al. 1997).  Fire helps reduce plant competition by eliminating the majority of the mid-story and understory of the ecosystem, which creates an increase in light penetrating to the forest floor. A more intense fire can cause a significant change of woody vegetation on the ecosystem (Langevelde et al. 2003). In 1966, the use of prescribed burning was eliminated at Tall Timbers Research Station in Tallahassee, Florida. After the first fifteen years of fire exclusion, the changes in wildlife abundance and vegetation were obvious. The amount of groundcover decreased from 85% to 21%, while the canopy cover increased from 43% to 91% (Engstrom et al. 1984).  Fire can indirectly reduce the potential of future mortality through decreasing competitive and self-shading pressure (Zimmermann et al. 2010). Fire can also decrease plant cover, biomass and density of grass layers (Drewa et al. 2001). Fire is used in many savannas and grasslands to stimulate plant growth and control woody plant densities (McPherson, 1995).

So why do we care about plant-plant interactions with fire? Plants need resources such as water, light, phosphorus, and nitrogen to survive. Fire can be used to remove plants and open up space on the ground. This open space can then be colonized by plants of the same or different species (Begon et al. 1990). Fire can stimulate many plant species creating enhanced seed germination, flowering, and seedling recruitment (Bond et al. 1997). Fire can help certain ecosystems strive in many ways. Not only does fire have the ability to increase herbivory, it can influence plant survival and growth (Crawley, 1983). Many plant species depend on fire for reproduction, and without the presence of fire many of these plants could become extinct. A few of these plant species include longleaf pines, wiregrass, and giant sequoias. It is very important to understand that many plant and animal species depend on fire. If an ecosystem has less competition, then many fire dependent plants can colonize the area. Fire has the ability to set back succession and promote plant growth. Fire can be used in a variety of ways such as agriculture, woodlands, and fields. Fire has also been used as a management tool to restore native grasslands. Fire is a very useful tool that can be used to reduce plant competition and boost plant growth. The species composition that emerges after a fire can also benefit wildlife.

A study performed by Zimmermann et al. showed that increased standing dead biomass was associated with increased tuft mortality through the presence of fire (Figure 1). Fire reduced the standing dead biomass and created a less competitive environment.

Figure 1.

Predicted tuft mortality depending on neighbor abundance quantified by the living basal area of neighbors (NA_LBA), standing dead biomass (SDB) and fire.

My research on plant-plant interactions with fire has given me a better understanding of how fire impacts plants. I have concluded that these interactions can be attributed to three key points. 1) Fire can remove debris and litter from the ground that allows for plants to establish. 2) Fire intensity is crucial for determining desired species composition. 3) Fire can help reduce competition by killing some plants and allowing sunlight to reach the ground. Fire impacts the environment through the changes in plant communities and reducing plant competition. Fire can have a major impact on the environment in both positive and negative ways. The use of fire has been used as a management tool for hundreds of years. I have personally used prescribed fires to burn around 2,000 acres, and I have seen how many ecosystems strive after the application of fire. However, wildfires can create a problem for the environment. I have found through my research that the changes in plant communities and competition are related to fire.

Literature Cited

Engstrom, R.T., R. L. Crawford and W. W. Baker. 1984. Breeding bird populations in relation to changing forest structure following fire exclusion: A 15-year study. Wilson Bull. 96: 437-450.

Van Langevelde, Frank, et al. "Effects of fire and herbivory on the stability of savanna ecosystems." Ecology 84.2 (2003): 337-350.

P.B. Drewa, K.M. Havstad Effects of fire, grazing, and the presence of shrubs on Chihuahuan desert grasslands Journal of Arid Environments, 48 (2001), pp. 429–443

G.R. McPherson The role of fire in the desert grasslands M.P. McClaran, T.R. van Devender (Eds.), The Desert Grassland, The University of Arizona Press, Tucson (1995), pp. 130–151

 Zimmermann J., Higgins S., Grimm V. Grass mortality in semi-arid savanna: The role of fire, competition and self-shading. Perspectives in Plant Ecology, Evolution and Systematics. 12.1 (2010), pp. 1-8.

W.J. Bond Fire R. Cowling, D. Richardson, S. Pierce (Eds.), Vegetation of Southern Africa, Cambridge University Press, Cambridge (1997), pp. 421–446

Begon, M., J. L. Harper, and C. R. Townsend. "Ecology: Individuals." Populations and (1990).

Crawley, Michael J. Herbivory. The dynamics of animal--plant interactions. Blackwell Scientific Publications, 1983.

Plant-biotic Interactions with Fire

Plant-Biotic Interactions With Fire

In this blog I will be discussing the interactions between plants and fire. Aldo Leopold is considered to be the godfather of conservation and has left a major impact on the wildlife techniques that we use today. Leopold had five wildlife management techniques. These techniques were an axe, cow, plow, match, and a gun.  Aldo Leopold once said, “Fire has always been part and parcel of the evolutionary background of our present species in many regions.” Prescribed fires are commonly used to promote plant growth and set back succession. Wildfires are fires that are burning out of containment and can have various intensities. While some people view fire as a detrimental thing to the environment, it can be very beneficial. For example, the Great Smoky Mountain wildfire destroyed many homes and businesses but it could result in the betterment of some of the ecosystems that were burned. Many plant species rely on fire for their existence. These plants have many adaptations that help them survive these fires. A few of these adaptations include serotinous cones and thick bark. Fires also clear debris from the soil’s surface allowing for seeds to be in contact with bare mineral soil. Fire can have a major impact on the environment in many ways. If you have never seen an area that has recently been burned, then you are in for a treat. What was once a place that was not anesthetically pleasing and covered in plant litter becomes a magnificent field of green plants emerging from the ground. Fire impacts the biotic factors in the environment through the change of plant consumption and reduced competition.

The presence of fire is very important for herbivory. The great Aldo Leopold went on to say, “fire may well be the single most important factor in determining what animal and vegetable life will thrive in many areas.” Fire can help improve both the nutritional and quantity of food available to herbivores. This increase in food abundance can aid in the increase of carrying capacities, growth rates, and reproduction for many herbivores (Mellars, 1976).  The use of fire and grazing plays a vital role in both the maintenance and establishment of savannas and grasslands (Milchunas et al. 1988).  When fire occurs in an ecosystem, herbivores typically select recently burned areas (Vinton et al. 1993). Fire isn’t just used for forests and grasslands, but for agriculture as well. The severity of herbivore grazing is correlated to the intensity of the fire. If there is a large amount of grazing on an area there tends to be less fuel load for the fire, which will cause a less severe impact on the ecosystem. On the other hand, a more intense fire can cause a significant change of woody vegetation on the ecosystem (Langevelde et al. 2003). In 1966, the use of prescribed burning was eliminated at Tall Timbers Research Station in Tallahassee, Florida. After the first fifteen years of fire exclusion, the changes in wildlife abundance and vegetation were obvious. The amount of groundcover decreased from 85% to 21%, while the canopy cover increased from 43% to 91% (Engstrom et al. 1984).

So why do we care about the plant-biotic interactions with fire? Animals need food to survive. In North America, two very important influences on the function and structure of grasslands are herbivore grazing and fire (Vinton et al. 1993). Ecosystems that have experienced a fire generally have a robust amount of vegetation in the understory. This in increase in plant abundance in the understory allows for animals to eat them more easily. An increase in plant consumption by animals can allow for them to have a higher carrying capacity, increased growth rates, and more successful reproduction. The increased amount of beneficial plant material located on the forest floor can also be attributed to the lack of plant competition that is caused by fire. Herbivore numbers and fire are two ways that landowners can meet their desired objectives (Levich et al. 2009). Sometimes land managers need to cut down valuable trees in order to increase sunlight to the forest floor. This is one of the management tools that is used that most of the public does not like. Most hunters want to hunt around oak trees and they think that cutting some of those trees down is a stupid idea, but what about the other eight or nine months that those trees aren’t producing mast? Fire helps reduce plant competition by eliminating the majority of the mid-story and understory of the ecosystem, which creates an increase in light penetrating to the forest floor. So if you were a deer, would you rather have acorns to eat three or four months out of the year or would you rather have a robust amount of grasses, forbs, and seedlings to eat? Fire doesn’t just increase the amount of forage, it also provides specific habitat that some animals need to survive.

           

Animals need food, water, cover, and shelter to help then strive in an ecosystem. The presence of fire has the ability to create early successional habitat that some species desire. There are many species that depend on fire. A few of these species are white-tailed deer, wild turkey, northern bobwhite, red-cockaded woodpecker, and many other birds (Brennan et al. 1998). The Northern Bobwhite Quail is a perfect example of a species that depends on fire. Leopold stated that the northern bobwhite “was undoubtedly evolved in an environment that was always subject to occasional burning” Quail are also known as the “fire bird” and need fire to help create the necessary habitat that they need. Quail require fire every one to two years to help restore their habitat (Graves, personal communication).

It is very important to understand that many wildlife species need fire to be successful. The use of fire has decreased over the years, and as a result, so have the wildlife species that depend on them (Table 1). It is because of the lack of fire that many species are in decline, threatened, and even endangered (Table 1). The following table was produced from the findings that Brennan et al. 1998 found in their study of fire-dependent wildlife species without the presence of fire. 

Table 1. Terrestrial vertebrates from southern pine forests and savannas that have affinities for habitats maintained by frequent fire.

                            Species                                                   Current Status

Gopher tortoise	Threatened
Greater prairie-chicken	Endangered
Northern bobwhite	Declining
Red-cockaded woodpecker	Endangered
Bachman’s sparrow	Declining
Sherman’s fox squirrel	Declining
Eastern indigo snake	Threatened
Florida grasshopper sparrow	Endangered

 “Endangered and threatened status according to U.S. Fish and Wildlife Service listed vertebrate species index, January 31, 1998. Declining status determined from various sources.

My research on plant-biotic interactions with fire has given me a better understanding of how fire impacts plants and animals. I have concluded that these interactions can be attributed to three key points. 1) Many ecosystems and wildlife species depend on fire. 2) The use of fire has decreased, and as a result, many fire-dependent species are struggling. 3) Herbivores can influence the intensity of the fire by reducing the fuel load.

Fire impacts the environment through the changes in plant consumption and reduced plant competition. Fire can have a major impact on the environment in both positive and negative ways. The use of fire has been used as a management tool for hundreds of years. I have personally used prescribed fires to burn around 2,000 acres, and I have seen how many ecosystems strive after the application of fire. However, wildfires can create a problem for the environment. I have found through my research that the changes in plant consumption and competition are related to fire.

Literature Cited

Mellars, Paul. "Fire ecology, animal populations and man: a study of some ecological relationships in prehistory." Proceedings of the Prehistoric Society. Vol. 42. Cambridge University Press, 1976.

Milchunas, D. G. , O. E. Sala , and W. K. Lauenroth . 1988. A generalized model of the effects of grazing by large herbivores on grassland community structure. Am. Nat. 132:87–106.

Vinton, M. A. , D. C. Hartnett , E. J. Finck , and J. M. Briggs . 1993. Interactive effects of fire, bison (Bison bison) grazing and plant community composition in tallgrass prairie. Am. Midl. Nat. 129:10–18.

Van Langevelde, Frank, et al. "Effects of fire and herbivory on the stability of savanna ecosystems." Ecology 84.2 (2003): 337-350.

Levick, Shaun R., et al. "The relative influence of fire and herbivory on savanna three-dimensional vegetation structure." Biological Conservation 142.8 (2009): 1693-1700.

Brennan, L.A.; Engstrom, R.T.; Palmer, W.E. 1998. Whither wildlife without fire?. Transactions of the 63rd North American Wildlife and Natural Resources conference; 1998 March 20-25; Orlando, FL. Washington, DC: Wildlife Management Institute: 402-414.

Graves, Chris. Personal Communication. 2016.

Engstrom, R.T., R. L. Crawford and W. W. Baker. 1984. Breeding bird populations in relation to changing forest structure following fire exclusion: A 15-year study. Wilson Bull. 96: 437-450.

Plant-Environment Interactions with Fire

Plant-Environment Interactions With Fire

In this blog I will be discussing the interactions between plants and fire. Prescribed fires are commonly used to promote plant growth and set back succession. Wildfires are fires that are burning out of containment and can have various intensities. While some people view fire as a detrimental thing to the environment, it can be very beneficial. For example, the Great Smoky Mountain wildfire destroyed many homes and businesses but it could result in the betterment of some of the ecosystems that were burned. Many plant species rely on fire for their existence. These plants have many adaptations that help them survive these fires. A few of these adaptations include serotenous cones and thick bark. Fires also clear debris from the soil’s surface allowing for seeds to be in contact with bare mineral soil. Fire can have a major impact on the environment in many ways. Fire impacts the environment through the change of soil nutrients available and soil erosion.

https://commons.wikimedia.org/wiki/File:Prescribed_fire_GWJNF_Steven_Q_Croy_USDAFS_1995.jpg

The change in vegetation caused by fire can affect soil erosion in ways such as rill formation and sheet flow (McNabb & Swanson 1990). Vegetation and leaf litter are very important in the stabilization of soil. Without vegetation and leaf litter present, there is an increase in soil erosion due to the increase of rainfall intensity hitting the ground and the total amount of precipitation that comes in contact with the ground (Kutiel & Inbar 1993). The severity of the fire is very important when dealing with erosion. Fire severity can be measured either by the maximum soil temperature, by the volume of fuel burnt, or by its effects on vegetation and soils.  (Walker et al. 1986). Low intensity fires mostly burn the understory layer of vegetation, while high intensity fires can burn every level of vegetation. Low intensity fires have a minor effect on organic matter and soil structure, however high intensity fires can create temperatures high enough to break down soil aggregates (Prosser & Williams 1998). Fires cause the soil surface to be bare, thus increasing the risk for runoff. The increased risk of runoff is caused by the burning of organic matter and creates a loose soil surface. This organic matter is very important because it aids in soil cohesion (Giovannini & Lucchesi 1983). There are many factors that control erosion following a fire. Some of the main factors that control erosion are soil type, ground litter, infiltration rate, and vegetation cover (Prosser & Williams 1998). These factors that control erosion are changed during and after the fire, but will return to their normal state over time (Brunsden & Thormes 1979). It could take many years before the vegetation and soil are back to normal. After the soil, ground litter, and vegetation cover are back to their normal state following a fire, these factors can become slightly more resistant to erosion and reduce the amount of runoff (Prosser & Williams 1998). Ian Prosser and Lisa Williams performed a study on runoff for areas that had been burned and had not been burned. Their results showed that the burnt plots had more runoff. Their results help show that fire has an impact on the amount of runoff produced.

Fire can also affect physical and chemical soil properties. Fire intensity and frequency have an effect on the amount of alteration of abiotic and biotic factors (Debano et al. 1977). An intense fire that occurs in areas that have high erosion potential can cause significant alterations in the environment  (Swanson 1981). During low intensity fires, the amount of nitrogen lost at the soil’s surface is less than fifty percent (Dunn & Debano 1977). On the other hand, fire can increase the amount of elements in the soil. Some of the elements that fire increases are K, Mg, Ca, and Na. The amount of phosphorus in the soil following a fire is variable. Fire can also increase the amount of soil exchangeable Ca^2+ and Mg^2+ (Murphy et al. 2005). If the fire becomes hot enough, then phosphorus, potassium, and sulfur can be volatilized (Raison et al. 1985).

P. Kutiel and M. Inbar performed a study to better understand the impacts of fire on soil nutrients and soil erosion. They suggested that medium intensity forest fires and light could cause an increase in soil fertility without causing a major difference in soil erosion (Kutiel & Inbar 1993). Their results showed that there was a significant increase in available forms of nitrogen. The available forms of nitrogen were NH4-N and NO3-N. Below are graphs that show the changes in NH4-N (a) and NO3-N (b) concentrations at the soil surface (0-5 cm) after a moderate wildfire in a mature pine forest plantation (Kutiel & Inbar 1993).

Solid lines = burnt soil; dotted line = Un-burnt soil.

Vertical lines indicate standard deviations.

solid lines = burnt soil; dotted line = unburnt soil.

Vertical lines indicate standard deviations.

So why do we care about the plant-environment interactions with fire? The answer is simple. Fire impacts soil nutrients and soil erosion. If a fire changes the amount of soil nutrients available, then some plants may not have enough nutrients to grow. Plants need a certain amount of nutrients to be able to grow and without these nutrients those plants don’t stand a chance of surviving. We also need to care about soil erosion. The studies that I have examined indicate that fire increases the amount of soil erosion. An increase in soil erosion can have impacts on watersheds and the loss of nutrient rich soil that plants need to grow in. Just imagine a mudslide going into a river. Can you see all of all of the mud dirtying up the water? This event can have a major impact on the river’s ecosystem as well as the plant ecosystem. Soil erosion can cause sedimentation in watersheds, which can kill aquatic vegetation and animals through the decrease in oxygen levels that they need to live. Soil erosion can also increase the amount of pollutants that are unwanted in certain areas. This can be caused by the runoff collecting things such as herbicides and dispersing them into other areas. Remember that fire can change the factors that control soil erosion. The main factors that control erosion are soil type, ground litter, infiltration rate, and vegetation cover (Prosser & Williams 1998). It is very important to know how fire intensity plays a role in both soil erosion and soil nutrients. A low intensity fire can cause little to no impact on soil erosion and nutrients, while a high intensity fire can cause a significant change on soil erosion and soil nutrients. Plants require nitrogen, calcium, phosphorus, potassium, sulfur, and magnesium in order to live. If a fire is hot enough it can eliminate phosphorus, potassium, and sulfur from the soil surface. So if a fire is really hot it can eliminate half of the nutrients that plants need to survive.

Fire impacts the environment through the change of soil nutrients available and soil erosion. Fire can have a major impact on the environment in both positive and negative ways. The use of fire has been used as a management tool for hundreds of years. I have personally used prescribed fires to burn around 2,000 acres, and I have seen how many ecosystems strive after the application of fire. However, wildfires can create a problem for the environment. I have found through my research that the changes in soil nutrients and soil erosion are related to fire intensity.

Literature Cited

McNabb, D.H. & Swanson, F.J.(1990): Effects of fire on soil erosion. In: J.D. Walstad, S.R. Radosevich & D.V. Sandberg (Eds.), Natural and prescribed fire in Pacific Northwest Forests. Oregon State University Press, Corvallis, Oregon. 159-173.

Dunn, P.H. & Debano, L.F. (1977): Fire's effect on biological and chemical properties of chaparral soils. In: Proceedings of the Symposium on the Environmental Consequence of Fire and Fuel Management Ecosystems. ESDA Forest Service General Technical Report. WO-3, 75-84.

Debano, L.F., Dunn, P.H. & Conrad, C.E. (1977): Fire's effects on physical and chemical properties of chaparral soils. In: Proceedings of the Symposium on the Environmental Consequence of Fire and Fuel Management Ecosystems. ESDA Forest Service General Technical Report. WO-3, 65- 74.

Swanson, F.J. (1981): Fires and geomorphic processs. In: Proceedings, Fire regimes and ecosystems conferences. Honolulu, 1979~ Gen. Tech. Rep. WO-26 USDA, Washington, DC, 401--420.

Kutiel, Pua, and Moshe Inbar. "Fire impacts on soil nutrients and soil erosion in a Mediterranean pine forest plantation." Catena 20.1-2 (1993): 129-139.

            Walker, J., Raison, R. J., and Khanna, P. K. 1986. “Fire”, in Russell, J. J. and Isbell, R. F. (Eds), Australian Soils: The Human Impact. University of Queensland Press, Brisbane. pp. 185-216.

            Brunsden, D. and Thornes, J. B. 1979. `Landscape sensitivity and change', Trans. Inst. Brit. Geogr., 4, 463±484.

            Prosser, Ian P., and Lisa Williams. "The effect of wildfire on runoff and erosion in native Eucalyptus forest." Hydrological processes 12.2 (1998): 251-            265.

Raison, R.J.,  P.K. Khanna, and P.V. Woods. Mechanisms of element transfer to the atmosphere during vegetation fires. Can. J. For. Res. 1985. 15:132–140

Murphy, J. D., et al. "Wildfire effects on soil nutrients and leaching in a Tahoe Basin watershed." Journal of Environmental Quality 35.2 (2006): 479-489.