Abstract:Noxious Weeds - A Biological Wildfire

Noxious or invasive weeds and wildfires have many things in common and some distinct differences. Invasive weeds and wildfires both impact plants, animals, watersheds, and recreation. Many ecosystems have evolved with wildfires and while wildfires initially destroy much the plant community, recovery occurs over time. Weeds also may alter or destroy the existing plant community, but unlike fire, recovery rarely occurs without significant management input.

Wildfire and weed spread are very similar. Both start from a small beginning, display exponential growth, and generate an expanding perimeter. Burning embers suspended in wind create new fires ahead of the expanding fire perimeter and similarly, weed seeds create new small infestations ahead of the expanding perimeter of the main weed infestation.

The process of fighting wildfires and invasive weeds have striking similarities and whether they realize it or not, state and federal land managers that have been trained to fight wildfires, also have been trained to battle invasive weeds in a logical and efficient manner. The first step in battling a wildfire is fire size-up where information about the fire is gathered, options are determined and evaluated, then a plan is developed. The first step in battling weeds also can be thought of as weed size-up where information about the weeds is gathered (e.g. weed species present, habitat considerations), management options are determined and evaluated, and then a written weed management plan is developed.

Firefighters always try to contain the wildfire within a defendable perimeter and focus their attention on developing such a perimeter while quickly extinguishing all spot fires outside of the main blaze. Weed management should take a similar tact by focusing attention on confining the main infestation inside a defendable perimeter. Begin weed control on the perimeter and then work back toward the center of the infestation and always, always first control the small satellite infestations outside or inside of the defined perimeter so they do not continue to expand exponentially into a huge infestation.

Fire mop-up entails extinguishing every ember, which is a long and tedious process, but is absolutely essential for success. Similarly, weed mop-up can be thought of in a similar light where all weeds and their propagules are eliminated from the area. This too is a long and tedious chore and is essential for success, particularly for small satellite infestations.

Revegetation is essential after a wildfire, but this may occur naturally or might be assisted by land managers as part of their wildfire plan. Revegetation is of critical importance in noxious weed management. Depending upon size of the infestation, revegetation may occur naturally, but often land managers assist the process by seeding.

One of the most striking differences between wildfire management and weed management is when the processes begin. About 54% of all wildfires are initially attacked when the incident size is 0.1 acres and 93% of all wildfires are attacked when they are 10 acres or less in size. Only 2% of wildfires are initially attacked when the burned area is at least 1000 acres. In contrast, only 11% of noxious weed infestations are initially attacked when they are 0.1 acres or less, 75% of noxious weed infestations are attacked when they are 10 acres in size or greater, and 31% of weed infestations are first attacked when they exceed 1000 acres! Clearly, weed management should follow the wildfire management paradigm relative to when the battle is begun.

Many of the challenges that weed managers face today are similar to those that already have been experienced and solved in wildland fire management. Weed managers should adopt this logical and efficient paradigm.

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