Human activities have led to an ongoing biodiversity loss and an accompanying loss of genetic diversity. This process is often referred to as Holocene extinction, or sixth mass extinction. For example, it was estimated in 2007 that up to 30% of all species will be extinct by 2050.[4]Destroying habitats for farming is a key reason why biodiversity is decreasing today. Climate change also plays a role.[5][6] This can be seen for example in the effects of climate change on biomes. This anthropogenic extinction may have started toward the end of the Pleistocene, as some studies suggest that the megafaunal extinction event that took place around the end of the last ice age partly resulted from overhunting.[7]
Definitions
Shown in a museum, various models of species across various taxa and orders visualize the variety of life on earth.
Biologists most often define biodiversity as the "totality of genes, species and ecosystems of a region".[8][9] An advantage of this definition is that it presents a unified view of the traditional types of biological variety previously identified:
functional diversity (which is a measure of the number of functionally disparate species within a population (e.g. different feeding mechanism, different motility, predator vs prey, etc.)[12])
Biodiversity is most commonly used to replace the more clearly-defined and long-established terms, species diversity and species richness.[13] However, there is no concrete definition for biodiversity, as its definition continues to be defined. Other definitions include (in chronological order):
An explicit definition consistent with this interpretation was first given in a paper by Bruce A. Wilcox commissioned by the International Union for the Conservation of Nature and Natural Resources (IUCN) for the 1982 World National Parks Conference.[14] Wilcox's definition was "Biological diversity is the variety of life forms...at all levels of biological systems (i.e., molecular, organismic, population, species and ecosystem)...".[14]
A publication by Wilcox in 1984: Biodiversity can be defined genetically as the diversity of alleles, genes and organisms. They study processes such as mutation and gene transfer that drive evolution.[14]
The 1992 United Nations Earth Summit defined biological diversity as "the variability among living organisms from all sources, including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems".[15] This definition is used in the United Nations Convention on Biological Diversity.[15]
Gaston and Spicer's definition in their book "Biodiversity: an introduction" in 2004 is "variation of life at all levels of biological organization".[16]
According to estimates by Mora et al. (2011), there are approximately 8.7million terrestrial species and 2.2million oceanic species. The authors note that these estimates are strongest for eukaryotic organisms and likely represent the lower bound of prokaryote diversity.[18] Other estimates include:
220,000 vascular plants, estimated using the species-area relation method[19]
1.5-3million fungi, estimates based on data from the tropics, long-term non-tropical sites and molecular studies that have revealed cryptic speciation.[24] Some 0.075million species of fungi had been documented by 2001;[25]
The number of microbial species is not reliably known, but the Global Ocean Sampling Expedition dramatically increased the estimates of genetic diversity by identifying an enormous number of new genes from near-surface plankton samples at various marine locations, initially over the 2004–2006 period.[27] The findings may eventually cause a significant change in the way science defines species and other taxonomic categories.[28][29]
Since the rate of extinction has increased, many extant species may become extinct before they are described.[30] Not surprisingly, in the animalia the most studied groups are birds and mammals, whereas fishes and arthropods are the least studied animals groups.[31]
The World Wildlife Fund's Living Planet Report 2024 found that wildlife populations declined by an average 73% since 1970.
During the last century, decreases in biodiversity have been increasingly observed. It was estimated in 2007 that up to 30% of all species will be extinct by 2050.[4] Of these, about one eighth of known plant species are threatened with extinction.[35] Estimates reach as high as 140,000 species per year (based on Species-area theory).[36] This figure indicates unsustainable ecological practices, because few species emerge each year.[37] The rate of species loss is greater now than at any time in human history, with extinctions occurring at rates hundreds of times higher than background extinction rates.[35][38][39] and expected to still grow in the upcoming years.[39][40][41] As of 2012, some studies suggest that 25% of all mammal species could be extinct in 20 years.[42]
In absolute terms, the planet has lost 58% of its biodiversity since 1970 according to a 2016 study by the World Wildlife Fund.[43] The Living Planet Report 2014 claims that "the number of mammals, birds, reptiles, amphibians, and fish across the globe is, on average, about half the size it was 40 years ago". Of that number, 39% accounts for the terrestrial wildlife gone, 39% for the marine wildlife gone and 76% for the freshwater wildlife gone. Biodiversity took the biggest hit in Latin America, plummeting 83 percent. High-income countries showed a 10% increase in biodiversity, which was canceled out by a loss in low-income countries. This is despite the fact that high-income countries use five times the ecological resources of low-income countries, which was explained as a result of a process whereby wealthy nations are outsourcing resource depletion to poorer nations, which are suffering the greatest ecosystem losses.[44]
A 2017 study published in PLOS One found that the biomass of insect life in Germany had declined by three-quarters in the last 25 years.[45] Dave Goulson of Sussex University stated that their study suggested that humans "appear to be making vast tracts of land inhospitable to most forms of life, and are currently on course for ecological Armageddon. If we lose the insects then everything is going to collapse."[46]
In 2020 the World Wildlife Foundation published a report saying that "biodiversity is being destroyed at a rate unprecedented in human history". The report claims that 68% of the population of the examined species were destroyed in the years 1970 – 2016.[47]
Of 70,000 monitored species, around 48% are experiencing population declines from human activity (in 2023), whereas only 3% have increasing populations.[48][49][50]
Summary of major biodiversity-related environmental-change categories expressed as a percentage of human-driven change (in red) relative to baseline (blue)
Since the Stone Age, species loss has accelerated above the average basal rate, driven by human activity. Estimates of species losses are at a rate 100–10,000 times as fast as is typical in the fossil record.[62]
Loss of biodiversity results in the loss of natural capital that supplies ecosystem goods and services. Species today are being wiped out at a rate 100 to 1,000 times higher than baseline, and the rate of extinctions is increasing. This process destroys the resilience and adaptability of life on Earth.[63]
In 2006, many species were formally classified as rare or endangered or threatened; moreover, scientists have estimated that millions more species are at risk which have not been formally recognized. About 40 percent of the 40,177 species assessed using the IUCN Red List criteria are now listed as threatened with extinction—a total of 16,119.[64] As of late 2022 9251 species were considered part of the IUCN's critically endangered.[65]
Some studies have however pointed out that habitat destruction for the expansion of agriculture and the overexploitation of wildlife are the more significant drivers of contemporary biodiversity loss, not climate change.[5][6]
Distribution
Distribution of living terrestrial vertebrate species, highest concentration of diversity shown in red in equatorial regions, declining polewards (towards the blue end of the spectrum)
Biodiversity is not evenly distributed, rather it varies greatly across the globe as well as within regions and seasons. Among other factors, the diversity of all living things (biota) depends on temperature, precipitation, altitude, soils, geography and the interactions between other species.[72] The study of the spatial distribution of organisms, species and ecosystems, is the science of biogeography.[73][74]
There is local biodiversity, which directly impacts daily life, affecting the availability of fresh water, food choices, and fuel sources for humans. Regional biodiversity includes habitats and ecosystems that synergizes and either overlaps or differs on a regional scale. National biodiversity within a country determines the ability for a country to thrive according to its habitats and ecosystems on a national scale. Also, within a country, endangered species are initially supported on a national level then internationally. Ecotourism may be utilized to support the economy and encourages tourists to continue to visit and support species and ecosystems they visit, while they enjoy the available amenities provided. International biodiversity impacts global livelihood, food systems, and health. Problematic pollution, over consumption, and climate change can devastate international biodiversity. Nature-based solutions are a critical tool for a global resolution. Many species are in danger of becoming extinct and need world leaders to be proactive with the Kunming-Montreal Global Biodiversity Framework.
Terrestrial biodiversity is thought to be up to 25 times greater than ocean biodiversity.[77] Forests harbour most of Earth's terrestrial biodiversity. The conservation of the world's biodiversity is thus utterly dependent on the way in which we interact with and use the world's forests.[78] A new method used in 2011, put the total number of species on Earth at 8.7million, of which 2.1million were estimated to live in the ocean.[79] However, this estimate seems to under-represent the diversity of microorganisms.[80] Forests provide habitats for 80 percent of amphibian species, 75 percent of bird species and 68 percent of mammal species. About 60 percent of all vascular plants are found in tropical forests. Mangroves provide breeding grounds and nurseries for numerous species of fish and shellfish and help trap sediments that might otherwise adversely affect seagrass beds and coral reefs, which are habitats for many more marine species.[78] Forests span around 4 billion acres (nearly a third of the Earth's land mass) and are home to approximately 80% of the world's biodiversity. About 1 billion hectares are covered by primary forests. Over 700 million hectares of the world's woods are officially protected.[81][82]
The biodiversity of forests varies considerably according to factors such as forest type, geography, climate and soils – in addition to human use.[78] Most forest habitats in temperate regions support relatively few animal and plant species and species that tend to have large geographical distributions, while the montane forests of Africa, South America and Southeast Asia and lowland forests of Australia, coastal Brazil, the Caribbean islands, Central America and insular Southeast Asia have many species with small geographical distributions.[78] Areas with dense human populations and intense agricultural land use, such as Europe, parts of Bangladesh, China, India and North America, are less intact in terms of their biodiversity. Northern Africa, southern Australia, coastal Brazil, Madagascar and South Africa, are also identified as areas with striking losses in biodiversity intactness.[78] European forests in EU and non-EU nations comprise more than 30% of Europe's land mass (around 227 million hectares), representing an almost 10% growth since 1990.[83][84]
Generally, there is an increase in biodiversity from the poles to the tropics. Thus localities at lower latitudes have more species than localities at higher latitudes. This is often referred to as the latitudinal gradient in species diversity. Several ecological factors may contribute to the gradient, but the ultimate factor behind many of them is the greater mean temperature at the equator compared to that at the poles.[85]
Even though terrestrial biodiversity declines from the equator to the poles,[86] some studies claim that this characteristic is unverified in aquatic ecosystems, especially in marine ecosystems.[87] The latitudinal distribution of parasites does not appear to follow this rule.[73] Also, in terrestrial ecosystems the soil bacterial diversity has been shown to be highest in temperate climatic zones,[88] and has been attributed to carbon inputs and habitat connectivity.[89]
In 2016, an alternative hypothesis ("the fractal biodiversity") was proposed to explain the biodiversity latitudinal gradient.[90] In this study, the species pool size and the fractal nature of ecosystems were combined to clarify some general patterns of this gradient. This hypothesis considers temperature, moisture, and net primary production (NPP) as the main variables of an ecosystem niche and as the axis of the ecological hypervolume. In this way, it is possible to build fractal hyper volumes, whose fractal dimension rises to three moving towards the equator.[91]
Brazil's Atlantic Forest is considered one such hotspot, containing roughly 20,000 plant species, 1,350 vertebrates and millions of insects, about half of which occur nowhere else.[98][99] The island of Madagascar and India are also particularly notable. Colombia is characterized by high biodiversity, with the highest rate of species by area unit worldwide and it has the largest number of endemics (species that are not found naturally anywhere else) of any country. About 10% of the species of the Earth can be found in Colombia, including over 1,900 species of bird, more than in Europe and North America combined, Colombia has 10% of the world's mammals species, 14% of the amphibian species and 18% of the bird species of the world.[100]Madagascar dry deciduous forests and lowland rainforests possess a high ratio of endemism.[101][102] Since the island separated from mainland Africa 66million years ago, many species and ecosystems have evolved independently.[103]Indonesia's 17,000 islands cover 735,355 square miles (1,904,560km2) and contain 10% of the world's flowering plants, 12% of mammals and 17% of reptiles, amphibians and birds—along with nearly 240million people.[104] Many regions of high biodiversity and/or endemism arise from specialized habitats which require unusual adaptations, for example, alpine environments in high mountains, or Northern European peat bogs.[102]
Accurately measuring differences in biodiversity can be difficult. Selection bias amongst researchers may contribute to biased empirical research for modern estimates of biodiversity. In 1768, Rev. Gilbert White succinctly observed of his Selborne, Hampshire"all nature is so full, that that district produces the most variety which is the most examined."[105]
Apparent marine fossil diversity during the Phanerozoic
Biodiversity grew fast during the Phanerozoic (the last 540million years), especially during the so-called Cambrian explosion—a period during which nearly every phylum of multicellular organisms first appeared.[108] However, recent studies suggest that this diversification had started earlier, at least in the Ediacaran, and that it continued in the Ordovician.[109] Over the next 400million years or so, invertebrate diversity showed little overall trend and vertebrate diversity shows an overall exponential trend.[10] This dramatic rise in diversity was marked by periodic, massive losses of diversity classified as mass extinction events.[10] A significant loss occurred in anamniotic limbed vertebrates when rainforests collapsed in the Carboniferous,[110] but amniotes seem to have been little affected by this event; their diversification slowed down later, around the Asselian/Sakmarian boundary, in the early Cisuralian (Early Permian), about 293 Ma ago.[111] The worst was the Permian-Triassic extinction event, 251million years ago.[112][113] Vertebrates took 30million years to recover from this event.[114]
The most recent major mass extinction event, the Cretaceous–Paleogene extinction event, occurred 66million years ago. This period has attracted more attention than others because it resulted in the extinction of the non-aviandinosaurs, which were represented by many lineages at the end of the Maastrichtian, just before that extinction event. However, many other taxa were affected by this crisis, which affected even marine taxa, such as ammonites, which also became extinct around that time.[115]
The biodiversity of the past is called Paleobiodiversity. The fossil record suggests that the last few million years featured the greatest biodiversity in history.[10] However, not all scientists support this view, since there is uncertainty as to how strongly the fossil record is biased by the greater availability and preservation of recent geologic sections.[116] Some scientists believe that corrected for sampling artifacts, modern biodiversity may not be much different from biodiversity 300million years ago,[108] whereas others consider the fossil record reasonably reflective of the diversification of life.[117][10] Estimates of the present global macroscopic species diversity vary from 2million to 100million, with a best estimate of somewhere near 9million,[79] the vast majority arthropods.[118] Diversity appears to increase continually in the absence of natural selection.[119]
Diversification
The existence of a global carrying capacity, limiting the amount of life that can live at once, is debated, as is the question of whether such a limit would also cap the number of species. While records of life in the sea show a logistic pattern of growth, life on land (insects, plants and tetrapods) shows an exponential rise in diversity.[10] As one author states, "Tetrapods have not yet invaded 64 percent of potentially habitable modes and it could be that without human influence the ecological and taxonomic diversity of tetrapods would continue to increase exponentially until most or all of the available eco-space is filled."[10]
It also appears that the diversity continues to increase over time, especially after mass extinctions.[120]
On the other hand, changes through the Phanerozoic correlate much better with the hyperbolic model (widely used in population biology, demography and macrosociology, as well as fossil biodiversity) than with exponential and logistic models. The latter models imply that changes in diversity are guided by a first-order positive feedback (more ancestors, more descendants) and/or a negative feedback arising from resource limitation. Hyperbolic model implies a second-order positive feedback.[121] Differences in the strength of the second-order feedback due to different intensities of interspecific competition might explain the faster rediversification of ammonoids in comparison to bivalves after the end-Permian extinction.[121] The hyperbolic pattern of the world population growth arises from a second-order positive feedback between the population size and the rate of technological growth.[122] The hyperbolic character of biodiversity growth can be similarly accounted for by a feedback between diversity and community structure complexity.[122][123] The similarity between the curves of biodiversity and human population probably comes from the fact that both are derived from the interference of the hyperbolic trend with cyclical and stochastic dynamics.[122][123]
Most biologists agree however that the period since human emergence is part of a new mass extinction, named the Holocene extinction event, caused primarily by the impact humans are having on the environment.[124] It has been argued that the present rate of extinction is sufficient to eliminate most species on the planet Earth within 100 years.[125]
New species are regularly discovered (on average between 5–10,000 new species each year, most of them insects) and many, though discovered, are not yet classified (estimates are that nearly 90% of all arthropods are not yet classified).[118] Most of the terrestrial diversity is found in tropical forests and in general, the land has more species than the ocean; some 8.7million species may exist on Earth, of which some 2.1million live in the ocean.[79]
It is estimated that 5 to 50 billion species have existed on the planet.[126] Assuming that there may be a maximum of about 50 million species currently alive,[127] it stands to reason that greater than 99% of the planet's species went extinct prior to the evolution of humans.[128] Estimates on the number of Earth's current species range from 10million to 14million, of which about 1.2million have been documented and over 86% have not yet been described.[129] However, a May 2016 scientific report estimates that 1 trillion species are currently on Earth, with only one-thousandth of one percent described.[130] The total amount of related DNAbase pairs on Earth is estimated at 5.0 x 1037 and weighs 50billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as four trillion tons of carbon.[131] In July 2016, scientists reported identifying a set of 355 genes from the last universal common ancestor (LUCA) of all organisms living on Earth.[132]
There have been many claims about biodiversity's effect on the ecosystem services, especially provisioning and regulating services.[142] Some of those claims have been validated, some are incorrect and some lack enough evidence to draw definitive conclusions.[142]
Ecosystem services have been grouped in three types:[142]
Provisioning services which involve the production of renewable resources (e.g.: food, wood, fresh water)
Regulating services which are those that lessen environmental change (e.g.: climate regulation, pest/disease control)
Cultural services represent human value and enjoyment (e.g.: landscape aesthetics, cultural heritage, outdoor recreation and spiritual significance)[143]
Experiments with controlled environments have shown that humans cannot easily build ecosystems to support human needs;[144] for example insect pollination cannot be mimicked, though there have been attempts to create artificial pollinators using unmanned aerial vehicles.[145] The economic activity of pollination alone represented between $2.1–14.6billion in 2003.[146] Other sources have reported somewhat conflicting results and in 1997 Robert Costanza and his colleagues reported the estimated global value of ecosystem services (not captured in traditional markets) at an average of $33trillion annually.[147]
Provisioning services
With regards to provisioning services, greater species diversity has the following benefits:
Greater species diversity of plants increases fodder yield (synthesis of 271 experimental studies).[74]
Greater species diversity of plants (i.e. diversity within a single species) increases overall crop yield (synthesis of 575 experimental studies).[148] Although another review of 100 experimental studies reported mixed evidence.[149]
Greater species diversity of trees increases overall wood production (synthesis of 53 experimental studies).[150] However, there is not enough data to draw a conclusion about the effect of tree trait diversity on wood production.[142]
Regulating services
With regards to regulating services, greater species diversity has the following benefits:
Greater species diversity
of fish increases the stability of fisheries yield (synthesis of 8 observational studies)[142]
of plants increases carbon sequestration, but note that this finding only relates to actual uptake of carbon dioxide and not long-term storage; synthesis of 479 experimental studies)[74]
of plants increases soil nutrientremineralization (synthesis of 103 experimental studies), increases soil organic matter (synthesis of 85 experimental studies) and decreases disease prevalence on plants (synthesis of 107 experimental studies)[151]
of natural pest enemies decreases herbivorous pest populations (data from two separate reviews; synthesis of 266 experimental and observational studies;[152] Synthesis of 18 observational studies.[153][154] Although another review of 38 experimental studies found mixed support for this claim, suggesting that in cases where mutual intraguild predation occurs, a single predatory species is often more effective[155]
Agricultural diversity can be divided into two categories: intraspecific diversity, which includes the genetic variation within a single species, like the potato (Solanum tuberosum) that is composed of many different forms and types (e.g. in the U.S. they might compare russet potatoes with new potatoes or purple potatoes, all different, but all part of the same species, S. tuberosum). The other category of agricultural diversity is called interspecific diversity and refers to the number and types of different species.
Agricultural diversity can also be divided by whether it is 'planned' diversity or 'associated' diversity. This is a functional classification that we impose and not an intrinsic feature of life or diversity. Planned diversity includes the crops which a farmer has encouraged, planted or raised (e.g. crops, covers, symbionts, and livestock, among others), which can be contrasted with the associated diversity that arrives among the crops, uninvited (e.g. herbivores, weed species and pathogens, among others).[156]
Associated biodiversity can be damaging or beneficial. The beneficial associated biodiversity include for instance wild pollinators such as wild bees and syrphid flies that pollinate crops[157] and natural enemies and antagonists to pests and pathogens. Beneficial associated biodiversity occurs abundantly in crop fields and provide multiple ecosystem services such as pest control, nutrient cycling and pollination that support crop production.[158]
Although about 80 percent of humans' food supply comes from just 20 kinds of plants,[159] humans use at least 40,000 species.[160] Earth's surviving biodiversity provides resources for increasing the range of food and other products suitable for human use, although the present extinction rate shrinks that potential.[125]
Human health
The diverse forest canopy on Barro Colorado Island, Panama, yielded this display of different fruit
Biodiversity's relevance to human health is becoming an international political issue, as scientific evidence builds on the global health implications of biodiversity loss.[161][162][163] This issue is closely linked with the issue of climate change,[164] as many of the anticipated health risks of climate change are associated with changes in biodiversity (e.g. changes in populations and distribution of disease vectors, scarcity of fresh water, impacts on agricultural biodiversity and food resources etc.). This is because the species most likely to disappear are those that buffer against infectious disease transmission, while surviving species tend to be the ones that increase disease transmission, such as that of West Nile Virus, Lyme disease and Hantavirus, according to a study done co-authored by Felicia Keesing, an ecologist at Bard College and Drew Harvell, associate director for Environment of the Atkinson Center for a Sustainable Future (ACSF) at Cornell University.[165]
Some of the health issues influenced by biodiversity include dietary health and nutrition security, infectious disease, medical science and medicinal resources, social and psychological health.[166] Biodiversity is also known to have an important role in reducing disaster risk and in post-disaster relief and recovery efforts.[167][168]
Biodiversity provides critical support for drug discovery and the availability of medicinal resources.[169][170] A significant proportion of drugs are derived, directly or indirectly, from biological sources: at least 50% of the pharmaceutical compounds on the US market are derived from plants, animals and microorganisms, while about 80% of the world population depends on medicines from nature (used in either modern or traditional medical practice) for primary healthcare.[162] Only a tiny fraction of wild species has been investigated for medical potential.
Marine ecosystems are particularly important,[171] although inappropriate bioprospecting can increase biodiversity loss, as well as violating the laws of the communities and states from which the resources are taken.[172][173][174]
Business and industry
Many industrial materials derive directly from biological sources. These include building materials, fibers, dyes, rubber, and oil. Biodiversity is also important to the security of resources such as water, timber, paper, fiber, and food.[175][176][177] As a result, biodiversity loss is a significant risk factor in business development and a threat to long-term economic sustainability.[178][179]
Philosophically it could be argued that biodiversity has intrinsic aesthetic and spiritual value to mankindin and of itself. This idea can be used as a counterweight to the notion that tropical forests and other ecological realms are only worthy of conservation because of the services they provide.[180]
Biodiversity also affords many non-material benefits including spiritual and aesthetic values, knowledge systems and education.[62]
A variety of objective means exist to empirically measure biodiversity. Each measure relates to a particular use of the data, and is likely to be associated with the variety of genes. Biodiversity is commonly measured in terms of taxonomic richness of a geographic area over a time interval. In order to calculate biodiversity, species evenness, species richness, and species diversity are to be obtained first. Species evenness is the relative number of individuals of each species in a given area.[181]Species richness[182] is the number of species present in a given area. Species diversity[183] is the relationship between species evenness and species richness. There are many ways to measure biodiversity within a given ecosystem. However, the two most popular are Shannon-Weaver diversity index,[184] commonly referred to as Shannon diversity index, and the other is Simpsons diversity index.[185] Although many scientists prefer to use Shannon's diversity index simply because it takes into account species richness.[186]
Analytical limits
Less than 1% of all species that have been described have been studied beyond noting their existence.[187] The vast majority of Earth's species are microbial. Contemporary biodiversity physics is "firmly fixated on the visible [macroscopic] world".[188] For example, microbial life is metabolically and environmentally more diverse than multicellular life (see e.g., extremophile). "On the tree of life, based on analyses of small-subunit ribosomal RNA, visible life consists of barely noticeable twigs. The inverse relationship of size and population recurs higher on the evolutionary ladder—to a first approximation, all multicellular species on Earth are insects".[189]Insect extinction rates are high—supporting the Holocene extinction hypothesis.[190][58]
Biodiversity changes (other than losses)
Natural seasonal variations
Biodiversity naturally varies due to seasonal shifts. Spring's arrival enhances biodiversity as numerous species breed and feed, while winter's onset temporarily reduces it as some insects perish and migrating animals leave. Additionally, the seasonal fluctuation in plant and invertebrate populations influences biodiversity.[191]
Male Lophura nycthemera (silver pheasant), a native of East Asia that has been introduced into parts of Europe for ornamental reasons
Barriers such as large rivers, seas, oceans, mountains and deserts encourage diversity by enabling independent evolution on either side of the barrier, via the process of allopatric speciation. The term invasive species is applied to species that breach the natural barriers that would normally keep them constrained. Without barriers, such species occupy new territory, often supplanting native species by occupying their niches, or by using resources that would normally sustain native species.
Species are increasingly being moved by humans (on purpose and accidentally). Some studies say that diverse ecosystems are more resilient and resist invasive plants and animals.[192] Many studies cite effects of invasive species on natives,[193] but not extinctions.
Invasive species seem to increase local (alpha diversity) diversity, which decreases turnover of diversity (ibeta diversity). Overall gamma diversity may be lowered because species are going extinct because of other causes,[194] but even some of the most insidious invaders (e.g.: Dutch elm disease, emerald ash borer, chestnut blight in North America) have not caused their host species to become extinct. Extirpation, population decline and homogenization of regional biodiversity are much more common. Human activities have frequently been the cause of invasive species circumventing their barriers,[195] by introducing them for food and other purposes. Human activities therefore allow species to migrate to new areas (and thus become invasive) occurred on time scales much shorter than historically have been required for a species to extend its range.
At present, several countries have already imported so many exotic species, particularly agricultural and ornamental plants, that their indigenous fauna/flora may be outnumbered. For example, the introduction of kudzu from Southeast Asia to Canada and the United States has threatened biodiversity in certain areas.[196] Another example are pines, which have invaded forests, shrublands and grasslands in the southern hemisphere.[197]
Hybridization and genetic pollution
The Yecoro wheat (right) cultivar is sensitive to salinity, plants resulting from a hybrid cross with cultivar W4910 (left) show greater tolerance to high salinity
Endemic species can be threatened with extinction[198] through the process of genetic pollution, i.e. uncontrolled hybridization, introgression and genetic swamping. Genetic pollution leads to homogenization or replacement of local genomes as a result of either a numerical and/or fitness advantage of an introduced species.[199]
Hybridization and introgression are side-effects of introduction and invasion. These phenomena can be especially detrimental to rare species that come into contact with more abundant ones. The abundant species can interbreed with the rare species, swamping its gene pool. This problem is not always apparent from morphological (outward appearance) observations alone. Some degree of gene flow is normal adaptation and not all gene and genotype constellations can be preserved. However, hybridization with or without introgression may, nevertheless, threaten a rare species' existence.[200][201]
A schematic image illustrating the relationship between biodiversity, ecosystem services, human well-being and poverty. The illustration shows where conservation action, strategies, and plans can influence the drivers of the current biodiversity crisis at local, regional, to global scales.
Conservation biology is reforming around strategic plans to protect biodiversity.[203][208][209][210] Preserving global biodiversity is a priority in strategic conservation plans that are designed to engage public policy and concerns affecting local, regional and global scales of communities, ecosystems and cultures.[211] Action plans identify ways of sustaining human well-being, employing natural capital, macroeconomic policies including economic incentives, and ecosystem services.[212][213]
In the EU Directive 1999/22/EC zoos are described as having a role in the preservation of the biodiversity of wildlife animals by conducting research or participation in breeding programs.[214]
Protection and restoration techniques
Removal of exotic species will allow the species that they have negatively impacted to recover their ecological niches. Exotic species that have become pests can be identified taxonomically (e.g.,with Digital Automated Identification SYstem (DAISY), using the barcode of life).[215][216] Removal is practical only given large groups of individuals due to the economic cost.
As sustainable populations of the remaining native species in an area become assured, "missing" species that are candidates for reintroduction can be identified using databases such as the Encyclopedia of Life and the Global Biodiversity Information Facility.
Gene banks are collections of specimens and genetic material. Some banks intend to reintroduce banked species to the ecosystem (e.g.,via tree nurseries).[217]
Reduction and better targeting of pesticides allows more species to survive in agricultural and urbanized areas.
Location-specific approaches may be less useful for protecting migratory species. One approach is to create wildlife corridors that correspond to the animals' movements. National and other boundaries can complicate corridor creation.[218]
Mother and child at an orangutan rehab facility in Malaysia
Protected areas, including forest reserves and biosphere reserves, serve many functions including for affording protection to wild animals and their habitat.[219] Protected areas have been set up all over the world with the specific aim of protecting and conserving plants and animals. Some scientists have called on the global community to designate as protected areas of 30 percent of the planet by 2030, and 50 percent by 2050, in order to mitigate biodiversity loss from anthropogenic causes.[220][221] The target of protecting 30% of the area of the planet by the year 2030 (30 by 30) was adopted by almost 200 countries in the 2022 United Nations Biodiversity Conference. At the moment of adoption (December 2022) 17% of land territory and 10% of ocean territory were protected.[222] In a study published 4 September 2020 in Science Advances researchers mapped out regions that can help meet critical conservation and climate goals.[223]
Protected areas safeguard nature and cultural resources and contribute to livelihoods, particularly at local level. There are over 238 563 designated protected areas worldwide, equivalent to 14.9 percent of the earth's land surface, varying in their extension, level of protection, and type of management (IUCN, 2018).[224]
The benefits of protected areas extend beyond their immediate environment and time. In addition to conserving nature, protected areas are crucial for securing the long-term delivery of ecosystem services. They provide numerous benefits including the conservation of genetic resources for food and agriculture, the provision of medicine and health benefits, the provision of water, recreation and tourism, and for acting as a buffer against disaster. Increasingly, there is acknowledgement of the wider socioeconomic values of these natural ecosystems and of the ecosystem services they can provide.[225]
A national park is a large natural or near natural area set aside to protect large-scale ecological processes, which also provide a foundation for environmentally and culturally compatible, spiritual, scientific, educational, recreational and visitor opportunities. These areas are selected by governments or private organizations to protect natural biodiversity along with its underlying ecological structure and supporting environmental processes, and to promote education and recreation. The International Union for Conservation of Nature (IUCN), and its World Commission on Protected Areas (WCPA), has defined "National Park" as its Category II type of protected areas.[226]Wildlife sanctuaries aim only at the conservation of species
Forest protected areas
Percentage of forest in legally protected areas (as of 2020).
Forest protected areas are a subset of all protected areas in which a significant portion of the area is forest.[78] This may be the whole or only a part of the protected area.[78] Globally, 18 percent of the world's forest area, or more than 700 million hectares, fall within legally established protected areas such as national parks, conservation areas and game reserves.[78]
There is an estimated 726 million ha of forest in protected areas worldwide. Of the six major world regions, South America has the highest share of forests in protected areas, 31 percent.[227] The forests play a vital role in harboring more than 45,000 floral and 81,000 faunal species of which 5150 floral and 1837 faunal species are endemic.[228] In addition, there are 60,065 different tree species in the world.[229] Plant and animal species confined to a specific geographical area are called endemic species.
In forest reserves, rights to activities like hunting and grazing are sometimes given to communities living on the fringes of the forest, who sustain their livelihood partially or wholly from forest resources or products.
Approximately 50 million hectares (or 24%) of European forest land is protected for biodiversity and landscape protection. Forests allocated for soil, water, and other ecosystem services encompass around 72 million hectares (32% of European forest area).[230][231]
The concept of nature-positive is playing a role in mainstreaming the goals of the Global Biodiversity Framework (GBF) for biodiversity.[234] The aim of mainstreaming is to embed biodiversity considerations into public and private practice to conserve and sustainably use biodiversity on global and local levels.[235] The concept of nature-positive refers to the societal goal to halt and reverse biodiversity loss, measured from a baseline of 2020 levels, and to achieve full so-called "nature recovery" by 2050.[236]
Citizen science
Citizen science, also known as public participation in scientific research, has been widely used in environmental sciences and is particularly popular in a biodiversity-related context. It has been used to enable scientists to involve the general public in biodiversity research, thereby enabling the scientists to collect data that they would otherwise not have been able to obtain.[237]
Volunteer observers have made significant contributions to on-the-ground knowledge about biodiversity, and recent improvements in technology have helped increase the flow and quality of occurrences from citizen sources. A 2016 study published in Biological Conservation[238] registers the massive contributions that citizen scientists already make to data mediated by the Global Biodiversity Information Facility (GBIF). Despite some limitations of the dataset-level analysis, it is clear that nearly half of all occurrence records shared through the GBIF network come from datasets with significant volunteer contributions. Recording and sharing observations are enabled by several global-scale platforms, including iNaturalist and eBird.[239][240]
Legal status
A great deal of work is occurring to preserve the natural characteristics of Hopetoun Falls, Australia while continuing to allow visitor access.
UN BBNJ (High Seas Treaty) 2023 Intergovernmental conference on an international legally binding instrument under the UNCLOS on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction (GA resolution 72/249)
Convention on International Trade in Endangered Species (CITES);
Global agreements such as the Convention on Biological Diversity, give "sovereign national rights over biological resources" (not property). The agreements commit countries to "conserve biodiversity", "develop resources for sustainability" and "share the benefits" resulting from their use. Biodiverse countries that allow bioprospecting or collection of natural products, expect a share of the benefits rather than allowing the individual or institution that discovers/exploits the resource to capture them privately. Bioprospecting can become a type of biopiracy when such principles are not respected.[241]
On the 19 of December 2022, during the 2022 United Nations Biodiversity Conference every country on earth, with the exception of the United States and the Holy See, signed onto the agreement which includes protecting 30% of land and oceans by 2030 (30 by 30) and 22 other targets intended to reduce biodiversity loss.[222][242][243] The agreement includes also recovering 30% of earth degraded ecosystems and increasing funding for biodiversity issues.[244]
European Union
In May 2020, the European Union published its Biodiversity Strategy for 2030. The biodiversity strategy is an essential part of the climate change mitigation strategy of the European Union. From the 25% of the European budget that will go to fight climate change, large part will go to restore biodiversity[210] and nature based solutions.
Give €20billion per year to the issue and make it part of the business practice.
Approximately half of the global GDP depend on nature. In Europe many parts of the economy that generate trillions of euros per year depend on nature. The benefits of Natura 2000 alone in Europe are €200 – €300billion per year.[246]
National level laws
Biodiversity is taken into account in some political and judicial decisions:
The relationship between law and ecosystems is very ancient and has consequences for biodiversity. It is related to private and public property rights. It can define protection for threatened ecosystems, but also some rights and duties (for example, fishing and hunting rights).[citation needed]
Law regarding species is more recent. It defines species that must be protected because they may be threatened by extinction. The U.S. Endangered Species Act is an example of an attempt to address the "law and species" issue.
Laws regarding gene pools are only about a century old.[247] Domestication and plant breeding methods are not new, but advances in genetic engineering have led to tighter laws covering distribution of genetically modified organisms, gene patents and process patents.[248] Governments struggle to decide whether to focus on for example, genes, genomes, or organisms and species.[citation needed]
Uniform approval for use of biodiversity as a legal standard has not been achieved, however. Bosselman argues that biodiversity should not be used as a legal standard, claiming that the remaining areas of scientific uncertainty cause unacceptable administrative waste and increase litigation without promoting preservation goals.[249]
India passed the Biological Diversity Act in 2002 for the conservation of biological diversity in India. The Act also provides mechanisms for equitable sharing of benefits from the use of traditional biological resources and knowledge.
History of the term
1916 – The term biological diversity was used first by J. Arthur Harris in "The Variable Desert", Scientific American: "The bare statement that the region contains a flora rich in genera and species and of diverse geographic origin or affinity is entirely inadequate as a description of its real biological diversity."[250]
1967 – Raymond F. Dasmann used the term biological diversity in reference to the richness of living nature that conservationists should protect in his book A Different Kind of Country.[251][252]
1980 – Thomas Lovejoy introduced the term biological diversity to the scientific community in a book.[254] It rapidly became commonly used.[255]
1985 – According to Edward O. Wilson, the contracted form biodiversity was coined by W. G. Rosen: "The National Forum on BioDiversity ... was conceived by Walter G.Rosen ... Dr. Rosen represented the NRC/NAS throughout the planning stages of the project. Furthermore, he introduced the term biodiversity".[256]
1985 – The term "biodiversity" appears in the article, "A New Plan to Conserve the Earth's Biota" by Laura Tangley.[257]
1988 – The term biodiversity first appeared in publication.[258][259]
1988 to Present – The United Nations Environment Programme (UNEP) Ad Hoc Working Group of Experts on Biological Diversity in began working in November 1988, leading to the publication of the draft Convention on Biological Diversity in May 1992. Since this time, there have been 16 Conferences of the Parties (COPs) to discuss potential global political responses to biodiversity loss. Most recently COP 16 in Cali, Colombia in 2024.[260]
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.
Extinction is the termination of a taxon by the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" after a period of apparent absence.
Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources is limited.
Conservation status is a measure used in conservation biology to assess an ecoregion's degree of habitat alteration and habitat conservation. It is used to set priorities for conservation.
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.
Habitat conservation is a management practice that seeks to conserve, protect and restore habitats and prevent species extinction, fragmentation or reduction in range. It is a priority of many groups that cannot be easily characterized in terms of any one ideology.
An ecological or environmental crisis occurs when changes to the environment of a species or population destabilizes its continued survival. Some of the important causes include:
A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation. Norman Myers wrote about the concept in two articles in The Environmentalist in 1988 and 1990, after which the concept was revised following thorough analysis by Myers and others into "Hotspots: Earth's Biologically Richest and Most Endangered Terrestrial Ecoregions" and a paper published in the journal Nature, both in 2000.
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.
Habitat destruction occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved to elsewhere or are dead, leading to a decrease in biodiversity and species numbers. Habitat destruction is in fact the leading cause of biodiversity loss and species extinction worldwide.
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, and Conservation International.
Reconciliation ecology is the branch of ecology which studies ways to encourage biodiversity in the human-dominated ecosystems of the anthropocene era. Michael Rosenzweig first articulated the concept in his book Win-Win Ecology, based on the theory that there is not enough area for all of earth's biodiversity to be saved within designated nature preserves. Therefore, humans should increase biodiversity in human-dominated landscapes. By managing for biodiversity in ways that do not decrease human utility of the system, it is a "win-win" situation for both human use and native biodiversity. The science is based in the ecological foundation of human land-use trends and species-area relationships. It has many benefits beyond protection of biodiversity, and there are numerous examples of it around the globe. Aspects of reconciliation ecology can already be found in management legislation, but there are challenges in both public acceptance and ecological success of reconciliation attempts.
In biology, a refugium is a location which supports an isolated or relict population of a once more widespread species. This isolation (allopatry) can be due to climatic changes, geography, or human activities such as deforestation and overhunting.
Global biodiversity is the measure of biodiversity on planet Earth and is defined as the total variability of life forms. More than 99 percent of all species that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 2 million to 1 trillion, but most estimates are around 11 million species or fewer. About 1.74 million species were databased as of 2018, and over 80 percent have not yet been described. The total amount of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at 5.0 x 1037, and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).
Tropical ecology is the study of the relationships between the biotic and abiotic components of the tropics, or the area of the Earth that lies between the Tropic of Cancer and the Tropic of Capricorn. The tropical climate experiences hot, humid weather and rainfall year-round. While many might associate the region solely with the rainforests, the tropics are home to a wide variety of ecosystems that boast a great wealth of biodiversity, from exotic animal species to seldom-found flora. Tropical ecology began with the work of early English naturalists and eventually saw the establishment of research stations throughout the tropics devoted to exploring and documenting these exotic landscapes. The burgeoning ecological study of the tropics has led to increased conservation education and programs devoted to the climate. Tropical ecology provides a wealth of natural resources to humans, this includes contributing to the carbon cycle, with the ability to store 50% of carbon emissions as well as turnover 40% of global oxygen. However, despite the natural services provided by tropical ecology, deforestation is a threat of tropical rainforests. Any plant of interest can be exploited for commercial reasons and extraction of these specific plant species can be at a rapid rate without time for healthy regeneration. Most of the global plant biodiversity is hosted in tropical areas, however studies in this area is mostly covered by scientist from Northern countries. Inclusion of scientist from countries where rainforest is present is heavily encouraged because it extends global knowledge and research which advances scientific contributions, benefiting tropical ecology.
There is an ongoing decline in plant biodiversity, just like there is ongoing biodiversity loss for many other life forms. One of the causes for this decline is climate change. Environmental conditions play a key role in defining the function and geographic distributions of plants. Therefore, when environmental conditions change, this can result in changes to biodiversity. The effects of climate change on plant biodiversity can be predicted by using various models, for example bioclimatic models.
Defaunation is the global, local, or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. 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. Since then, the term has gained broader usage in conservation biology as a global phenomenon.
Forest restoration is defined as "actions to re-instate ecological processes, which accelerate recovery of forest structure, ecological functioning and biodiversity levels towards those typical of climax forest", i.e. the end-stage of natural forest succession. Climax forests are relatively stable ecosystems that have developed the maximum biomass, structural complexity and species diversity that are possible within the limits imposed by climate and soil and without continued disturbance from humans. Climax forest is therefore the target ecosystem, which defines the ultimate aim of forest restoration. Since climate is a major factor that determines climax forest composition, global climate change may result in changing restoration aims. Additionally, the potential impacts of climate change on restoration goals must be taken into account, as changes in temperature and precipitation patterns may alter the composition and distribution of climax forests.
Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in biological diversity in a given area. The decrease can be temporary or permanent. It is temporary if the damage that led to the loss is reversible in time, for example through ecological restoration. If this is not possible, then the decrease is permanent. The cause of most of the biodiversity loss is, generally speaking, human activities that push the planetary boundaries too far. These activities include habitat destruction and land use intensification. Further problem areas are air and water pollution, over-exploitation, invasive species and climate change.
The Biodiversity of South Africa is the variety of living organisms within the boundaries of South Africa and its exclusive economic zone. South Africa is a region of high biodiversity in the terrestrial and marine realms. The country is ranked sixth out of the world's seventeen megadiverse countries, and is rated among the top 10 for plant species diversity and third for marine endemism.
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↑ Jude, David (1995). Munawar, M. (ed.). The lake Huron ecosystem: ecology, fisheries and management. Amsterdam: S.P.B. Academic Publishing. ISBN978-90-5103-117-1.
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↑ Beech, E.; Rivers, M.; Oldfield, S.; Smith, P. P. (4 July 2017). "GlobalTreeSearch: The first complete global database of tree species and country distributions". Journal of Sustainable Forestry. 36 (5): 454–489. Bibcode:2017JSusF..36..454B. doi:10.1080/10549811.2017.1310049.
↑ Booth, Hollie; Milner-Gulland, E.J.; McCormick, Nadine; Starkey, Malcolm (July 2024). "Operationalizing transformative change for business in the context of Nature Positive". One Earth. 7 (7): 1235–1249. doi:10.1016/j.oneear.2024.06.003.
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↑ Shiva, Vandana (January 2007). "Bioprospecting as Sophisticated Biopiracy". Signs: Journal of Women in Culture and Society. 32 (2): 307–313. doi:10.1086/508502.
↑ Einhorn, Catrin (19 December 2022). "Nearly Every Country Signs On to a Sweeping Deal to Protect Nature". The New York Times. Retrieved 27 December 2022. The United States is just one of two countries in the world that are not party to the Convention on Biological Diversity, largely because Republicans, who are typically opposed to joining treaties, have blocked United States membership. That means the American delegation was required to participate from the sidelines. (The only other country that has not joined the treaty is the Holy See.)
↑ Terbogh, John (1974). "The Preservation of Natural Diversity: The Problem of Extinction Prone Species". BioScience. 24 (12): 715–722. doi:10.2307/1297090. JSTOR1297090.
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