Into the Trees

You know how when you're a kid you want to climb everything? Tables, curtains, trees, chicken coops, cars -- you name it. Well, that inclination never really left me, and in August 2012 I was able to satiate those childhood urges under the guise of "work!"

Leaving the Florida summer behind, I packed all my gear into Ruby (my "new" Ford Ranger) and headed west, making it out to Flagstaff, Arizona in three days.

With a camper on top, Ruby's better than any hotel

Sitting just under 7,000 feet, Flagstaff is an adventurer's dream town: an hour from the Grand Canyon, literally encircled by National Forest, only a few miles south of the San Francisco Peaks (Arizona's highest mountains), surrounded by some of the top rock climbing in the country and home to the best coffee shop the world has ever known, Macy's. As I was to be camping for the next three months, I first gathered some maps at the Coconino National Forest office and perused the real estate offerings -- I wanted to be close enough to town so commuting wouldn't be an issue, but far enough away that the Peaks were the only structures I could see on the skyline. After scouting out a few spots I headed just north of town, finding a gorgeous campsite at the base of the mountains.

 Home sweet home

Foraging Lepidopteran in a high meadow beneath the San Francisco Peaks

Though after getting to Flagstaff I realized I should have probably moved there long ago, what initially drew me to Arizona was the chance to work on a study concerning the invasion of an exotic tree pathogen into the American Southwest. Northern Arizona University (NAU) graduate student Betsy Goodrich and her advisor, Dr. Kristen Waring, are working with the native Southwestern White Pine (Pinus strobiformis) to proactively address threats brought about by the lethal white pine blister rust (WPBR), a fungal disease that has already caused significant stand mortality in the Pacific Northwest. Check out the video below, made at NAU and featuring Betsy and Kristen.



WPBR affects 5-needle pines (those which have 5 needles per fasicle, or "bundle"), including Eastern White Pine (Pinus strobus), western white pine (P. monticola) and southwestern white pine (P. strobiformis). Though its effects on high elevation ecosystems can be severe, from a purely biological perspective, it does have a fascinating life history, and the story of its spread in the U.S. is quite a tale.

 This juvenile Horny Toad (Phrynosoma spp.) wasn't too happy to get picked up,
but even that grumpy look can't hide the cuteness

Many thanks to Jim Worrall over at forestpathology.org for lots of the info in this post

In the mid-19th century, American land managers realized that the voracious wood consumption of the past 200 years was quickly depleting North American timber stands. This called for expansive replanting, but without many established nurseries in the New World, seed was instead shipped back to Europe, where the seedlings could be raised by knowledgeable silviculturalists in well-equipped nurseries. Once grown to an appropriate size for outplanting, the seedlings were shipped back to the U.S. Unfortunately, this transatlantic exchange opened up an avenue for Old World tree diseases to make their way to the New World, carried on American tree seedlings that had been infected while in European nurseries. WPBR was one such disease, first showing up on the East Coast in 1898, then on the West Coast in 1910, carried on White Pine seedlings grown in Germany and France. Though the disease spread along both coasts, it's been felt most strongly in the Pacific Northwest, where many stands of these ecologically and commercially important species have suffered extensive mortality. In 2009, WPBR was found in eastern Arizona, but Betsy and Kristen hope to get a head start on unraveling the mechanisms behind disease resistance before the fungus takes hold in the Southwest.

Mexican Campion (Silene laciniata)

But where it gets really interesting is when we look at how exactly this fungus (Cronartium ribicola) spreads. (If you'd rather not get bogged down in the details and vocabulary, skip this next bit). We start with the pine infection, which happens when one type of Cronartium spores, called basidiospores, enter pine needles through their stomata, establish a fungal infection and then grow down into the tree's bark. Eventually the infected area swells and becomes a discolored canker. In late summer, the fungus produces fruiting structures (analogous to the toadstools we're used to seeing on the forest floor) called spermogonia that produce another kind of spore called spermatia. These spermatia lie in a sweet drop of liquid that attracts insects, who then (unknowingly) carry the spores to other spermogonia, where they find their way onto receptive hyphae. The fusion of the spermatia and hyphae establish the dikaryon.

Next spring, other specialized reproductive structures, whitish-yellow blisters called aecia, appear where the spermogonia were the year before. Inside the aecia are masses of yet another kind of spore, aeciospores, whose abundance eventually pops the blister, releasing the aeciospores into the air. The aecia then break down, but the bark they colonized also dies. This annual spermogonia / aecia cycle is what eventually kills the tree as the fungus colonizes new bark, leaving "dead zones" in its wake.

But do these aeciospores go and infect other pines? No, that would be too simple! Instead, these spores (which can travel hundreds of kilometers) are only able to infect gooseberry (Ribes spp.), a relatively common forest shrub.

WPBR requires two hosts to complete its complex life cycle:
the eponymous pine, and Gooseberry (Ribes sp.), seen above

The aeciospores infect the new spring leaves of Ribes, and within two weeks the fungus is producing yet another kind of spore, urediniospores, housed in structures called uredinia on the underside of the Ribes leaves. These spores are released and reinfect Ribes, building up a large infection. Then in the fall, you guessed it -- another reproductive structure is produced, called a telium, full of teliospores. When weather conditions are right (cool and wet), these teliospores germinate and form basidia, which in turn produce lots of basidiospores. (Remember those? They're the first spore type I mentioned.) These disperse with the wind and, if they're lucky, come in contact with a white pine needle, where they enter through the stomata and start the whole process over again.

Scarlet Gilia (Ipomopsis aggregata)

Luckily my job did not in any way require a working knowledge of this complex life cycle. I just climbed trees! Well, mostly -- there was some community classification and environmental data to collect, but for the most part, we climbed. Our job took us all over eastern Arizona and western New Mexico to chase the elusive cone of the Southwestern White Pine. From the cones, Betsy could get seed, some of which went to seed banks, but most of which was to be used (as explained in the video above) to explore the spatial distribution and genetic basis of resistance to WPBR (as some pine individuals are more resistant to the disease than others). This knowledge could be invaluable in planning for effective forest management under the threat of a WPBR invasion in the Southwest.

 The Whitewater-Baldy Fire was the largest fire in New Mexico's history, burning more than 290,000 acres during the summer of 2012. This composite photo shows the aftermath just a few months later -- you can follow the blaze's path by the ashy brown and black, though a stand of unscathed aspens is turning gold on the far left. The fire consumed vast swaths of forest in the Gila Wilderness, including areas I had visited only a year earlier.

Our climbing team consisted of Chris, Shaughn and me, and after a couple days of training with Terry (US Forest Service), we were certified tree climbers! Don't get me wrong, I love vegetation surveys, but there's no field job like scaling a 90 foot pine and then getting to rappel down.

 Rappelling down an old Southwestern White Pine. We learned all matter of handy knots during this gig, from Blake's hitch to figure-8's to the ever-reliable anchor hitch.  

Shaughn (alimb) and Chris (aground) collecting in New Mexico

Going out for eight days at a time, we were able to see some of the best high elevation forest the Southwest has to offer. From Mount Graham in southeastern Arizona to the Gila Wilderness in New Mexico, each day brought new trees and each treetop provided fresh vistas -- a sunset from a pine crown is unlike any other.

What a climb. Can you spot Chris?

Chris admiring a beautiful (and low-hanging!) crop of cones

The only drawback to collecting pine cones is the sap...there is LOTS of sap. At the end of eight days I could barely separate the fingers on my hand -- seriously. And when you're covered in sticky sap, grime clings to you even more than it usually does in the woods. Needless to say, fall 2012 was definitely the dirtiest I have ever been. At the end of the first trip, Shaughn and I were legitimately concerned that we would not ever be able to get the dirt off of our arms. Proof of my concern? I bought a kitchen scouring pad to take in the shower.

Glistening with sap...but under those scales are precious seeds!

Hygiene logistics were made a bit difficult by the fact that Shaughn and I were living in the woods for three months, even on our off days, but we managed with the generosity of Betsy, Karen and Chris, who let us use their shower any time we needed. And man, never before had I felt the incredible luxury of having a shower. Living out of a tent is an easy way to learn just how little we really need to be content, and somehow, when you're in the woods, little chores that might seem a hindrance in residential life -- getting firewood, cooking dinner, fetching water -- are rewarding activities unto themselves.

Quinoa, a non-native species...best eat it before germination

I'll admit this looks like a diverse collection of slugs, but they're actually delicious mushrooms. Erik Nelson, an NAU mycologist, was kind enough to take Shaughn and me out on a foraging trip. Afterward, we feasted!

After climbing season ended in early October, I stayed on for a couple weeks to help harvest seeds from the cones. I told myself I would stay in Flag until my water bottle froze in my tent -- I made it through a few light snow showers before that happened, but the day before Halloween I packed up my truck, said goodbye to Betsy and crew, and headed back east. But not before paying a visit to our national treasure, the Grand Canyon, which we'll explore in the next post!

This OCD squirrel has neatly separated his cone stash: Douglas Fir (Pseudotsuga menziesii) in the background, White Fir (Abies concolor) in the front