Scientists See Signs of Trouble at the Forest Edge: Xingu Field Notes – PART TWO

Written by Bronson Griscom on . Posted in Learn


Today’s post is the second of a four-day series drawn from the field notebook of Bronson Griscom, Ph.D., The Nature Conservancy’s Director of Forest Carbon Science, who recently returned from a trip to the Amazon. In the northern Brazilian municipality of São Felix do Xingu, where forests are rapidly being cleared for cattle ranches, The Nature Conservancy is working with landowners, communities, businesses and governments to support sustainable economic development that protects and restores forests. In this series of posts and videos, Griscom brings us along into the forests on the edge of ranchlands to explain the science behind forest restoration.  

March 11 Continued: “Sweating” Forests Make It Rain

Here in Brazil’s rainforest, you would need a microscope to see the gazillions of tubules running up through each tree trunk that are pumping water out into the atmosphere through pores in the leaves. It’s called transpiration, and it’s responsible for half of the rain that falls in Amazonia.

No trees, no water pumps, and the rains falter — the very rains that farmers depend upon.

The challenges here in the Brazilian Amazon are different from those my ancestors faced in New England, but it seems to be a repeat of the same old story: killing the goose that laid the golden eggs.

Right about now a downpour of rain would be a godsend. We trudge on under the pounding tropical sun towards what looks like a line of broccoli on the horizon. Time melts into infinity…sun, grass, and thorny bushes. Then suddenly we are at the forest edge.

The land here slopes upward, and the earth is rocky. We push through a curtain of dense vegetation into the relief of a cool shaded forest understory. But, as I suck on my water bottle and wipe the sweat from my brow, I begin to notice that something is wrong. The forest is silent, the understory is bare, and the trees are small.

We had classified this forest from satellite imagery as an undisturbed fragment. But the trees are no bigger than telephone poles. Our satellite information on this place is wrong. What happened here?

Mark Ashton, a Yale University expert on forest restoration, and a mix of Sherlock Holmes and Bilbo Baggins, has already solved the mystery.

“See this?” he says with his British accent, holding a chunk of black charcoal. “Recent fire.”

He is standing beside the charred base of a massive Brazil nut tree, or what once was one. The huge dead tree arcs far above the low tree canopy like the arm and arthritic fingers of a giant.

We visit another patch in the afternoon. In contrast to the first patch, this one is in a low spot, with signs of seasonal flooding, so the original forest would have been dominated by a different community of trees and understory plants.

Even here, escaped fires during the dry season have left a degraded forest, a shadow of its original diversity and structure. Yet still these fragments are a critical refuge for some resilient plants and animals.

(Click the video below to see what the team found in the underbrush.)

We stop at a third patch, and it’s the same story.

Too Much Lost?

We return to town that evening saddened. If the natural nurseries are all in this state, then we can build artificial nurseries and plant trees out, but that is often an expensive exercise in frustration, and would never bring back the diversity that once was.

I lay in bed that night, sleepless, and recall a line from author Aldo Leopold, considered the father of the conservation movement: “The first law of intelligent tinkering is to save all of the parts.”

Certainly my own country has not set an example in that regard, at least on private lands, so who can blame Brazil? Aldo spoke of the need for a land ethic, and Brazil took an inspiring step in that direction with their Forest Code. But enforcement seems to have come late in places like this.

Is it too late here in the vast ranches of southeastern Amazonia? As I finally fade into sleep, I recall one more quote from Aldo, “One of the penalties of an ecological education is that one lives alone in a world of wounds.”

Yeah, get your little violin out for me – I need it.

Bronson Griscom, Ph.D., is Director of Forest Carbon Science for The Nature Conservancy. Catch up on the rest of Bronson’s Xingu Field Notes – Part One: Scientists Search for Healthy Forest on Amazon Frontier and Part Three: Scientists Wonder: What Life Flourishes in a Fragment of Forest. Visit Planet Change in the next few days for Part Four of his adventures trekking through Brazil’s frontier forests.

Videography by: Oliverio Cortez

Thumbnail photo: Oliverio Cortez (Bronson Griscom and members of the team set out through the edge of pastures looking for healthy forests.)

Photo by: Oliverio Cortez (A charred dead tree in a degraded forest patch indicates recent burning.)

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Planet Change is a Nature Conservancy blog site designed to share stories about actions the Conservancy and others around the world are taking to fight carbon pollution and the impacts of climate change, and to help people feel the connections between climate change and their daily lives and understand actions they can take.

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