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September-October 2007
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< previous | 1 | 2 | 3 | 4 Much primeval tropical forest has been lost to logging, “so our efforts are now focused,” says Ashton, “on strengthening general theory in order to actively manage those remaining islands in which most of Asia’s biodiversity is becoming conned.” He and his colleagues have come far, he believes, in understanding how the diversity of trees is sustained—and with it the ark of insects and micro-organisms that depend on the trees and that comprise the bulk of a forest’s biodiversity. When researchers get the whole story, they will be able to show, he says, that “each rain-forest tree species, notwithstanding their superficial similarity in many respects, possesses at least one attribute by which it competitively succeeds, proving tter than the rest in a certain respect.” He wants to learn more about the interactions between tree species, and how the action is mediated by pollinators, or seed dispersers, or seed predators. For instance, the forest can be seen in one aspect as an exquisitely regulated clock. Certain trees ower in a sequence with other trees, timing critical to their mutual success because they share the same insect pollinator and avoid overwhelming it by owering seriatim. Ashton also needs to know more about pathogens, which he predicts will be seen to play the lead role in sustaining the diversity of the forest: when any tree population gets too dense, a pathogen knocks it down, providing the single major means whereby other species can ll the vacant space created, thereby building diversity. In a talk he gave in Tokyo about what science can do to sustain biodiversity, Ashton did not leave the lectern until he had suggested what policymakers should do, and quickly. “Tropical rain forests have declined so rapidly because the value to their owners is as capital to liquidate, but [that value is] low in the medium term in comparison to tree crops—rubber, oil palm, industrial wood and ber species. Their value is, rather, to us—to offset our carbon emissions but, more particularly, for their genetic information….This genetic diversity is irreplaceable. It will eventually prove vital to its owners, as it is for us now. We are beginning to compensate forest owners for their carbon sequestration but, so far, remain free riders for their genetic information, of which we in the industrialized world will be principal bene ciaries.” Ashton had in mind, for instance, that those diverse trees have developed diverse chemical defenses, of potential pharmaceutical and other value. “Unless we get used to the idea that we have to pay some rental to protect that biodiversity,” he says, “I’m not optimistic for the future.” With the continuously assembling database from CTFS’s research plots, “we’re now getting a capacity to monitor change at a very precise level,” says Ashton. “This gives us the obligation to look at unidirectional change in the dynamics and distribution of biomass not just in these individual forests, but on a regional and global basis. Then we must look for possible causes—changes in the climate, atmospheric chemistry, the carbon level, and so forth. Starting at the particular—the interacting species—and then working out to general questions of global change, is the rigorous way to proceed. There’s no one else doing anything like that, certainly not on a global scale. So the Arnold Arboretum is bang in the middle of one of the most important elds of research of our time, having in a way been just a pretty place to visit on a Sunday afternoon for many years. I’m very proud of that. That’s what I wanted to do originally. It’s taken me 30 years.” Christopher Reed is executive editor of this magazine. Fall programs at the Harvard Museum of Natural HistoryPlants Matter Fall Lecture SeriesLife on Earth depends on plants. The fall lecture series focuses on the relevance of plants and plant biology to critical social and environmental issues affecting our daily lives. Lessons from Tropical Rainforests: Science for Sustaining Biodiversity. Lecture by Peter Ashton. More than half Earth's biodiversity is confined to the tropics and three quarters of that is in lowland rainforests, some of which are already reduced to fragments. Harvard Professor and Japan Prize winner Peter Ashton discusses how we are beginning to understand how biodiversity is sustained, so that we can finally apply the right policies and management. Ashton's most prominent work is his leadership since the 1980s in research projects aimed at conservation and the sustainable use of tropical forests. He has promoted a network of "Forest Dynamic Plots" to examine their biological diversity, biological productivity, and role in stabilizing global climate. 6:00 pm. Free and open to the public. Harvard Museum of Natural History, 26 Oxford Street , Cambridge  
 
 
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