Japangrass (Microstegium vimineum) is a nonnative, invasive annual grass that is capable of overtaking forest understories in eastern U.S. forests. Fire is one tool that can be used to manage Japangrass. Fire prescriptions to control Japangrass include burning in early spring just after Japangrass germinates, but before overstory trees have leafed out, or burning during August and September before Japangrass has seeded. Burning during mid-summer is difficult because of high litter moisture as a result of overstory forest shading. Japangrass can also be managed using a variety of herbicides, including grass-selective herbicides at relatively low application rates.
What is the best fuel mixture to use in my drip torch?
Gasoline, diesel, and kerosene are the fuels most often used in drip torches. Recommended mixture ratios depend on personal preference and ambient temperatures. A common mixture is 60% diesel or kerosene and 40% gasoline when temperatures exceed 75ºF. When temperatures are below 75ºF, a 50:50 ratio may be used. Exceeding 50% gasoline is not recommended because of increased volatility. Greater diesel/kerosene mixtures may be useful under high fuel moisture conditions.
How often should I burn my fields?
When managing fields or openings for wildlife that use herbaceous openings, burn frequently enough to prevent plant succession and not allow woody species to dominate the area. This may be every 1-3 years. However, many wildlife species use woody or brushy cover. When managing for these species, the fire-return interval will be longer to maintain desirable woody plant composition and structure. Burning every 4-7 years in the eastern US with low to moderate fire intensity will usually maintain a woodland mosaic with scattered trees, shrubs, brambles, and a herbaceous understory. These intervals are recommended if annual precipitation is greater than 30 inches. In more arid regions, the interval will be longer. For more general information, see “How often should I conduct a prescribed fire?”
Will fire kill my hardwoods?
This is a common question regarding burning in hardwood forests in the eastern U.S. The short answer is yes, fire can kill hardwoods, but fire can also kill pine trees or any other type of tree. The key to hardwood tree mortality is fire intensity and duration. Low-intensity fire with flame lengths of 6-12 inches typically will not harm upland hardwood species unless woody debris has accumulated at the base of the tree. Use a conservative prescription, on the first burn in particular, to limit fire intensity and duration. Before burning your forest or woodland for the first time, walk through the area you intend to burn and remove any slash or accumulated woody debris from around the trunks of high-value trees, whether for wildlife or timber. Accumulated woody debris, when ignited, may retain heat long enough to damage the cambium (inner bark layer) and injure or stress the tree. Unless there has been a recent windstorm, ice storm, or other such event, most trees will be clear of debris and clearing can be done fairly quickly.
The Great Plains Fire Learning Network, Reconnecting People, Lands and Fire
The Fire Learning Network (FLN), is a cooperative program of the US Forest Service, Bureau of Indian Affairs, Bureau of Land Management, US Fish and Wildlife Service, and National Park Service, along with The Nature Conservancy. This network supports public-private partnerships in landscapes that are engaged in collaborative fire planning and implementation, providing a means for sharing and vetting tools and innovations to help expand the use of fire for natural community restoration. FLN communities have been established nationwide and an e-newsletter is regularly publshed.
Three Focal Landscapes of the Great Plains Regional FLN
Among the 47 FLN landscapes now working to accelerate restoration at local, regional and national scales are the three focal landscapes of the Great Plains regional FLN: the Loess Hills (Iowa), Lower Loup River (Nebraska) and Refugio-Goliad Prairie (Texas). These landscapes provide leadership, share lessons learned, and maintain a link to the national FLN for other Great Plains landscapes, including the Prairie Coteau (South Dakota), Niobrara-Sandhills (Nebraska), and Southern Iowa.
Working Hard to Make a Difference in the Landscape
The FLN is working hard to advance lessons learned from mangers and private landowners and to apply them at a scale that will make a difference in the landscape. Strategies include supporting landowner burn associations, helping volunteer fire departments offer prescribed fire to their community members, creating mobile burn crews and offering prescribed fire training exchanges (TREX). As a result of these efforts, 56,000 acres have been treated with prescribed fire during TREX events since 2008. TREX events are a great way to learn from experienced fire professionals as well as to share your skills with others. Look for the annual calls for participants.
To learn more about the FLN and these fire training exchanges visit: http://www.conservationgateway.org/topic/fire-learning-network.
Pre-burn briefings set the stage for successful burns. Maps, whether computer generated or hand drawn, can improve communication. Folks from state, federal, county, The Nature Conservancy, and a volunteer fire department discussed plans for the day’s burn. Photo by Susanne Hickey.
What weather conditions are important to consider when planning and conducting a prescribed fire?
The primary weather conditions to consider when planning and conducting a prescribed fire are relative humidity, wind speed and direction, temperature, and mixing height. Most prescribed fires are conducted with relative humidity between 30–50%. Burning with relative humidity below 25% can be tricky as spotfires are likely and suppression becomes challenging. Burning with relative humidity above 50% is often ineffective because of high fine fuel moisture content. Forecast wind speed is for winds 20 feet above surrounding obstructions. The actual wind speed at ground level is usually less. Wind speeds of 2-15 miles per hour are common for most prescriptions. Winds greater than 15 miles per hour can create containment challenges in the event of an escape or spotfire. Mixing height is the distance aboveground where smoke is mixed with the atmosphere. The mixing height and transport wind speeds at that elevation influence smoke dispersal. A mixing height of at least 1,700 feet is recommended for most prescriptions.
Livestock Weight Gain and Patch-burn Management
Achieving optimum livestock production on rangelands many times can conflict with wildlife conservation strategies that require lower stocking rates to maintain suitable habitat. Traditionally, livestock producers try to maximize gain per-acre by uniformly managing vegetation in pastures. Often this is achieved either by heavily grazing, burning the entire pasture, or both. This management strategy can create suitable habitat for some wildlife species, but poor quality habitat for others.
Patch Burning
Combining the spatial and temporal interaction of fire and grazing (patch-burning) a conservation-based approach to land management can be achieved. This practice can increase rangeland biodiversity by creating heterogeneous vegetation structure and composition that is beneficial to multiple wildlife species. However, for conservation strategies to be successfully implemented, they need to be both effective and economically sustainable. In both mixed-grass prairie and tallgrass prairie, cattle weight gain was compared in pastures with traditional fire and grazing management (continuous grazing, with periodic fire on tallgrass prairie and seasonal grazing without fire on mixed-grass prairie) and conservation based management (pyric-herbivory applied through patch burning), both at a moderate stocking rate. Stocker cattle weight gain, calf weight gain, and cow body condition score were comparable between the traditional and conservation based management at the tallgrass prairie site for the duration of the eight-year study, indicating that conservation management doesn’t decrease livestock production or profitability.
In the mixed-grass prairie pastures, stocker cattle gain was not different between traditional and conservation management for the first four years. However, stocker cattle in conservation based management out gained cattle in traditional management beginning in year five and remained 27% greater for the next six years of the study. Moreover, cattle weight gain under conservation management varied less year to year making profitability more consistent. Traditional management in mixed-grass prairie did not include fire, the process that improved range conditions and likely was associated with increased stocker cattle performance under conservation management. In conclusion, pyric-herbivory is a conservation-based rangeland management strategy that returns fire to the landscape without reduced stocking rate, deferment, or rest.
Figure 1. Cattle weight gain on traditionally managed and patch-burn managed tallgrass prairie.
Figure 2. Cattle weight gain on traditionally managed and patch-burn managed mixed-grass prairie. An * indicates years when patch-burned managed cattle gained more than traditionally managed cattle.
Burning in the Growing Season Effects on Grass
When land managers start a prescribed burning program they often wonder whether fire will kill their grass, particularly during the growing season. To answer this question, the history of grasslands/shrublands needs to be considered. Fire is common through much of North America as a natural disturbance and a land management tool. Native Americans used fire as a part of their everyday existence from cooking meals to preparing camp sites and even hunting and warfare. With so much fire being used, historically, landscapes burned throughout the year. However, the intentional use of growing-season fire as a management tool remains controversial due to potential damage to fire sensitive herbaceous plant species that may be of benefit to both livestock and wildlife.
Growing-season grazing is a common practice that, if done at appropriate stocking rates, can benefit pastures as a whole. The common practice of growing-season grazing and growing-season fire were compared to see if there was a difference in plant growth and survival. For 10 years, plant communities burned in the dormant season and during the growing season and were monitored. The study found that the particular time of year that the fire occurred did not affect the plant community. The amount of rainfall was the dominant driving factor affecting grass production.
Figure 1. The relative abundance of little bluestem in pastures burned in the dormant season or the growing season. The solid line represents the rainfall received on the pastures the previous growing season.
Individual little bluestem plants were burned at multiple developmental stages to see how growing-season fire affected survival and growth. Plant age was the primary factor affecting plant survival with nearly all seedlings dying when burned. However, once plants reached 18 weeks old, survival was nearly 100%. Plant survival was similar for plants that were burned or clipped to simulate grazing suggesting that growing-season burning doesn’t have any greater effect on plants that grazing. One advantage that growing-season burning had was that both aboveground production and belowground biomass were both increased after burning, while growing-season clipping reduced production.
Figure 2. Above-ground grass production on plants either burned and clipped or clipped alone.The letters represent groups that had similar production.
Figure 3. Below-ground root production on plants either burned and clipped or clipped alone.The letters represent groups that had similar production.
Grasses in the Great Plains are well adapted to both grazing and burning during the growing season and can be included in a successful land management strategy.
Burning During A Drought
Landowners often are unable to carry out their fire program due to periodic droughts. Drought does present several challenges to using prescribed fire such as: lack of fuels, dangerous conditions, and burn bans. However, even during droughts, conditions safe to burn are often present. Further, droughts present some opportunities to meet certain objectives such as reduction of overstory fuels and creating a patchy burn.
Concerns
One of the primary limiting factors of a drought relative to fire is the lack of fine fuels. Lack of precipitation can lead to a reduction in grass growth in grasslands and leaf production in hardwood forests. These fine fuels are needed to carry fires. Therefore, fires many be patchy in nature or not carry across the burn unit at all. Another issue is that droughts are often accompanied by high temperatures and wind speeds which make conducting prescribed fire unsafe. Even when conditions may be safe, burn bans may remain in place for long periods of time during droughts due to perceived risk by policy makers. Droughts can place stress on plants and animals, and therefore many landowners are concerned about carrying out a fire that may negatively impact these already stressed plants and animals. The lack of rain following a fire is also a concern as grass and other plants may not respond and allow for extended periods of lack of cover, forage, and erosion potential.
Opportunities
The concerns listed above can also be viewed as opportunities. For instance, patchy burns are sometimes the desired outcome. This is especially true for wildlife management. If only 50% of the burn unit is consumed by fire, this may be exactly what the prescription called for. If the manager is attempting to remove overstory forest cover, burning during dry conditions when trees are stressed may be the perfect time to accomplish the objective (assuming you can safely carry out the fire).
Considerations
Always ensure that the fire is carried out under safe conditions that you have a reasonable chance of containing the fire. While burning during extreme conditions may yield desirable outcomes, safety is the first priority. Ensure there is adequate personnel and equipment for the conditions and that the burns are legal at all times.
As weather is always an unknown, it is advisable to hedge and only burn portions of the landscape during droughts. This will ensure that some cover, forage, etc will remain until favorable weather returns.
Soil erosion is often a concern after a fire during drought as there is little ground cover. Much of this concern is unfounded as root biomass has tremendous soil stability potential. However, on steep slopes and in certain soil textures, extra considerations may be warranted.
A final consideration is that fire frequency is the most important consideration regarding fire effects. Thus, you should do everything possible to maintain the appropriate fire frequency to meet your objectives. This will often mean burning under conditions that are not perfect. At times when fire is not possible, remember that you will need to burn those units as soon as conditions allow to stay as close to the appropriate fire return interval as feasible.
What was the primary source of fires before European settlement of North America?
Historically, fires in North America came from two primary sources, lightning and humans. See full length article for more detailed information.