Montana: How We Work

Battling Weeds

The old adage that a stitch in time saves nine might well be applied to the battle against noxious weeds. When faced with a choice between attacking a large, well-established patch of weeds or jumping on the first few plants to show, it’s probably more effective to go for the newbies.

That’s one of the findings in a new report produced by scientists at The Nature Conservancy in Montana. Through complex computer models, their analysis produced results that can save money while producing the greatest success on the land for both ranching and conservation.

For a lot of people, weeds are mostly a nuisance. They’re those perky dandelions that seem to have set their deep roots in concrete. Some people even find them appealing, like the cheery oxeye daisies that brighten a summer meadow. To ranchers and biologists, weeds are noxious invaders that can destroy the land’s value as food and shelter for both livestock and wildlife. Even as the battle against the spread of invasive plants has intensified across the West, many of the strategies used were based more on hunches and small scale results than solid science. But with millions of acres at risk from invasive plants, and limits to the resources available to stop their spread, we need to find the most effective ways to fight this plague on a large scale.

To find the answer, Conservancy scientists created a set of complex computer models to simulate different strategies in three areas of the state: The Rocky Mountain Front, The Centennial Valley and the Montana Glaciated Plains. The target was two of the state’s most persistent invasives: Leafy spurge and Spotted knapweed.  Using the model, they could simulate different funding levels and management strategies over 40-year periods, comparing the extent of weed invasions, treatment costs, and the economic benefits of weed control under different regimes. 

The scientists collected data from the existing literature, their own on-the-ground observations and from experts and other land managers. They included information on the rate that weeds spread in different conditions, the impacts of different budget allocations for weed control and the loss of grazing value.

Here are some results:

  • Not surprisingly, perhaps, the analysis found that any treatment is better than none; yet all treatments are not equal. 
  • Delaying treatment or applying it inconsistently may lead to a bigger invasion down the road.
  • Early detection of new outbreaks and hitting small patches was consistently more effective than focusing on large, established patches. Traditionally, the latter get attention because they are often most visible.

Strategic management of invasive weeds protects and enhances the natural and economic value of the land – values that are far greater than the cost of the effort. In short, done right, weed control efforts more than pay for themselves in the long run.

The researchers stress that their results are conservative, but it’s clear that different strategies can produce very significant benefits…or losses. The decisions we make now will have profound effects on our future options. 

 Click here to read an executive summary or the full report



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