The Dirty Understory
The non-native salt cedar is a plague on many waterways in the U.S., but over the past few years in Albuquerque, with a little money, time and effort, the reign of salt cedars could be coming to an end
“Salt cedar” is a term most Albuquerqueans have heard before. Also known as “tamarisk,” the plant came to the U.S. in the early 1800's as an ornamental shrub, but by the '50s had overtaken many waterways throughout the West, including our own local Bosque.
The species, which is native to northern Africa and Eurasia, is extremely resilient, spreading both vegetatively and sexually. It resists fire and has the ability to out-compete and eliminate other species by drawing salt from water in the ground with its long roots, storing it in its leaves and depositing it into the soil. Another one of its survival tactics, which is what makes it so menacing to New Mexico in particular, is intercepting water from other plants in the surrounding ecosystem. The shrub-like trees can sometimes grow to 50 feet and form dense thickets and monocultures along waterways.
The trees weren't regarded as a problem in the West during the '20s and were even planted for bank stabilization along the Rio Puerco during that time. But in the '50s, their problematic nature was discovered, and efforts to do away with the water-loving invasives began.
Since that pivotal moment in the salt cedar's history, the shrubs have put up a good fight, and many eradication efforts have failed. And they're not alone: Russian olive, tree of paradise and Russian elm also plague riverbanks in the West.
Now scientists, activists and governmental agencies are all working together in a concerted effort to rid our local Bosque, which is Spanish for “river woods,” of salt cedar and other non-natives, and restore its riparian vegetation. The attack is being fought chemically (with herbicides sprayed aerially or individually applied), mechanically (bringing in machinery to pull up trees by their roots) and biologically (scientists are on the verge of releasing a non-native beetle in areas of the West, not including Albuquerque, that is the salt cedar's natural enemy).
All three methods have been attempted in Albuquerque, and currently a combination of machinery, individual herbicide application and vigilance seems to have contained the majority of salt cedar. Matt Schmader, as the manager of the city's Open Space Division, oversees the 21 miles and 4,300 acres of Bosque in Albuquerque. In a recent interview with the Alibi, he illustrated a picture of progress.
Do you think salt cedar will ever really be eliminated from the Bosque? It sounds as though it's nearly impossible unless there are people pulling them out one by one over a long, dedicated period of time.
It really is a matter of money and consistent follow-up and know-how. But here in Albuquerque, the situation has really been quite dramatically transformed; I can take you to places where you could not walk through the Bosque, and last summer we had machinery working on these areas and it completely cleared it out. So instead of getting a tree that's eight inches in diameter and 20 feet high, all massed together, you cut them all down and mulch them up. You may end up having resprouts in the next year which are one inch in diameter and grow 10 feet high, but you cut them down again and put herbicide on the cut area, and you keep at it and eventually they don't come back. There are places like Bosque Del Apache, where they had no cottonwood trees and it was 100-percent solid salt cedars, and they had to keep at it for years because it was such a huge problem, but even that area is getting transformed. The difference is that in Albuquerque our Bosque is fortunate that salt cedar is sprinkled throughout, but was never really solid salt cedar.
Historically, did it accidentally sprout up in Albuquerque or was it intentionally planted at some point?
Salt cedar is such a successful pervasive weed that it just spread everywhere like wildfire, so in Albuquerque what happened was, because we had a lot of patches of native vegetation, it had to compete, and in some places it competed pretty well and in other places it wasn't able to. But places like the Pecos River are almost completely salt cedar, and in Arizona almost every waterway in the entire state has nothing on it but salt cedar.
I heard about a project where they sprayed an herbicide aerially on the Pecos River, and some ranchers weren't happy because their grasslands and some of their trees were killed.
You can't apply the wrong techniques in the wrong places. So what we've done in Albuquerque is a combination of machine [and chemical] work. Herbicide is only applied through a little hand sprayer on each of the cut stumps, [and then we perform] extraction, which is pulling them up by the roots, and follow-through.
So that's what the strategy is right now on the city's part?
That's the city's strategy, and since we've got continuous funding for it we can do it over a period of years, and that means we will win the battle.
Where does the city get its money for eradication?
The City of Albuquerque has its own funding, and this is because the mayor, after the fires in 2002 and 2003, said he would make the Bosque as safe at we could make it, as far as catastrophic fire [goes]. He added staff and brought in equipment to manage fires.
Do you think there's any chance there will be fires again in the Albuquerque Bosque?
Well, never like we had. The difference is that there's always a chance for some small fire to happen because it's the woods, but the catastrophic fires that we had, where once it started it would just race through several hundred acres at a time, can never happen because we spent the entire year last year taking that fuel load out. There are a couple of pockets that are still left because there are some research stations where they didn't want the experiments ruined and various things like that. In Albuquerque, we'll never [again] have fires like we had.
Is burning natural or is it a product of an unhealthy Bosque?
It's really the product of an unhealthy Bosque. They've tabulated the cause of the fires and well over 90 percent of them are human-caused; it's not like lightning strikes or that sort of thing. And the species in the Bosque are not fire-adapted; if you have a forest fire up in the hills, then there's great response by tree species that like fire and all of that. But cottonwoods have a high death rate, and so that's why if an area burns you've got to go right in and start replanting to make sure non-natives don't take over. It's really quite a complex set of issues.
And then there's the question of increasing river flows. Some people think that if you get rid of the salt cedar and the Russian olive there will be more water; what's your take on that?
It's being studied to quantify how much, but I have no doubt that it will increase the return flow. It's just a question of how much, because salt cedar is only a part of it; you have other non-natives like elm trees and Russian olives and several other types of species like tree of heaven. Once you take up all of those, you can't just leave it barren, you have to replace it with native vegetation, which will need some of the water that you'd get back. But in general, it's just the mathematics of it—there's no way you can take up all of those trees and not have it result in some water getting back into the ground. It's got to help. People have reported that they've seen areas moist that they haven't seen moist in years. It's sort of anecdotal; but there are very elaborate studies being done about how much water these trees take up.
What do you expect to see once the salt cedar is eradicated; what will be the changes in the Bosque?
The key to it is to actively replant back behind areas that have been cleared, and the replanting needs to be done with native shrubs so that salt cedar can't out-compete in those areas, so there are a whole variety of those native shrubs.
What are some of them, what are the main ones that you guys will use?
New Mexico olive, three-leaf sumac, wolfberry and willows. Cottonwood is a big tree, and the salt cedar and Russian olive occupy right under the big trees, [in] what they call the understory; so when you clear that out, all you have is big trees and grass, so you've got to replace it with shrubs. What we're going to do is replace them with native species so it gets restored back to a much healthier condition.
To contact the author, e-mail firstname.lastname@example.org.