Elizabeth Kolbertr discusses the Sixth Extinction )

The biodiversity crisis — i.e. the rapid loss of species and the rapid degradation of ecosystems — is probably a greater threat than global climate change to the stability and prosperous future of humankind on Earth. 

- professor Carsten Rahbek, Director for the Center for Macroecology, Evolution and Climate, University of Copenhagen.

temperature zones are migrating towards the equator at 5 km/year

- Dennis Meadows, author of Limits to Growth

Biodiversity is humanity’s life-support system, delivering everything from food, to clean water and air, to recreation and tourism, to novel chemicals that drive our advanced civilization. Yet there is an increasingly well-documented global trend in biodiversity loss, triggered by a host of human activities

- Camilo Mora, University of Hawaii

We believe that ongoing loss of biological diversity is diminishing the ability of ecosystems to sustain human societies

- Andrew Gonzalez, associate professor of biology and the Quebec Centre for Biodiversity Science, McGill University

We’ve reached a point where efforts to preserve species and biological diversity might no longer be an act of altruisms

- Diane Srivastava, professor of zoology and the Biodiversity Research Centre at University of British Columbia

As much as the consensus statements by doctors led to public warnings that tobacco use is harmful to your health, this is a consensus statement by experts who agree that loss of Earth’s wild species will be harmful to the world’s ecosystems and may harm society by reducing ecosystem services that are essential to human health and prosperity

- Bradley Cardinale, associate professor at the University of Michigan

There are still tens of millions of unknown wild species out there.  More than half of our global pharmaceutical and agricultural sectors exist because of bioprospecting among wild species.  So it would make sense for biodiversity to be protected and used sustainably, as a raw material for continued discovery and wealth creation 

- Dr Julian Caldecott

Introduction

Soon, the majority of humanity will live in cities. Underlying this trend is a disturbing truth; humans are becoming more and more alienated from our own natural environment. In fact, it is our insular lifestyle that artificially decouples us from nature and eliminates the vital feedback loop necessary for the kind of stewardship that will result in a sustainable coexistence.

Human beings are a part of the natural ecosystem but our footprint has become so large that we now control or alter 40% of all landmass on the planet (excluding glaciers). Our dominance has dramatically skewed natural ecosystems. Our human activities is increasing species extinction at a rate several orders of magnitude faster than the fossil records; 100 to 1000 times faster than the natural extinction rate.

This is all driven by a current nonsustainable economic paradigm that inherently pits human development against natural systems. Yet, this is a false dichotomy. For without the hidden capital of natural ecosystems, there would be no way human civilizations could even exist. If there were ever a time to recognize the inter-connectedness of all nature, it is now.

Figure 1: Major biomes on the planet

Predicted percentage of ecological landscape being driven toward changes in plant species as a result of projected human-induced climate change by 2100. Image credit: NASA/JPL-Caltech

Predicted percentage of ecological landscape being driven toward biome-level changes in plant species as a result of projected human-induced climate change by 2100. Biomes are major ecological community types. Image credit: NASA/JPL-Caltech

 

New major political effort is being made to replace this outdated economic system with a new sustainable governance paradigm that recognizes a much broader definition of natural capital into its fundamental constitution. Not surprisingly, it is being led not by developed countries with huge vested interest in continuing the current system, but by the tiny government of Bhutan, a small country with relatively little of the natural resources highly sought after by capitalists and where compassion is an integral part of the society. Recognizing the crucial role a new economic paradigm will play in stopping environmental degradation, it has been rapidly supported by 68 other countries.

The major problem behind biodiversity loss and ecosystem degradation is our outdated economic system which places little or no value upon natural capital, albeit in a very narrow way.

- JGVW

 In our current economic paradigm, the more humans develop, the greater the harm for all the planets remaining species. But humanity does not live in a vacuum. In fact, our health critically depends on the health of all the other species on the planet. Because of nature’s interdependency, threatening the survival of the planet’s other species is also threatening the survival of our own species.  Just as with the case of climate change, our damage is becoming so pronounced that we will soon begin to experience large positive feedback effects. In fact, biodiversity loss and climate change are intimately related. It is well known that the rate of environmental degradation accelerates as species disappear. Species exist in complex inter-relationships which are required to maintain the health of natural ecosystems which support human society in many ways – from water, to CO2 sequestration, to natural resources.

The earth is comprised of a number of major biomes such as ocean, desert, forest, fresh water, etc…Due to the exponential increase in human stressors, many of these biomes are approaching collapse, with dire consequences not just for humanity but all life on earth.

Background – Why is Biodiversity so important to us?

Economy and Ecology both come from the same Greek root,  οἴκος  which means “house”. It is clear then that in economic activities, humans, like the other species of the planet are simply trying to take care of our home. Yet we have become so disconnected with our true home, the planet that we are in danger of destroying it. We often hear talk of leaving a broken planet to our children but where are the children in all this? Where are the vietnam-like protest movements? They are nowhere to be found. Our children have been raised in homes far away from trees, forests and lakes, indoors surrounded by video games, iphones, tablets and cartoons for babysitters. They are content to be immersed in their video games, little Nero’s doing modern fiddling while modern Rome burns. As environmental writer George Monbiot writes in his piece Housebroken, we have become so alienated and disconnected from the land, the true source of wealth for all human beings that our children are nowhere to be found in this environmental movement.

Figure 1: Humans / environment feedback loop

Figure 2: Severed human / environment feedback loop due to manufacturing

Where once we grew our own food, made our own clothing, built our own homes, now these are all done for us. Manufacturing plants shield us from nature and severe the natural feedback loops that exist when people produce directly for themselves or there communities. Today, citizens of the developed countries go to supermarkets to buy supplies that are manufactured for us in distant plants. We know nothing about what ingredients go into our food or how manufacturers acquire the resources to create the products we consume. Consumerism naturally shields us from knowing what is really happening. The entire retail production and sales chain protects us from the truth because if we knew, we wouldn’t want to support them.

Figure 3: How human economy fundamentally depends upon the planet for ecological services

Biodiversity, Ecosystems, & Ecosystem Services

What is the value of nature?

Biodiversity Loss is becoming a Critical Issue for Human Survival

A variety of global changes are driving rates of species extinction that greatly outpace background rates in the fossil record. If these trends continue, projections suggest that within 240 years Earth may face the sixth mass extinction

- Hooper DU et al.

 A paper released to coincide with Rio +20 addresses the increasing seriousness of biodiversity loss,  A global synthesis reveals biodiversity loss as a major driver of ecosystem changepublished in Nature, June 7, 2012 by scientist David U. Hooper et al. shows that biodiversity loss will impact human societies in ways far more profound than first thought.

“Some people have assumed that biodiversity effects are relatively minor compared to other environmental stressors,” said biologist David Hooper of Western Washington University, the lead author of the paper. However, Hooper says “Our results show that future loss of species has the potential to reduce plant production just as much as global warming and pollution.” Until this study, it had been unclear how biodiversity losses stack up against other human-caused environmental changes that affect ecosystem health and productivity. This analysis now establishes that reduced biodiversity affects ecosystems at levels comparable to those of global warming and air pollution.

Many people take vital things like water purity, food production, a stable climate and air quality for granted, unaware that they are largely provided by communities of organisms. If we lose those communities, we lose these vital functions. The very high rates of modern extinctions–due to habitat loss, overharvesting and other human-caused environmental changes–could reduce nature’s ability to provide these critical goods and services.

Genetic diversity has many other positive benefits to humanity including:

  • increasing the yield of commercial crops
  • enhancing the production of wood in tree plantations
  • improving the production of fodder in grasslands
  • increasing the stability of yields in fisheries
  • providing the source for novel new drug therapies

Plant diversity also contributes to:

  • greater resistance to invasion by exotic plants
  • inhibits plant pathogens such as fungal and viral infections
  • enhances above-ground carbon sequestration through enhanced biomass
  • increases nutrient re-mineralization and soil organic matter

The authors of this paper performed a research review of over 1,000 ecological studies published in 192 peer reviewed journals since the 1992 Rio Summit. They reached two major conclusions:

  1. there is mounting evidence that extinctions are altering key processes important to the productivity and sustainability of Earth’s ecosystems
  2. further species loss will accelerate change in ecosystem processes but it is unclear how these effects compare to the direct effects of other forms of environmental change that are both driving diversity loss and altering ecosystem function

The researchers used a suite of meta-analyses of published data to show that the effects of species loss on two important ecosystem processes – productivity and decomposition of dead plants by bacteria and fungi—are of comparable magnitude to the effects of many other global environmental changes.

  • Intermediate levels of species loss (21–40%) reduced plant production by 5–10%, comparable to previously documented effects of ultraviolet radiation and climate warming. At intermediate levels, species loss generally had equal or greater effects on decomposition than did elevated CO2 and nitrogen addition
  • Higher levels of extinction (41–60%) had effects rivalling those of ozone, acidification, elevated CO2 and nutrient pollution
  • The identity of species lost also had a large effect on changes in productivity and decomposition, generating a wide range of plausible outcomes for extinction

As human populations grow in both size and ecological footprint, plants and animals are becoming extinct at a rate not seen in eons. Studies suggest:

  • about one-quarter of the earth’s mammal species will be gone in 20 years
  • the oceans have lost about 90 per cent of their large fish
  • about 17,000 endangered species in the world

Scientists believe that even these figures are a massive underestimate because  theys only apply to the known species, which is estimated to be a fraction of the total number of species on the planet.

The study clearly showed that the ecosystem consequences of local species loss are as quantitatively significant as the direct effects of several global change stressors that have mobilized major international concern and remediation efforts.

Biodiversity Loss: Overwhelming Consensus from many scientists

A study entitled  Scientists’ opinions on the global status and management of biological diversity published in the Nov, 2011 issue of Conservation Biology (25: 1165-1175) reveals unanimous agreement of major biodiversity loss from a diverse cross-section of scientists. Dr. Murray Rudd from the Environment Department at the University of York surveyed 583 conservation scientists and found:

  • 99.5%  agreement that a a serious loss of biological diversity is either ‘likely’, ‘very likely’, or ‘virtually certain’
  • 72.8 % agreement that loss is ‘very likely’ or ‘virtually certain’ from scientists based in Western Europe
  •  90.9% agreement that loss is ‘very likely’ or ‘virtually certain’ from scientists based in Southeast Asia
  • 79.1 % of respondents stated that acceleration of the loss of biological diversity by human activities is virtually certain

Conservation Alone is insufficient to protect against Biodiversity Loss

A 2011 study published in Marine Ecology Progress Seriesreveals a surprising result: humanities existing conservation measures are insufficient to stem global biodiversity loss. Camilo Mora and Peter F. Sales, authors of the study Ongoing global biodiversity loss and the need to move beyond protected areas: a review of the technical and practical shortcomings of protected areas on land and sea performed a literature review of existing studies and data and concluded that effectiveness of existing, and the current pace of the establishment of new, protected areas will not be able to overcome current trends of loss of marine and terrestrial biodiversity. Another way the authors put this is:

In short, the extent of coverage by PAs is still limited and is growing at a slower rate than that at which biodiversity threats are developing

- Camilo Mora and Peter F. Sales

Today there are globally over 100,000 protected areas covering 17 million square kilometers of land and 2 million square kilometers of oceans but it is still not enough. The rate of conservation lags too far behind the rate of human encroachment on natural ecosystems.

Figure 5: Mechanism of human effect on biodiversity. Left: Cascade showing the connections between human population, human
needs, effects on biodiversity and conservation measures. Right: Actual temporal trend of the world’s human population (from the
United Nations World Human Population Prospects, http://esa.un.org/unpp/), ecological footprint of the world’s human population
(from Fig. 1b in Kitzes et al. 2008), response index (i.e. combined extent of conservation strategies such as protected area extent
and biodiversity coverage, policy responses to invasive alien species, sustainable forest management and biodiversity-related
aid; from Fig. 2c in Butchart et al. 2010) and trend in the global living planet index as a proxy for biodiversity status
(data from Hails 2008)  (Source: Camilo Mora et al.)

 

Dr. Camilo Mora said: “Given the considerable effort and widespread support for the creation of protected areas over the past 30 years, we were surprised to find so much evidence for their failure to effectively address the global problem of biodiversity loss. Clearly, the biodiversity loss problem has been underestimated and the ability of protected areas to solve this problem overestimated.”

The authors concluded that biodiversity loss is unlikely to be stemmed without directly addressing the ecological footprint of humanity. In particuliar, this study, in combination with previous study shows that under current conditions of human comsumption and conservative scenarios of human population growth, the cummulative use of natural resources of humanity will amount to the productivity of up to 27 Earths by 2050.

Figure 6: Projections for (a) human population size, (b) human
ecological demand and (c) ecological debt under different
scenarios of human population growth and use of natural
resources. Ecological demand is calculated by multiplying the
size of the world’s human population by the average yearly
demands of a person and dividing this amount by the Earth’s
biocapacity; this yields the number of planet Earths required
to meet the whole human demand. Ecological debt is calculated
as the cumulative ecological demand beyond the Earth’s biocapacity;
this is also referred as ‘overshoot’. We ran a business-as-usual
scenario (black solid lines) considering the United Nations
projections on human population size (http://esa.un.org/unpp/),
the current average annual consumption per person (in terms of
area necessary to meet consumption demands) and Earth’s biocapacity
(i.e. 2.1 and 11 billion ha in 2002, respectively; Kitzes et al. 2008).
We also show projections under the ‘rapid reduction’ scenario
suggested by Kitzes et al. (2008) (grey solid line obtained directly
from Fig. 3 in Kitzes et al. 2008). In this scenario, the Earth’s
biocapacity increased by 20% (e.g. through transference of
technology for improving agriculture and aquaculture production)
and demand by 2050 decreased by reducing CO2 emissions and fisheries
catches by 50%, and by stabilizing urban land expansion among other
things. Using Kitzes et al.’s (2008) ‘rapid reduction’ scenario,
we modeled the tendency of overshoot to reach zero in 2050
(‘sustainability by 2050’ scenario) and calculated the ecological
demand and number of people under that scenario accordingly. That
result suggests that to get out of an overshoot by 2050, we would
have to implement the conditions of the ‘rapid reduction’ scenario
plus stabilize human population at its current size (see dotted line
in [a]). This could be achieved by reducing the current birth rate
of 0.01995 to the current mortality rate of 0.0082 or ~1 child per
women by 2050. As reference we also provide projections given current
human consumption (i.e. 2.1 ha per person) and no further natality
(‘zero natality’ scenario)
(Source: Camilo Mora et al.)

 

Limitations of the Current Conservation Strategy

Dr. Mora et al. point out the 5 limitations of existing conservation strategies:

Expected growth in protected area coverage is too slow

  • Over 100,000 areas are now protected worldwide but strict enforcement occurs on just 5.8% of land and 0.08% of ocean
  • 30% is the minimum target widely advocated for effective biodiversity conservation
  • At current rates, it will take 185 years in the case of land and 80 years for oceans to protect this 30%
  • The rapid rate of climate change, habitat loss and resource exploitation is predicted to cause the extinction of many species even before 2050
  • Therefore, the conservation rate is far too slow to have any real impact

 

Inadequate Size and Connectivity of Protected Areas 

  • Protected areas must be sufficiently large to sustain viable populations in the face of the inevitable mortality of some individuals trespassing their borders
  • Areas must be close enough together for a healthy exchange of individuals among protected populations
  • Globally over 30% of the protected areas in the ocean, and 60% on land are smaller than 1 square kilometer — too small for many larger species
  • They are too far apart to allow a sufficient exchange among populations for most species

Protected Areas do not Protect Against All Human Threats

Biodiversity loss is triggered by human stressors including:

  1. habitat loss
  2. overexploitation
  3. climate change
  4. pollution
  5. invasive species

Protected areas are useful only against overexploitation and habitat loss. The other three will continue to increase biodiversity loss. Approximately 83% of protected areas on the sea and 95% of protected areas on land are located in areas with continuing high impact from multiple human stressors.

Underfunding

  • Effective management in existing protected areas requires an estimated $24 billion per year
  • Global expenditures on protected areas in 2011 are estimated at US $6 billion per year
  • Budget growth has been slow and is unlikely to reach adequate levels of protection for existing or for adding new protected areas

Conflicts with human development

  • Humanity’s footprint on Earth continues to expand to meet human development needs
  • Placing 30% of world habitats under protection will lead to intense conflicts with competing human interests– many people would be displaced and livelihoods impaired
  • Forcing a trade-off between human development and sustaining biodiversity is unlikely to lead to a solution with biodiversity preserved

Continuing to apply the current conservation approach of creating more protected areas will continue the  biodiversity loss. The only real alternative is to get serious about reducing our ecological footprint.

The Impact of Shifting Temperature Zones

Species are currently migrating both to higher altitudes and latitudes.  The study Rapid Range Shifts of Species Associated with High Levels of Climate Warming by Professor Ralf Ohlemüller et al used a meta-analysis to estimate that the distributions of thousands of species have recently shifted to higher elevations at a median rate of 11.0 meters per decade, and to higher latitudes at a median rate of 16.9 kilometers per decade. On a daily rate, that’s an average 5 meters a day. These rates are approximately two and three times faster than previously reported. For the first time ever, this study shows that the amount by which the distributions of species have changed is correlated with the amount the climate has changed in that region.

The 2,000 species include birds, mammals, reptiles, insects, spiders and plants in Europe, North America, Chile, Malaysia, and South Africa’s Marion Island. By grouping the studies together and analyzing their results, researchers found for the first time a link between 1) how hot it was getting and 2) where organisms were moving. “This research shows that it is global warming that is causing species to move towards the poles and to higher elevations,” said co-author I-Ching Chen.

 

 (Source:  Rapid Range Shifts of Species Associated with High Levels of Climate Warming)

Pine Beetle Epidemic, British Columbia, Canada

The Pine beetle infestation in British Columbia, Canada serves as a warning of the effects of sudden ecosystem change and the inability for ecosystems to be prepared to adapt. The Pine beetle is native to British Columbia and has traditionally served a key purpose in regulating the health of the forest by attacking old or weakened trees and fostering the development of a younger forest after the older trees died or were destroyed by fire.

Over most of the Interior of British Columbia, extreme winter weather of colder than – 35 Celsius for at least several days or even weeks historically killed most of the pine beetle population, limiting the duration of, and damage from, periodic epidemics. However, these cold winter periods stopped after 1995/96. The warming temperatures due to global warming have eliminated the cold spells, allowing the normally constructive tree-killing Pine beetle population to explode and migrate to areas that were historically too cold for them most years. The tree species at these high elevations never evolved strong defences,” said Ken Raffa, a University of Wisconsin-Madison professor of entomology and a senior author of a report commissioned by the BC government.  The epidemic has destroyed 58% of all the pine in the province (or 710 million cubic meters of forest timber) and both the provincial and federal governments have spent hundreds of millions of dollars trying to combat the mountain pine beetle epidemic.

The trees killed by the Pine beetles also contribute to higher forest fire risk creating a triple positive CO2 feedback loop:

  1. loss of carbon sinks – the trees killed by the pine beetle no longer exist to sequester CO2
  2. the decaying trees now become carbon sources of CO2
  3. CO2 sources increase due to forest fires from increase in dry dead plant matter of the dead trees

Conservation Zones

As temperature zones, migrate, conservation will become problematic. Conservation areas are usually fixed in location but as temperature zones migrate at anywhere from 2 to 5 km/year, species which the conservation area is meant to protect may naturally move out of the conservation areas.

No Flowers for Pollinators

Research being conducted in Colorado  show an earlier bloom to early-blooming flowers, which tend to be very temperature-sensitive, and a later bloom to late-blooming flowers. This leaves a flowerless gap in the middle of the year for creatures, such as bees, that until now have adapted to flowers of some sort throughout the late spring, summer, and early fall.  It is unclear how this will affect pollinators such as bees. Will their populations decline in midsummer, or shift their activities earlier or later in the year, or will they leave the area altogether?

Oceanic Species Migration

Climate Change and European Marine Ecosystems Research (CLAMER) scientists are reporting that warming ocean waters are causing the largest movement of marine species seen on Earth in more than two million years:

  • Arctic, melting sea ice during recent summers has allowed a passage to open up from the Pacific ocean into the North Atlantic, allowing plankton, fish and even whales to into the Atlantic Ocean from the Pacific.
  • The discovery has sparked fears delicate marine food webs could be unbalanced and lead to some species becoming extinct as competition for food between the native species and the invaders stretches resources.
  • Rising ocean temperatures are also allowing species normally found in warmer sub-tropical regions to into the northeast Atlantic.
  • A venomous warm-water species Pelagia noctiluca has forced the closure of beaches and is now becoming increasingly common in the waters around Britain.
  • The highly venomous Portuguese Man-of-War, which is normally found in subtropical waters, is also regularly been found in the northern Atlantic waters.
  • A form of algae known as dinoflagellates has also been found to be moving eastwards across the Atlantic towards Scandinavia and the North Sea.
  • Huge blooms of these marine plants use up the oxygen in the water and can produce toxic compounds that make shellfish poisonous.
  • Plankton sampling in the north Atlantic over the past 70 years have also shown that other species of plankton, normally only found in the Pacific ocean, have now become common in Atlantic waters.

Professor Chris Reid of the Sir Alister Hardy Foundation for Ocean Science at the Plymouth Marine Laboratory has deep concerns about warming ocean trend, especially if the Arctic ice melts and marine species in the Pacific find a path to migrate to the Altantic. The last time this occurred 2 to 3 million years ago, it resulted in the extinction of a large number of Atlantic ocean species

  • It seems for the first time in probably thousands of years a huge area of sea water opened up between Alaska and the west of Greenland, allowing a huge transfer of water and species between the two oceans.
  • The opening of this passage allowed the wind to drive a current through this passage and the water warmed up making it favourable for species to get through.
  • In 1999 we discovered a species in the north west Atlantic that we hadn’t seen before, but we know from surveys in the north Pacific that it is very abundant there. This species died out in the Atlantic around 800,000 years ago due to glaciation that changed the conditions it needed to survive.
  • The implications are huge. The last time there was an incursion of species from the Pacific into the Atlantic was around two to three million years ago.
  • Large numbers of species were introduced from the Pacific and made large numbers of local Atlantic species extinct.
  • The impact on salmon and other fish resources could be very dramatic. The indications are that as the ice is continuing to melt in the summer months, climate change could lead to complete melting within 20 to 30 years, which would see huge numbers of species migrating.
  • It could have impacts all the way down to the British Isles and down the east coast of the United States.
  • The opening of this passage allowed the wind to drive a current through this passage and the water warmed up making it favourable for species to get through.
  • In 1999 we discovered a species in the north west Atlantic that we hadn’t seen before, but we know from surveys in the north Pacific that it is very abundant there.
  • This species died out in the Atlantic around 800,000 years ago due to glaciation that changed the conditions it needed to survive.
  • The implications are huge. The last time there was an incursion of species from the Pacific into the Atlantic was around two to three million years ago.
  • Large numbers of species were introduced from the Pacific and made large numbers of local Atlantic species extinct.
  • The impact on salmon and other fish resources could be very dramatic. The indications are that as the ice is continuing to melt in the summer months, climate change could lead to complete melting within 20 to 30 years, which would see huge numbers of species migrating.
  • It could have impacts all the way down to the British Isles and down the east coast of the United States.
  • With the jellyfish we are seeing them move further north from tropical and subtropical regions as a result of warming sea temperatures.
  • The invading plankton species is likely to cause widespread changes to the food web in the Atlantic ocean as the invading species are less nutritious than native species, which are eaten by many fish and large whales.
  • Changes in populations of tiny animals called copepods, which are an essential food source for fish such as cod, herring and mackerel, are already being blamed for helping to drive the collapse of fish stocks as the native species of copepods have been replaced with smaller less nutritious varieties.
  • This has resulted in declines in North Sea birds while Harbour porpoises have also migrated northwards North Sea after sand eels followed the poleward movement of the copepods they ate.

The Impact of vanishing Apex Predators

Recent scientific research reveals that top predators play a vital role in ecology and their rapid disappearance is already having profound effects on land, freshwater and ocean ecosystems around the world.

apex predators - Trophic downgrading of planet earth 2011 fig 1

Figure 8: Impacts of top predators absence or presence (Source: Trophic downgrading of planet earth)

apex predators - Trophic downgrading of planet earth 2011 fig 2

Figure 9: Impacts of top predators absence or presence (Source: Trophic downgrading of planet earth)

apex predators - Trophic downgrading of planet earth 2011 fig 3

Figure 10: Impacts of top predators absence or presence (Source: Trophic downgrading of planet earth)

apex predators - Trophic downgrading of planet earth 2011 fig 4

Figure 11: Impacts of loss of top predators on ecological parameters (Source: Trophic downgrading of planet earth)

apex predators - Status and Ecological Effects of the World's Largest Carnivores figure 2

Figure 12: Species increase and decrease as a result of Apex predator decline (Source: Status and Ecological Effects of the World’s Largest Carnivores)

apex predators - Status and Ecological Effects of the World's Largest Carnivores figure 4

Figure 13: Wolf apex predator trophic effects on other species (Source: Status and Ecological Effects of the World’s Largest Carnivores)

apex predators - Status and Ecological Effects of the World's Largest Carnivores figure 6

Figure 14: Impact of various factors on declining apex predators (Source: Status and Ecological Effects of the World’s Largest Carnivores)

References:

actionbioscience website

dopa website