Authors: Christopher Redmond, Mary Knapp

Spring is the optimal time for many people to do prescribed burns across Kansas, especially in the Flint Hills. It invigorates grass/crop growth, reduces noxious weeds, and eliminates the pile up of excessive dead material. These dead foliage and organic materials, often called fuels, that have accumulated on the surface can be variable from season to season. If an area of land is never burned, fuels will simply pile up on the ground over the years, often falling over with weight of winter wind and snow.

These fuels can accumulate over just a one-year period as well, in some years more so than others. In the Flint Hills, grasses, weeds, and other “one hour” fuels are warm-season plants and exhibit their growth from spring to summer. They get the name “one hour” fuels because that is how fast they can dry out and “cure.”

In 2015, a significant amount of such dead vegetative fuel was produced across most of Kansas. Near record rains in May and June brought flooding to much of Kansas, especially southern portions of the state. These rains saturated the soil and provided a large source of moisture for plant growth. Above-average temperatures during the summer utilized the abundant moisture and provided extensive growth of perennial grasses and weeds. In addition, a warm and nearly snowless winter this year for much of Kansas wasn’t able to knock these tall fuels down. Although we have had some winds, they mostly haven’t been accompanied by rains or snow/ice events, and thus haven’t been successful in knocking down these fuels, either. Therefore, last year’s aggressive plant growth remains vertical. Vertical fuels are much more susceptible to drying out rapidly and are a very efficient fire carrier. When fuels fall down and lay horizontally, they act as a sponge since they are packed more tightly, and hold moisture.

Figure 1. May rains were above normal for most of the state in 2015, especially in the southwest and central part of the state.
Figure 2. June temperatures were above normal statewide, aiding in widespread plant growth in 2015.

What does this mean for spring burning in Kansas this year? Fire managers will need to be extra vigilant when planning prescribed fires in the region. Several methods can be used to anticipate the impact of this fuel load, such as:

Christopher Redmond, Weather Data Library

Mary Knapp, Weather Data Library