Adventures of a Woman in Field Biology
Yale University Press
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The Rain-Forest Canopies of Australia
Yet another continent of life remains to be discovered, not upon the earth, but one to two hundred feet above it, extending over thousands of square miles ... there awaits a rich harvest for the naturalist who overcomes the obstaclesgravitation, ants, thorns, rotten trunks and mounts to the summits of the jungle trees.
William Beebe, G. Inness Hartley, and Paul G. Howes, Tropical Wild Life in British Guiana, 1917
My love affair with the rain forest did not begin with the canopy. When I first arrived in Australia in 1978 and began my graduate studies in 1979, I never gave a single thought to the notion of climbing trees, let studying what lives up there. I was passionately interested in rain forests, but (like most of my colleagues who aspired to understand the tropics) my horizons were limited by the age-old tradition of making observations at ground level and occasionally using binoculars.
Like most students, I yearned to study the dynamic, cuddly inhabitants of the forestthe monkeys (koalas, in the case of Australia), birds, or even butterflies. Instead, I selected a more benign, yet essential, elementthe plants. Several popular accounts have told of women scientists who work with apes or other animals, but I thought that plants deserved a chance, too. I considered them to be as adventurous and passionate as their faunal counterparts. Marvelous twisting vines travel hundreds of meters atop the canopy; aggressive strangler figs wrap around host trees and suffocate them; bromeliad tanks provide watery homes for frogs and salamanders and insects; tiny thrips fly long distances fraught with danger to locate specific flowers for pollination. In short, the lives of plants are full of a mystery that rivals that of any mammal. Perhaps best of all, the tropical rain forest boasts a level of activity and complexity unrivaled anywhere on the planet, and it has become a lifelong challenge to me and others seduced by its botanical mysteries.
During the 1970s, tropical rain forests were still considered a biological black box (in other words, a big dark region full of unknown phenomena). How many species existed in these complex forests? What mechanisms led to the coexistence of so many creatures in one place? Could we understand the intricate relationships between animals and plants in the rain forest before all were destroyed? As a botany student, I found the tropics compelling. Armed with a tolerance for mud, leeches, and damp notebooks, I wanted to confront the enigmas of this poorly understood ecosystem.
My childhood and undergraduate education took place in the more familiar forests of upstate New York, where the annual shedding of leaves and the reliable spring renewal of foliage brought great comfort. A product of the temperate zone throughout my childhood, I suffered the malady typical of many field biologists: a temperate bias. I perceived nature based on what I observed in temperate ecosystems, and this limitation made it difficult to fathom the complexities of tropical forests. Patterns such as evergreen leaves, continuous flowering, winter migrant-bird populations, and leaf fall in December were much harder for me to accept than the convenient summer-winter contrasts of northern temperate maple forests. My graduate studies took me to an unknown forest type, halfway around the world and in a different hemisphere. From this adventure I hoped to gain a clearer picture of some of the complexities of the particular black box called the tropical rain forest.
I had completed a master's degree in ecology in 1978 at University of Aberdeen in Scotland, writing a thesis about the seasonality of highland birch trees. I had huddled under my electric blanket in a student house with no heat or hot water, and often lived on "road-kill" (rabbit stew collected on the roadside after class) to offset my subsistence budget. Like many graduate students, I endured less than acceptable physical conditions in order to gain the opportunity to study new ideas and, in this case, an entirely new continent of plants and animals. Appreciative of the opportunity to thaw out after the chill of the Scottish highlands, and at the same time eager to study tropical forests, I accepted a scholarship from the botany department at the University of Sydney. I was so naive, however, that I failed to realize that Sydney was more than a thousand kilometers from the tropics. Off I went in October 1978 to the land down under, to pursue my botanical dreams.
I had selected Australia as my first site for rain-forest research for several reasons. It was English speaking. Its forests remained some of the least studied in the world. It boasted superb ecological gradients from cool rain forests on the mountaintops to lowland rain forests in the humid valleys, and inland to dry forest on the West-facing slopes. In addition, what aspiring biologist is not fascinated by an island continent abounding with such unique creatures as koalas, wallabies, and cassowaries, to name but a few. I chose to work in the "lucky country," as Australians affectionately call their part of the worldperhaps lucky for a white male, but not for an American woman scientist in the 1970s. I never thought about the cultural challenges: an outback attitude that rigidly segregated gender roles, and a pioneering philosophy that was admirable yet emulated the American West of the last century where issues such as conservation were sometimes overlooked.
In an evolutionary sense, Australia is intriguing because it represents the interface of two groups of plants, the tropical flora from Indonesia and a temperate floral element originating in Antarctica and New Zealand. This overlap provides a relatively high diversity within one continent, and associations of plants found nowhere else on the globe. Australia is also one of the few developed, English-speaking nations to have tropical rain forests. One might assume that it could serve as a model for other countries in terms of excellence in tropical rain-forest management and conservation. In reality, like many other countries, Australia has made mistakes in its attempts to manage natural resources. As recently as the late 1970s, only a handful of individuals had attempted to study its tropical rain forests, and virtually none had ventured into the canopy.
The first challenge of my research career in Australia was to locate and recognize a rain forest, not necessarily a simple task for a student afflicted with temperate bias! My graduate supervisor, Peter Myerscough, a gentleman botanist of English origin and a wonderful teacher, suggested that I simply drive north from Sydney until the foliage became lush green. Such instructions, albeit simple, seemed daunting in a country of 7,682,300 square kilometers (almost as large as the United States at 9,809,390 square kilometers). But his advice was useful, since 95 percent of forests in Australia were a bluish-gray color, from the genus Eucalyptus that constituted the dry, or sclerophyll, forest.
The remaining 5 percent of the forests on this island continent were rain forests with a luxuriant green canopy. Rain forest was distributed in a narrow band along the coastal escarpment of eastern Australia. The mountain ranges spanning the northeast coastline created a rain shadow with moisture adequate to support rain-forest vegetation. By definition, rain forests receive over 2,000 millimeters of rainfall annually. In evolutionary history, tropical rain forest was once spread over much of the continent of Australia. This land mass (part of Oceania) was then called Gondwanaland, and its forests were continuous with Indonesia. Tree species of a tropical nature were defined as the Indo-Malaysian element of Australian vegetation; a second component of flora existed in southeastern Australia, called cool temperate or Antarctic (the term Antarctic refers to its proximity to the continent of Antarctica). It was composed of flora shared among Chile, New Zealand, and southeastern Australia. These two contrasting vegetation types, the Indo-Malaysian and Antarctic elements, overlapped on one continent to make up the Australian rain-forest flora. Despite their small land area, rain-forest patches in Australia represent a relatively high proportion of the country's floral diversity as compared to their dry-forest counterparts.
During the Jurassic period, drier conditions in Australia resulted in expansion of the dry sclerophyll forest distribution and subsequent reduction of the rain forests. Many of those naturally occurring rain-forest patches have since been reduced or even removed entirely, owing to logging and clearing for agriculture. In the mid-1800s, "timber-getters" cleared and settled many sections of eastern Australia in their search for red cedar (Toona ciliata, family Meliaceae), a highly desirable furniture wood. The isolated patches (many along steep gullies) of rain forest that remain today in Australia are a consequence of evolution, as well as of human exploitation.
I did not set out to be a canopy biologist. As my research developed, a natural progression of ideas simply led me into the treetops. My initial forays into the bush were frustrating, because I had few colleagues. No other students and no faculty at the University of Sydney were involved in rain-forest research, so my information came either from books or from fortuitous interactions with visiting scientists. When first contemplating the immensity of designing a doctoral project, I was determined to study butterflies in the rainforest canopy. I envisioned myself sitting in a swing up in the foliage, counting colorful species of Lepidoptera and having a wonderful time. My supervisor was more realistic and reminded me that a dissertation required extensive data collection. He worried that I might go to the rain forest and find no butterflies, because of their mobility and cryptic behavior. I reluctantly switched to something less mobile: trees. I decided to study the growth patterns of rain-forest leaves, which was an expansion of my master's work in Scotland on phenology (seasonality) and photosynthesis of birch trees-although tree canopies in the highlands of Scotland had been only 15 feet high!
Little information about rain-forest leaves existed in the literature, despite the fact that foliage was the driving force of a forest ecosystem. Prior to the 1970s, the majority of ecological work in rain forests had been descriptive rather than experimental. What were the growth patterns or seasonal dynamics of leaves? They included birth, survival, longevity, death, and decay. My hope was that it would be possible to employ valid experimental design in my research if I dealt with leaves as units of replication rather than entire trees which were too large and cumbersome to replicate with ease.
As is typical of a dedicated graduate student who was passionate about her research, I literally threw myself into fieldwork, living and breathing data and ideas on rain-forest canopies. My aim was to understand the leaf-growth dynamics of the most common tree species in the rain forests in the tropics and subtropics of Eastern Australia, and to measure the impact of herbivores on the survival of leaves. My questions included: What was the lifespan of a leaf in a tropical tree canopy? What factors triggered leaf flush events? What influences caused leaves to die in this warm environment, where winter cold obviously did not trigger abscission?
To answer these questions, I marked thousands of leaves in the canopy, giving careful attention to sampling design with respect to factors such as space (differences between species, sites, heights in the trees, individual trees, among branches) and time (differences in leaf growth with respect to seasons and years). I selected five tree species for comparisons of leaf growth dynamics, mainly because I could not possibly study all of the thousands that constituted the tropical forest canopy. All five species were ecologically important and possessed traits reputed to protect them from insect damage (for example, nasty stinging hairs, extreme toughness, rarity, or toxicity). Over time I documented the battles of my marked leaves against herbivores, which were a major influence on longevity. Little did I know that some of my leaves would have lifespans of over twelve years, making the duration of my fieldwork much longer than anticipated. Such surprises were indicative of that temperate bias formulated during my youth in upstate New York, where leaves lived only six to eight months.
To test various hypotheses about leaf growth dynamics in rain forests, I could have selected leaves at ground level for my measurements. But it is arguable that my results would have been biased to shady conditions, and atypical of most foliage that grew high above the forest floor in a sunny environment. Gazing upward from ground level, I saw another compelling reason to investigate the canopy rather than limit my research to the forest floor: most of the biodiversity was concentrated in the treetops. Herbivores may be important to the growth dynamics of leaves. Evidence collected in the late 1970s by Terry Erwin of the Smithsonian Institution suggested that the majority of insects on Earth inhabited the forest canopy. My curiosity about the canopy was reinforced by this potential plethora of insect-plant interactions.
I did not intend to climb trees as a career. In fact, I tried desperately to think of alternatives to climbingsuch as training a monkey, utilizing large telephoto cameras on pulleys, or working along cliff edges where rain-forest treetops were at eye level before cascading into valleys below. None of these methods seemed feasible for accurate data collection, so I finally decided to become an arbornaut!
I shall never forget my first climb. The date was March 4, 1979 (my mother's birthday), and the tree was a coachwood (Ceratopetalum apetalum, family Cunoniaceae). This species grew to 30 meters in Royal National Park just south of Sydney. By good fortune, excellent patches of coastal warm-temperate rain forest remained there, despite urban sprawl. I intended to use this local site for photosynthesis measurements and other studies that might benefit from the close proximity of the University of Sydney. Coachwood, one of my five study species, was an economically important timber species, with tough waxy leaves that looked as though they would be difficult for insects to chew.
I was fortunate enough to be "adopted" by a local spelunking club, whose members taught me about hardware and ropes for climbing even though their techniques had been developed for underground caves. They must have found my ignorance and naivet quite amusing. Because mountaineering shops and catalogs for outdoor products were not yet available in Australia, I sewed my first harness by hand from seat-belt webbing, following the advice of my teachers, Julia James and Al Warrild. After a practice session in a tree outside the botany department at the University of Sydney, we mounted an aerial expedition into a coachwood, where I learned to rig a tree with a slingshot and rappel. As with most beginners, my first climb was fraught with flailing, upside-down maneuvers as I struggled to center my body weight in a position conducive to dangling from a rope. The sensation was superbdespite all my sore muscles the next day!
From then on, I never looked back ... or down! After further instruction I thought myself capable of reaching the leaves of any structurally sound tree in the Australian rain forest. Armed with such paraphernalia as 70 meters of Bluewater II static climbing rope, my homemade harness, two Jumars, a whales-tail, a homemade slingshot, a large supply of sinkers and fishline, and field notebooks, I was ready to study life in the treetops.
During my years of canopy research in Australia, I drove hundreds of thousands of kilometers to conduct monthly monitoring of leaves in the canopies of many trees in temperate, subtropical, and tropical rain forests. I developed a permanent list of useful field equipment (see Appendix). These excursions also afforded me the opportunity to see life in the outback, and to embrace the culture of this island continent. I encountered many people whose kindness enriched my field experiences and forever touched my heart: the ranger who offered small nips of scotch after long, rainy days in the trees; the wood-carver in Dorrigo who transformed old fenceposts into beautiful bowls and taught me to recognize the timbers of my favorite trees; my technician, Wayne Higgins, whose keen eye and steady hand almost never failed to shoot the line over the branch; and the many friends who accompanied me on sampling trips and enthusiastically endured leeches and heights. There were also colorful characters: the thieves who stole a fallen cedar tree out of the national park; the milk-bar (coffee-shop) owners, horrified by my khaki clothes and the machete hanging from my belt, who nonetheless served a terrific milkshake; the counterculture Australians with hallucinogenic aspirations, who continually collected rain-forest fruits and seeds to smoke or otherwise ingest; the human "moth," a rancher who ventured into the local pub whenever its light went on; and the occasional tourist who came to the national park in stiletto heels, walked a short distance onto the trail, only to scream "Leeches!!!" and stumble hurriedly back to her car.
After overcoming my initial dilemmas of learning to recognize a rain forest and climbing trees, I selected several long-term study sites in national parks or reserves. At each location I rigged replicate trees for permanent canopy access. The biggest challenge was undoubtedly the giant stinging tree, or gympie-gympie (Dendrocnide excelsa, family Urticaceae). This species, as its name implies, has thousands of stinging hairs that coat both leaves and petioles. Its physical hairs can painfully tear the skin, besides which chemical hairs inject a toxin into the freshly scratched surface. In 1908 an Australian chemist named Petrie reported that stinging trees have a toxicity up to thirty-nine times stronger than that of common nettles. Both giant stinging trees and common nettles are in the same plant family (Urticaceae), but nettles grow approximately 3 feet high in fields, whereas stinging trees grow to zoo feet in rain-forest gaps. Because I was interested in longevity and survival as part of leaf growth dynamics, defensive hairs piqued my curiosity.
The Mount Keira Preserve overlooking Wollongong, New South Wales, was suggested to me as an auspicious site for stinging trees. Evidently the slight disturbances (landslides, road-building) on the escarpment created excellent conditions for the growth of this pioneer tree (that is, a tree that colonizes open areas or disturbed sites). Stinging trees grew within the preserve, to 150 feet with a diameter of up to 8 feet, along a trail system built by Boy Scouts who sometimes camped there. Unfortunately, my elation at this discovery was quickly dampened by the Scout caretaker, whose uninvited flirtatious overtures rendered my use of the Scout trails rather uncomfortable and downright risky. To avoid awkward confrontations, I decided to enter the preserve from the opposite side of the mountain and make my own private trail.
After reconnoitering, I found a wonderful gully, where it was likely that no human being had ever ventured. Superb lyrebirds (Menura superba, family Menuridae) were in full song when I first trekked through my newfound patch of remnant rain forest. These magnificent passerine birds were one of the unique rewards of working in Australia. Territorial pairs of lyrebirds inhabited most of my field sites, and over the years I was privileged to watch their magnificent courtship displays. Lyrebirds imitated other birds, developing an extensive repertoire of fifteen to twenty different sounds. They often repeated their medleys for long durations (without a breath, it seemed), and their rich and beautiful tones resonated through the forest. Lyrebirds were a constant, treasured companion throughout my years of Australian research. Ironically, the Mount Keira lyrebirds had some unusual imitations in their repertoire: dogs barking, lawn mowers buzzing, and trucks downshifting. These were perhaps a foreboding commentary on the urban development that was fast encroaching on this region.
In my secret gully I selected trees for climbing. In the case of giant stinging trees, I ascended a neighboring tree and reached across (with gloves) to its branches. Each sampling trip without fail resulted in several stings, but I became quite accustomed to this fiery sensation, similar to a bee sting. Even the dead, dried leaf material retained its stinging capacity. My hands almost always bore the resulting red inflammations, which seemed impossible to avoid owing to my continuous sampling schedule.
My methods were relatively simple. I used a waterproof pen to number leaves sequentially on different branches at different heights of different trees, and then returned monthly to monitor growth, damage, coloration, and eventual death. I traced leaf areas to measure insect damage and kept notebooks of information on leaf growth patterns. From these long-term measurements, I quickly accumulated a large database on the growth dynamics of thousands of rain-forest leaves. The ink lasted remarkably well and enabled me to monitor each leaf permanently for as long as it lived.
I also erected litter traps to sample and collect falling leaf material throughout each month of the year. This was a fairly traditional mode of calculating forest biomass by surveying the weight of wood, foliage, and flowers. A litter trap consists of a 1-meter by 1-meter mesh collecting structure, supported by legs of plastic pipe. When I set out to construct my first traps, unanticipated effects of the Australian labor unions caused me considerable stress. First a transport strike occurred. Then followed a summer holiday period of two months, during which it was impossible to obtain the materials I needed. The strength of the Australian labor unions gave them total control over certain aspects of life. These delays taught me one valuable lesson: to plan my research far in advance.
After I finally had the litter traps and climbing trees set up in my secret gully, I ventured forth eagerly after the first month to empty the trap contents and collect my first samples. It was September, early spring on the Australian calendar. Descending into the gully, I was surprised to feel the ground near my feet moving. In my haste I barely missed stepping on an Australian brown snake (Pseudonaja textilis, family Elapidae). This extremely venomous species is renowned for its aggressive behavior during the spring nesting season. Moving ahead more cautiously, I was totally overwhelmed by what I saw. The ground was literally swarming with snakes, all of them poisonous species. Such a multitude had obviously assembled to bask in these perfect sun spots ... Indiana Jones, take note! I delicately tiptoed out of my snake-filled gully and sighed with relief when safely back in the university car. This dangerous predicament forced me to abandon the gully entirely, for all my attention would have been riveted on the ground rather than on the treetops. I eventually managed to find a rain-forest patch on the lower slopes of Mount Keira Preserve with excellent stinging trees to study, but without swarms of snakes or harassment by caretakers.
Levels of herbivory of up to 42 percent leaf-surface-area removal per year were measured in the canopies of these giant stinging trees, despite the apparent defense of stinging hairs. A host-specific chrysomelid beetle (Hoplostines viridipenis, family Chrysomelidae) was adapted to chew exclusively on these veritable pincushions. The levels of herbivory were the highest of any Australian rain-forest tree that I measured. How did this species tolerate such significant loss of photosynthetic tissue? And why did such supposed defenses fail to protect the leaves? Apparently the fast growth rate of stinging trees and their relatively low investment in leaf tissue (leaves were thin and short-lived) enabled the trees to replace damaged foliage without dying. And the stinging hairs that were so effective in defending leaves from humans were obviously not effective in deterring beetles. Presumably in Asia, where the Urticaceae family evolved, this mode of plant defense was very successful against mammal predators. I was incredulous, all the same, to realize that, despite the toxic hairs, the stinging trees suffered more insect damage than any other rain-forest tree that I measured. High levels of variability in defoliation among different species was a startling discovery, and led to further study.
My second long-term field site was established at an elevation of 1,700 meters in the cool temperate or montane rain forests of New England National Park in New South Wales. This region of Australia was ironically called New England because a few deciduous trees (oak, maple) thrived in several nearby towns, turning color in the autumn just as they do in my homeland of upstate New York. My field camp in New England National Park was a tiny hut called Tom's Cabin (named after the first ranger of the park, according to local lore, not a legacy of Harriet Beecher Stowe's Uncle Tom, as I had first assumed). It stood at the boundary (or ecotone) of rain forest and wet sclerophyll forest amid a stand of my third study species, Antarctic beech (Nothofagus moorei, family Fagaceae). The sun almost never shone on Tom's Cabin. It was a world of mist, moss, fungus, clouds, constant drizzle, and cool air blowing in from the coast onto this east-facing escarpment. Often those cool breezes turned into raging storms; snapping branches and falling trees provided background music as I huddled inside my cabin measuring leaf areas or counting insects. There was no electricity, but the cabin boasted an enormous gas-operated shower, large enough to accommodate a cow (or so claimed the ranger). It was an incredible luxury to return to the cabin after a wet, exhausting day of tree climbing and find the gas bottle full enough to allow a hot shower; it was devastating to arrive and find it empty, which happened more often than I care to remember. Equipped with lanterns, matches, food supplies, and notebooks, Tom's Cabin became my base camp from which I tackled the cool temperate rain-forest canopies. I was even "adopted" by a native tiger cat (Dasyurus maculatus, family Dasyuridae), who became tame enough to creep into the cabin and defiantly grab a steak from my fireplace grill. Although I was sorry to sacrifice the steak, it was marvelous to glimpse this unusual marsupial cat at close range.
As a woman working long weeks alone in remote places, I was fortunate to have very few experiences that engendered fear. Locals would occasionally take the wrong road home from the pub and end up pounding raucously on my door, but for the most part the world went on without me when I stayed at Tom's Cabin. Most Australian men probably viewed me as an eccentric. Later I was teased because my Rockport hiking boots were the ugliest women's shoes my father-in-law had ever seen, or because I was not adept with a pressing iron (an essential skill for snaring a husband in rural Australia). The notion of a woman traveling 10,000 miles to a remote continent to study tree canopies was not only preposterous, but downright suspicious, to most of the Australian men I encountered. To travel even 100 miles to pursue intellectual ideas that had no practical basis in the kitchen or bedroom may in fact have been laughable to many rural Australians, male or female. My sojourns in the bush were often lonely. Field research by its nature requires long periods of solitude, first to make observations and collect data, and second to write up the results. But I found these times alone to be very strengthening, as they encouraged me to develop confidence in myself.
The cool temperate or cloud forests reminded me superficially of the temperate deciduous forests of my childhood. Antarctic beech was related to the American beech of the northern deciduous forests. In Oceania the cool temperate rain forests were remnants of the Antarctic rain-forest element that extended from southern Queensland down into Tasmania and New Zealand. They were a fascinating example of naturally occurring monocultures in nature, with beech trees occupying approximately 95 percent of cool temperate forest canopies. (A forest stand with one dominant tree species is called monodominant.) In New South Wales these pure stands of Antarctic beech represent a potential feast for a leaf-feeding insect. How can a tree species that dominates the forest manage to protect itself from insect epidemics? Does the plant produce toxins to defend itself?. Antarctic beech was my third study species, which enabled me to ask questions about how monocultures protect themselves from insect epidemics.
During my years of canopy research from Tom's Cabin, I encountered my first strange case of a UFO (unidentified feeding organism). In 1979 the Antarctic beeches lost enormous amounts of leaf area to a mysterious herbivore that attacked the foliage for two weeks in October (alas, while I was not present) and then disappeared. What was left was a severely defoliated population of leaves, with no sign of the guilty marauders. In the course of my career I have repeatedly observed evidence of defoliators, then spent hours, weeks, even years to find the responsible munchers. Antarctic beech exhibited a slightly temperate leafing pattern (like its American beech relatives), where approximately half of the leaves emerged every spring (September-October) and half senesced in autumn (April-June). With this massive flush of new foliage, some opportunistic herbivore had adapted its life cycle to invade the beech canopies at the appropriate time and devour the tender new leaves. Every year the beech trees lost more than half of their new foliage from this UFO.
Because of this seasonal pattern, I had to wait a full year after my first observation of the massive defoliation to solve the beech mystery. I was nervous and apprehensive. Obviously, it was possible that the defoliator might not return two years in a row. Perhaps 1979 was part of a cycle that only occurred every twenty-five years and I would never find the culprit. All the same, I packed my gear for a long stay in Tom's Cabin the following spring and built several hardwood ladders that mounted the beech minks, to facilitate canopy access day or night, rain or shine.
On the first warm evening in late September, I was rewarded for my efforts. Prowling in the canopy with my flashlight, I saw the subtle movements of a few tiny caterpillars, dangling from the young leaves on delicate threads of silk. But I did not observe them feeding on the beech leaves. I returned several successive days, and the numbers of caterpillars virtually exploded until approximately ten larvae occupied each new leaf. And they began feeding! First they ate the uppermost leaf, presumably the most tender and soft, since it was the youngest tissue. As the caterpillars grew a little bigger and their mouthparts became slightly stronger, they ate the next leaf, gradually moving down the branch in lawnmower fashion, growing larger as they fed on successively tougher leaves. I made careful measurements of their abundance and feeding rates. Then, as suddenly as they had arrived, the caterpillars were gone. The new leaves were mere skeletons. I had not managed to collect any larvae to rear and hatch into adults for identification, and the defoliators escaped unidentified. Discouraged, I returned to Sydney to wait yet another year to complete my beech-herbivore saga.
(C) 1999 Yale University All rights reserved. ISBN: 0-300-07818-8
There is growing concern globally on the green house effect caused by carbon dioxide emission. Biomass conversation is a way to create a net decrease in overall carbon atmospheric pools (paragraph 1, page 2) and contribute to clear energy. Dawson Forest Products intends to implement biomass conversation project to meet the current environmental requirement from Canadian government, but the associate capital cost for installation is very high. Through payback period calculation, the case study shows that Dawson Forest Products have an opportunity to gain the investment back within ten years. The recommendation is to continue the project and watch out the expense closely to ensure the positive return on the investment.
Dawson Forest Products produce lumber used for residential and commercial housing. As wood residues are the byproducts of the lumber production process, the business can become self-contained by utilizing those waste residues to generate energy for mill production, which is the purpose of biomass conversion project. Once implemented, the manufacturing plant would enhance efficiency, reduce the natural gas use and the associated greenhouse gas emission. It seems win-win solution, but with the consideration of huge capital investment and extended project duration, this project may not have good return on investment. It is time to decide whether to continue or cancel the project.
Root Cause Analysis
The benefit of this project is apparent as it contributes to both air pollution reduction and energy save at the same time. The saving from below aspects:
1. Profit gain from sale of carbon offset: the profit would be $178, 910 CAD per year based on 10,545 ton CO2 in this case study;