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Loss of Biodiversity – a bigger problem than most of us realize?


Building local understanding

One of the wonders of this part of Ontario is the Muskoka Watershed Council – a unique made-in-Muskoka solution to the need for effective environmental management in a region strongly dependent on its natural environment for its economic well-being. Now in its 14th year, the Watershed Council is an on-going, voluntary collaboration between our municipal government and our community. Its purpose is to promote the wise management and use of our wonderful natural environment, through environmental assessment, advocacy for wise management, communication and education concerning environmental issues, and demonstration of effective management or remediation strategies. Government provides two part-time staff, and access to meeting space and the considerable resources of its planning department, while the community provides a suite of volunteers and, through the small non-profit, Friends of the Muskoka Watershed, office space, equipment and supplies, financial management, and access to sources of grant funding inaccessible to a government department. My involvement as one of those volunteers in the Watershed Council over the last several years has been a gratifying use of my time, my experience and my skills.

Late in 2010, the Muskoka Watershed Council commenced an investigation of the status of biodiversity in our region by undertaking an unusual and rewarding set of conversations with long-time residents. Yes, scientists like me travelled around the distant corners of Muskoka talking to old-timers, people who had been on the land for generations, asking them to talk about the changes they had seen.

I remember the first of these meetings, in a small meeting room at the Bracebridge United Church, seated on mis-matched kitchen chairs, late on a snowy afternoon in November, with coffee and cookies to sustain us. Six of us from the Watershed Council sat and listened as eight long-time residents remembered the past. They were all older than any of us (and some of us are ‘up there’). They included retired farmers, loggers, a hydraulic engineer, a retired teacher, a former government worker and businessman. We told them what we were trying to do – gain a picture of how our environment had changed over the almost 200 years since European settlement commenced, and then we sat back and listened as the memories poured forth. They knew this part of the world, and their knowledge frequently included lessons from previous generations that had also lived here. Their knowledge was also definitely land knowledge rather than town knowledge. They knew how this place had changed.

It was a great meeting, because the memories were rich in detail, and included such irrelevancies as how stupid certain other individuals, not present, had been; how crazy certain government policies had been; and how wonderful certain long-remembered events that they had shared had been. I came away knowing that I had just been listening to wise elders talking around the campfire, handing down the stories that keep our communities whole. Stories rich in traditional knowledge and deeply held beliefs, stories derived from experience rather than from books, YouTube, or Twitter. Beyoncé was not mentioned once. I recommend such conversations even if you are not chasing information on biodiversity.

That meeting was followed by five others, in various venues over the course of the winter. I met some amazing people, and heard some amazing stories. We combined what we learned from these meetings, with what we could learn from the science literature to produce a report which is found here. (Having written the report, we also produced a short summary brochure, and incorporated biodiversity loss into our communication and education effort. The 2nd Muskoka Summit on Environment in 2012 focused on biodiversity.)

The primary messages I derived from these conversations were that 1) people who had lived on the land had seen measurable changes in abundances of certain species, 2) most of these changes were ones in which a species became less common or disappeared, but that 3) in explaining these changes to themselves, most people spoke eloquently about the cycles that exist in nature, and about the balance of nature, except when they were accounting for obvious losses due to hunting out of game, removal of forest to create farmland, or eradication of pests. There were fewer beaver (still too damned many in some people’s view) for obvious reasons to do with trapping and draining of swampland, but the losses of Canada jays or bluebirds were likely part of a cycle in which balance would ultimately be restored. While these old-timers were concerned at the extent of development, and the influx of lots of city people who do not understand Muskoka, even they did not clearly see the reductions in abundance of wild flora and fauna which have taken place.

Biodiversity – What is it? What does it do? Why does it matter?

Biodiversity is a complicated concept. It refers to the extent of variety in an ecosystem – the variety of distinctive habitats present, the number of species, their relative and absolute abundances in each habitat, the genetic diversity within each species population, and so on. Species extinction is the most obvious evidence of loss of biodiversity, but more subtle changes such as loss of genetic variability within populations (a common result if a population falls to very low numbers), loss in overall abundance of organisms, and simplification/homogenization of the landscape so that fewer habitats are present all represent loss of biodiversity. Ecological theory and empirical knowledge both suggest strongly that loss of biodiversity is something to avoid because of its impacts on the ecological functioning of ecosystems. In particular, high biodiversity confers resilience on an ecosystem, equipping it to better withstand environmental changes whether these be long-term shifts or shorter-term episodes of flooding, drought or fire.

Humanity has a long history of degrading biodiversity, starting in the Pleistocene with our progressive hunting out of large mammals in many parts of the world, and continuing with over-harvest, introduction of invasive pests, and destruction of habitat all important at the present time. Unfortunately, the pace with which we reduce biodiversity has been increasing rapidly as our numbers and our economy grow. Large portions of the planet’s surface are now radically altered by human activities, and these radically altered places are also far simpler biologically. Biodiversity has been greatly reduced, but people tend not to notice slow changes in biodiversity. It has proved difficult to build any sense of urgency concerning this problem.
McCauley defaunation Science 2015 F1.large

Over the last 50,000+ years, humans have been defaunating the planet, initially by hunting out large terrestrial species, and later by degrading and expropriating habitat. We started later in the oceans and are only now beginning extensive habitat alteration there. Image © DJ McCauley & Science.

People tend not to notice biodiversity loss because we are not evolved to pay attention to slow processes, and we simply don’t see them happening. Also, we mostly seek stability in our lives, cherishing beliefs in the balance of nature or the compassion of a personal god, while avoiding thinking about the fact that we are all perched perilously on a beautiful blue marble hurtling through space at phenomenal speed, on a path and towards a destination totally outside our knowledge or control. If something were to happen to that blue marble, such as being hit by a modestly large asteroid, there is little we could do to avoid the consequences for our lives, so best wrap ourselves in the comfort of a belief in balance and stability. Under these circumstances, biodiversity loss, which is gradual and subtle, can be a very tough sell. And yet, we should be very concerned.

The Push to Make Biodiversity Relevant

On February 5th 2015, Nature published a one-page commentary by Ehsan Masood, arguing that a major international initiative to stem biodiversity loss is going to require strong support if it is to be effective. The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) was established three years ago by the international community to build a scientific basis, and political support, for global actions to stop the losses of biodiversity and move us toward a more sustainable management of the planet. Patterned on the IPCC, it will need to develop a stature and a record of performance sufficient to do for biodiversity what IPCC has done for the climate – build an unimpeachable science-based argument that will support the need, and provide a basis, for the international legal instruments essential to achieve, real changes in our impacts on global biodiversity.

Because our impacts on biodiversity are a direct consequence of the rapid growth in our economy, there are likely to be powerful opponents to any actions designed to protect biodiversity. IPBES held its third meeting in late January; its first report due in 2019 will deal specifically with the issue of loss of pollinators and the consequences for agriculture and the well-being of natural plant communities.

All species ultimately disappear, either becoming extinct or evolving into a recognizably different species. Some 99% of species that have ever existed on this planet are already extinct, but the pattern of extinction through time is not constant. Instead there has been a general ‘background’ level, and five episodes of far higher rates, termed mass extinctions, in which at least 75% of all species present go extinct. The last mass extinction, at the end of the Cretaceous, killed off the last of the dinosaurs. Estimates of the present rate of extinctions for well-known, mostly larger organisms, such as mammals, birds and amphibians, range from about 0.01% to 0.7% of species per year. These are about 100 times higher than equivalent rates over the past 65 million years, and rates likely over the next century may be as much as 100 times higher still. By 2100, if expectations are fulfilled, a substantial proportion of currently living species will no longer exist, and our world will be that much poorer. Potentially, we will be moving into a sixth mass extinction, and our world will be radically simplified.

Last October, Derek Tittensor of UNEP’s World Conservation Monitoring Centre and Dalhousie University, together with dozens of co-authors from all over the world, published a sober analysis of how we are doing on biodiversity in Science. They reviewed progress on each of the 20 biodiversity-related Aichi Targets agreed on by the Convention on Biological Diversity when it met in Aichi, Japan in 2010. Their analysis suggested that “despite accelerating policy and management responses to the biodiversity crisis, the impacts of these efforts are unlikely to be reflected in improved trends in the state of biodiversity by 2020” We are making some progress, but not nearly enough.

The reason for such dire expectations for biodiversity is that our assault on the planet, far from easing, has continued its rapid expansion. First, as Patrick Gerland, of the UN Population Division, and several colleagues pointed out in Science on 10th October 2014, The UN has revised its projections for the global human population upwards. At 2100, our global population will likely lie between 9.6 and 12.3 billion; while growth rate will have continued to fall, our population will still be growing. More people means more demands on the planet.

Second, in an article set to appear in Anthropocene Review in April, and now available on-line, Will Steffan of Stockholm University and Australian National University, and four colleagues in Australia and Sweden, have updated the ‘great acceleration’ graphs first produced in 2004. These graphs are plots of 12 indicators that record the trajectory since 1750 of the ‘human enterprise’ and plots that track the trajectory, over the same time frame, of 12 key indicators of the structure and functioning of the Earth system. Updating these graphs from 2000 to 2010 has scarcely altered the story they tell.

Beginning in about 1950, there has been a dramatic increase in the size of our ecological footprint. In their words, quoted from their original 2004 report,

One feature stands out as remarkable. The second half of the twentieth century is unique in the entire history of human existence on Earth. Many human activities reached take-off points sometime in the twentieth century and have accelerated sharply towards the end of the century. The last 50 years have without doubt seen the most rapid transformation of the human relationship with the natural world in the history of humankind.

Steffan Fig 1 Anthropocene_The_Great_Acceleration_-_2015-02-08_17.06.23

Figure 1 from Steffan et al Anthropocene Review 2015. These 12 indicators reveal a rapidly growing human impact on the planet since about 1950 – an increase that does not yet appear to be slowing. Image © W. Steffan.

Steffan Fig 3 Anthropocene_The_Great_Acceleration_-_2015-02-08_17.07.56

Figure 3 from Steffan et al Anthropocene Review 2015. These 12 indicators reveal rapidly growing changes to the planet since about 1950 – changes likely due to the growing human impacts. Image © W. Steffan.

In the new report, Steffan and colleagues have replaced two indicators with alternatives, and have partitioned 10 of the 12 human enterprise indicators to reveal increases in OECD countries, the BRICS, and the rest of the world. Still, despite the economic slowdown of 2008-9, the new graphs confirm that the rampant changes taking place since 1950 have continued through the first decade of the 21st century – rampant changes in human activities, and rampant changes in the nature of the Earth system. It is this phenomenal growth in our footprint on the planet that is responsible for the growing impacts on biodiversity.

One of the replaced indicators had been the rate of species extinctions. The new graphs instead use the percentage decrease in modeled mean abundance for terrestrial mammal species, relative to their abundance in undisturbed ecosystems (actually a better indicator of the aggregated human pressure on the terrestrial biosphere). This indicator begins to rise slowly around 1850, more steeply by 1950, and is now approaching a 30% decline. Think about that. The average terrestrial mammal is now 30% less abundant than it would be if its ecosystem was undisturbed. Less abundant populations are necessarily more prone to extinction when a bad year, a disease outbreak, or some other variable event makes life difficult.

Present-day changes in biodiversity

So let’s talk about the changes in biodiversity that are occurring. Rates of extinction for well-studied groups like mammals, birds and amphibians are substantially higher than they were for ancestors to those groups throughout the Cenozoic and appear likely to go higher. If these are representative of other types of organism, we could be entering the sixth mass extinction in a few years with more than 75% of all living species disappearing from the earth. The average abundance of terrestrial mammals has declined close to 30% as humans expropriate habitat, or kill them off. Again, if a reduction in abundance of that magnitude is typical for all types of organisms, we are simplifying ecosystems, allowing for less genetic diversity within populations, and pushing populations towards extinction. Is there other available evidence that the situation is really this dire?

Evidence of the severity of the human impact on the planet is all around us. In the 16th January issue of Science, Doug McCauley of U.C. Santa Barbara, and four colleagues from other US universities published a report drawing attention to our defaunation of the oceans. In it, they make the point that we have had a >50,000 year head start in defaunating the land, but are now starting to catch up in the oceans as well. Using IUCN Red List data on species extinctions since 1500, they contrast the rapid rise in terrestrial extinctions with the modest increase in extinctions of marine species, but they caution that we may be about to enter a period of rapid increase in the oceans as well. A graph showing this is hidden in the supplementary material for their paper. It compares IUCN-recorded extinctions since 1500 for terrestrial and marine organisms. Their main text includes a set of graphs that are eerily similar to those Steffan and colleagues provided to show the growing global human impact on the planet, except they mostly start in the mid- to late-20th century. Given that trawling has already had significant impact on the structure of benthic communities covering some 50 million km2 of seafloor, and that we are now commencing other forms of ‘interference’ with the marine environment, we should anticipate an increase in impacts on marine biodiversity.

cumulative extinctions land and sea McCauley et al Science 2015

Figure S1 from McCauley et al 2015 showing the pattern of extinctions since 1500 for terrestrial (green) and marine (blue) organisms. Only 15 extinctions of marine species have been recorded by IUCN. Both curves should be considered minimal estimates since many ‘unknown’ species have doubtless also been lost. The unlabeled box to the right is a probably period of a marine industrial revolution. Graph © DJ McCauley & Science

Figure 5 McCauley et al Science 2015 marine footprint

Figure 5 from McCauley et al, Science 2015 showing rates of increase in several indicators of human impact on marine ecosystems. The graphs are reminiscent of the indicators of the ‘great acceleration’ identified by Steffan and colleagues, except that the timelines commence in the mid- to late-20th century. Image © DJ McCauley & Science

More than 90% of large pelagic fish are now less extensively distributed than before our commercial fishing commenced – a consequence of our overfishing. Close to a third of coastal species of smaller fish and invertebrates also reveal significant reductions in range. And overfishing has reduced global abundance of marine fishes by about 90% — that is, there is only 10% of biomass of fish flesh swimming in the oceans compared to when we first commenced commercial fishing.

Back on land there are many pieces of evidence of reduced biodiversity beyond the increasing rate of extinction. We have appropriated close to 40% of all land to human uses (see Steffan’s Fig 3 above). While this land is not devoid of life, it is occupied by monoculture agriculture, highways, parking lots, and cities offering far fewer opportunities for biodiversity than natural environments. We have radically reduced the amount of old-growth forest, and significantly reduced the amount of all forests including less biodiverse secondary forests and tree plantations. We also have polluted rivers and estuaries, and created enormous dead zones in the coastal ocean.

On 24th June 2012, Lonesome George, the last living member of the Pinta Island race of Galapagos tortoise died. He had lived many years at the Charles Darwin Research Center, but attempts to breed him with females of other races had all failed. His genetic line came to an end, but he is now on permanent display at the American Museum of Natural History. On September 1st 2014, we were briefly reminded to remember the passing of Martha, the last passenger pigeon, which had died that day, one hundred years earlier at the Cincinnati Zoo. On September 6th, Australia’s Daily Mail published a short piece, including a link to a 1933 video, to acknowledge the death of Benjamin, the last known Tasmanian tiger, which died September 7th 1936 at the Hobart Zoo (the video, embedded in a 1964 short film, is a hoot). While his species may have persisted a bit longer in the wild, the last confirmed sighting was in 1930. In 1996, Australia declared September 7th National Threatened Species Day. On 14th December 2014, news reports bubbled up that one of the six remaining northern white rhinoceros had died. An animal that formerly ranged over parts of north-western Uganda, southern Chad, south-western Sudan, the eastern part of Central African Republic, and north-eastern Democratic Republic of the Congo had already been reduced to three animals living at Ol Pejeta Conservancy in central Kenya, one animal in a zoo in the Czech Republic and two in San Diego. The San Diego male died, likely of old age. There is argument over whether the northern subspecies is sufficiently distinct to be considered a separate species from the far more numerous southern subspecies, but IUCN considers this issue largely moot, because with only five closely related individuals (the Kenyan three all came from the Czech zoo, and the remaining female in San Diego is past reproductive age) it seems highly unlikely that it will be possible to reestablish a pure-bred population large enough to resist extinction. The northern white rhino genes might be saved by successfully cross-breeding with the southern subspecies, and there is even discussion of long-term cryo-storage of eggs and sperm.

four extinctions

The Thylacine or Tasmanian tiger; Martha, the last Passenger pigeon; one of the remaining Northern white rhinos; and Lonesome George, last of the Pinta Galapagos tortoises. All except the rhino are now gone. Images (from left to right) © Neitshade5 (colored version of 1933 photo), Carl Hansen/Smithsonian Inst., Jason Prince/Shutterstock, Peter Sale.

We are likely to hear more stories like those of the northern white rhino, the Tasmanian tiger, the passenger pigeon, or the various Galapagos tortoises. Each is poignant, sometime quite personal; each marks a final end to a wonderful example of what life can be. All four of these examples fell because of human hunting. They were more valuable dead than alive. The giant tortoises found on several of the tropical archipelagos were enormously abundant in the 16th to 18th century, were easily captured, could live many weeks on their backs on the deck of a ship, and were simply too valuable as food to be left to lead their tortoise lives on their home islands. They belonged to no man and were therefore free for the taking. Passenger pigeons are described by IUCN as a nomadic species, breeding and foraging in vast flocks millions of birds strong. They exploited seasonally available crops of beechmast, acorns and chestnuts; scouting for food sources and information-sharing were likely to have required flocks of a certain critical size, below which survival would be compromised. Birds nested in April or May in vast colonies typically 16 by 5 km in size. They were easily shot and provided tasty food, however, it was the expansion of the railroads and the felling of the eastern and mid-western forests that provided easy access to both the birds and an enormous market in the cities on the east coast during the mid- to late-1800s. Commercial hunting, on a vast scale became practical. The last wild bird was shot in 1900. The Tasmanian tiger, as a predator was seen by the early sheep-herding settlers of Tasmania as vermin to be eradicated. The government helped with a handsome bounty. In fact, it was shy, nocturnal, and probably would have done little damage to animals the size of sheep. The advent of dogs, and changes to its habitat probably aided its demise. And the northern white rhino, like all rhinos, has suffered dearly because of the value attached to rhino horn in Chinese traditional medicine. All five species of these magnificently lumbering land mammals that used to range widely over Eurasia and Africa are in danger of extinction. The Javan and Sumatran species, currently with 40-60 and about 250 animals respectively, are termed Critically Endangered by IUCN. The ~2,500 greater one-horned, or Indian rhinos are Vulnerable, the 4000 or so black rhino of southern Africa are Critically Endangered, and the white rhino is divided into the northern race Extinct in the Wild, and the southern race Near Threatened with a population of about 20,000 animals. Only the southern white rhino has increased its numbers substantially in recent years, and all species are far less abundant than they were 100 years ago. (The black rhino has declined 90% since 1960, for example.) Sport hunting initially, now closely controlled, and poaching for horn are the chief reasons for their perilous status, although alteration of habitat and appropriation of habitat to human use also have played a role.

It is simply not true that only the rare species, or the one with a restricted range, is at risk of extinction. The passenger pigeon was at one time the most abundant bird in the North American sky. One fell over giant tortoises on oceanic islands. And rhinos were a major part of the African savannah fauna.

I’ve just finished reading a book by Andrew Isenberg about the near extinction of the American bison (Cambridge UP, 2000). Some of the numbers are astounding. The western short-grass prairie likely supported about 30 million bison early in the 18th century when native Americans had not yet commenced use of the horse. However, because of their habit of aggregating in enormous herds during the summer rutting season there are many eye-witness accounts of enormous numbers being seen – herds that extended from horizon to horizon for three days, herds numbering 100,000 or more. They lived in a very variable environment with fire, drought, and severe winters all taking turns to cut into bison production. They were well adapted to this environment, and could recover their numbers quickly in good years.


The American bison, once the largest and most important animal of the short-grass prairie, almost became extinct because of over-hunting. Photo © Julie Larsen Maher WCS

Initially, native Americans used the bison as just one of a number of sources of food and other materials. Their hunts, on foot, required close coordination and cooperation among large numbers of hunters – a factor which Isenberg suggests helped maintain group cohesion and cooperative social structures. With the advent of the horse, traders seeking buffalo robes and other furs, and a commercial economy there was a shift in the mode of hunting, the purpose for hunting, and the degree to which hunting of bison dominated native life. The European diseases that fragmented communities no doubt contributed to these changes. Native Americans began hunting bison from horses, operating in far smaller, independent groups, and taking hides for trade, and their impact on the bison grew markedly. Euroamericans also began to enter the bison trade, for skins almost exclusively, and the railroads increased the access to the rapidly industrializing cities to the east. The US government saw removal of the bison as a good step to ‘prepare’ the range for cattle, and as a good way to force the remaining native Americans onto reservations. Impact on the bison grew further, and an animal that needed to assemble in large herds to reproduce effectively rapidly declined in numbers.

Commercial harvest rose sharply from essentially nothing in 1800 to some 150,000 skins a year by 1850 when the market began to fall as bison became increasingly rare. In the late 1800s some urban folk began arguing for the protection of some of what remained, largely out of romantic ideals that conferred mythic value on the presumed pattern of frontier life with natives, traders and bison all living in happy harmony – a harmony that had never existed. Other preservationists wanted bison for recreational hunting, even arguing that bison should be preserved for shooting by the upper classes rather than left to be used by natives. Out of such muddled philosophies gradually emerged the idea of conservation, and that idea is the only reason there are any bison around today. Yet, 250 years ago, the bison was the largest, and the dominant animal of North America. People can change the world radially in remarkably short time; in this case they did it with a few horses, some early repeating rifles, and a market that could use all the leather that could be procured. It’s the same story as the story of depletion of world fisheries, or the removal of old-growth forests. Consumption today rather than sustainable management for tomorrow. I know we are not finished.

buffalo hunt

The iconic image of the plains natives riding bareback and hunting bison with bow and spear marks a brief period in a rapidly changing history, not a static image of a glorious time now past. It was a history of decline, both for the bison and for the natives.

And so we have a biodiversity crisis, a steady simplification of ecosystems, a continuing removal of redundancy and variability. Just what we do not need in a world which is changing rapidly, a world in which life needs to be adaptable, and capable of responding effectively to new environmental conditions.

An APP for ecological resilience?

It might be efficient to channel all terrestrial production of organic matter through a handful of inbred creatures to feed humans, foregoing the myriad pathways that sometimes lead to other endpoints, like eagles, and mountain lions, and soil microbes. But doing so does not offer flexibility as conditions for life change. I don’t think it is prudent or wise. And it certainly leaves the world a tattered remnant of what it used to be. The extent of our hubris is such that we vaguely see the biodiversity crisis happening without ever giving a thought to whether our own security as a species on this planet might be in danger if it continues. Maybe Google will develop an app for ecological resilience and we can all download it to our phones?

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