November 29, 2011
The Ancient Practice of Ecosystem Creation
As a young ecologist, Joseph Mascaro was trained to see invasive species as inherently destructive to the existing ecosystem. But away from the classroom, out in the field, Mascaro discovered that ecosystems are always-already “novel,” with newly arrived species mixed up with long-established natives. Novel ecosystems, he found, are more than a tale of ecological destruction. “Humans are not only destroyers of ecosystems, but also makers, often unintentionally,” writes Mascaro. As a consequence, forward-facing ecologists might engage in prospective intervention, a strategy that implicitly recognizes that newly arriving species are here to stay and works with them for the best diversity and functional outcomes.
Thursday, March 26, 987 BC.
On the other side of the planet, smelters are bellowing in Europe. The Zhou Dynasty has begun. 52,403,609 people inhabit the Earth. None of them live in Hawaii.
I fill my lungs with cool, fresh air. A rich, thick taste of vegetation with floral notes. It is 6:26 a.m. Rays of sunshine kiss the tops of hulking, gnarled Ohia trees, lighting up their soft red flowers. I hear and see birds. Lots of them.
I recognize ‘I‘iwi, a cardinal-size bird with screaming red feathers and a gently curved beak, dancing happily through the canopy. Alongside it is a smaller red bird with a black tail and black beak, called Apapane. The equally small Elepaio is a flycatcher with brown and white feathers and a straight, tiny black beak. It sings an effortless jumpy chatter and eagerly raises the feathers on top of its head.
I know these birds from a few years ago — er, a few millennia into the future — when I was catching them for the US Geological Survey. Their names, which might seem meaningless in this time-forgotten paradise, help me identify them: they are the Hawaiian enunciation of each bird’s song.
But there are birds I’ve never heard and only seen in drawings. An elongated version of the Apapane, with a silver head and a black chest, is perched in a large palm tree. This is ‘Ula-‘ai-hawane, a bird that will ultimately be wiped out by habitat loss and avian malaria. There is a goldfinch-size bird that could be called nondescript were it not for an absurdly long, arching beak. This is the Akialoa, which will eventually run out of delicate lobelias to feed upon. Most striking is a huge black and yellow bird — almost a foot tall — with puffs of yellow feathers on its shoulders. The bird is so massive I can hear its talons grip the soft bark of an Ohia branch. This is the ‘O‘o, which will one day be hunted to death for its gorgeous feathers.
It is a beautiful time in Hawaii. There are no mosquitoes. No bees, ants, or snakes. There are no canoes. No floral print shirts. No orchids. There are no oranges, avocados, cucumbers, or even coconuts. At this time, the flora and fauna that will one day populate Honolulu and Hilo reside on distant continents.
This is Hawaii at the dawn of the Anthropocene.
Human activity throughout the biosphere has altered every ecosystem on Earth, some more than others. Islands, by virtue of their isolation, have been altered more than most places.1 The amount of destruction that humans have wrought in these environments is monumental: Hawaii has the highest rate of extinctions of any US state. As a result, Hawaii has captivated ecologists who seek to understand humanity’s reach over the biosphere.
In their classic and important 1981 book, Extinction, Paul and Anne Ehrlich describe the unspooling of Hawaii’s intricate ecosystems as Polynesians and Europeans laid waste to its shores. The tone of the book is grim, laden with words like “havoc,” “decimation,” and “garbage,” and culminates with a warning that those who brought introduced species with them should know better: “They are simply unaware of basic principles of ecology and thus the various ways in which populations and species may be endangered by changes in their environment.”2
Peter Ward, a paleontologist with a gift for breaking down the geologic timescales over which mountains rise and fall, is a tick more poetic in his 1994 book The End of Evolution:
A gigantic extinction has taken place on Hawaii, on other islands, and on other continents. There are no villains, except, perhaps, for the people who foolishly introduced creatures to feed their vanity or pocketbook. People arrived, and species died. Hawaii offers a tremendous lesson; it shows that many species on the Earth cannot tolerate the least human disturbance, so delicately are they balanced on the precarious tightrope of nature. Hawaii tells us that the Third [Extinction] Event is not only something to fear in the future; it has been long under way.3
The Ehrlichs, Ward, and many others have used Hawaii’s recent ecological history — both its extinctions and its raft of species introductions — as a kind of canary-in-the-coal-mine warning for the remainder of Earth’s ecosystems. In doing so, they have critically raised our awareness of what is at stake: the unique ecosystems and species throughout the biosphere that are today threatened due to human activities.
Yet, there is more to this story than a tale of ecological destruction. Humans are not only destroyers of ecosystems, but also makers, often unintentionally. Only over the last several decades have ecologists begun to focus on the function of the “novel” ecosystems that have emerged as a result of human activities. Novel ecosystems are those greatly influenced by human impacts on the environment (eg, temperature changes, carbon dioxide levels, and the introduction of nonnative species), but are distinguished from ecosystems where humans control day-to-day processes as in farms and urban areas.4 Simply put, novel ecosystems are the nonregressive consequence of human activity in the biosphere.
Thus, novel ecosystems represent more than simple human transformation of the biosphere — a feat that logging and fire accomplished. Rather, human civilization has set in motion ecological processes that are constructive and additive. Hawaii has more naturalized, introduced plants than it has native plants — a phenomenon that is not limited to Hawaii or even to islands.5 Its novel ecosystems are diverse and complex: collections of organisms living together, cycling nutrients, eating the sun, growing, dying, having sex, and dispersing their offspring. Novel ecosystems are so abundant in low elevation areas in Hawaii that they are responsible for nearly all ecosystem functioning.
Today, humans increasingly depend on novel ecosystems. Understanding them — how they function and how species behave within them — is essential to efforts to preserve the threatened species and ecosystems that ecologists and conservationists care about.
As a young ecologist, I was trained to see introduced species as a kind of pollution no different from dioxin toxicity or aluminum poisoning. I learned to recognize weeds by gestalt. Plants growing in excess: blankets of garlic mustard across the forest floor. Plants growing at odd times: lush understories of buckthorn and honeysuckle, still green in a Wisconsin December. The melancholy of weeds overrunning a native forest was equal only to the euphoria of hacking at them with machetes and poisoning them with Roundup.6
Four years studying Hawaii’s novel ecosystems gave me a different perspective: they are diverse, beautiful, and fascinating. Each day I drove a US Forest Service truck to explore the different habitats. Guiding me was a detailed USGS map of stratigraphic history, complete with lava flows dated with the year or time interval they appeared on the surface, crackling down the slope of Mauna Loa or Kilauea before they solidified. I roamed these rocky jungles for months, and saw something unique almost every day.
I encountered towering Albizia — an incredibly fast-growing, pancake-topped tree from Southeast Asia that can reach a girth of two meters in just 50 years. I spent the night catching fish in introduced mangroves with a fisheries biologist. He briefed me on the mangroves’ effects: just as in native mangrove habitat, introduced mangroves on Hawaii strain sediment from river discharge, which protects coral reefs and provides habitat for native fishes. I scoured an 80-year-old experimental tree planting on a remote cliffside, and found that several native tree species were happily completing their life cycles underneath a diverse canopy of introduced trees.7
In one of my most astonishing expeditions, I found a population of Araucaria trees, some of which were remnants of a planting but were reproducing well on their own. The ancient species is endemic to New Caledonia, a tiny fragment of the continent of Gondwanaland, floating alone in the South Pacific.8 There is a short list of places with more ancient endemism than Hawaii, and New Caledonia is at the top of it. Like the Ginkgo, araucarias are something of a Lazarus clan, having peaked in abundance in the Jurassic Period and subsequently bottled away for eons.
Novel ecosystems were also the site of fierce competition between multiple introduced species. I witnessed massive colonies of the introduced rose apple tree, spreading as monocultures up the valleys of the Hamakua Coast. They were a textbook destructive invasive plant, right up until they were nearly wiped out by an introduced rust disease. Over the years, each colony of rose apple I crawled through became lighter and lighter as the overhead vegetation died. Dozens of tree species colonized these areas, dramatically increasing diversity as the monocultures disassembled.
Appreciating novel ecosystems did not replace or contradict my sadness at the loss of Hawaii’s historical, native ecosystems. In my search for strange and novel, I would often stumble into a puka9 of ancient Ohia trees, covered with ‘ie‘ie vines and peperomia. These lost worlds gave the sense of visiting pre-Anthropocene Hawaii, until a jet rumbled overhead or a Mynah bird squawked in the distance.
But my attention inexorably turned away from the crumbling species interactions of the past, and toward the nascent interactions of the future. In clumps of ‘ie‘ie vines, I would catch a glimpse of Japanese white-eye, a timid, tiny introduced bird that — I was to learn — became a principle pollinator of ‘ie‘ie.10 This native plant is now partially dependent on the introduced bird for its welfare, and it is not an isolated example.11 My experience in Hawaii affirmed that the story of novel ecosystems is not one of wholesale replacement, but of tangled interactions among native and introduced species.
Ecosystems are by definition complex. As a result, they make fruitful ground for analogy. In Extinction, the Ehrlichs famously compared ecosystems to airplanes, wherein each species was a rivet and the popping of rivets inevitably led to a crash. Shahid Naeem still compares ecosystems to computers: their collapse always one capacitor, chip, or wire failure away.12 On complexity, these analogies have lasting value. On process, however, they are hopelessly out of date. They imply singular, explicit functionality: airplanes and computers either function correctly or they do not. Ecosystems are altogether different. They are better thought of as rivers: meandering through time, responding to a landscape of external forces, spawning new tributaries as the rains change.
A lasting failure of the airplane and computer analogies is that ecosystems absorb new components. A fistful of rivets, chucked at an airplane, will scatter helplessly to the tarmac. In ecosystems, those rivets — those new species with new personalities, ambitions, and functional traits — stick. This process, which ecologists have for more than a half-century referred to as “invasion,” is one of the driving forces behind the formation of novel ecosystems. Therefore, the functioning of ecosystems is determined not simply by species losses, but also by species additions.13 For the new arrivals, their behavior is agnostic to the role of humans: “To the coconut, I suspect it is of little importance whether it floated by itself in an ocean current or was lodged in the hull of a native dugout canoe which in turn floated on the ocean current,” said forester Stephen Spurr.14
The arrival of new species (and the departure of old) that drives the formation of novel ecosystems is governed by the individualistic theory of ecological communities.15 This theoretical model of ecosystems predicts that species respond individually to environmental changes. In other words, ecosystems are not as discrete or organized as they appear, but are ephemeral groups of species whose compositions are governed by the individual physiological characteristics of each species and the local environment. This theory stands in contrast to the organismal model, in which ecosystems behave as discrete units on the landscape, moving as a whole in response to environmental changes.16
Spurr waxed on the implications of the individualistic model as it propagated through ecology in the 1960s: “The wilderness ecosystem consists of all of the plants and animals that are there at a given point in space and a given instant in time. All were migrants there.”17 Chronically under-cited paleoecologists and palynologists, who tend to think about ecosystems on longer timescales, empirically validated the individualistic model in the 1970s and 1980s.18 They looked at ecosystems’ changes through time and found that — quite simply — there were no airplanes. Ecosystems were transients, expressed only at unique times and places.19 The shifting climates that governed the ice ages and the intervening warm periods produced unique, subtly different forests. In 2002, ecologist Hazel Delcourt captured the implications of the individualistic model for modern ecosystems in the face of climate change and species invasions:
Existing biological communities will be pulled apart, disassembled into their individual species components. Species that are common today may become uncommon or may be lost forever to extinction. New combinations of species will emerge that may include many species not originally native…20
Detractors of the novel ecosystems concept treat it as a new formulation in ecological theory, introduced in 1997 and gaining wider attention in 2006.21 In fact, while the term first appeared in 1997, the concept flows directly from the individualistic model and does not require any new theory to be tested and validated.22
Failure to ascribe the individualistic model to the appearance of new ecological communities has resulted in an endless suite of misinterpreted ecological phenomena. Consider the Millennium Ecosystem Assessment report, which asserted that introduced species do not contribute to biodiversity: “Ecosystem degradation by human activities may temporarily increase species richness in the limited area of the impact due to an increase in exotic or weedy species, but this is not a relevant increase in biodiversity.”23 On the contrary, the diversity effects of introduced species stem from the same theoretical patterns and processes as the diversity effects of native species.24
Consider species interactions between introduced species. For example, some young Hawaiian lava flows are colonized shortly after they cool by an introduced tree called Ironwood, native to Australia and commonly introduced throughout the Pacific. The vegetation produced by Ironwood provides new niche space for introduced ferns and other tree species such as strawberry guava and autograph tree — natives of Brazil and the Caribbean, respectively. The new arrivals are capable of surviving only by virtue of Ironwood’s modification of the ecosystem.25
If the identities and origins of each species were disregarded, ecologists would call this phenomenon simply succession. But when origin is concerned, invasion biologists and a great many ecologists refer to this event as “invasion meltdown.”26 Note that interactive and synergistic effects of species are broadly considered progressive and positive, while those among introduced species are akin to reactor disasters. The processes do not differ in any theoretical aspect whatsoever; they are equally predicted by the individualistic model of ecological communities.
The persistence of such contradictions in the field of ecology attests to a lack of theoretical continuity between the subdisciplines of succession, where the battle between the organismal and individualistic theories was largely settled by 1990, and invasion biology, where the myth of the balance of nature has lumbered on like a zombie for a quarter-century.27
In 2000, ecologists killed the last introduced cat on Macquarie Island — a chilly, windswept crag in the South Pacific. Environmentalists who were savvy about Southern Hemisphere geography rejoiced at the victory: successful eradications of introduced species are exceedingly rare. But just as ecologists were uncorking their champagne bottles, something went wrong. The island’s rabbit population — also introduced — exploded. The cats had been keeping the rabbits in check. Suddenly free of predation, they began gobbling up Macquarie’s endemic vegetation, stripping whole hillsides.28
Like many ecosystems in the Anthropocene, Macquarie’s not-from-around-here food web differed dramatically from what existed prior to human meddling; yet ecologists failed to appreciate the novel ecosystem’s complexity or consider the possibility that actions to return Macquarie to its historical condition might have negative, unintended consequences.
Ecology has made enormous strides in explaining the mechanisms that control the distribution of species on Earth. But when we, as ecologists, have inserted ourselves as designers in ecosystems, we have done so almost entirely retrospectively. We have used our understanding of the past — the roster of species that once were, or the litany of interactions that once operated — as a blueprint for the reconstruction of what we almost invariably consider a machine, with a perfect set of parts and idealistic function. We rarely consider the positive roles of newly arriving species, some of which have been undergoing unrestricted natural selection for centuries in the novel ecosystems of the Anthropocene.
By its nature, the Anthropocene is a nonregressive state, and novel ecosystems are a nonregressive outcome of human activity in the biosphere. Thus, in deploying a retrospective view as ecosystem designers, ecologists have so far failed to meet the moment of the Anthropocene. To do so, we must accept that we can design prospectively, that we can intervene in ecosystems in the context of their present functions and with an eye toward their future functions as the Anthropocene rolls on.
Detractors of the novel ecosystems concept continuously point to the world prior to human influence as an ultimate moral authority. Yet they fail to attribute the proper theory to the organization of that world. In full view of the individualistic model, the interventions proposed strain credibility, and teeth-gnashing follows. Those who reject the novel ecosystems concept recommend that we “seek to reestablish — or emulate, insofar as possible — the historical trajectory of ecosystems, before they were deflected by human activity, and to allow the restored system to continue responding to various environmental changes.”29
With “emulate,” the authors concede that reversing ecological change is often impossible; in fact, this is a diagnostic feature of novel ecosystems: they are a nonregressive consequence of human activity. Thus, the sort-of romantic handing-back-of-the-baton that restorationists envision is often simultaneously impossible and fraught with disquieting value judgments. The detractors insist that “all ecosystems are candidates for restoration,” but because ecosystem change means the enmeshing of old species and new, classical restoration can even harm native biodiversity, including — as we saw on Macquarie Island — endemic or endangered species that have developed novel interactions with introduced species.
Proponents of the novel ecosystems concept don’t ask that we never restore, or that we abandon concern for endangered species, or that we throw up our hands and accept defeat. Hardly. We merely ask that we add these — obviously real — ecosystems to our lexicon and think prospectively about how to coexist with them. Classical restoration to prehuman, historical states may still make sense in some ecosystems. But the reality of global change means that historical ecosystems are becoming archaic: no longer fitting modern environmental conditions. As a result, even when we succeed, there is no one to hand off the baton to. We are creating analogues and signing up to maintain them indefinitely, lest they turn toward novel states.
We must also come to grips with our motivations. When we attempt to re-create an ecosystem that existed before humans, we are not healing or acting on behalf of nature. We are acting as makers. We are acting on our own anthropocentric desire to reimagine a world that no longer exists.
In this way, “restoration” is not the reversal of the Anthropocene. It is a merely another of its syndromes.
Geologists are vigorously debating the demarcation of the Anthropocene. The first forest fire, the first cultivated field, the first internal combustion engine, the first atomic detonation: each is a logical marker. Throughout the discussion, geologists have emphasized that humans are not the first species — nor even the most effective — to alter the biosphere on a planetary scale.30 But we are the first to come to the precipice of our handiwork with the cognizance to intervene. Our route forward hinges on a choice between looking backward to a mythically balanced nature for design input, or engaging in prospective intervention.
At the most basic level, prospective intervention is simply novel ecosystem planning and management. This strategy implicitly recognizes that newly arriving species are here to stay and works with them for the best diversity and functional outcomes.31 In more-advanced formulations, other arts might be explored — assisted migration, rewilding, deextinction, geoengineering, and even terraforming. In all cases, ecologists will need an open frame of mind, driven by the individualist concept of ecological communities. In the most advanced cases, they will need new tools entirely.
Prospective intervention starts with abandoning allegiance to historical composition and function in ecosystems. Conceptually, ecologists have taken baby steps toward this view. In the field of ecological restoration, alternative strategies that employ some introduced species have made inroads.32 But oftentimes, the goal remains retrospective, and introduced species are summarily excluded because they were not part of the original ecosystem.33 A prospective goal would be to encourage resilient ecosystems that maintain high diversity and robust functioning through a range of environmental conditions, regardless of the historical ranges of the species involved.
New tools for prospective intervention would also help ecologists weigh advanced strategies such as assisted migration. Knowing the historical ranges of species has value when determining whether they are native or introduced, but this is not an indicator of their behavior in novel ecosystems. A more versatile tool would be a comprehensive understanding of the fundamental niche space of all species: the range of environmental conditions over which those species can or cannot physiologically operate. With this knowledge, ecologists would be able to improve predictive models of the organization of novel ecosystems in various environmental conditions.34
Prospective intervention implies a degree of hubris, but it does not mean controlling nature. With the increasingly complex and diverse novel ecosystems of the Anthropocene, nature has afforded us an opportunity to enable those systems to flourish, protecting biological diversity and human welfare at the same time.
It has been 3,000 years since Hawaii began to feel the effects of the Anthropocene. At first it was a gradual, almost imperceptible increase in carbon dioxide caused by forest clearing half a world away. One and a half millennia later, the first Polynesians reached Hawaiian shores. They brought rats, coconuts, candlenut, and taro. They cultivated valleys in Na Pali and Waipio — places that today don’t look all that different. They hunted the ‘O‘o, the ‘Ula-‘ai-hawane, and other birds that had never before seen mammals, let alone those that governed. Newly arriving plants gradually made their way up the slopes of Haleakala and Mauna Loa, crowding out lobelias and clermontias.
Centuries later, Captain Cook landed with muskets, pigs, naturalists, and disease. He dumped ballast teaming with maggots in Kealakekua Bay and poured weevil-ridden flour on the pristine sand. He rankled governments and ruptured cultures. His spawn slaughtered birds four islands away, carried on the wings of man’s greatest foe.
Within two centuries, Japanese bombs pummeled the USS Arizona, skyscrapers climbed the rim of Diamond Head crater, and nuclear submarines steamed out of Pearl Harbor. SUVs roamed the beaches of Kona. Golden mirrors were hoisted onto Mauna Kea’s summit, peering into the Milky Way.
In a special irony, Mauna Loa became the carbon dioxide measurement locale of choice — 13,000 feet above the sea, its roof is a barren moonscape. It sits above a deck of clouds, clinging to rickety cabins, windy outhouses, and scattered cairns on hiking trails. The summit is littered with trinkets left by weary travelers: a doll, a plastic bottle with dregs of gin. It is here, in this windswept rock field — a place that looks almost nothing like the rest of our majestic home — that we measure its most urgent of vital signs.
I often contemplate Hawaii 3,000 years hence. I wonder whether efforts to preserve its most critically endangered plants and animals will succeed. I wonder what will become of its raft of new tenants — banana poka, African land snail, gecko, Chinese banyan, and billy goat. Farms may go back to forests, but these creatures won’t depart Hawaii. They will continue interacting with one another, evolving and organizing into novel ecological systems.
From this vantage, the Anthropocene is not a disaster. It is the next reach of a river in time. And its course is ours to make./
1. For example, Peter Vitousek, Nutrient Cycling and Limitation: Hawai‘i as a Model System, Princeton University Press, 2004); see also John J. Ewel, et al., “Islands: Where novelty is the norm,” in Novel Ecosystems: Intervening in the New Ecological World Order, eds. Richard J. Hobbs, et al. (Hoboken: John Wiley & Sons, Ltd, 2013).
2. Anne Ehrlich and Paul Ehrlich, Extinction (New York: Random House, 1981).
3. Peter Ward, The End of Evolution (New York: Bantam, 1994). Ward is one of the first to treat human influence on the biosphere as a mass extinction-level event. Because our knowledge of other extinction events has increased, current treatments detail five past mass extinctions, with human influence possibly causing a sixth; for example, Elizabeth Kolbert, The Sixth Extinction: an Unnatural History (New York: Henry Holt & Co., 2014).
4. Richard J. Hobbs, et al., (eds.) Novel Ecosystems: Intervening in the New Ecological World Order (Hoboken: John Wiley & Sons, Ltd, 2013).
5. Dov F. Sax and Steven D. Gaines, “Species diversity: from global decreases to local increases,” Trends in Ecology and Evolution 18, no. 11 (2003).
6. A rite of passage for “environmental” scientists. Many control measures for introduced species reach militarism in the extreme. The Nature Conservancy funds a “stinger” delivery of herbicide via helicopter sorties. In the past, herbicide-filled paintball guns were used.
7. Joseph Mascaro, “Eighty Years of Succession in a Noncommercial Plantation on Hawaii Island: Are Native Species Returning?” Pacific Science 65, no. 1 (2011).
8. Notable in that it is not basaltic lava, which is the substrate that builds most of the Pacific Islands. New Caledonia became an island when dinosaurs ruled the Earth.
9. A “hole” in Hawaiian. As lava flows, it burns and scars forest ecosystems. Occasionally, a flow will fork as it makes its way down the volcanic slopes. A divot will remain, bottled off from introduced rats and pigs, where native plants can continue to thrive.
10. Paul Alan Cox, “Extinction of the Hawaiian avifauna resulted in a chance of pollinators for the ieie, Freycinetia arborea,” Oikos 41, no. 2 (1983).
11. Jeffrey T. Foster and Scott K. Robinson, “Introduced birds and the fate of Hawaiian rainforests,” Conservation Biology 21, no. 5 (2007).
12. Joseph Mascaro, “From Rivets to Rivers,” in Novel Ecosystems: Intervening in the New Ecological World Order, eds. Richard J. Hobbs, et al. (Hoboken: John Wiley & Sons, Ltd, 2013).
13. David A. Wardle, et al., “Terrestrial ecosystem responses to species gains and losses,” Science 332, no. 6053 (2011).
14. Stephen H. Spurr, “The Value of Wilderness to Science,” in Tomorrow’s Wilderness, ed. Francoise Leydet (San Francisco: Sierra Club, 1963).
15. Henry A. Gleason, “The individualistic concept of the plant association,” Bulletin of the Torrey Botanical Club 53, no. 1 (1926).
16. Frederic E. Clements, “Plant Succession: an Analysis of the Development of Vegetation,” Carnegie Institution of Washington Publication, 242 (1916).
17. Spurr, 1963.
18. For North America and Europe, see Hazel R. Delcourt, et al., “Dynamic plant ecology: the spectrum of vegetational change in space and time,” Quaternary Science Reviews 1, no. 3 (1982); Margaret Bryan Davis, “Quaternary history and the stability of forest communities,” in Forest Succession: Concept and Applications, eds. Darrell C. West, et al. (New York: Springer, 1981), 132–152; and Margaret Bryan Davis, “Quaternary history of deciduous forests of Eastern North America and Europe,” Annals of the Missouri Botanical Garden 70, vol. 5 (1983). For a broader review, see Stephen T. Jackson, “Vegetation, environment, and time: the origination and termination of ecosystems,” Journal of Vegetation Science 17, no. 5 (2006).
19. This observation is sometimes taken to the extreme for those that suggest abandoning the ecosystem concept entirely. It is a fine concept, in my view, so long as it reflects the sound theoretical architecture of the individualistic model. See Robert V. O’Neill, “Is it time to bury the ecosystem concept? (With full military honors, of course!)” Ecology 82, no. 12 (2001).
20. Hazel R. Delcourt, Forests in Peril: Tracking Deciduous Trees from Ice-age Refuges into the Greenhouse World (Blacksburg, VA: The McDonald and Woodward Publishing Company, 2002).
21. The term first appears in F. Stuart Chapin, III, and Anthony M. Starfield, “Time lags and novel ecosystems in response to transient climatic change in arctic Alaska,” Climatic Change 35, no. 4 (1997). Widespread adoption began with Richard J. Hobbs, et al., “Novel ecosystems: theoretical and management aspects of the new ecological world order,” Global Ecology and Biogeography 15, no. 1 (2006). Detractors include Carolina Murcia, et al., “A critique of the ‘novel ecosystem’ concept,” Trends in Ecology and the Environment 29, no. 10 (2014).
22. Joseph Mascaro, et al., “Origins of the Novel Ecosystems Concept,” in Novel Ecosystems: Intervening in the New Ecological World Order, eds. Richard J. Hobbs, et al. (Hoboken: John Wiley & Sons, 2013).
23. Millennium Ecosystem Assessment, Ecosystems and human well-being: biodiversity synthesis (Washington, DC: World Resources Institute, 2005).
24. Biological diversity is mechanistically tied to ecosystem functions such as productivity and nutrient turnover, primarily through two mechanisms: the “selection” effect and niche complementarity; for details, see Joseph Fargione, et al., “From selection to complementarity: shifts in the causes of biodiversity-productivity relationships in a long-term biodiversity experiment,” Proceedings of the Royal Society B 274, no. 1611 (2007). Although introduced species change the relative importance of these two processes, their effects nonetheless follow from the same set of rules. For Hawaii, see Joseph Mascaro, et al., “Novel forests maintain ecosystem processes after the decline of native species,” Ecological Monographs 82, no. 2 (2012). See also Brian J. Wilsey, et al., “Biodiversity maintenance mechanisms differ between native and novel exotic-dominated communities,” Ecology Letters 12, no. 5 (2009).
25. This pattern can be seen on the Kapoho flow of 1960 on Hawaii Island. Ironwood is one of several introduced nitrogen-fixing trees that accelerate succession, for both native and introduced trees. See Joseph Mascaro, et al., “Limited native plant regeneration in novel, exotic-dominated forests on Hawai‘i,” Forest Ecology and Management 256: 593–606 (2008); Peter Vitousek and Lawrence Walker, “Biological invasion by Myricafaya in Hawai‘i: plant demography, nitrogen fixation, ecosystem effects,” Ecological Monographs 59, no. 3 (1989); R. Flint Hughes and Julie S. Denslow, “Invasion by a N2-fixing tree alters function and structure in wet lowland forests of Hawaii,” Ecological Applications 15, no. 5 (2005).
26. Daniel Simberloff and Betsy Von Holle, “Positive interactions among nonindigenous species: invasional meltdown?” Biological Invasions 1, no. 1 (1999).
27. See Mark A. Davis, et al., “Charles S. Elton and the dissociation of invasion ecology from the rest of ecology,” Diversity and Distributions 7, no. 1–2 (2001); J. Baird Callicott, “Choosing appropriate temporal and spatial scales for ecological restoration,” Journal of Biosciences 27, no. 4 (2002), 409–420.
28. Elizabeth Svoboda, “The Unintended Consequences of Changing Nature’s Balance,” New York Times, February 16, 2009.
29. Murcia, 2014.
30. Compared to Stromatolites—who reigned for two billion years and oxygenated our atmosphere—we look like King Edward VIII: brief, fraternizing, and indecisive.
31. Hobbs, et al., 2013.
32. John J. Ewel and Francis E. Putz, “A place for alien species in ecosystem restoration,” Frontiers in Ecology and the Environment 2, no. 7 (2004), 354–360.
33. Jennifer L. Funk, et al., “Restoration through reassembly: plant traits and invasion resistance,” Trends in Ecology and Evolution 23, no. 12 (2008), 695–703.
34. John W. Williams and Stephen T. Jackson, “Novel climates, no-analog communities, and ecological surprises,” Frontiers in Ecology and the Environment 5, no. 9 (2007), 475–482.
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Joseph Mascaro is a tropical ecologist and Program Manager for Impact Initiatives at Planet Labs, a company that operates the largest fleet of Earth-imaging satellites.
BREAKTHROUGH JOURNAL ISSUE 5
by Jesse Ausubel
by Martin W. Lewis
by Ted Nordhaus, Michael Shellenberger, and Jenna Mukuno