Defaunation

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The World Wildlife Fund's Living Planet Report 2022 found that wildlife populations declined by an average 69% since 1970. 1970- Decline in species populations - Living Planet Index.svg
The World Wildlife Fund’s Living Planet Report 2022 found that wildlife populations declined by an average 69% since 1970.

Defaunation is the global, local, or functional extinction of animal populations or species from ecological communities. [4] The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. [5] This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". [6] [5] [7] Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. [8] Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of Neotropical forests. [9] Since then, the term has gained broader usage in conservation biology as a global phenomenon. [4] [9]

Contents

It is estimated that more than 50 percent of all wildlife has been lost in the last 40 years. [10] In 2016, it was estimated that by 2020, 68% of the world's wildlife would be lost. [11] In South America, there is believed to be a 70 percent loss. [12] A 2021 study found that only around 3% of the planet's terrestrial surface is ecologically and faunally intact, with healthy populations of native animal species and little to no human footprint. [13] [14]

In November 2017, over 15,000 scientists around the world issued a second warning to humanity, which, among other things, urged for the development and implementation of policies to halt "defaunation, the poaching crisis, and the exploitation and trade of threatened species." [15]

Drivers

Overexploitation

Rhino poaching Rhino poaching.jpg
Rhino poaching

The intensive hunting and harvesting of animals threatens endangered vertebrate species across the world. [16] [5] Game vertebrates are considered valuable products of tropical forests and savannas. In Brazilian Amazonia, 23 million vertebrates are killed every year; [17] large-bodied primates, tapirs, white-lipped peccaries, giant armadillos, and tortoises are some of the animals most sensitive to harvest. [18] Overhunting can reduce the local population of such species by more than half, as well as reducing population density. Populations located nearer to villages are significantly more at risk of depletion. [18] Abundance of local game species declines as density of local settlements, such as villages, increases. [19]

"There were around 10,000,000 African elephants at the beginning of the 20th century, and now there are only about 450,000 remaining. In several countries, all elephant populations have gone EX, and the great beasts are now absent from many large regions of other countries they once occupied."--Gerardo Ceballos and Paul R. Ehrlich Number of African elephants.svg
"There were around 10,000,000 African elephants at the beginning of the 20th century, and now there are only about 450,000 remaining. In several countries, all elephant populations have gone EX, and the great beasts are now absent from many large regions of other countries they once occupied."—Gerardo Ceballos and Paul R. Ehrlich

Hunting and poaching may lead to local population declines or extinction in some species. [21] Most affected species undergo pressure from multiple sources but the scientific community is still unsure of the complexity of these interactions and their feedback loops. [4] [22]

One case study in Panama found an inverse relationship between poaching intensity and abundance for 9 of 11 mammal species studied. [23] In addition, preferred game species experienced greater declines and had higher spatial variation in abundance. [23]

Habitat destruction and fragmentation

Lacanja burn shows deforestation Lacanja burn.JPG
Lacanja burn shows deforestation

Human population growth results in changes in land-use, which can cause natural habitats to become fragmented, altered, or destroyed. [5] Large mammals are often more vulnerable to extinction than smaller animals because they require larger home ranges and thus are more prone to suffer the effects of deforestation. Large species such as elephants, rhinoceroses, large primates, tapirs and peccaries are the first animals to disappear in fragmented rainforests. [24]

A case study from Amazonian Ecuador analyzed two oil-road management approaches and their effects on the surrounding wildlife communities. The free-access road had forests that were cleared and fragmented and the other had enforced access control. Fewer species were found along the first road with density estimates being almost 80% lower than at the second site that which had minimal disturbance. [25] This finding suggests that disturbances affected the local animals' willingness and ability to travel between patches.

Fishbone deforestation pattern. This was found in Bolivia and is visible from satellite Sugarcane Deforestation, Bolivia, 2016-06-15 by Planet Labs.jpg
Fishbone deforestation pattern. This was found in Bolivia and is visible from satellite

Fragmentation lowers populations while increasing extinction risk when the remaining habitat size is small. [26] When there is more unfragmented land, there is more habitat for more diverse species. A larger land patch also means it can accommodate more species with larger home ranges. However, when patch size decreases, there is an increase in the number of isolated fragments which can remain unoccupied by local fauna. If this persists, species may become extinct in the area. [26]

A study on deforestation in the Amazon looked at two patterns of habitat fragmentation: "fish-bone" in smaller properties and another unnamed large property pattern. The large property pattern contained fewer fragments than the smaller fish-bone pattern. The results suggested that higher levels of fragmentation within the fish-bone pattern led to the loss of species and decreased diversity of large vertebrates. [27] Human impacts, such as the fragmentation of forests, may cause large areas to lose the ability to maintain biodiversity and ecosystem function due to loss of key ecological processes. [28] This can consequently cause changes within environments and skew evolutionary processes. [9]

In North America, wild bird populations have declined by 29%, or around three billion, since 1970, largely as the result of anthropogenic causes such as habitat loss for human use, the primary driver of the decline, along with widespread use of neonicotinoid insecticides and the proliferation of domesticated cats allowed to roam outdoors. [29]

Invasive species

Human influences, such as colonization and agriculture, have caused species to become distributed outside of their native ranges. [5] Fragmentation also has cascading effects on native species, beyond reducing habitat and resource availability; it leaves areas vulnerable to non-native invasions. Invasive species can out-compete or directly prey upon native species, as well as alter the habitat so that native species can no longer survive. [5] [25] [30]

In extinct animal species for which the cause of extinction is known, over 50% were affected by invasive species. For 20% of extinct animal species, invasive species are the only cited cause of extinction. Invasive species are the second-most important cause of extinction for mammals. [31]

Global patterns

Tropical regions are the most heavily impacted by defaunation. [4] [5] [9] These regions, which include the Brazilian Amazon, the Congo Basin of Central Africa, and Indonesia, experience the greatest rates of overexploitation and habitat degradation. [8] However, specific causes are varied, and areas with one endangered group (such as birds) do not necessarily also have other endangered groups (such as mammals, insects, or amphibians). [32]

Deforestation of the Brazilian Amazon leads to habitat fragmentation and overexploitation. Hunting pressure in the Amazon rainforest has increased as traditional hunting techniques have been replaced by modern weapons such as shotguns. [5] [33] Access roads built for mining and logging operations fragment the forest landscape and allow hunters to move into forested areas which previously were untouched. [33] The bushmeat trade in Central Africa incentivizes the overexploitation of local fauna. [5] Indonesia has the most endangered animal species of any area in the world. [34] International trade in wild animals, as well as extensive logging, mining and agriculture operations, drive the decline and extinction of numerous species. [34]

Ecological impacts

Genetic loss

Inbreeding and genetic diversity loss often occur with endangered species populations because they have small and/or declining populations. Loss of genetic diversity lowers the ability of a population to deal with change in their environment and can make individuals within the community homogeneous. If this occurs, these animals are more susceptible to disease and other occurrences that may target a specific genome. Without genetic diversity, one disease could eradicate an entire species. Inbreeding lowers reproduction and survival rates. It is suggested that these genetic factors contribute to the extinction risk in threatened/endangered species. [35]

Seed dispersal

Effects on plants and forest structure

The consequences of defaunation can be expected to affect the plant community. There are three non-mutually exclusive conclusions as to the consequences on tropical forest plant communities:

  1. If seed dispersal agents are targeted by hunters, the effectiveness and amount of dispersal for those plant species will be reduced [9] [36]
  2. The species composition of the seedling and sapling layers will be altered by hunting, [9] and
  3. Selective hunting of medium/large-sized animals instead of small-sized animals will lead to different seed predation patterns, with an emphasis on smaller seeds [9] [37]

One recent study analyzed seedling density and composition from two areas, Los Tuxtlas and Montes Azules. Los Tuxtlas, which is affected more by human activity, showed higher seedling density and a smaller average number of different species than in the other area. Results suggest that an absence of vertebrate dispersers can change the structure and diversity of forests. [38] As a result, a plant community that relies on animals for dispersal could potentially have an altered biodiversity, species dominance, survival, demography, and spatial and genetic structure. [39]

Poaching is likely to alter plant composition because the interactions between game and plant species varies in strength. Some game species interact strongly, weakly, or not at all with species. A change in plant species composition is likely to be a result because the net effect removal of game species varies among the plant species they interact with. [23]

Effects on small-bodied seed dispersers and predators

As large-bodied vertebrates are increasingly lost from seed-dispersal networks, small-bodied seed dispersers (i.e. bats, birds, dung beetles) and seed predators (i.e. rodents) are affected. Defaunation leads to reduced species diversity. [40] [41] This is due to relaxed competition; small-bodied species normally compete with large-bodied vertebrates for food and other resources. As an area becomes defaunated, dominant small-bodied species take over, crowding out other similar species and leading to an overall reduced species diversity. [37] The loss of species diversity is reflective of a larger loss of biodiversity, which has consequences for the maintenance of ecosystem services. [5]

The quality of the physical habitat may also suffer. Bird and bat species (many of who are small bodied seed dispersers) rely on mineral licks as a source of sodium, which is not available elsewhere in their diets. In defaunated areas in the Western Amazon, mineral licks are more thickly covered by vegetation and have lower water availability. Bats were significantly less likely to visit these degraded mineral licks. [33] The degradation of such licks will thus negatively affect the health and reproduction of bat populations. [33]

Defaunation has negative consequences for seed dispersal networks as well. In the western Amazon, birds and bats have separate diets and thus form separate guilds within the network. [42] It is hypothesized that large-bodied vertebrates, being generalists, connect separate guilds, creating a stable, resilient network. Defaunation results in a highly modular network in which specialized frugivores instead act as the connector hubs. [42]

Food webs

According to a 2022 study published in Science , terrestrial mammal food web links have declined by 53% over the past 130,000 years as a result of human population expansion and accompanying defaunation. [43]

Ecosystem services

Changes in predation dynamics, seed predation, seed dispersal, carrion removal, dung removal, vegetation trampling, and other ecosystem processes as a result of defaunation can affect ecosystem supporting and regulatory services, such as nutrient cycling and decomposition, crop pollination, pest control, and water quality. [4]

Conservation

Efforts against defaunation include wildlife overpasses [44] and riparian corridors. [45] Both of these can be otherwise known as wildlife crossing mechanisms. Wildlife overpasses are specifically used for the purpose of protecting many animal species from the roads. [44] Many countries use them and they have been found to be very effective in protecting species and allowing forests to be connected. [44] These overpasses look like bridges of forest that cross over many roads, like a walk bridge for humans, allowing animals to migrate from one side of the forest to the other safely since the road cut off the original connectivity. [44] It was concluded in a study done by Pell and Jones, looking at bird use of these corridors in Australia, that many birds did, in fact, use these corridors to travel from one side of forest to the other and although they did not spend much time in the corridor specifically, they did commonly use them. [44] Riparian corridors are very similar to overpasses they are just on flat land and not on bridges, however, they also work as connective "bridges" between fragmented pieces of forest. One study done connected the corridors with bird habitat and use for seed dispersal. [45] The conclusions of this study showed that some species of birds are highly dependent on these corridors as connections between forest, as flying across the open land is not ideal for many species. [45] Overall both of these studies agree that some sort of connectivity needs to be established between fragments in order to keep the forest ecosystem in the best health possible and that they have in fact been very effective. [44] [45]

Marine

Defaunation in the ocean has occurred later and less intensely than on land. A relatively small number of marine species have been driven to extinction. However, many species have undergone local, ecological, and commercial extinction. [46] Most large marine animal species still exist, such that the size distribution of global species assemblages has changed little since the Pleistocene, but individuals of each species are smaller on average, and overfishing has caused reductions in genetic diversity. Most extinctions and population declines to date have been driven by human overexploitation. [47]

Overfishing has reduced populations of oceanic sharks and rays by 71% since 1970, with more than three quarters of species facing extinction. [48] [49]

Consequences

Marine defaunation has a wide array of effects on ecosystem structure and function. The loss of animals can have both top-down (cascading) and bottom-up effects, [50] [51] as well as consequences for biogeochemical cycling and ecosystem stability.

Two of the most important ecosystem services threatened by marine defaunation are the provision of food and coastal storm protection. [46]

See also

Related Research Articles

<span class="mw-page-title-main">Holocene extinction</span> Ongoing extinction event caused by human activity

The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event caused by humans during the Holocene epoch. These extinctions span numerous families of plants and animals, including mammals, birds, reptiles, amphibians, fish, and invertebrates, and affecting not just terrestrial species but also large sectors of marine life. With widespread degradation of biodiversity hotspots, such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background extinction rates and is increasing. During the past 100–200 years, biodiversity loss and species extinction have accelerated, to the point that most conservation biologists now believe that human activity has either produced a period of mass extinction, or is on the cusp of doing so. As such, after the "Big Five" mass extinctions, the Holocene extinction event has also been referred to as the sixth mass extinction or sixth extinction; given the recent recognition of the Capitanian mass extinction, the term seventh mass extinction has also been proposed for the Holocene extinction event.

<span class="mw-page-title-main">Biodiversity</span> Variety and variability of life forms

Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic, species, and ecosystem level. Biodiversity is not distributed evenly on Earth; it is usually greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than 10% of earth's surface and contain about 90% of the world's species. Marine biodiversity is usually higher along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future as a primary result of deforestation. It encompasses the evolutionary, ecological, and cultural processes that sustain life.

<span class="mw-page-title-main">Wildlife</span> Undomesticated organisms that grow or live wild in an area without being introduced by humans

Wildlife refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced by humans. Wildlife was also synonymous to game: those birds and mammals that were hunted for sport. Wildlife can be found in all ecosystems. Deserts, plains, grasslands, woodlands, forests, and other areas, including the most developed urban areas, all have distinct forms of wildlife. While the term in popular culture usually refers to animals that are untouched by human factors, most scientists agree that much wildlife is affected by human activities. Some wildlife threaten human safety, health, property, and quality of life. However, many wild animals, even the dangerous ones, have value to human beings. This value might be economic, educational, or emotional in nature.

<span class="mw-page-title-main">Conservation biology</span> Study of threats to biological diversity

Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an interdisciplinary subject drawing on natural and social sciences, and the practice of natural resource management.

<span class="mw-page-title-main">Atlantic Forest</span> South American forest

The Atlantic Forest is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and the Misiones Province of Argentina, where the region is known as Selva Misionera.

<span class="mw-page-title-main">Frugivore</span> Organism that eats mostly fruit

A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and nutritional composition of fruits. Frugivores can benefit or hinder fruit-producing plants by either dispersing or destroying their seeds through digestion. When both the fruit-producing plant and the frugivore benefit by fruit-eating behavior the interaction is a form of mutualism.

<span class="mw-page-title-main">Habitat fragmentation</span> Discontinuities in an organisms environment causing population fragmentation.

Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment, and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species. More specifically, habitat fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats.

<span class="mw-page-title-main">Seed dispersal</span> Movement or transport of seeds away from the parent plant

In spermatophyte plants, seed dispersal is the movement, spread or transport of seeds away from the parent plant. Plants have limited mobility and rely upon a variety of dispersal vectors to transport their seeds, including both abiotic vectors, such as the wind, and living (biotic) vectors such as birds. Seeds can be dispersed away from the parent plant individually or collectively, as well as dispersed in both space and time. The patterns of seed dispersal are determined in large part by the dispersal mechanism and this has important implications for the demographic and genetic structure of plant populations, as well as migration patterns and species interactions. There are five main modes of seed dispersal: gravity, wind, ballistic, water, and by animals. Some plants are serotinous and only disperse their seeds in response to an environmental stimulus. These modes are typically inferred based on adaptations, such as wings or fleshy fruit. However, this simplified view may ignore complexity in dispersal. Plants can disperse via modes without possessing the typical associated adaptations and plant traits may be multifunctional.

<span class="mw-page-title-main">Wildlife conservation</span> Practice of protecting wild plant and animal species and their habitats

Wildlife conservation refers to the practice of protecting wild species and their habitats in order to maintain healthy wildlife species or populations and to restore, protect or enhance natural ecosystems. Major threats to wildlife include habitat destruction, degradation, fragmentation, overexploitation, poaching, pollution, climate change, and the illegal wildlife trade. The IUCN estimates that 42,100 species of the ones assessed are at risk for extinction. Expanding to all existing species, a 2019 UN report on biodiversity put this estimate even higher at a million species. It is also being acknowledged that an increasing number of ecosystems on Earth containing endangered species are disappearing. To address these issues, there have been both national and international governmental efforts to preserve Earth's wildlife. Prominent conservation agreements include the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the 1992 Convention on Biological Diversity (CBD). There are also numerous nongovernmental organizations (NGO's) dedicated to conservation such as the Nature Conservancy, World Wildlife Fund, the Wild Animal Health Fund and Conservation International.

<span class="mw-page-title-main">Biological Dynamics of Forest Fragments Project</span>

The Biological Dynamics of Forest Fragments Project is a large-scale ecological experiment looking at the effects of habitat fragmentation on tropical rainforest. The experiment which was established in 1979 is located near Manaus in the Brazilian Amazon rainforest. The project is jointly managed by the Amazon Biodiversity Center and the Brazilian Institute for Research in the Amazon (INPA).

An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem. Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific food sources, mutualistic, or forced to coexist with an invasive species that is introduced to the ecosystem. Species introductions to a foreign ecosystem can often devastate entire communities, and even entire ecosystems. These exotic species monopolize the ecosystem's resources, and since they have no natural predators to decrease their growth, they are able to increase indefinitely. Olsen et al. showed that exotic species have caused lake and estuary ecosystems to go through cascade effects due to loss of algae, crayfish, mollusks, fish, amphibians, and birds. However, the principal cause of cascade effects is the loss of top predators as the key species. As a result of this loss, a dramatic increase of prey species occurs. The prey is then able to overexploit its own food resources, until the population numbers decrease in abundance, which can lead to extinction. When the prey's food resources disappear, they starve and may go extinct as well. If the prey species is herbivorous, then their initial release and exploitation of the plants may result in a loss of plant biodiversity in the area. If other organisms in the ecosystem also depend upon these plants as food resources, then these species may go extinct as well. An example of the cascade effect caused by the loss of a top predator is apparent in tropical forests. When hunters cause local extinctions of top predators, the predators' prey's population numbers increase, causing an overexploitation of a food resource and a cascade effect of species loss. Recent studies have been performed on approaches to mitigate extinction cascades in food-web networks.

<span class="mw-page-title-main">Wildlife corridor</span> Connecting wild territories for animals

A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures. This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding, and reduced genetic diversity that often occur within isolated populations. Corridors may also help facilitate the re-establishment of populations that have been reduced or eliminated due to random events. This may potentially moderate some of the worst effects of habitat fragmentation, whereas in urbanization can split up habitat areas, causing animals to lose both their natural habitat and the ability to move between regions to access resources. Habitat fragmentation due to human development is an ever-increasing threat to biodiversity, and habitat corridors serve to manage its effects.

Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability of empty niches lead to increased speciation. As a result, island ecosystems comprise 30% of the world’s biodiversity hotspots, 50% of marine tropical diversity, and some of the most unusual and rare species. Many species still remain unknown.

<i>Igapó</i> Flooded Amazon forests in Brazil

Igapó is a word used in Brazil for blackwater-flooded forests in the Amazon biome. These forests and similar swamp forests are seasonally inundated with freshwater. They typically occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found in a range of climate zones, from boreal through temperate and subtropical to tropical. In the Amazon Basin of Brazil, a seasonally whitewater-flooded forest is known as a várzea, which is similar to igapó in many regards; the key difference between the two habitats is in the type of water that floods the forest.

Empty forest is a term coined by Kent H. Redford's article "The Empty Forest" (1992), which was published in BioScience. An "empty forest" refers to an ecosystem that is void of large mammals. Empty forests are characterized by an otherwise excellent habitat, and often have large, fully grown trees, although they lack large mammals as a result of human impact. Empty forests show that human impact can destroy an ecosystem from within as well as from without.

<span class="mw-page-title-main">Mauro Galetti</span> Brazilian ecologist and conservation biologist

Mauro Galetti. is a Brazilian ecologist and conservation biologist. He is a full professor in the Department of Biodiversity at the Universidade Estadual Paulista, Rio Claro, São Paulo and has worked at Stanford University (USA), Aarhus University (Denmark) and the University of Miami (USA). He also holds a position as a Courtesy Associated Professor at Florida International University, Miami, FL. Galetti's work has centered on the analysis of the ecological and evolutionary consequences of defaunation. He was awarded by WWF in 1998 and was a Tinker Fellow at Stanford University and a visiting professor at Aarhus Universitet, Denmark in 2017.

<span class="mw-page-title-main">Linear infrastructure intrusions</span>

Linear infrastructure intrusions into natural ecosystems are man-made linear infrastructure such as roads and highways, electric power lines, railway lines, canals, pipelines, firebreaks, and fences. These intrusions cause linear opening through the habitat or breakage in landscape connectivity due to infrastructure creation and maintenance, which is known to have multiple ecological effects in terrestrial and aquatic ecosystems. These effects include habitat loss and fragmentation, spread of invasive alien species, desiccation, windthrow, fires, animal injury and mortality, changes in animal behaviour, pollution, microclimate and vegetation changes, loss of ecosystem services, increased pressures from development, tourism, hunting, garbage disposal, and associated human disturbances. These intrusions, considered crucial infrastructure for economic sectors such as transportation, power, and irrigation, may also have negative social impacts on indigenous and rural people through exposure to novel social and market pressures, loss of land and displacement, and iniquitous distribution of costs and benefits from infrastructure projects. The study of the ecological effects of linear infrastructure intrusions has spawning sub-fields of research such as road ecology and railroad ecology.

<span class="mw-page-title-main">Biodiversity loss</span> Extinction of species and local ecosystem loss reduction or loss of species in a given habitat

Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, depending on whether the environmental degradation that leads to the loss is reversible through ecological restoration/ecological resilience or effectively permanent. The current global extinction, has resulted in a biodiversity crisis being driven by human activities which push beyond the planetary boundaries and so far has proven irreversible.

Rodolfo Dirzo is a professor, conservationist, and tropical ecologist. He is a Bing Professor in environmental science at Stanford and a senior fellow at the Stanford Woods Institute for the Environment. His research interests mainly focus on plant-animal interactions, evolutionary ecology, and defaunation in the tropics of Latin America, Africa, and the Central Pacific. He was a member of the Committee on A Conceptual Framework for New K-12 Science Education Standards, co-authoring the framework in 2012, and continues to educate local communities and young people about science and environmental issues. 

References

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