The United Nations has declared 2011 the International Year of Forests, an interestingly ambiguous title that can be read as either celebratory or cautionary. Our review of recent forest-related research is similarly mixed: It seems that for every paper that warns forests are at risk from climate change, another suggests that, if well-managed, they could help mitigate its impact.
Playing the role of victim and savior simultaneously is a lot to ask, but then forests have always played a dual role in the lives of man. In literature and folklore, they represent both the terror of the wild (they're the traditional refuge of trolls, elves and demons) and the restorative qualities of the natural world (as in so many of Shakespeare's comedies). Snow White calls the forest home, but so does Bigfoot.
The word "forest" apparently originated as a judicial term. In his 1992 book Forests: The Shadow of Civilization, Robert Pogue Harrison of Stanford University links the English word to the Latin foris, meaning outside or excluded. The term referred to land that was placed off-limits by royal decree, where it could not be "cultivated, exploited or encroached upon."
Forest law was introduced into Britain in the 11th century by William the Conqueror, who was apparently also William the Conservationist. It was codified sufficiently by 1592 for the delightfully named jurist John Manwood to write a treatise on the topic. In it, he calls a forest a place where "wild beasts and fowls rest and abide" for the king's "delight and pleasure." Disappointingly, there is nary a mention of carbon capture.
In biological terms, the world's oldest forest is located in upstate New York, near the small town of Gilboa. At least, that's what Binghamton University biologist William Stein reported in 2007 in the journal Nature. Three years earlier, he and his team discovered a 6-foot-long portion of a fossilized tree trunk dating back approximately 380 million years, which places it among the first generation of towering timbers. As Scientific American noted, "The rise of forests with trees like the Gilboa caused the removal of carbon dioxide from the air and temperatures to drop, creating climates like those experienced today."
Showing a disturbing lack of gratitude, humans have been determinedly destroying woodland at an alarming rate. According to a recent United Nations report, "Deforestation and forest degradation, through agricultural expansion, conversion to pastureland, infrastructure development, destructive logging, fires etc., account for nearly 20 percent of global greenhouse gas emissions - more than the entire global transportation sector and second only to the energy sector."
The United Nations has responded by creating the UN-REDD Programme. (The acronym, strained even by international organization standards, stands for Reducing Emissions from Deforestation and forest Degradation.) It will offer developing nations incentives (read: cash) to "reduce emissions from forested lands and invest in low-carbon paths to sustainable development." The effort could have a substantial impact, but only if it's carefully implemented; well-intentioned programs from the past have yielded unexpected and unwelcome results.
One example: The University of Exeter's Luiz Aragao analyzed satellite images of the Amazon rain forest in Brazil. Last summer in the journal Science, he reported that 59 percent of areas where deforestation rates decreased between 2000 and 2007 have seen an increase in forest fires. "Forest landscapes in Amazonia are becoming more fragmented and, therefore, a growing proportion of forests is exposed to the leakage of accidental fires from adjacent farms," wrote Aragao and co-author Y.E. Shimabukuro.
Partially cleared land is inviting to farmers, who employ a "slash and burn" technique to make room for planting crops. But these fires can't easily be controlled, and they often spread to forest land, emitting carbon into the atmosphere in the process. "The implication for REDD is that we first need a system that can monitor fires," the researchers concluded. "There is also a need to shift land use in the Amazon to a system where fire is not used."
So, when it comes to saving forests, local residents are the problem. Or are they the solution? That's the conclusion of a 2009 study by University of Illinois geographer Ashwini Chhatre. Writing in the Proceedings of the National Academy of Sciences, he suggested that when the U.N. starts handing out checks, it should bypass national capitals and proceed straight to the residents living in or near the forests in question.
Chhatre and the University of Michigan's Arun Agrawal focused on forest commons — community-owned and managed forests. Their analysis of 80 commons on three continents found they stored, on average, higher levels of carbon than government-owned and managed forests. "Local communities restrict their consumption of forest products when they own forest commons, thereby increasing carbon storage," they wrote.
The researchers found local autonomy is associated with "low livelihood benefits but high carbon storage, as communities defer use" of their local forests. The opposite was true of forest land owned by national governments, which are generally predisposed to exploit resources. Chhatre and Agrawal concluded that "transfer of ownership over larger forest common patches to local communities, coupled with payments for improved carbon storage, can contribute to climate change mitigation without adversely affecting local livelihoods." Like politics, perhaps all effective conservation methods are local.
Then again, larger environmental trends can sometimes offset local efforts. A 2007 study in the journal Ecology Letters reported tree growth in both Panama and Malaysia, as measured by trunk diameter, has decreased by 25 percent over the past two decades. The apparent culprit, according to Wake Forest University ecologist Kenneth Feeley, is warmer weather combined with less rain. That's precisely the opposite of what climate change optimists had hoped, and if the phenomenon is found to be widespread, conservation efforts will have to be increased to take smaller tree size into account. When it comes to trunks and carbon storage, size definitely matters.
Given such setbacks, creative thinking is called for, and there's no shortage of it among today's researchers. Scientists have speculated — separately — that invasive earthworms and dried mushrooms could increase woodlands' carbon-capturing capabilities. Swedish scholars have suggested fertilizing forests, presumably not with fossil fuel-based compounds. And then there are bats, which appear to be nature's answer to Johnny Appleseed.
Writing in the journal Conservation Biology in 2008, a research team led by Detlev Kelm of Berlin's Leibniz Institute for Zoo and Wildlife Research described a decidedly low-tech project in Costa Rica. Kelm and his colleagues placed 2-meter-tall boxes in open areas once occupied by tropical forest, hoping these artificial roosts would prove attractive to bats.
The winged mouse-like mammals found the accommodations pleasing, and thanks to their droppings, between five and 20 times as many seeds were deposited around the roosts compared to comparable clearings that lacked these man-made caves. Even better, the seeds included those of "pioneer" plants — rapidly growing foliage that provides cover for other plants to grow, as well as a home for birds and insects. When thinking forest regeneration, never underestimate the power of guano.