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 excessive dead plant material. These materials, often called fuels, can be variable from season to season. If an area of land is never burned, fuels accumulate and pile up on the ground over the years, often falling over with winter wind and snow.
However, fuel accumulations occur on a yearly basis even on burned areas. Warm-season grasses, weeds, and other one-hour fuels exhibit their growth from spring to summer. They are called “one hour” fuel because that is typically the speed at which they can dry out and “cure,” and be receptive to burn in a fire. The amount of plant growth, and thus production of these fuels, can vary considerably from one season to the next.
In 2016, near record rains in 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. Favorable temperatures during the summer utilized the copious moisture and provided extensive growth of perennial grasses and weeds.
Figure 1. June rains were above normal for most of the state in 2016, especially in the southwest and central part of the state. You can find this and other maps at: http://climate.k-state.edu/maps/monthly/index.php?inMonth=6&inYear=2016
Another factor that has heightened fire risk this spring is the warm and nearly snowless winter so far in much of Kansas. Because of the lack of widespread snow and/or ice, the tall fuels produced as a result of environmental conditions have not yet been knocked down to the ground. Although we have had some winds, they haven’t occurred along with 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 rapid curing/drying out, which makes them a very efficient fire carrier, and will exhibit increased fire behavior. When fuels fall down and lay horizontally, they act as a sponge due to being packed more tightly, and hold moisture much adequately.
Considering all these factors, what does this mean for spring burning in Kansas this year? Fire managers need to be extra vigilant when planning prescribed fires in the region. Some of the steps fire managers can take to mitigate the impact of this fuel load include:
Christopher Redmond, Weather Data Library
Mary Knapp, Weather Data Library