Climate change is both a the subject of serious scientific research and a political minefield --- so much so that it has given rise to contrasting icons in the American popular culture.
Encouraged by the oil companies and other interests who would rather not change their ways of doing things, there has been the rise of the "tree hugger" stereotype, the "environmental terrorists" who go off the deep end in misguided reactions to what George W. Bush calls "fuzzy science."
On the other extreme, there are the zealots from countries that trashed their forest cover centuries ago, and which are now the current leaders in greenhouse gas emissions, who insist that the way out of the planet's dilemma must surely be for better educated people from the industrialized world to wrest control of the Amazon rainforest from the governments and peoples of South America, so that it can be preserved to their satisfaction. There may even be a few fools on this side of the equation who believe that "The Day After Tomorrow" is a serious warning rather than a campy work of Hollywood fiction.
But climate change is a serious topic for serious scientists, who because of the political implications (not the least of which comes in the form of threats to government research funding) tend to be very scrupulous about their work.
On August 17 the people who attended the Smithsonian Tropical Research Institute's (STRI's) Tuesday noon lecture series at the Tupper Auditorium got a sneak preview of some of that serious work. William F. Laurance, who works with STRI and in Manaus, Brazil with the Biological Dynamics of Forest Fragments Project, was talking to an audience composed primarily of other scientists, not to announce a dramatic new finding but to talk about some research that may lead somewhere and to in a give-and-take do some brainstorming with his peers.
The subject of Laurance's talk was "Composistional Shifts in Undisturbed Neotropical Forests: Effects of Climate Change?"
As a preface, the biologist admitted that his research on the topic is "pretty preliminary work at this point." Moreover, it's a matter that has popped up in the course of studying something else, the biological effects of forest fragmentation.
To do a proper scientific study of the changes that happen when a forest is fragmented, it is usually required that plots in undisturbed forests must be studied alongside the fragmented forest plots, the former as "controls" to set benchmarks against which fragmentation's effects might be measured. And so it was with the work that Laurance, along with STRI's Richard Condit and a bunch of grad students, is doing in Brazil.
But an odd thing happened. "We discovered that our controls weren't behaving as controls --- they were changing," Laurance said. It seems that the mix of trees was changing over the years.
To a reputable scientist, that's a major cause for concern --- not so much for fear of the jeering know-nothings but because non-random controls will skew the outcome of a scientific study. So Laurance and his colleagues began looking for errors, a search that led them to the published findings of other biologists. It turned out that a colleague had shown the same trend that they were seeing in their control plots. Fast-growing canopy and emergent trees were increasing, and smaller, slower-growing understory trees were declining. There was an overall acceleration in forest dynamics, with most genera of tree growing more quickly. Comparing data taken in 1985 and 2000, nearly 30 percent of the species in control plots showed significant changes, which, Laurance said, was "nearly 30 times more significant changes than expected by chance."
By comparison, however, at Barro Colorado Island's famous 50-hectare forest plot tree mortality and recruitment went down, while in Amazonia these factors were increasing. So an across-the-board uniform change in the forests of the tropical Americas is not what seems to be happening.
At the outset of his talk Laurance noted some likely suspects for changes that may be coming down. There are "unprecedented" changes in land use, "particularly in the tropics." We see the greatest carbon dioxide levels in the atmosphere in at least 20 million years, and the increase in levels of this gas is accelerating. Fossil fuel consumption in the developing countries is way up.
However, Laurance is not ready to make any definitive declarations about causes and effects on the data he has available. What he was doing at that STRI activity was instead picking the brains of other scientists for suggestions about where and how to look next. The discussion got into the advisability of tree ring studies and experiments in old growth forests, speculations about whether Barro Colorado Island's differences from Amazonia may stem from the fact hat the island is a forest fragment, the need to look at how El Niño effects might be skewing data and possible defects in experimental design. There was a suggestion that studies of temperate forests, which have faster growth rates during spring and summer than tropical forests experience, might be instructive.
To an ideologue with a fixed position to support, that latter discussion could be Exhibit A for a charge of "fuzziness." But in the scientific world, such caution in the face of uncertainty is a hallmark of professionalism.
Also in this section:
More differences than similarities in tropical forests
Do New World tropical forests reflect climate change?
Studying forest fragmentation's effects through insects
