A new study of aspens on the San Francisco Peaks shows they’re struggling to grow to full-sized trees. Two decades of drought have taken a toll on the trees that draw flocks of visitors to the Peaks each autumn. KNAU’s Melissa Sevigny spoke with Northern Arizona University forest ecologist Mike Stoddard about one surprising solution: asking hunters to help.
You set up these plots on the south side of the peaks, and basically compared what the aspens are doing now to what they were like 20 years ago?
Exactly. When we set up these plots about 20 years ago it was right in the height of this prologued drought, probably one of the worst droughts we’ve seen in modern history. Right about that time, the whole West was seeing these widespread die offs of all tree species, especially aspen—that’s where the term SAD came about, Sudden Aspen Decline…. Sure enough, you know, we saw about 40 percent mortality, especially in the younger—not necessarily the younger, but the smaller diameter and lower elevation aspen.
That’s significant, does that fit in with aspen throughout the West dying off?
Definitely. Even though our data set is over 30 years, I would say most of that decline happened, or was punctuated, right after 2000, and that totally lines up with what was happening West-wide… But the feel-good part of this story is really there’s regeneration going on. The bad part is we’re not seeing it get to these tree structures.
And why is that happening, do you know? Why do you get new little trees, but they’re not growing up into big trees?
I think it’s a combination of things. Definitely climate and drought, warmer temperatures, and then there’s definitely the herbivory going on. There’s elk. Elk is causing havoc up on the Peaks. But what’s really cool is local land managers saw the same sort of situation, they’re not seeing a lot of new aspens becoming trees, so they got to together and they wanted to do something about it. The local wildfire folks and the local foresters go together and said we have a problem here, we’re not seeing aspen recruitment. They collaborated to put more pressure on elk through hunting, public hunting. They’re definitely reduced the number of the elk up there, and that’s helped tremendously.
Maybe we should mention here that the species of elk we have in Arizona are actually nonnative, they were shipped in from Yellowstone about a century ago, to replace the native elk that were hunted into extinction.
Exactly. There’s all sorts of ideas on ‘we should eradicate them,’ and all that. But people love seeing elk. People love hearing them. They’ve been here for over a century. They’ve kind of naturalized in here. So adaptive management can really help both elk and aspen prosper for the future.
Why does this work matter to you? Why do you think people should care about the fate of aspens on the San Francisco Peaks?
Aspens, especially on the San Francisco Peaks—this is the core southern extent of aspen, its range. With aspen comes a lot of biodiversity… And it’s just a great source of bringing people together outside, getting people outside. Leaf peeping and all that sort of thing, super fun. I think that’s something needed more within our communities, is just getting outside.
Mike Stoddard, thank you so much for speaking with me today.
Thank you so much.
