Invasive plants are a big problem in Utah. Cunning interlopers like cheatgrass and red brome can outcompete native vegetation, crowd habitats and steal water and other vital soil nutrients.
It’s a problem that’s spread across much of the West, too.
The Bureau of Land Management already deals with invasive plants on 79 million of its 245 million acres. That’s why the federal agency approved seven new herbicides to kill invasives on its land nationwide.
“If we don't remove this now, what is it going to look like 10 years from now?” said Seth Flanigan, a BLM senior invasive species specialist based in Idaho.
The herbicides — Aminocyclopyrachlor, Clethodim, Fluazifop-P-butyl, Flumioxazin, Imazamox, Indaziflam and Oryzalin — join 21 others previously approved by the BLM. Flanigan pointed out that some of these chemicals aren’t necessarily new to Utah, since they’re already allowed on other public lands.
“These are being used by our partners across the landscape. The BLM is somewhat the last one to start using these specific herbicides.”
Another reason to fight invasives now is the plants’ impact on wildfire risk, he said.
Desert landscapes are sparsely vegetated, dotted with shrubs that have bare ground between them. Invasive grasses like cheatgrass and red brome can fill in those gaps. That not only adds more fire fuel, but it also connects the vegetation — which can spread a fire further and faster.
“The desert Southwest especially is not evolved to be able to deal with that sort of fuel continuity and disturbance across an entire landscape,” Flanigan said.
That same dynamic may also increase the risk of a fire returning sooner than it would otherwise. That’s because invasive annual grasses often grow back before native plants can recover from a fire.
Having fewer invasive plants would also improve habitat for wildlife, like the endangered Mojave Desert tortoises that live in the BLM-managed Red Cliffs National Conservation Area near St. George. Conservation groups already worry about the pressures tortoises and other species there face from development.
The fight, however, needs to be done the right way, said Judy Hohman, a board member with the Desert Tortoise Council.
“We're definitely in favor of the BLM taking measures to halt the introduction and spread and proliferation of non-native plant species,” Hohman said. “But in the council's opinion, the BLM could be doing more. We don't understand why they aren't doing more.”
Some BLM offices tend to be more reactive than proactive, she said, relying too heavily on herbicides to kill invasive plants after they’ve become established. Instead, she’d like to see the agency do more to keep invasives from spreading by requiring off-highway vehicles and livestock operators to clean off any potential seeds they’re carrying before entering BLM land.
There are concerns about mixing chemicals and wildlife, too, which the Desert Tortoise Council sent to the BLM during the agency’s decision process.
One concern is direct contact between herbicides and tortoises. That can be mitigated by timing applications to coincide with colder seasons when tortoises are usually dormant. But that’s not a hard and fast rule, Hohman said.
“It could be a nice sunny day the next day (and) a tortoise could come out and start eating vegetation that you just sprayed less than 24 hours earlier. So it's really complicated,” she said.
Sometimes younger tortoises will come out of their underground burrows on colder days when most adult tortoises wouldn’t. If it rains, they may go above ground for a while even if the weather isn’t to their liking.
Another concern is herbicides entering a tortoise’s diet. While invasive plants are typically not a food of choice, Hohman said tortoises have been known to eat them.
It’s also unclear how long the herbicides remain active on different surfaces. Tortoises eat rocks and soil as part of their digestive process because they don’t have teeth to grind up their food. So lingering herbicides could still enter their bodies. She said that should be factored into decisions about applying the chemicals.
The BLM’s approval doesn’t mean these herbicides can be used in Utah immediately, Flanigan said. Each local land office would first need to do an environmental impact study with a public comment period before any application.
Then local offices could decide on a case-by-case basis how to mitigate potential herbicide impacts by doing things like creating buffer zones around sensitive landscapes or waterways, he said. The BLM would also post notifications at trailheads and other recreation entry points so hikers and campers would know if there’s a recent or upcoming herbicide use.
In some cases, the risks of using a particular herbicide might outweigh the rewards, and the agency may go a different route, like mowing or mechanically removing the plants. “We're looking into the future” to ensure the longevity of public lands and it’s helpful to have extra options, Flanigan said.
“We use any tool available to us … and one of those tools is the use of herbicides.”
