Biology professor Selvadurai Dayanandan shows his affection for trees, at the Loyola Campus. His study of aspen trees has economic and environmental repercussions. While some tree species may take hundreds of years to grow fully, “industry is starting to use aspen for pulp and paper, and they can grow to maturity in relatively few years.”
Selvadurai Dayanandan was raised amidst the Sinharaja rain forest in Sri Lanka, a world heritage site and repository of tremendous biodiversity, including the giant dipterocarpaceae trees that form a canopy over the forest. This explosion of life inspired Dayanandan, now a Concordia biology professor, to ask, “How does such biodiversity arrive? And once achieved, how is it maintained?” He quenched this curiosity by pursuing an academic career in botany and using the Sinharaja as a research site.
Woodlands across the globe, from the Sinharaja to Canadian boreal forests, present important ecological challenges. From the evolutionary history of the tallest trees to the development of subterranean fungal communities and a host of other issues, researchers in Concordia’s Department of Biology, including Dayanandan, combine labour-intensive fieldwork with modern genetic analysis to understand some of the complex ways in which such ecosystems thrive — and in which their survival is threatened.
“The biology department has two main research thrusts,” biology chair Luc Varin explains. “One toward molecular biology and the other toward ecology.” The 19-member department comprises molecular biology researchers, including Varin himself, who studies biochemical aspects of plant growth; Patrick Gulick, who explores wheat responses to stress at a molecular level; and Elaine Newman, who looks at gene expression in E. coli. In the area of ecology, researchers include Emma Despland, examining insect-plant interactions; James Grant, exploring competitive aggression among salmon; and Paul Widden, investigating the role of fungal systems in forests.
Recently, though, Concordia’s researchers have begun blending the two approaches. For instance, those in Dayanandan’s lab use both ecological and genetic research in their analyses of biodiversity and regeneration in forests; Widden’s doctoral student, Tonia DeBellis, develops DNA profiles of mycorrhizal fungi; Grant has worked with Dayanandan on mapping genetic traits in salmon. “There is a lot of interchange now between molecular and ecology groups,” says Varin. Indeed, the department will be hiring a faculty member who will work between ecology and genomics to fill an NSERC senior chair in genomics. In addition, a $3 million Canada Foundation for Innovation (CFI) grant has helped the university establish the Centre for Structural and Functional Genomics, a collaborative research facility on the Loyola Campus that is drawing an ever-widening circle of participants. Broadly speaking, much of the department’s research focuses on forest ecosystems, areas where Dayanandan and Widden have distinguished themselves — although as experts on two quite different aspects of life in the forest.
Forest from the trees
“If you take a big forest, and fragment it by setting up towns, agriculture, or ranching,” asks Dayanandan, “do the remaining patches of forest behave normally? Once groups get isolated genetically, they tend to lose diversity.” Dayanandan has studied forests on four continents, exploring the parameters that affect biodiversity, and recently collaborated with Concordia geography professor David Greene to explore regeneration in boreal forests in Alberta. When a forest is destroyed by fire, the first trees to grow are aspens, which take about 20 years to reach a large size. The shade cover provided by the aspens enables the growth of spruce, which eventually tower over the aspen trees. As aspens do not prosper in the shade, they die out and spruce become the dominant tree in the forest — until they’re wiped out by forest fire and the process begins again. In the natural cycle, fires can be counted on every 100 years or so.
Biodiversity and regeneration are central concerns in Dayanandan’s lab, which includes doctoral students Cathy Calegeropoulos and Mona Hamzeh. Calegeropoulos has worked with both Dayanandan and Greene in analyzing seed dispersal — that is, how far seeds travel from the tree that produces them. Her findings will give scientists a better sense of how forests evolve and how biodiversity might be maintained. “For instance, after a clear cut, what is the probability of natural seeding when you have trees at the edge of the cut region?” she asks. Calegeropoulos is now taking DNA from seeds found in the field and using it to identify the mother trees, to track the exact distances travelled. “This way we can really describe what the dispersal pattern looks like,” she says.
Hamzeh is investigating stress responses in forest trees. “Most of the genetic markers identified to study evolution in forest trees are neutral markers; no one has targeted specific markers associated with fitness, like salt tolerance, drought tolerance or carbon dioxide tolerance,” she explains. “Following genetic tracks among tree species will also give a sense of how different species may have evolved.” The work of Calegeropoulos and Hamzeh could have profound implications for forest management and conservation, in addition to telling us how forests come to develop their particular mix of species.
“The focus in our lab is on genetics and evolution, but of course we’ve developed other related areas,” says Dayanandan. “While forestry research is our main interest, the same genetic tools can be applied to other disciplines.” As a result, Dayanandan’s lab — located in the new Renaud Science Complex — collaborates with other scientists on research into a range of different areas, such as salmon genetics with James Grant.
Fun with fungi
Biologist Paul Widden in his Science Complex lab. Widden began his career as a fungal ecologist looking for species present in different ecosystems. But when a graduate student asked him to supervise her research on endomycorrhizal fungi in the sugar maple system, he agreed, and hasn’t looked back.
The forest isn’t composed of trees alone, of course, and to understand diversity, one must look down as well as up. Paul Widden studies fungi communities, and more recently has become interested in mycorrhizal fungal systems. “The fungus will grow into the roots of a plant, allowing it to obtain carbon from the plant’s photosynthesis,” he says. “However, the fungi are also providing nutrients in return.” Fungus grows in a structure with filaments spreading through the soil; the whole network is referred to as mycelium.
“It’s like a cottony mass,” says Widden. “Look at Brie or Camembert — the fuzzy white stuff outside is the mycelium of fungus that ripens the cheese.” The forest is rife with mycelia. “The roots of a tree, without the fungus, can’t really explore a very great volume of soil, or penetrate into the finest pores within soil,” he says. “But when trees are associated with fungi and have the mycelium infiltrating the nooks and crannies of the soil, then the tree has access to much greater amounts of soil, and thus nutrients” — such as phosphorus, nitrogen and microelements. The fungi benefit from photosynthesis.
Different types of plants host different mycorrhizal fungi: ectomycorrhizal systems, in which the fungi grow between the cell walls in the root, interact with oak, beech and almost all conifers; endomycorrhizal systems, in which the fungi actually penetrate the cells of the root, favour trees such as sugar maple and cherry, as well as most agricultural crops; ericoid mycorrhiza attach to members of the ericoid family, including blueberries and Labrador tea. Many common mushrooms, including the gourmet delicacy morel mushroom and hallucinogenic “magic” mushrooms, are the fruit of mycorrhizal systems.
Fire vs. cutting
What happens, though, when these symbiotic relationships are disturbed? With funding from the Natural Sciences and Engineering Research Council (NSERC), Widden and his graduate students, Song Cheng and Sarah McNair, are researching this question, in part by assessing the effects of fires and clear cuts. “Fire is a natural regenerative process which clears out the boreal forest on a regular basis,” says Widden. “Forest industries claim to mimic the natural regenerative situation.” Widden’s research will test that claim. Using sites along the forest edge next to a disturbance — a burn or a cut — he and McNair are investigating how below-ground processes differ between the disturbed and the presumably undisturbed areas. “How does the mycorrhizal fungal system shift, how does decomposition shape the system, and how do nitrogen and nutrient levels shift as a result of a disturbance? Our hypothesis is that you have very different nutrient dynamics when you have a fire as opposed to clear cutting, where you lose the nutrients when you lose the trees.
“There were so many assumptions that had never been tested,” he continues. “Most people didn’t work with communities, but with the relations of specific fungi to specific plants. Much of this sort of research is closely tied into benefiting crops and trees” — for instance, by creating an inoculum, a fungal injection that would help plants grow. “But plants treated with an inoculum often do not thrive in a natural environment,” Widden points out. “A better approach is to understand the system and then adapt your practices to it. But while this approach helps the farmer and the crops, [agricultural-product giant] Monsanto doesn’t get anything.”
The urge to produce something marketable points to a fundamental problem, he argues. “Often our industrial applications involve destroying natural systems, and then selling them back, rather than learning about the systems and adapting our practices to them.”
The research carried out by Dayanandan, Widden and their graduate students can be labour intensive, involving the collection of materials — from core samples of soil to seeds dispersed across the forest floor. And of course, one must fend off the hostile predators of the Canadian outdoors. “This summer in Abitibi,” says Widden, “we were attacked by every type of biting bug — black flies, mosquitoes and horseflies — at the same time. You really don’t want to hang around.”
Simultaneously, he savours some of the less tangible rewards of his efforts. “Some of the things you find growing on the forest floor are quite incredible,” says Widden. “They’re beautiful.”
Patrick McDonagh, PhD 98, is a Montreal freelance writer.
If you’d like to learn more about Concordia’s Department of Biology, visit artsandscience.concordia.ca/biology
