Conifer-Hunting in Mexico

Day 9: Saturday, February 12

We got up early this morning and I think we were out on the road by 0815 or so. We knew we had a full day ahead and were intent on getting to Nevado de Toluca. We went through a number of interesting villages en route and it would have been nice to stop, but time was just too short. Just above Malinalco we saw an interesting juniper and in retrospect we should have stopped for a detailed inspection but we didn't and we never saw it again.

From our perspective, Toluca itself was hell. We got stuck in some nasty traffic, air pollution was awful, and we kept getting gassed by diesels. Finally we broke free of the town and the road immediately started climbing. Interestingly, the first (lowest) conifers were a stand of Abies religiosa on north-facing slopes. There were some fine, large trees in these stands, and later in the afternoon we collected some good cones and foliage samples there and Bob lasered a few trees—the tallest was 157 feet, one of the two tallest trees we saw in Mexico. A few kilometers farther, in a forest consisting mostly of Pinus pseudostrobus and Pinus montezumae, we turned off the highway and started up a gravel road toward the peak of Nevado de Toluca).

This is Saturday, and Nevado de Toluca is a very nice place to escape the smog and crowds of Mexico City, so there were a lot of people driving up the mountain. Soon after we turned onto the gravel road, it turned into a Pinus hartwegii (Perry would add Pinus rudis, but I tend to agree with Farjon and Styles in not distinguishing the two species) forest, and that was the only pine species from there to timberline (4026 m, according to Bob's GPS). The road is long and winding, and indeed I think half of it is above the timberline. Two hundred meters below timberline is full forest, mostly closed canopy, with trees mostly to 75 cm dbh and 30.5 m tall, most dominants only about 100 years old, and the very oldest maybe 250 though we did not core any and contented ourselves with a few rough stump counts. Then, at the timberline there is a transition from closed canopy forest of trees 15 m tall, to no trees and a tallgrass tussock meadow, in a space of about 15 m vertical. There are still a few widely scattered trees for maybe another 200 m of elevation but they are never more than a few meters tall and the cover is always much less than 1%. Krummholz does not occur, but some trees above timberline have the "pom-pom" form that we saw on the pass on Highway 175 crossing from Oaxaca to Veracruz (see Day 5). Over the course of the day we saw the timberline on nearly every side of the volcano, and the same situation applies throughout. The elevation of timberline varies by maybe 100 m (it was hard to tell; 50-200 m), seemingly in response to drought—the lowest timberlines are on S-facing slopes. (I have since heard that burning to maintain grazing in the alpine grasslands is a significant factor in maintaining the timberline on this mountain.)

The road starts up the west side of the mountain and traverses the north and east sides in the course of a long and winding climb into the large (maybe 1.5 kilometer diameter) crater, which has two crater lakes separated by a large resurgent dome, I think of dacite. En route are a microwave station and a guesthouse and a second kiosk (the first is at the park entrance, 10 pesos) where you pay 3 pesos per person to continue upwards. The road was a bit rough but the traffic was almost all passenger cars, some of them nice low-slung models, and some nice motorcycles—at one point we saw a GS1150 run into the ditch when an army Hummer came screaming down the mountain. The road peaks at about 4,200 m elevation and then descends about 100 m to the crater lakes. At 4,164 m we passed one of the few rock outcrops (nearly all of the roadside is tephra and colluvium) and here we found Juniperus monticola forma compacta, endemic to Nevado de Toluca.

At the summit between the crater lakes, I took off and walked to the mountaintop—or at least the south summit. There's also a west summit, which to me was indistinguishable in elevation, as well as a bunch of subsidiary peaks around the crater rim. It was about a 500 m climb, supposedly topping out at 4,609 m, which is the highest I've ever been on a proper summit although I walked higher following ridgelines in Tibet. Some of it, thanks to my going off-route, involved fairly exposed class 4 climbing at 4,500 m elevation. (For future reference, the real route traverses along the south slope, staying left of 3 gendarmes, until about due south of the summit, and then goes upwards.) Coming down is simply a scree slope all the way to the west crater lake. The book says that it is commonly snowy up here in February, in fact people come here for the skiing, but today the only snow was in tiny patches on boulder-shaded parts of the north slope above 4,300 m. No one else was up there, although a few people would hike up to 200 m above the crater floor and there was a small herd of very scrawny cattle at about 4,350 m. The summit views were glorious. I could see west to the line of clouds marking the Pacific airmass, and east to the line marking the Atlantic one, and Izta and Popo were clearly visible, and a small lenticular cloud marked the location of Pico de Orizaba. The smog filling the valley of Mexico was clearly visible, obscuring objects below about 3,800 m elevation, and I could see how the smog was flowing out of the valley toward Toluca. The sky was a deep cobalt blue.

We then drove down the mountain and headed for Morelia, but didn't get that far. We had another rough transit through Toluca and finally reached the cuota, making it to the village of Maravatío, about a hundred kilometers east of Morelia, shortly after sunset. Here we are in a plain but comfortable little hotel that I suspect is mostly frequented by truckers. The décor has some nice woodcarving and our rooms (separate for Bob) were each 175 pesos. Just two blocks away we found a plain restaurant serving splendid food and presentable drinks, where we squandered 275 pesos on the best stuff in the house.

Continue to Day 10

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