Last walk in the forest: near Zungarococha

11/07/2011

For my last couple of days in Peru, the plan is to keep things simple and relatively close to home. Seth has one more sample he needs to collect at a field site–a bioluminescent fungus that lives in the bark of one of his trees. After that he and Karen will be at work deciding which of his belongings are going to stay in long term storage at the IIAP station and either pitching or packing the rest. They will be leaving Peru and returning to the States, just a couple of days after I’m heading onwards to Argentina.

Seth’s sites are something like twenty kilometers farther down the Iquitos-to-Nauta highway. He probably doesn’t need more than a few minutes to do his collection at one of the sites but wants to show us a couple of different important habitats that we haven’t yet seen: varillal and chamisal, both growing on patches of white sand soils, which is nutrient-poor as compared with the red clay that is the more common soil type in the Amazon.

For most of the earth’s history the Amazon flowed in directions different from its present manifestation, initially draining the western half of the supercontinent of Gondwanaland before South America split off from Africa. With the South American plate moving westward and into/over the Nazca plate, the resulting orogeny gave rise to the Andes on the western edge of the continent like a geologic beaver dam, blocking the great river’s access to the Pacific. In the ensuing epochs, enormous inland seas form and drain. There’s a period where the basin drains northward into the Caribbean, but that stops after uplift of the the northwestern edge of the South American plate extends eastward across Venezuela. An inland sea forms again until finally a path out and into the Atlantic opens up, and that’s my oversimplified paleo-hydrological understanding of how things got to the way they are today. The Amazon drains the largest and one of the most rainy (15-25 meters of rain per year) watersheds in the world. That comes to something close to 300,000 cubic meters of water per second during high-flow periods. The size of the river is unimaginable until it is seen.

embiopterids are easily located by the shield of silk that covers them on the trunk of a tree

But let’s get back to Seth and his scientific focus. Given that the Amazon basin has never had much opportunity for uplift, it is very flat. And given its history, the soils tend to be the fine-grained stuff–silt and clay eroded from outlying highlands and deposited as lake bottom. There’s hardly a rock to be found around here. Different sediments from different sources vary in their quality–the silts washed off of the Andes most recently is very fertile while the patches of white sand–eroded from who-knows-where but it is much older stuff–is comparatively devoid of nutrients. This low-lying part of the Peruvian Amazon is especially patchy in soil type, and when you add the fact that parts of the forest become flooded during high-water periods and some areas drain nicely and others stay mucky, this adds yet another dimension of diversity of the “physical environment.” If you were to strip away all the life from this area, you’d still be looking at a lot of variation despite the fact that topologically it’s a relatively flat and featureless landscape.

"huffing" the crushed leaflet from a volatile Protium

Instead of being the classic “highly diverse rain forest” you might associate with upland tropical forest, this area is characterized as a mosaic of diverse kinds of forest with no one type having great numbers of species (low alpha diversity) but having an impressive level of biodiversity when taken on a larger scale that incorporates the different habitats (high beta diversity).  People studying biodiversity in these parts gravitate towards questions about how the soil heterogeneity may or may not contribute to overall diversity in an evolutionary way–i.e., did new species originate within this area because of the patchy nature of soil types. I think Seth’s doc advisor is one of these people.

Well, that’s making a short story long. The point of it all is that after nearly a week in Peru we still hadn’t seen the reason for Seth’s being here. And as things turned out, we wouldn’t get to–not this time, anyways.  Up to this point our trip had been perfectly free of unforeseen delays–we had been able to cram our activities and new experiences in one after another, pausing only at the end of the day when I could scarcely muster up the energy before crashing to put some words into these blog entries to make the framework for what could be later be completed into the posts you’re seeing here. But now. A chubasco struck, making the prospect of a 26 km mototaxi ride less than appealing (but giving me time to write in my room at the hostel, which was good I suppose). With the weather clearing later in the morning, Seth headed out to the IIAP station to make the solution he uses for collection. By the time Karen and I met up with him there it was time for a very late lunch, leaving us with not nearly enough time to make it to the distant field sites.

an as-yet-undescribed species of Protium. we know at least that this is one of the volatile forms

We opted instead for a visit to a site just past Zungarococha, a community where Seth is considering making a home when he comes back to Peru next June. Though it’s not far from the IIAP Quistococha station, the road there is unpaved and badly rutted, and our mototaxi’s front tire was already low at the outset but was completely flat before too long And so we had to walk the rest of the way–which we all wanted to do anyway since the mototaxi ride was both painfully bumpy and painfully slow.

Seth finally got a chance to show us some Protium, the funny little plants that claim part of his fascination–at least the part that he’s obliged to show in order to keep his doc advisor pleased with him. Protium’s family, the Burseraceae, is the source of both frankincense and myrrh, and we had found some copal (local frankincense, the solidified resin of Protium copal) for sale in the market at Belen.  The Protium of the Amazon are basically divided into three kinds: sap with highly volatile aromatics, sap with latex, and clear sap.  The volatile ones actually spew out a little hydrocarbon-y aerosol when a leaflet is broken off from the rachis. They’re like living butane canisters and should come with signs cautioning people to not smoke nearby.

found throughout the neotropics, Paraponera is called the "bullet ant" after the way it hurts if you get bitten and stung (more like two bullets)

After having a bit of a survey of three or four species of Protium and a good number of Protium look-alikes, other plants and arthropods, it was time to return to the city.  We walked most of the way back to the highway, past an agricultural station of the university, a swimming hole (located near a pig farm and it smelled a bit, too), Zungarococha, and then we caught a mototaxi to take us back to the station.

Later back at the hostel we had a beer-tasting for my final night in Iquitos–actually Karen and I had already decided that Cusqueña was hands-down the best option (though not an Amazonian brew), and we were just trying to determine the runner-up.

Cusqueña (the blond one, not the dark one in this pic), was easily the most drinkable of the beers we tried

We theoretically could have made it out to see the chamisal the next day (same day as my departure), we never did-the weather in the morning was again not especially cooperative. Instead, we went through our photos from the trip, taking a few notes to help jar our memories when it came time to catalog and document.  After I left Karen and Seth spent the remaining time–two days–just packing and cleaning. Yeah, I pretty much just stayed through the fun part and when there was work to do I was gone already. Upon returning to the states Seth was headed first to a wedding, then to Woods Hole for a summer course, then on to Berkeley for the regular grad student-y stuff (like teaching undergrads). Karen will be in New England, near her family home, for a while.

My next stop will be in Argentina, on a visit to my good friend Mike who lives in Buenos Aires.

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