ENSC Exam 2 (Biodiversity and Human Population)

What does "GDP per person" represent?

"GDP per person" represents the average level of economic well-being This measure can also be stated as "GDP per capita" NOTE: Population growth rates have decline in many parts of the world. Countries with highest standard of living, in general, have the lowest population growth rates; these countries have gone through the "demographic transition."

What does "GDP" refer to?

"GDP" refers to the Gross Domestic Product, a measure of each country's economic output.

When does population momentum occur?

"Population Momentum" occurs when a large percentage of the population is in reproductive years, or younger; such a population is characterized by a "pinched population profile."

What was Malthus' perspective on population growth?

"Population, if unchecked by food supply, tends to grow at a geometric rate." Furthermore, stated Malthus, "As population double and redoubles, it is exactly as if the globe were halving in size, until finally it has shrunk so much that food and subsistence fall below the level necessary of life." Fundamental to Malthus doctrine was the notion that natural resources were fixed in quantity. As human numbers expand, human welfare is affected negatively by shortages of resources. This concept is reflected by the "limit to growth" hypothesis.

What is aesthetic value?

"The beauty of nature is reflected in each and every species

How does the Millennium Ecosystem Assessment define biodiversity?

"biodiversity refers to diversity at multiple scales of biological organization (genes, populations, species, and ecosystems) and can be considered at any geographic scale (local, regional, or global)" and "Biodiversity is the variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part"

What does demographic transition refer to?

"demographic transition" refers to a relationship that have been observed to occur in numerous societies, throughout recent history.

What do improvements in economic well-being tend to be associated with?

- declining birth rates -declining death rates NOTE: As a society's people become better off, they tend to live longer and have fewer children, on average.

What is "existence value"?

-"The uniqueness of life has value, in and of itself" -Many people derive benefit on non-material level from known that unique species exist - even though they may never have an opportunity to experience that uniqueness personally (Example: elephant)

Most of the world's major trouble spots over the past several decades have been in areas of rapid population growth:

-Central America (1980s) -The Middle East: Continues to be among the world's rapidly growing regions -Africa: Somalia, Darfur, and Kenya- all areas of major civil conflict in the 21st century- are all growing rapidly

What are major threats to threatened and endangered species, as determined by Welcome and others?

-Disease (3%) -Overexploitation (17%) -Pollution (24%) -Alien species (49%) -Habitat degradation/loss (85%)

What are ESA critics' major arguments?

-Economic Value Criteria: Critics of the ESA often state a belief that the economic and social costs associated with protecting imperiled species exceed whatever benefits are associated with these measures, and therefore that the Act should be amended to require that the economic costs of species protection should be considered in listing decisions. -Listing Standards: Some ESA critics have argued that many species protected by the Act are not truly endangered (ex: The Telco Dam snail-darter controversy) -Property Rights: Opponents of the Act state that it has a negative effect on the owners of private property, and that it creates negative incentives for property owners. -Effectiveness: Critics of the Act contend that the Act has been ineffective. (ex: "In the 32 years the ESA has been on the books, just 34 of the nearly 1,300 U.S. species given special protection have made their way of the "endangered" or "threatened" lists. There is a less than 1% recovery rate (which is not good))

What are terms used to define listing status?

-Endangered: "Any species that is in danger of becoming extinct throughout all or significant part of its range." -Threatened: "Any species that is likely to become an endangered species within the foreseeable future throughout all or significant part of its range." -Listed: Any species on either the threatened or endangered list -Candidate: Any species being evaluated for listing NOTE: Only listed species are subject to ESA protections

Scientific research generates information and knowledge that be put to work protecting species. For example:

-Field research to determine the status of existing species: number of individuals, age distribution, mortality rates, population trends. Resources will not be devoted to species protection unless the need for protection has been documented (ex: whooping crane) -Research to determine minimum habitat size parameters for various types of species ("island ecology"). This can be usefully applied in preserving natural habituated, developing species protection plans under the Endangered species Act (ex: whooping crane) -Research to determine appropriate means for capture, captive breeding, and re-lrease of wild species (ex: California condor) -Research to determine geographic distribution of at-risk species -Research to characterize and understand protection mechanisms

According to the ESA, the United States Fish and Wildlife Service is required to do what?

-List all species considered to be threatened or endangered -Evaluate scientific data describing the status of species that are candidates for listing as threatened and endangered, an determine whether or not they should be listed -Establish recovery plans for endangered species and threatened species

What are some vulnerable traits?

-Low reproductive rate (California condor) -Specialized niche (Giant Panda) -Narrow distribution (Many endemic species) -Fixed migratory patterns (Whooping crane) -Rare (small population) (Many endemic species) -Commerically valuable (Black rhino) -Requires large range (California condor) -Feeds at high trophic level (Bald eagle)

What are some concepts of value that have been applied to species preservation and biodiversity?

-Measurable economic value ("utilitarian") >As harvestable resources (example: timber) >As capable of providing unique services or products (example: food products) >As genetic resources >"Option value" -Non-Tangible Economic Value ("Non-utilitarian") >Value as part of food webs, contributors to ecosystem function >"Existence value" >Aesthetic vale

What are major provisions of the National Environmental Policy Act (NEPA)?

-NEPA makes federal government actions subject to U.S. environmental standards and legislation NEPA requires that U.S. government decisions take environmental implications of decision into account -NEPA requires that any proposals for "legislation or other major federal actions significantly affecting the quality of the human environment" must be justified by a detailed statement of environment impact, which considers adverse impacts that would result from the proposed action, and evaluates alternatives which might avoid that adverse impact.

How are future species extinction rates projected? (What methods are used to know how rapidly species are becoming extinct?)

-Qualitative: assess drivers of biodiversity change, characterize biotic response at species or system level Example: Climatic shift can cause extinction of species that are unable to migrate -Threat/Environmental Change Analysis: model potential affects of environmental change on species density Example: Climate in habitats that are essential to certain amphibians species is likely to change with time -Population Viability Analysis: A new approach for projecting future species losses: As the number of individuals within a population declines, so does that species' viability within that population due to the increased likelihood of inbreeding.

Proponents of the Act assert that these failures have more to do with the manner in which it is being administered than with basic requirements. What doe ESA proponents contend?

-The listing process is too slow -Recovery plan are funded at level inadequate to the task at hand -More rapid listing would provide agencies with greater range of options, so protection could be accomplished at lesser social and economic cost.

What environmental problems tend to occur in association with rapid population growth?

-Tropical deforestation: A number of nations in central America, where rapid deforestation has been occurring , are growing rapidly. In Brazil, rapid population growth has been a direct driver of tropical deforestation. Central Africa is one of the world's most rapidly growing regions. Today, industrial demands for wood product, driven by economic growth, are the primary cause of SE Asia's forest harvests. -Desertification: The Sahel (sub-Saharan) region of central Africa has been subject to severe desertification, resulting in a diminishment of the land's biological capacity to produce food. Overgrazing by subsistence farmed in the area has contributed to desertification in this region. -Armed conflict: War has environmental impacts. (example: Saddam Hussein's "environmental terrorism" during he first Gulf War... Hussein discharged raw crude oil into the Persian Gulf) NOTE: Rapid population growth has fanned flames of conflict that originate in ethnic and/or religious tensions -Poverty: Extreme poverty is an environmental problem because people will do water is needed to survive (example: Haiti's native vegetation was forest but less than 2% of Haiti's land remains forested today. This deforestation has been driven by the needs of an impoverished people, with no other way to survive.) NOTE: poverty-driven environmental degradation diminishes the environments capacity to provide good and services that can sustain a population that is within that environment's carry capacity

How fast are species becoming extinct? (Is there an "extinction" crisis? Can it be determined?

-Uncertainty regarding actual number of species -Some species listed as described may have been described years ago, and have not been thoroughly evaluates in recent years for extinction or threat. -A species is not generally considered to be extinct until not seen for 50 years -Tropical forest clearing

What are the major "high" income nations?

1. Canada 2. U.S. 3. W. Europe 4. Japan 5. Australia 6. New Zealand

What are the top 6 most populous nations?

1. China 2. India 3. U.S.A 4. Indonesia 5. Brazil 6. Pakistan

How can humans protect species from extinction?

1. Generate scientific knowledge about species life habits, species preservation mechanisms 2. Apply that knowledge in habitat preservation, wildlife management, species preservation efforts 3. Establish laws and regulations: in society, laws and regulations are an important mechanism for controlling human behavior

Method used by T. Erwin to Estimate Beetle Species

1. Remove all beetles from Luehea 2. 1100 species found in canopy 3. Estimates 163 species endemic to Luehea canopy: 20% Herbivores, 5% Predators, 10% Fungivores and 5% Scavengers 4. Beetles represent 40% of all known arthropod species Therefore: 400 total species specific to Luehea canopy (163 is 40% of 400) 5. Canopy is typically twice as diverse as below ground. Therefore, 600 beetle species specific to Luehea tree 6. Luehea is one of 50,000 tropical tree species. Therefore: At least 30,000,000 tropical beetle species (50,000x600=

What are the requirements of the Endangered Species Act (ESA)?

1. U.S. Fish and Wildlife Service is required to identify and list all threatened and endangered species in the U.S. and abroad (NOTE: Listing criteria are solely biological. Economic factors are not considered in listing decisions) 2. ESA requires Departments of Interior and Commerce to develop Recovery Plans for each listed species; and it authorizes the departments to implement the recovery plans. 3. The ESA prohibits interstate commerce, hunting, trapping, collecting, or injuring protected species. 4. The ESA directs federal agencies not fund or authorize projects that jeopardize listed species or their habitats.

What type of economy is Germany?

A "mature" economy with declining population

Ecosystem

A dynamic complex of plant, animal, and microorganisms communities and the nonliving environment interacting as a functional unit

Population

A group of ORGANISMS of one SPECIES that INTERBREED and live in the same place at the same time

Species

A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

What was Lester Brown's perspective on population growth?

A leadership role in calling attention to the degradation of the world's ecosystems that is occurring in response to population pressures, and its implication for future human welfare. The world's ecosystems, according to this logic, are its "biological capital." Loss of this capital will of necessity have a negative impact on human welfare. Destruction of ecosystems and loss of biological capital-- the source of ecological services provided by global ecosystems -- is essentially irreversible on a human timescale. Therefore, it is imperative for the world's governments to take rapid action to HALT population growth.

What is Zero Population Growth (ZPG)?

A population growth rate of 0.0% (or less)

What is a recovery plan?

A recovery plan is a set of actions that can be taken by government agencies to aid the recovery of a listed species (Example: restricted harvested of timber on government and private lands within the "old growth" forest of NW US that sere as Spotted Owl habitat; biologist to retrieve eggs from condor nests, raise the hatchlings in captivity, and release those hatchling to the wild)

What is the cause for the largest percentage of at-risk species threat by habitat destruction/degradation?

Agriculture

Who was Malthus? What did he write? What was it about?

An English clergyman who wrote "An Essay on the Principle of Population" in 1798

Who was Garrett Hardin? What did he write? What was it about?

An ecologist who wrote "Tragedy of the Commons," and essay describing the fate of a commonly-held pasture in a rural village, when villa faced no price or penalty for grazing animals on the pasture's grasses

Who was Julian Simon? What did he write? What was it about?

An economist who developed controversial theories about population growth. Simon's well known book was entitles "The Ultimate Resource." The title refers to member of the human race, who develop and utilize powers of creativity, ingenuity, and industriousness in their quest for survival

What does a NEPA Environmental Impact Statement (EIS) study involve?

Analysis of alternative to the proposed action

What are "Background" extinction rates?

Are those that predated the human species' dominance of earth system

What is the definition of species area relationships?

As a way of studying how human activities and other ecosystem disturbances affect species richness within such areas.

In the rapidly developing parts of the world such as SE Asia other than China, demographic transition is occurring at what rate?

At much more rapid rate

In which of the following nations is the largest percentage of the population older than 65 years in age? Chile, Egypt, Iran, India, Australia

Australia

Why is the profile "pinched"?

Because it is so much narrower at the top than at the bottom, indicative of rapidly growing population. It is very difficult to slow the growth of a population which exhibits this characteristic. The population can double within a timespan as short as a generation. When even birth rates decline rapidly the total population will continue to increase.

To calculate a population growth rate

Birth rate minus Death rate Rate of Natural increase + or - Net Migration Rate Population Growth Rate

Generally, as economic well being increases for a given population

Birth rates decline Death rates decline Fertility rates decline

What does the Code of Federal Regulations (CFR) have?

CFR has numerous provisions governing preparation of NEPA environmental impact statements

What are major areas of tropical deforestation?

Central and South America, central Africa, and southeastern Asia.

What do federal actions include?

Construction projects, legislation, and the granting of permits under federal statutes.

According to the Millennium Ecosystem Assessment Estimates:

Contemporary extinction rates far exceed background rates, and future rates are expected to increase

In the worlds s non-industrialized (developing nations over the 1950-to-2000 period, average birth rates have ___ and average death rates have ____

Declined; declined

An analysis by Taylor and others demonstrated what about recovery plan implementation?

Demonstrated that species numbers tended to recover as response to recovery plan implementation (i.e. the longer the recovery plan was in place, the more likely that species numbers increased) which ESA supports interpret to indicate that the ESA is effective.

Who was Lester Brown? What did he write? What was it about?

Director of the Worldwatch Institute, and environment think-tank in Washington DC

What was the result of the Telco Dam controversy?

ESA critics won legal battle over the economic value of preserving a species.

What was Garrett Hardin's perspective on population growth?

Estimate of the global carrying capacity for human population: 50 billion, about 8 times the population of today. Diminished of life quality for all humans would be likely if human populations were to approach that number.

What is the difference between evaluated and NOT evaluated species?

Evaluated: classified species Not Evaluated: Don't really know species exist

What is "option value"?

For each and every species: there is a possibility that it may contain some unique property capable of providing economic value of which we are unaware today

What was Julian Simon's perspective on population growth?

Fundamental to Simon's perceptive is the notion that natural resources are NOT "fixed" but respond to technology. The source of technology, of course is people, therefore, more people is a good thing. Example: "green revolution" (i.e. the development of higher yielding crop varieties, chemical fertilizers and pesticides)

What are the levels of biological organization referenced by the term "biodiversity"?

Genes Populations Species Ecosystems

Which of the following nations has come closest to achieving "Zero Population Growth"? Nigeria, China, USA, Germany, Bangladesh

Germany

Developing nations typically have a higher replacement level fertility than industrialized nations because developing nations usually

Have higher infant mortality rates

What are some of the factors likely to be responsible for the relationship between declining birth rates and declining death rates?

Health Care Food availability Working conditions Medicare Delay in childbearing Greater opportunities "social security" less need for children expensive to care for children

What are some reasons for why the US has declined to replacement level fertility?

Immigration (immigrant groups tend to have higher fertility rates than native populations) Income disparities (birth rates and death rates are lower for upper-income groups)

Which nation highest population growth rate? France or India

India

Which species has the greatest number of unnamed species estimated?

Insect and myriapods

Which life form contains the largest number of the earth's know species?

Insects

What did the bill introduced in the US House of Representatives in 2005 propose?

It proposed to compensate property owners for any loss of property value (>50%) suffered if a listed species was found on the property after purchase, or if the species known to be on the property was listed after purchases?

How are numbers of "undiscovered" species estimated?

Known/Undiscovered Ratios- For mammals, birds, other forms that are well enumerated: Approximately twice as many species in tropics as in temperate regions. (1:2 Ration) Body Size Ratios: Researchers have constructed relationships in an effort to determine how many species not been observed- Extrapolations Based on Body Size Ratios (Log-Species density (y); log- mean body size (x) ) with Extrapolation (attempts to correct sampling bias) and Observed (reflects size-bias in sampling) Terry Erwin: Tropical Beetles If the ratio of numbers of tropical to temperate species is the same for insects as for mammals and birds, we many expect there to be something like two unnamed species of tropical insects for every one named temperates species

What is the Endangered Species Act (ESA)?

Legislation, enacted by the US in 1973 and amended in 1982 and 1987, is among the world's strictest species-protection national statues.

Why do species become "at risk" of extinction?

Life habitats make some species more vulnerable to extinction than others.

What does the term "extrapolation" mean?

Means to estimate a relationship beyond the range where the relationship has been observed.

What does the term "endemic" mean?

Means unique to a given area

Which nation has highest proportion of the population in the pre-productive age classes? Italy or Mexico

Mexico

What are "projected" extinctions?

Model-derived estimates using a variety of techniques

What is the USA Rate of Natural Increase from 1910 to 2005?

NOTE: the birth rate and rate of natural increase responded to societal change. Both declined rapidly in the early 20th century follow WW1 through the 1920s a pored of increasing prosperity that was followed by the Great Depression. Birth rates increased rapidly after WW2, producing the "Baby Boom" generation. The "echo baby boom" which occurred as the baby boomers had children, is evident in the late '80s and early '90s.

Describe Zero Population Growth (ZPG) in regards to population pyramids

Nations that are approaching "zero population growth" (i.e., a "population growth rate" of 0%) or have declining populations. Nations in this category include several former communist nations and the war-torn nations of former Yugoslavia. Populations approaching or below ZPG are prevalent on the European continent (including Spain, Italy, Sweden, Denmark, the United Kingdom - and France). Japan's population growth rate is 0.1%.

What does extinct in the wild refer to?

No longer occur in the wild but are in captivities

Has the US followed all parts of the "classic" model?

No, in the US overall birth rates have not declined to replacement level fertility despite our high level of economic well being.

"Hot spots" in the USA:

One of the most highly rates areas in the USA is the southern Appalachians, which extend from northeastern Tennessee into southwestern Virginia. The primary species of concern are aquatic- especially freshwater mussels but also fish species - in the Clinch and Powell Rivers, at the upper end of the Tennessee River drainage.

What is the threat that causes the second highest percentage of species affected in mammals?

Over exploitation

What is the National Environmental Policy Act (NEPA)? What does NEPA require of agencies of the federal government?

Passed in 1969 and sometimes called "Magma Carta" of modern U.S. environmental legislation. NEPA requires all agencies of the federal government to comply with environmental standards.

Why do people care about species extinctions?

People care about species extinctions because species have value!

How are world population projections prepared?

Prepared by projecting fertility rates for populations in different parts of the world, considering information such as current fertility rates, current socioeconomic actors that influence fertility rates, projected changes in those socioeconomic factors, and expectations of how changing socioeconomic factors may influence fertility rates

What does "Contemporary" refer to?

Refers to extinction rates calculated from current known extinctions (lower estimate) or know extinctions plus "possibly extinct" species (upper bound)

What is bulging population profile

Societies characterized by low population growth tend to have high ratios of older to younger citizens.

What are the 4 states of the "classic model" of demographic transition?

Stage 1. Pre-transiton: Both birth rates and death rates are HIGH, living standards are low, average life span are short, and the environment's carrying capacity keeps population in check. Stage 2. Economic well-being improves, typically due to development of technology that helps people to provide for their needs more easily and amply. Society develops improved hygiene and better medical care, an death rates decline - but birth rates remain constant or decline more slowly than death rates, so population growth rates increase. Population momentum occurs. Stage 3. Economic well being continues to improve, and societal structures develop that change the incentives for parents to have children. Birth rates decline and overall population growth rates slow. Stage 4. Both birth rates and death rates are LOW, and average life spans increase. Fertility is at replacement level or less, and population growth slows to ZPG levels.

Which species-groups have the most rapid extinction rates?

That species-groups whose numbers are known with greatest certainty appear to be experiencing the most rapid extinction rates

What is the population growth rate?

The "birth rate" and "death rate" of a population are the number of people born and the number of people who died, in any given year. These rates are typically expressed as a rate per 1000.

What are "intrinsic value" ?

The "right" of a species to exist, irrespective of human material and nonmaterial needs and desires

The ESA is interpreted to require that no federal permits be issues for projects that endanger or jeopardize endangered species or their habitats. How do federal agencies comply with this?

The application process for such permits often requires the applicant to survey the area that will be affected or otherwise document that the area does not contain endangered species or their habitat.

What is fertility rate?

The average number of live births to each woman during her child-bearing years

What is the replacement level fertility?

The number of children each woman must bear, on average, to main a 0% population-growth rate. An average replacement level fertility is about 2.1 in the industrialized nation and 2.5 in the developing nations.

What is population Doubling Time (DT)?

The number of years required for a population to double at a given Annual Growth Rate (AGR). If AGR = 1%, DT = 70 years If AGR = 2%, DT = 35 years If AGR = 3%, DT = 23 years If AGR = 4%, DT = 18 years

What is biodiversity?

The term "biodiversity" is commonly interpreted to mean "number of species."

Which species are easy to identify?

The total number of species is known with the most confidence for those life forms which are easiest to observe in the natural environment with the names eye - vertebrates and higher plants. Scientists believe enumerated species to be within 10% of the actual total for these groups. Many species within these groups also are well observed because they create tangible economic value, are used for recreation, act as threats to human beings, or otherwise influence human activity.

Population pyramids

The vertical axis represents age while the horizontal axis represents population numbers. Each horizontal bar represent the number of males or females within a given age category.

"Less Developed" vs. "More Developed" Nations

The world's more developed nations (also called "industrialized" nations, or "mature economies") are generally considered to include the U.S. and Canada, western Europe, Australia and New Zealand, and Japan. South Korea's economy has improved markedly in recent years and is sometimes included within the "more developed category." The "less developed" nations (also called "less industrialized" or "emerging economies") include all other areas of the world. Most of the world's population growth is taking place in the less develop nations, where most of the world's people reside. Fertility rates are higher and life expectancies are lower in less developed economies than in more developed economies.

What is the Convention on International Trade in Endangered Species (CITES)?

This is an international treaty, established in 1975, administered by United Nations Environmental Program and signed by 87 countries. CITES prohibits hunting or capture of 700 endangered and threatened species, and prohibits trade in these species or products derived from these species. The treaty attempts to limit the profits that can be derived from harvest of endangered species. The treaty had been somewhat effective, but not totally. Because cross-border smuggling and unregulated markets ("black markets") do occur, harvest of marketable species continues in some areas.

Which biome has the largest terrestrial vertebrate richness? Which biome has the smallest terrestrial vertebrate richness?

Tropical and sub-tropical moist broadleaf forests Tundra

what is an example of a "slow growth" profile?

U.S. in the Year 2014. Note that the effects of the "Baby Boom" generation, which occurred as births increased rapidly following the Great Depression and WW2, remain evident

Why do people care about biodiversity preservation?

Value of species -Intrinsic (species- or ecosystem-centered) -Instrumental (human-centered) >Non-utilitarian Existence, Aesthetic, Bequest (Giant Panda) >utilitarian Goods, recreation, services, information, option (plants)

What are the maximum richness for vascular plants, terrestrial mammals, and amphibians?

Vascular Plants: 10,000 Terrestrial Mammals: 258 Amphibians: 142

How many species exist?

We do not know how many species are extant. Today, the number of described species is about 1.8 million. Note: Problem- It is well known that species are incompletely enumerated

Will Steffan and the "Great Acceleration"

Will Steffan co-author of "Planetary boundaries: Guiding human development on a changing plant." This article is a "science-based analysis of the risk that human perturbations will destabilize the ES at the planetary scale," and suggests "boundaries" in human influence of key environmental indicators (such as freshwater use, ocean acidification, stratospheric ozone depletion, and climate-influencing gases)for the purpose of maintaining earth system stability. The dominant feature of the socio-economic trends is that the "economic activity of the human enterprise continues to grow at a rapid rate" and that stronger linkages are evident between such socioeconomic trends (including but not restricted to population growth) and essential environmental indicators and systems. They have termed this phenomenon as the "Great Acceleration"

Are the IUCN Red List Classification Criteria bias?

Yes, because elephants occupy larger area than small microorganisms

Genes

a unit of heredity that is transferred form a parent to offspring and is held to determine some characteristic of the offspring

What species are sensitive to to changes in temperature and moisture?

amphibians

The greatest numbers of threatened species occur as....

amphibians, mammals, and birds

Describe world population growth in the modern era

characterized by decreasing rates, although the number of people per year added to the world population remains substantial

United Nations projects continuing population growth rate ____

declines

According to the US Census Bureau projections, world-average population growth rates are expected to ____ over the 2000-2050 period

decrease

What is speciation?

development of new species

What is the number of species occurring within a given ecosystem influenced by?

ecosystem area

Based on an analysis of threats to at-rish high-order species, conducted by IUCN, what is the predominant threat that puts species "At risk" of extinction ?

habitat loss (85% of documented species affected)

Societies with ____ fertility rates tend to have a high proportion of total population in younger age categories

high

As the area of a given ecosystem type ____, so does the number of different species occurring with that are

increased

Described Species in 2013 vs. 2008 have (increased/ decreased) in the number of species

increased Note: Ferns = (-)1,025 because they have been extinct

A species is considered to be "possibly extinct" if ...

it is believed to be extinct by experts but extensive surveys have not yet been undertaken to confirm its disappearance

What does "species richness" mean?

means the number of species found within a given environment or area.

What is the threat that causes the second highest percentage of species affected in amphibians?

pollution

IN the IUCN system, "Threatened" refers to

species that are endangered, critically endangered, or vulnerable.

described species

those species that have been observed and classified

"extant"

when applied to species, means that individuals of that species are living today