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IvyPanda . "Biodiversity: Importance and Benefits." December 19, 2021. https://ivypanda.com/essays/biodiversity-importance-and-benefits/.

• Conserving Biodiversity: The Loggerhead Turtle
• Essentials of Biodiversity
• Biodiversity Conservation: Tropical Rainforest
• Importance of Conserving Electricity
• Biodiversity and Business Risk
• Biodiversity, Its Importance and Benefits
• Defining and Measuring Biodiversity
• Biodiversity Benefits for Ecology
• Aspects, Importance and Issues of Biodiversity
• Ecosystems: Biodiversity and Habitat Loss
• Effects of Forest Fires on Ecosystem
• Hydrosphere: Coral Reefs and Their Protection
• The Importance of Biodiversity in Ecosystem
• Exploring the Ecosystems Base
• Description of a Seascape Compilation

47.2 The Importance of Biodiversity to Human Life

Learning objectives.

• Identify chemical diversity benefits to humans
• Identify biodiversity components that support human agriculture
• Describe ecosystem services

It may not be clear why biologists are concerned about biodiversity loss. When biodiversity loss is thought of as the extinction of the passenger pigeon, the dodo bird, and even the woolly mammoth, the loss may appear to be an emotional one. But is the loss practically important for the welfare of the human species? From the perspective of evolution and ecology, the loss of a particular individual species is unimportant (however, the loss of a keystone species can lead to ecological disaster). Extinction is a normal part of macroevolution. But the accelerated extinction rate means the loss of tens of thousands of species within our lifetimes, and it is likely to have dramatic effects on human welfare through the collapse of ecosystems and in added costs to maintain food production, clean air and water, and human health.

Agriculture began after early hunter-gatherer societies first settled in one place and heavily modified their immediate environment. This cultural transition has made it difficult for humans to recognize their dependence on undomesticated living things on the planet. Biologists recognize the human species is embedded in ecosystems and is dependent on them, just as every other species on the planet is dependent. Technology smoothes out the extremes of existence, but ultimately the human species cannot exist without its ecosystem.

Human Health

Contemporary societies that live close to the land often have a broad knowledge of the medicinal uses of plants growing in their area. Most plants produce secondary plant compounds , which are toxins used to protect the plant from insects and other animals that eat them, but some of which also work as medication. For centuries in Europe, older knowledge about the medical uses of plants was compiled in herbals—books that identified plants and their uses. Humans are not the only species to use plants for medicinal reasons: the great apes, orangutans, chimpanzees, bonobos, and gorillas have all been observed self-medicating with plants.

Modern pharmaceutical science also recognizes the importance of these plant compounds. Examples of significant medicines derived from plant compounds include aspirin, codeine, digoxin, atropine, and vincristine ( Figure 47.8 ). Many medicines were once derived from plant extracts but are now synthesized. It is estimated that, at one time, 25 percent of modern drugs contained at least one plant extract. That number has probably decreased to about 10 percent as natural plant ingredients are replaced by synthetic versions. Antibiotics, which are responsible for extraordinary improvements in health and lifespans in developed countries, are compounds largely derived from fungi and bacteria.

In recent years, animal venoms and poisons have excited intense research for their medicinal potential. By 2007, the FDA had approved five drugs based on animal toxins to treat diseases such as hypertension, chronic pain, and diabetes. Another five drugs are undergoing clinical trials, and at least six drugs are being used in other countries. Other toxins under investigation come from mammals, snakes, lizards, various amphibians, fish, snails, octopuses, and scorpions.

Aside from representing billions of dollars in profits, these medicines improve people’s lives. Pharmaceutical companies are actively looking for new compounds synthesized by living organisms that can function as medicine. It is estimated that 1/3 of pharmaceutical research and development is spent on natural compounds and that about 35 percent of new drugs brought to market between 1981 and 2002 were from natural compounds. The opportunities for new medications will be reduced in direct proportion to the disappearance of species.

Agricultural Diversity

Since the beginning of human agriculture more than 10,000 years ago, human groups have been breeding and selecting crop varieties. This crop diversity matched the cultural diversity of highly subdivided populations of humans. For example, potatoes were domesticated beginning around 7,000 years ago in the central Andes of Peru and Bolivia. The potatoes grown in that region belong to seven species and the number of varieties likely is in the thousands. Each variety has been bred to thrive at particular elevations and soil and climate conditions. The diversity is driven by the diverse demands of the topography, the limited movement of people, and the demands created by crop rotation for different varieties that will do well in different fields.

Potatoes are only one example of human-generated diversity. Every plant, animal, and fungus that has been cultivated by humans has been bred from original wild ancestor species into diverse varieties arising from the demands for food value, adaptation to growing conditions, and resistance to pests. The potato demonstrates a well-known example of the risks of low crop diversity: the tragic Irish potato famine when the single variety grown in Ireland became susceptible to a potato blight, wiping out the crop. The loss of the crop led to famine, death, and mass emigration. Resistance to disease is a chief benefit to maintaining crop biodiversity, and lack of diversity in contemporary crop species carries similar risks. Seed companies, which are the source of most crop varieties in developed countries, must continually breed new varieties to keep up with evolving pest organisms. These same seed companies, however, have participated in the decline of the number of varieties available as they focus on selling fewer varieties in more areas of the world.

The ability to create new crop varieties relies on the diversity of varieties available and the accessibility of wild forms related to the crop plant. These wild forms are often the source of new gene variants that can be bred with existing varieties to create varieties with new attributes. Loss of wild species related to a crop will mean the loss of potential in crop improvement. Maintaining the genetic diversity of wild species related to domesticated species ensures our continued food supply.

Since the 1920s, government agriculture departments have maintained seed banks of crop varieties as a way to maintain crop diversity. This system has flaws because, over time, seed banks are lost through accidents, and there is no way to replace them. In 2008, the Svalbard Global Seed Vault ( Figure 47.9 ) began storing seeds from around the world as a backup system to the regional seed banks. If a regional seed bank stores varieties in Svalbard, losses can be replaced from Svalbard. The seed vault is located deep into the rock of an arctic island. Conditions within the vault are maintained at ideal temperature and humidity for seed survival, but the deep underground location of the vault in the arctic means that failure of the vault’s systems will not compromise the climatic conditions inside the vault.

Visual Connection

Art connection.

The Svalbard Global Seed Vault is located on Spitsbergen island in Norway, which has an arctic climate. Why might an arctic climate be good for seed storage?

Crop success s is largely dependent on the quality of the soil. Although some agricultural soils are rendered sterile using controversial cultivation and chemical treatments, most contain a huge diversity of organisms that maintain nutrient cycles—breaking down organic matter into nutrient compounds that crops need for growth. These organisms also maintain soil texture that affects water and oxygen dynamics in the soil that are necessary for plant growth. If farmers had to maintain arable soil using alternate means, the cost of food would be much higher than it is now. These kinds of processes are called ecosystem services. They occur within ecosystems, such as soil ecosystems, as a result of the diverse metabolic activities of the organisms living there, but they provide benefits to human food production, drinking water availability, and breathable air.

Other key ecosystem services related to food production are plant pollination and crop pest control. Over 150 crops in the United States require pollination to produce. One estimate of the benefit of honeybee pollination within the United States is $1.6 billion per year; other pollinators contribute up to $6.7 billion more.

Many honeybee populations are managed by apiarists who rent out their hives’ services to farmers. Honeybee populations in North America have been suffering large losses caused by a syndrome known as colony collapse disorder, whose cause is unclear. Other pollinators include a diverse array of other bee species and various insects and birds. Loss of these species would make growing crops requiring pollination impossible, increasing dependence on other crops.

Finally, humans compete for their food with crop pests, most of which are insects. Pesticides control these competitors; however, pesticides are costly and lose their effectiveness over time as pest populations adapt. They also lead to collateral damage by killing non-pest species and risking the health of consumers and agricultural workers. Ecologists believe that the bulk of the work in removing pests is actually done by predators and parasites of those pests, but the impact has not been well studied. A review found that in 74 percent of studies that looked for an effect of landscape complexity on natural enemies of pests, the greater the complexity, the greater the effect of pest-suppressing organisms. An experimental study found that introducing multiple enemies of pea aphids (an important alfalfa pest) increased the yield of alfalfa significantly. This study shows the importance of landscape diversity via the question of whether a diversity of pests is more effective at control than one single pest; the results showed this to be the case. Loss of diversity in pest enemies will inevitably make it more difficult and costly to grow food.

Wild Food Sources

In addition to growing crops and raising animals for food, humans obtain food resources from wild populations, primarily fish populations. For approximately 1 billion people, aquatic resources provide the main source of animal protein. But since 1990, global fish production has declined. Despite considerable effort, few fisheries on the planet are managed for sustainability.

Fishery extinctions rarely lead to complete extinction of the harvested species, but rather to a radical restructuring of the marine ecosystem in which a dominant species is so over-harvested that it becomes a minor player, ecologically. In addition to humans losing the food source, these alterations affect many other species in ways that are difficult or impossible to predict. The collapse of fisheries has dramatic and long-lasting effects on local populations that work in the fishery. In addition, the loss of an inexpensive protein source to populations that cannot afford to replace it will increase the cost of living and limit societies in other ways. In general, the fish taken from fisheries have shifted to smaller species as larger species are fished to extinction. The ultimate outcome could clearly be the loss of aquatic systems as food sources.

Link to Learning

View a brief video discussing declining fish stocks.

Psychological and Moral Value

Finally, it has been argued that humans benefit psychologically from living in a biodiverse world. A chief proponent of this idea is entomologist E. O. Wilson. He argues that human evolutionary history has adapted us to live in a natural environment and that built environments generate stressors that affect human health and well-being. There is considerable research into the psychological regenerative benefits of natural landscapes that suggests the hypothesis may hold some truth. In addition, there is a moral argument that humans have a responsibility to inflict as little harm as possible on other species.

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Biodiversity Explained: Facts, Myths, and the Race to Protect It

By MJ Altman on January 4, 2023

A baby sloth hangs in a tree at the Bosque da Ciência in Manaus, Brazil. PHOTO: Michael Dantas/United Nations Foundation

As ecosystems and habitats degrade and disappear worldwide, biodiversity — the interconnectedness of all forms of life on our planet — is in jeopardy. In light of a new global agreement to protect our lands, ocean, and waters, explore what biodiversity really means and what it will take to preserve life on Earth.

From microscopic fungi to mega forests, “biodiversity” is the collective term for the variety of life on Earth in all its forms. It is 4.5 billion years of evolution, embodied.

Biodiversity is responsible for our food, our soil, our water, our weather, even the air we breathe. Yet despite being a crucial foundation for our collective future, biodiversity is often lost amid conversations on climate change — until recently.

In December 2022, leaders from nearly 200 nations adopted a landmark UN agreement to reverse nature’s rapid decline before it’s too late. Known as the Kunming-Montreal Global Biodiversity Framework , it calls for protecting 30% of the planet’s land, ocean, and inland waters and includes 23 other targets to help restore and protect ecosystems and endangered species worldwide.

Here are 12 things you should know:

1. Biodiversity is more than just the total number of species on Earth.

“It is actually more complex than that,” Dr. Thomas Lovejoy, the late ecologist, told the United Nations Foundation in 2018. “It’s about the genetic diversity within species, the diversity of habitats, and the large biological units known as biomes.”

This includes the interactions that occur between species within ecosystems – primordial relationships that shape our environment in countless, often unseen ways.

“Without biological diversity, there is no other life on Earth — including our own,” he explained. “Even though we are often oblivious to it, this diversity of life is what provides clean water, oxygen, and all other things that end up being part of our diet, as well as clothing and shelter. It provides a lot of psychological benefits too, which are not much appreciated.”

2. We’re only just beginning to understand biodiversity’s influence and importance in our lives.

Earth’s many ecosystems rely on a delicate, complicated, and fascinating tangle of life that, in many ways, remains a mystery. In fact, the term “biological diversity” wasn’t introduced to the scientific community until 1980 in a research paper on species loss by Dr. Lovejoy. Scientists still haven’t identified all forms of life on the planet. New species are discovered every year.

A harbor seal swims through kelp off the coast of Southern California's Channel Islands. Seals are among the thousands of species that rely on kelp forests for food and shelter. PHOTO: Shutterstock/Joe Belanger

Take kelp, for example. These undersea forests provide sustenance and shelter for marine species like chinook salmon, which, in turn, serve as a staple food for orcas. And kelp also absorb excess carbon dioxide, which can help mitigate climate change.

3. The planet’s biodiversity holds enormous, untapped potential for medical and scientific breakthroughs.

Lovejoy described each species on the planet as a unique set of solutions for a particular set of biological problems. “Whoever would have thought a bacterium from a Yellowstone hot spring would revolutionize forensic and diagnostic medicine, make the human genome project possible, and confer benefits in the trillion-dollar range?” he wrote as a Senior Fellow at the United Nations Foundation, citing a previously unknown and seemingly inconsequential microbe discovered in 1966 that revolutionized genetic testing and immunization development, including the COVID-19 vaccine.

A flowering plant grows from a tree in the Amazon Rainforest, near the research station known as Camp 41 north of Manaus, Brazil. PHOTO: Michael Dantas/United Nations Foundation

Today, one-fourth of all modern medicines are derived from tropical plants, and 70% of all cancer drugs are natural or bio-inspired products. In the past decade, researchers in Nova Scotia found a soil fungus that can disarm antibiotic-resistant bacteria — a discovery that could transform the fields of medicine and agriculture. The possibilities for discovery and innovation are monumental.

4. Climate change and biodiversity are interconnected.

Climate change is causing biodiversity loss, and biodiversity loss is causing climate change. Here’s how: Destroying and degrading ecosystems releases more carbon dioxide into the atmosphere than burning fossil fuels.

Meanwhile, the consequences of burning fossil fuels — rising global temperatures, an increase in wildfires, and ocean acidification, to name a few — are threatening habitats and wildlife alike. In late 2019 and early 2020, for example, more than 60,000 koalas were killed by wildfires in Australia so massive that nearly 3 billion animals died or were displaced as a result. Earlier this year, the Australian government officially listed koalas as an endangered species.

At COP 27 last year, world leaders reached a historic agreement to create a “loss and damage” fund to support communities that are already feeling climate change’s disastrous impact, including biodiversity loss and its impact on livelihoods.

More than 60,000 koalas were killed by wildfires in Australia in late 2019 and early 2020. Increased wildfires and subsequent habitat loss are just one of the consequences of climate change. PHOTO: Patrick Kavanagh

5. Biodiversity can help us adapt to climate change.

The UN considers biodiversity our strongest natural defense against climate change. Land and ocean ecosystems currently absorb 60% of human-caused emissions , and they are the planet’s only way of storing massive amounts of carbon dioxide. Coastal wetlands, for example, protect against storm surges and flooding during extreme weather while also storing carbon dioxide and creating oxygen.

According to a joint estimate by the UN Development Programme and the Government of Papua New Guinea, every dollar invested in environmental protection generates more than $2,500 in so-called ecosystem services — water regulation, coastal protection, carbon storage, and other invisible functions that nature provides. It’s one of the reasons that Papua New Guinea launched the first-ever national, independent Biodiversity and Climate Fund to protect its status as one of just 17 “megadiverse” countries.

6. Less biodiversity means a higher risk of disease.

For decades, the scientific community has warned that biodiversity loss increases the spread of infectious disease . Why? Because extinction upsets the ecosystem in unpredictable ways, and the destruction of natural habitats increases interaction between humans and wildlife. Biodiversity essentially acts as a barrier between humans and animal-borne disease.

Species that tend to survive logging, farming, mining, wildlife trade and consumption, and other human activities behind widespread biodiversity loss are often “vectors of disease” like mice and mosquitoes, which host pathogens that are able to make the jump to humans. It’s one of the reasons why cases of Lyme disease in the northeast United States have spiked in recent decades: With fewer mammals to prey on, ticks are increasingly seeking out people. In fact, roughly 75% of emerging infectious diseases are zoonotic .

It’s also why researchers like Dr. Alessandra Nava and her team of virus hunters at Brazil’s Fiocruz Amazônia are tracking the spread of disease in bats, monkeys, and rodents in the world’s largest rainforest. Their goal is to stay a step ahead of future pandemics by better understanding the pathogens contained within the jungle’s creatures before they come in contact with humans — encounters that become more likely as the human footprint expands.

A golden-backed squirrel monkey at the Bosque da Ciência, a rainforest park in Manaus, Brazil. PHOTO: Michael Dantas/United Nations Foundation

7. Biodiversity on land depends on biodiversity in water.

Maintaining the ocean’s ecological balance is crucial for protecting biodiversity on land, as well as maintaining our ability to feed future generations. The ocean plays a vital role in regulating the planet’s weather and water and the air we breathe. It is also the planet’s largest source of protein , feeding more than 3 billion people every day who rely on fish as a staple food.

Yet the ocean remains a vastly unexplored ecological frontier. While scientists have identified 200,000 marine species , the actual number is estimated to be in the millions. Unsustainable fishing practices, pollution, climate change, and habitat destruction are threatening creatures that may vanish before we even knew they existed.

8. Our planet’s biodiversity is on the brink.

Some 1 million species are threatened with extinction right now. That’s more than any other time in history, and they’re disappearing at a rate that is 1,000 times the norm. The culprit is the way most humans consume, produce, travel, and live.

A 2019 UN report found that we have altered 75% of the planet’s terrestrial environment, 40% of its marine environment, and 50% of streams and rivers. Nearly three-fourths of our freshwater resources are devoted to crop or livestock production, which often means using pesticides, fertilizers, fuels, and antibiotics that pollute our rivers, streams, seas, and soil. Every day we are destroying habitats and degrading massive amounts of soil and water through industrial manufacturing and agriculture while jeopardizing precious natural resources that could be lost forever in our lifetime; in the past two decades, we’ve lost half of the planet’s coral reefs . Deforestation in the Amazon rainforest hit a record high last year; some 18% is gone already, with scientists warning that we’re approaching a tipping point toward potential collapse .

9. Sustainability is the only way forward.

Such irresponsible production and consumption of our natural resources come at a catastrophic cost. We are destroying our planet at an unprecedented rate and losing a vast number of plants, animals, insects, and marine life in the process — to the detriment of our own future. Humanity’s health and well-being are dependent on a biodiverse planet.

Fortunately, examples are emerging of a greener, more sustainable way of doing business. Circular economic models are becoming more common as companies realize the economic and environmental value of reducing, reusing, and recycling their supply chain. At the same time, more citizens are demanding sustainable sourcing and socially just labor practices from their consumer goods. In 2022, the founder of the outdoor retailer Patagonia announced plans to invest all of the company’s profits toward combating climate change . “If we have any hope of a thriving planet — much less a business — 50 years from now, it is going to take all of us doing what we can with the resources we have,” Yvon Chouinard wrote .

Along Brazil’s Rio Negro, fourth-generation logger Roberto Brito de Mendonça stands in the dining lodge of his community’s ecotourism lodge. He retired from the family business to help start the operation, which includes a newly built classroom named in honor of Dr. Lovejoy. PHOTO: Michael Dantas/United Nations Foundation

10. Indigenous communities are crucial.

For thousands of years, Indigenous communities have served as the planet’s most effective environmental stewards. Today, according to the UN, Indigenous people manage more than 20% of the planet’s land and 80% of its biodiversity. “For us, it is not a passion, or a job,” Hindou Ibrahim of the Mbororo tribe in Chad, an SDG (Sustainable Development Goal) Advocate and Indigenous rights activist, told the UN last year. “It is our way of living. And that’s what we have done for all generations.”

In 2015, the UN created the Local Communities and Indigenous Peoples Platform to ensure their formal participation in global negotiations on climate change.

11. Conservation is critical.

One of our most promising solutions is preservation. Restoring degraded ecosystems alone could provide up to one-third of the climate mitigation needed to keep the Earth from warming too far above pre-industrial levels. This means creating protected areas, curbing extractive capitalism, and restoring the planet’s enormous amount of degraded land.

People across the globe are leading efforts to do just that. One inspiring example is Rita Mesquita, who expanded the amount of protected rainforest in Brazil by 76% during her time in the country’s Ministry of the Environment. Today, she oversees programs that encourage residents and visitors alike in Manaus to interact with the surrounding Amazon rainforest.

A Rhinoceros Beetle in Costa Rica’s National Park Tortuguero. The rhino beetle is one of the strongest insects in the world with relation to its body size, but because its tropical lowland habitat has been deforested and overcut, it is struggling to survive. PHOTO: GRID-Arendal/Peter Prokosch

12. We need cooperation — and revolution — at all levels.

We need partnerships among countries, communities, consumers, and corporations. And we’re seeing signs of progress every day. In fact, at COP 27, the Governments of Brazil, Democratic Republic of Congo, and Indonesia announced an alliance to protect their respective rainforests. Their historic agreement could pave the way for more multilateral action and impact. Coming just a month later, the Kunming-Montreal Global Biodiversity Framework represents an enormous and long-awaited step toward halting extinction rates that some scientists are calling an existential crisis akin to climate change.

A huge part of the solution to the biodiversity challenge will be transforming how we approach the natural world and our place within it. As Dr. Lovejoy told the UN Foundation in 2018 , “There needs to be a major shift in perception from thinking of nature as something with a fence around it in the middle of an expansive, human-dominated landscape … to thinking about embedding our aspirations in nature.”

ENCYCLOPEDIC ENTRY

Biodiversity.

Biodiversity refers to the variety of living species on Earth, including plants, animals, bacteria, and fungi. While Earth’s biodiversity is so rich that many species have yet to be discovered, many species are being threatened with extinction due to human activities, putting the Earth’s magnificent biodiversity at risk.

Biology, Ecology

grasshoppers

Although all of these insects have a similar structure and may be genetic cousins, the beautiful variety of colors, shapes, camouflage, and sizes showcase the level of diversity possible even within a closely-related group of species.

Photograph by Frans Lanting

Biodiversity is a term used to describe the enormous variety of life on Earth. It can be used more specifically to refer to all of the species  in one region or ecosystem . Bio diversity refers to every living thing, including plants, bacteria, animals, and humans. Scientists have estimated that there are around 8.7 million species of plants and animals in existence. However, only around 1.2 million species have been identified and described so far, most of which are insects. This means that millions of other organisms remain a complete mystery.

Over generations , all of the species that are currently alive today have evolved unique traits that make them distinct from other species . These differences are what scientists use to tell one species from another. Organisms that have evolved to be so different from one another that they can no longer reproduce with each other are considered different species . All organisms that can reproduce with each other fall into one species .

Scientists are interested in how much biodiversity there is on a global scale, given that there is still so much biodiversity to discover. They also study how many species exist in single ecosystems, such as a forest, grassland, tundra, or lake. A single grassland can contain a wide range of species, from beetles to snakes to antelopes. Ecosystems that host the most biodiversity tend to have ideal environmental conditions for plant growth, like the warm and wet climate of tropical regions. Ecosystems can also contain species too small to see with the naked eye. Looking at samples of soil or water through a microscope reveals a whole world of bacteria and other tiny organisms.

Some areas in the world, such as areas of Mexico, South Africa, Brazil, the southwestern United States, and Madagascar, have more bio diversity than others. Areas with extremely high levels of bio diversity are called hotspots . Endemic species — species that are only found in one particular location—are also found in hotspots .

All of the Earth’s species work together to survive and maintain their ecosystems . For example, the grass in pastures feeds cattle. Cattle then produce manure that returns nutrients to the soil, which helps to grow more grass. This manure can also be used to fertilize cropland. Many species provide important benefits to humans, including food, clothing, and medicine.

Much of the Earth’s bio diversity , however, is in jeopardy due to human consumption and other activities that disturb and even destroy ecosystems . Pollution , climate change, and population growth are all threats to bio diversity . These threats have caused an unprecedented rise in the rate of species extinction . Some scientists estimate that half of all species on Earth will be wiped out within the next century. Conservation efforts are necessary to preserve bio diversity and protect endangered species and their habitats.

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Biodiversity and Ecosystem Stability

Introduction: Biodiversity, Stability, and Ecosystem Functioning

Climate change and other human-driven (anthropogenic) environmental changes will continue to cause biodiversity loss in the coming decades (Sala et al . 2000), in addition to the high rates of species extinctions already occurring worldwide (Stork 2010). Biodiversity is a term that can be used to describe biological diversity at a variety of different scales, but in this context we will focus on the description of species diversity. Species play essential roles in ecosystems, so local and global species losses could threaten the stability of the ecosystem services on which humans depend (McCann 2000). For example, plant species harness the energy of the sun to fix carbon through photosynthesis, and this essential biological process provides the base of the food chain for myriad animal consumers. At the ecosystem level, the total growth of all plant species is termed primary production, and — as we'll see in this article — communities composed of different numbers and combinations of plant species can have very different rates of primary production. This fundamental metric of ecosystem function has relevance for global food supply and for rates of climate change because primary production reflects the rate at which carbon dioxide (a greenhouse gas) is removed from the atmosphere. There is currently great concern about the stability of both natural and human-managed ecosystems, particularly given the myriad global changes already occurring. Stability can be defined in several ways, but the most intuitive definition of a stable system is one having low variability (i.e., little deviation from its average state) despite shifting environmental conditions. This is often termed the resistance of a system. Resilience is a somewhat different aspect of stability indicating the ability of an ecosystem to return to its original state following a disturbance or other perturbation.

Species Identity, Functional traits, and Resource-Use

Species diversity has two primary components: species richness (the number of species in a local community) and species composition (the identity of the species present in a community). While most research on the relationship between ecosystem diversity and stability has focused on species richness, it is variation in species composition that provides the mechanistic basis to explain the relationship between species richness and ecosystem functioning. Species differ from one another in their resource use, environmental tolerances, and interactions with other species, such that species composition has a major influence on ecosystem functioning and stability.

The traits that characterize the ecological function of a species are termed functional traits, and species that share similar suites of traits are often categorized together into functional groups. When species from different functional groups occur together, they can exhibit complementary resource-use, meaning that they use different resources or use the same resources at different times. For example, two animal predators may consume different prey items, so they are less likely to compete with one another, allowing higher total biomass of predators in the system. In the case of plants, all species may utilize the same suite of resources (space, light, water, soil nutrients, etc.) but at different times during the growing season — for example, early- and late-season grasses in prairies. Increasing species diversity can influence ecosystem functions — such as productivity — by increasing the likelihood that species will use complementary resources and can also increase the likelihood that a particularly productive or efficient species is present in the community. For example, high plant diversity can lead to increased ecosystem productivity by more completely, and/or efficiently, exploiting soil resources (e.g., nutrients, water). While primary production is the ecosystem function most referred to in this article, other ecosystem functions, such as decomposition and nutrient turnover, are also influenced by species diversity and particular species traits.

Diversity-Stability Theory

Theoretical models suggest that there could be multiple relationships between diversity and stability, depending on how we define stability (reviewed by Ives & Carpenter 2007). Stability can be defined at the ecosystem level — for example, a rancher might be interested in the ability of a grassland ecosystem to maintain primary production for cattle forage across several years that may vary in their average temperature and precipitation. Figure 1 shows how having multiple species present in a plant community can stabilize ecosystem processes if species vary in their responses to environmental fluctuations such that an increased abundance of one species can compensate for the decreased abundance of another. Biologically diverse communities are also more likely to contain species that confer resilience to that ecosystem because as a community accumulates species, there is a higher chance of any one of them having traits that enable them to adapt to a changing environment. Such species could buffer the system against the loss of other species. Scientists have proposed the insurance hypothesis to explain this phenomenon (Yachi & Loreau 1999). In this situation, species identity — and particular species traits — are the driving force stabilizing the system rather than species richness per se (see Figure 2).

In contrast, if stability is defined at the species level, then more diverse assemblages can actually have lower species-level stability. This is because there is a limit to the number of individuals that can be packed into a particular community, such that as the number of species in the community goes up, the average population sizes of the species in the community goes down. For example, in Figure 2, each of the simple communities can only contain three individuals, so as the number of species in the community goes up, the probability of having a large number of individuals of any given species goes down. The smaller the population size of a particular species, the more likely it is to go extinct locally, due to random — stochastic — fluctuations, so at higher species richness levels there should be a greater risk of local extinctions. Thus, if stability is defined in terms of maintaining specific populations or species in a community, then increasing diversity in randomly assembled communities should confer a greater chance of destabilizing the system.

Experiments and Observations Can Evaluate the Diversity-Stability Relationship

A wealth of research into the relationships among diversity, stability, and ecosystem functioning has been conducted in recent years (reviewed by Balvanera et al . 2006, Hooper et al . 2005). The first experiments to measure the relationship between diversity and stability manipulated diversity in aquatic microcosms — miniature experimental ecosystems — containing four or more trophic levels, including primary producers, primary and secondary consumers, and decomposers (McGrady-Steed et al . 1997, Naeem & Li 1997). These experiments found that species diversity conferred spatial and temporal stability on several ecosystem functions. Stability was conferred by species richness, both within and among functional groups (Wardle et al . 2000). When there is more than one species with a similar ecological role in a system, they are sometimes considered "functionally redundant." But these experiments show that having functionally redundant species may play an important role in ensuring ecosystem stability when individual species are lost due to environmental changes, such as climate change.

More recently, scientists have examined the importance of plant diversity for ecosystem stability in terrestrial ecosystems, especially grasslands where the dominant vegetation lies low to the ground and is easy to manipulate experimentally. In 1995, David Tilman and colleagues established 168 experimental plots in the Cedar Creek Ecosystem Science Reserve, each 9 x 9 m in size (Figure 3A), and seeded them with 1, 2, 4, 8 or 16 species drawn randomly from a pool of 18 possible perennial plant species (Tilman et al . 2006). Plots were weeded to prevent new species invasion and ecosystem stability was measured as the stability of primary production over time. Over the ten years that data were collected, there was significant interannual variation in climate, and the researchers found that more diverse plots had more stable production over time (Figure 3B). In contrast, population stability declined in more diverse plots (Figure 3C). These experimental findings are consistent with the theory described in the prior section, predicting that increasing species diversity would be positively correlated with increasing stability at the ecosystem-level and negatively correlated with species-level stability due to declining population sizes of individual species.

Experiments manipulating diversity have been criticized because of their small spatial and short time scales, so what happens in naturally assembled communities at larger spatial scales over longer time scales? In a 24-year study of naturally assembled Inner Mongolia grassland vegetation, Bai et al . (2004) observed variation in the biomass of species, functional groups, and the whole community in response to strong interannual variation in growing-season precipitation. They found that while the abundance of individual species fluctuated, species within particular functional groups tended to respond differently such that a decrease in the abundance of one species was compensated for by an increase in the abundance of another. This compensation stabilized the biomass productivity of the whole community in a fluctuating environment (see Figure 1). These findings demonstrate that local species richness — both within and among functional groups — confers stability on ecosystem processes in naturally assembled communities.

Experiments in aquatic ecosystems have also shown that large-scale processes play a significant role in stabilizing ecosystems. A whole-lake acidification experiment in Canada found that although species diversity declined as a result of acidification, species composition changed significantly and ecosystem function was maintained (Schindler 1990). This suggests that given sufficient time and appropriate dispersal mechanisms, new species can colonize communities from the regional species pool and compensate for those species that are locally lost (Fischer et al . 2001). This observation emphasizes the importance of maintaining connectivity among natural habitats as they experience environmental changes.

Evidence from multiple ecosystems at a variety of temporal and spatial scales, suggests that biological diversity acts to stabilize ecosystem functioning in the face of environmental fluctuation. Variation among species in their response to such fluctuation is an essential requirement for ecosystem stability, as is the presence of species that can compensate for the function of species that are lost. While much of the evidence presented here has focused on the consequences of changes in species diversity on primary production in natural ecosystems, recent research has found similar relationships between species diversity and ecosystem productivity in human-managed ecosystems (e.g., Jactel et al . 2005).

References and Recommended Reading

Bai, Y. et al. Ecosystem stability and compensatory effects in the Inner Mongolia grassland. Nature 431 , 181–184 (2004).

Balvanera, P. et al. Quantifying the evidence for biodiversity effects on ecosystem functioning and services. Ecology Letters 9 , 1146–1156 (2006).

Fischer J. M. et al . Compensatory dynamics in zooplankton community responses to acidification: Measurement and mechanisms. Ecological Applications 11 , 1060–1072 (2001).

Hooper, D. U. et al. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge and needs for future research. Ecological Monographs 75 , 3–35 (2005).

Ives, A. R. & Carpenter, S. R. Stability and diversity of ecosystems. Science 317 , 58–62 (2007).

Jactel, H. et al. A test of the biodiversity-stability theory: Meta-analysis of tree species diversity effects on insect pest infestations, and re-examination of responsible factors. Forest Diversity and Function 176 , 235–262 (2005).

McCann, K. S. The diversity-stability debate. Nature 405 , 228–233 (2000).

McGrady-Steed, J. et al. Biodiversity regulates ecosystem predictability. Nature 390 , 162–165 (1997).

Naeem, S. & Li, S. Biodiversity enhances ecosystem reliability. Nature 390 , 507–509 (1997).

Naeem, S. et al . Declining biodiversity can alter the performance of ecosystems. Nature 368 , 734–737 (1994).

Sala, O. E. et al. Global biodiversity scenarios for the year 2100. Science 287 , 1770–1774 (2000).

Schindler, D. W. Experimental perturbations of whole lakes as tests of hypotheses concerning ecosystem structure and function. Oikos 57 , 25–41 (1990).

Stork, N. E. Re-assessing current extinction rates. Biodiversity and Conservation 19 , 357–371 (2010).

Tilman, D. et al. Biodiversity and ecosystem stability in a decade-long grassland experiment. Nature 441 , 629–632 (2006).

Wardle, D. A. et al. Stability of ecosystem properties in response to above-ground functional group richness and composition. Oikos 89 , 11–23 (2000).

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• Biodiversity Essay

Essay on Biodiversity

Biodiversity is a term made up of two words - Bio meaning Life, and Diversity meaning Variety. The term biodiversity refers to the variety of life on Earth. Plants, animals, microbes, and fungi are all examples of living species on the planet.

Types of Biodiversity  

Genetic Biodiversity- Genetic diversity is the variation in genes and genotypes within a species, e.g., every human looks different from the other. 

Species Biodiversity- Species Diversity is the variety of species within a habitat or a region. It is the biodiversity observed within a community.

Ecosystem Biodiversity- Ecological biodiversity refers to the variations in the plant and animal species living together and connected by food chains and food webs.

Importance of Biodiversity 

Biodiversity is an integral part of cultural identity. Human cultures co-evolve with their environment and conservation is a priority for cultural identity. Biodiversity is used for Medicinal purposes.

Many plants and animals are used for medicinal purposes, like vitamins and painkillers. It contributes to climate stability. It helps in controlling the effects of climate change and managing greenhouse gases. 

Biodiversity provides more food resources. It supplies many vital ecosystems, such as creating and maintaining soil quality, controlling pests, and providing habitat for wildlife. Biodiversity has a relationship with Industry. Biological sources provide many Industrial materials including rubber, cotton, leather, food, paper, etc.

There are many economic benefits of Biodiversity. Biodiversity also helps in controlling pollution. Biodiversity helps in forming a healthy ecosystem. Biodiversity also acts as a source of recreation. Along with other factors, biodiversity helps in improving soil quality.

Long Essay on Biodiversity 

There are many economic benefits of Biodiversity. Biodiversity is a source of economic wealth for many regions of the world. Biodiversity facilitates Tourism and the Recreational industry. Natural Reserves and National Parks benefit a lot from it. Forest, wildlife, biosphere reserve, sanctuaries are prime spots for ecotourism, photography, painting, filmmaking, and literary works.

Biodiversity plays a vital role in the maintenance of the gaseous composition of the atmosphere, breakdown of waste material, and removal of pollutants.

Conservation of Biodiversity  

Biodiversity is very important for human existence as all life forms are interlinked with each other and one single disturbance can have multiple effects on another. If we fail to protect our biodiversity, we can endanger our plants, animals, and environment, as well as human life. Therefore, it is necessary to protect our biodiversity at all costs. Conservation of Biodiversity can be done by educating the people to adopt more environment-friendly methods and activities and develop a more harmonious and empathetic nature towards the environment. The involvement and cooperation of communities are very important. The process of continuous protection of Biodiversity is the need of the hour.

The Government of India, along with 155 other nations, has signed the convention of Biodiversity at the Earth Summit to protect it. According to the summit, efforts should be made in preserving endangered species. 

The preservation and proper management methods for wildlife should be made. Food crops, animals, and plants should be preserved. Usage of various food crops should be kept at a minimum. Every country must realize the importance of protecting the ecosystem and safeguarding the habitat. 

The Government of India has launched the Wild Life Protection Act 1972 to protect, preserve, and propagate a variety of species. The Government has also launched a scheme to protect national parks and sanctuaries. There are 12 countries - Mexico, Columbia, Peru, Brasil, Ecuador, Democratic Republic of Congo, Madagascar, India, China, Malaysia, Indonesia, and Australia, in which Mega Diversity Centres are located. These countries are tropical and they possess a large number of the world’s species.

Various hotspots have been made to protect the vegetation. There are various methods for conserving biodiversity. 

If biodiversity conservation is not done efficiently, each species would eventually become extinct due to a lack of appetite and hunger. This scenario has been a big issue for the last few decades, and many unique species have already become extinct. As a result of a lack of biodiversity protection, several species are still on the verge of extinction.

FAQs on Biodiversity Essay

1. What are the three types of Biodiversity?

Biodiversity is referred to as the variability that exists between the living organisms from different sources of nature, such as terrestrial, marine, and other aquatic ecosystems. Biodiversity has three levels, which are genetic, species, and ecosystem diversity. This is also considered as the type of ecosystem.

2. What is Biodiversity and why is it important?

Biodiversity is responsible for boosting the productivity of the ecosystems in which every species, no matter how small, has an important role to play. For example, a greater variety of crops can be obtained from a plant species which is in large numbers. If species diversity is in a greater amount, then it ensures natural sustainability for all life forms.

3. What is the connection between Biodiversity and the Food Chain?

If a single species goes extinct from the food chain, it will have an impact on the species that survive on it, putting them on the verge of extinction.

4. How are human beings affecting biodiversity?

Pollution- Pollution not only affects human beings, but also affects our flora and fauna, and we should control the pollution to conserve our biodiversity.

Population- Population control is a must to maintain a balance in our ecological system. Humans contribute to pollution by bursting crackers and by not following all the traffic rules.

5. How does Deforestation affect biodiversity?

Deforestation- Trees are very important for survival. They help in balancing out the ecosystem. Deforestation leads to the destruction of habitat. Deforestation should be stopped to protect our animals and plants. Deforestation not only removes vegetation that is important for removing carbon dioxide from the atmosphere, but it also emits greenhouse gases.

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Biodiversity and Health in the Urban Environment

Melissa r. marselle.

1 University of Surrey, School of Psychology, Guildford, GU2 7XH UK

Sarah J. Lindley

2 Department of Geography, School of Environment, Education and Development, University of Manchester, Oxford Road, Manchester, M13 9PL UK

Penny A. Cook

3 School of Health and Society, University of Salford, Salford, M6 6PU UK

Aletta Bonn

4 Department of Ecosystem Services, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany

5 Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Straße 159, 07743 Jena, Germany

6 Department of Ecosystem Services, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany

Purpose of review

Biodiversity underpins urban ecosystem functions that are essential for human health and well-being. Understanding how biodiversity relates to human health is a developing frontier for science, policy and practice. This article describes the beneficial, as well as harmful, aspects of biodiversity to human health in urban environments.

Recent findings

Recent research shows that contact with biodiversity of natural environments within towns and cities can be both positive and negative to human physical, mental and social health and well-being. For example, while viruses or pollen can be seriously harmful to human health, biodiverse ecosystems can promote positive health and well-being. On balance, these influences are positive. As biodiversity is declining at an unprecedented rate, research suggests that its loss could threaten the quality of life of all humans.

A key research gap is to understand—and evidence—the specific causal pathways through which biodiversity affects human health. A mechanistic understanding of pathways linking biodiversity to human health can facilitate the application of nature-based solutions in public health and influence policy. Research integration as well as cross-sector urban policy and planning development should harness opportunities to better identify linkages between biodiversity, climate and human health. Given its importance for human health, urban biodiversity conservation should be considered as public health investment.

Introduction

Biodiversity underpins ecosystem functions that are essential for human health and well-being [ 1 – 3 ]. However, biodiversity is declining at an unprecedented rate [ 2 ], threatening the health and well-being of all humans. Growing urbanisation is an additional threat to both human health [ 4 ] and biodiversity [ 5 ]. Urban areas also experience increasing climatic pressures driven not only by global climate change developments but also by urbanisation and associated local urban heat island effects [ 6 ]. This is because cities contain larger amounts of surfaces with thermal and structural properties which enhance heat storage and inhibit its loss; fewer vegetated surfaces that contribute to cooling; and higher heat emissions due to human activity, such as traffic or air conditioning. As global urban cover is projected to increase to 1.9 million km 2 with 5.2 billion people expected to live in urban areas by 2030 [ 5 ], action is needed to reduce future risks by designing healthy, liveable cities for both people and nature. Nature-based solutions may help to mitigate climate and health pressures in urban areas [ 7 , 8 •]. New alliances of the World Health Organization (WHO) and the Convention on Biological Diversity (CBD) are recognising this potential of aligning health, climate and biodiversity goals [ 9 •], while concrete and actionable evidence is needed to operationalise health-promoting measures.

Of the large body of research on nature and human health [ 10 – 12 ], few studies examine the influence of ecological characteristics on health [ 13 , 14 •, 15 ]. Moreover, the extensive research on ecosystem service benefits to human health and well-being often lacks specifics on the biodiversity involved [ 1 , 16 ]. Accordingly, we see a need to further develop knowledge of the ways in which specific elements of biodiversity itself matters for human health [ 17 , 18 ••]. A first, simplistic approach to measuring nature, for example as the amount of greenspace, has enabled a surge of new research and can serve as an important indicator for urban health planning goals [ 15 , 19 ]. Yet, it does not enable a clear understanding of how human health is influenced by the presence of, contact with, or change in different manifestations of biodiversity.

Research taking place over the past few decades has provided a much clearer picture of the connections between nature and human health in urban environments [ 11 , 20 , 21 ]. We now know much more about which elements of urban nature have positive and negative impacts and why those effects are seen. Emerging evidence underlines that benefits are not only due to the quantity of greenspace and bluespace in an area but also due to their quality. Biodiversity is a fundamental component of quality in this context, and therefore, research efforts are now turning to focus on understanding how and why biodiversity has an impact, and what this means for how we plan, design and manage urban areas of the future. This paper highlights the influences biodiversity of species and habitats has on human health and discusses new opportunities for understanding these relationships in order to conserve and enhance diversity for the health of both people and nature.

Definitions of Biodiversity and Health

‘Biodiversity’ (Box 1) and ‘health’ (Box 2) mean different things to different people [ 2 ]. The definitions adopted here enable comprehension of the concepts of biodiversity and human health. Clear definitions can facilitate collaboration between the natural sciences, social sciences and health sciences in understanding biodiversity’s influence on human health.

Box 1 Definition of biodiversity

Box 2 Definition of health

Recent Research Findings

Biodiversity is a cornerstone of human health and well-being. This section details the current evidence on biodiversity’s influence on physical, mental and social health and well-being.

Physical Health

There is a relatively large literature identifying indirect links between urban biodiversity and physical health. Understanding the connections between biodiversity and physical health is complicated by the use of multiple proxy indicators of biodiversity and health at a range of different scales [ 16 , 26 – 28 ]. Studies using specific biodiversity and physiological indicators have the potential to cut through some of this complexity, but these are still relatively rare [ 29 ]. Despite the uncertainties, existing evidence is revealing a number of direct and indirect influencing mechanisms, and these can be usefully linked with one or more of the eleven interconnected bodily systems [ 30 •].

One direct mechanism for the beneficial role of biodiversity on human health is associated with the ‘biodiversity hypothesis’ related to microbiome [ 31 ]. Symbiotic microbes within the human microbiome help explain healthy development of the immune system [ 31 , 32 ] and healthy functioning of the digestive system [ 33 ]. The diversity of an individual’s microbiome is strongly related to their lifestyle, environment and exposure characteristics [ 31 , 34 ]. People living in urban areas tend to have fewer opportunities to come into contact with beneficial microorganisms whether through dietary, airway or skin exposure pathways [ 31 ]. In one example, adolescent atopy was found to have statistically significant negative associations with the abundance and species richness of particular native flowering plants, with these plants being ~25% more abundant around the homes of healthy individuals [ 35 ]. In a cross-sectional observational study, primary school children exposed to higher fungal and fauna diversity around their schools were less likely to develop allergic sensitisation and to have improved lung function, respectively [ 36 , 37 ]. Recent reviews have identified a lack of experimental and intervention studies with an explicit focus on testing the biodiversity hypothesis in the context of physical health [ 29 , 30 ]. To address this gap, an urban biodiversity intervention in the gardens of a range of children’s day-care establishments in two cities in Finland has shown changes in both gut and skin microbiota and modified functioning of immune systems [ 34 ]. Other studies are now showing how interventions can also recolonise microbial communities lost through urbanisation [ 38 ]. Urban living can disrupt human microbiome biodiversity for any age group. For instance, pollution affects the richness of various environmental microbiome pools [ 34 , 39 ]. Such disruptions can, in turn, lead to increased incidence of associated disease, such as in the digestive and urinary/renal bodily systems [ 26 ]. Urban dwellers are also more likely to experience dysbiosis, the negative cycle of continued human microbial imbalances [ 33 ]. Since microbiomes are partly inherited, dysbiosis can have persistent generational impacts especially in urban areas [ 31 ].

Biodiversity underpins a range of specific ecosystem functions known to contribute to human health [ 14 •, 40 ], including mitigating the severity of urban environmental stressors [ 11 , 18 ••, 21 , 41 ]. Environmental noise is one such example. Here, stress-response mechanisms help explain how excessive noise impacts cardiovascular, respiratory, immune response and metabolic systems [ 42 ]. In turn, acoustic research shows how structural components of vegetation buffers noise, and demonstrates that dense and diverse planting schemes provide particularly effective noise barriers [ 43 , 44 ]. Although urban populations may not always report strong satisfaction rates with environmental noise (reduction) in areas with greater land cover diversity [ 45 ], the physical processes through which vegetation attributes modify acoustics are nonetheless clear [ 43 , 46 ]. People’s perceptions of the soundscapes of cities are thus important to consider, as the soundscape pleasantness of birds buffers the negative effects of traffic noise [ 47 ]. Air pollution is another example of an environmental stressor that biodiversity mitigates. Trees have been shown to reduce air pollution in cities, while they may also emit volatile organic compounds (VOCs), and the choice of right tree species matters to urban planning [ 48 , 49 ]. Vegetation with higher structural complexity and density can also be an effective barrier to ultrafine particles from roads [ 50 ]. Nevertheless, the mitigating effect of urban vegetation on air pollution is still under debate. This is due to complex chemical and physical interaction of plants with the surrounding air depending on vegetation structure (e.g. planting density) and specific functional traits (e.g. leaf area, water use strategy, pollen production, VOC and ozone production) [ 48 , 51 – 53 ]. Reducing exposure to extreme heat is the third example of how biodiversity mitigates environmental stressors. Extreme heat is of particular concern for the future due to climate change and more people living in urban areas, who may experience exacerbated urban heat island effects as well as higher vulnerabilities due to ageing populations [ 54 – 56 ]. Vegetation in cities can reduce these heat island effects by decreasing the air temperature through evapotranspiration and/or shading [ 57 ]. Vegetation abundance, structural characteristics, taxonomic diversity, species traits (e.g. leaf area, pigmentation and canopy structure), composition, functional diversity and functional identity are all known to affect the extent of cooling provided [ 14 •, 30 , 58 – 60 ].

In addition to mitigating urban environmental stressors, the biodiversity of urban ecosystems has been reported to have a net positive influence on a range of other beneficial functions and ecosystem services, too. They include pollination, soil protection and fertility, water quality regulation and pest control [ 14 •, 58 ]. Health influences can occur irrespective of direct contact with biodiverse places, e.g. when flood attenuation or water quality regulation occurs through wetlands upstream of cities. However, the abundance and physical proximity of areas of biodiversity are undoubtedly important for attaining health and well-being benefits [ 61 ]. Indeed, the greater propensity for people to engage in physical activity if there are pleasant, open spaces near to home is also a major driver of health outcomes, due to both the greater likelihood of beneficial exposures and the physical health benefits of the exercise itself [ 62 – 64 ].

Mental Health

Natural environments and greenspaces are beneficial for mental health and well-being [ 13 , 15 , 65 ]. While a large body of literature focuses on the spatial extent of a natural area or the amount of time spent in greenspace, fewer studies examine the influence of biodiversity in greenspaces on mental health and well-being [ 13 , 15 , 66 ]. The following discussion of the literature is organised by the tiers of biodiversity: ecosystems or habitats, species communities and single species [ 67 ].

A rich diversity of ecosystems and habitat types may improve mental well-being, but not mental health [ 68 •]. Several studies show no significant relationship between biodiversity of ecosystems or habitats and mental health [ 69 – 72 ]. With regard to mental well-being, there is mixed evidence, and this relates also to spatial scale of investigations. Fuller et al. [ 73 ] could show a positive association of the number of habitat types with psychological well-being. Greenspaces with higher biodiversity were related to better well-being compared to greenspaces low in biodiversity [ 74 ]. An investigation of forest habitats, however, found forest habitats of intermediate biodiversity linked to greater positive reported emotions, than forests of high and low diversity [ 75 ]. More diverse ecosystems or habitats (assessed with the Shannon diversity index of land cover and land use) were positively associated with greater quality of life in Finland [ 72 ], but not with psychological well-being in England [ 76 •]. In other studies, no effect was found for biodiversity on mental well-being for different ecosystems or habitats [ 77 – 79 ], protected areas [ 80 ] or different greenspace types [ 81 ].

There is some evidence that species richness of plants or animals can have a positive association on mental health and well-being [ 68 •]. There is mixed evidence on the influence of bird species richness on mental health, with some studies showing a significant association at large spatial scales [ 82 , 83 ] and in an experimental laboratory setting [ 84 ], and others at the neighborhood scale showing no relationship [ 85 ]. Plant species richness was associated with improved mental health at the regional district scale in Germany [ 83 ]. Although species richness of street trees at the very local scale (100 meters around the home) was not related to antidepressant prescriptions [ 86 •]. With regard to mental well-being, greater tree and plant species richness was related to better mood [ 84 , 87 ] and psychological well-being [ 73 ]. Species richness of flora and fauna was positively associated with subjective well-being [ 88 ]. Greater bird species richness was related to greater levels of life satisfaction [ 89 , 90 •], positive affect [ 84 , 91 ] and psychological well-being [ 73 , 76 •] at several spatial scales. However, no relationship was found between mammal, megafauna and tree species richness on life satisfaction at large spatial scales [ 90 •]. At the local scale, no relationship of butterfly species richness with psychological well-being could be ascertained [ 73 , 76 •], while a negative association was found between plant species richness and psychological well-being [ 76 •].

When information on the level of species richness in an urban area is not available, a proxy measure may be used [ 91 ]. This proxy measure is perceived biodiversity, i.e. a survey respondent’s rating of the number of different species that they think is present in an environment [ 92 ]. No study, to date, has examined the relationship between mental health and perceived species richness [ 68 •]. Regarding mental well-being, positive associations were found between perceived species richness of animals and plants and mood [ 91 , 93 ]. While relationships with scientifically recorded biodiversity were nonsignificant or even negative, associations were found to be positive for perceived species richness of birds, butterflies and trees and psychological well-being [ 76 •]. Marselle et al. [ 94 , 95 ] found no associations between perceived species richness of plants. Perceived plant species richness was positively related with restorative affect [ 96 ], but not subjective well-being [ 97 ]. No influence was found for the perceived number of native species or the perceived number of native insects on restorative affect [ 96 ]; this may be because perceived biodiversity depends on the visibility of the species and the extent to which is perceived as different [ 98 ].

Abundance of specific distinctive taxonomic groups may be important for mental health and well-being, as they may be more noticeable than species richness [ 76 •]. Indeed, studies that found nonsignificant results with species richness found significant results with abundance—and vice versa at different spatial scales. Regarding mental health, Cox et al. [ 85 ] found higher bird abundances in the afternoon—but not species richness—were associated with less depression, anxiety and stress in England. Marselle et al. [ 86 •] found that abundance of street trees, but not species richness, significantly reduced the risk of antidepressant prescriptions for individuals with low socio-economic status in the city of Leipzig. In contrast, Methorst et al. [ 83 ] found no association between bird abundance on mental health but found a significant association with bird species richness. Regarding mental well-being, people viewing photographs with greater abundance of fish/crustaceans reported greater reported happiness than when viewing photographs with lower abundance—although no effect was found with species richness [ 99 ]. These four studies highlight the importance of measuring species richness and abundance together, in order to discern the independent contribution of species richness [ 98 ].

Importantly, spatial scale may be a very important factor, as different causal mechanisms may account for the influence of the different tiers of biodiversity on mental health and well-being. For example, the mechanism driving the influence of species richness at the regional district scale may be related to overall landscape qualities that may promote mental well-being, while species richness at the local scale might be more related to stress reduction or attention restoration that promotes mental health and well-being [ 18 , 68 , 83 , 116 ]. Indeed, Marselle et al. [ 94 , 95 ] did not find a direct relationship between perceived bird species richness and mood, but found an indirect relationship mediated by perceived restorativeness [ 95 ]. Further research is needed to unravel these mechanisms.

Social Health

Social well-being is an important aspect of health. While the influence of greenspace on social interactions and social cohesion in one’s neighbourhood has been extensively studied [ 100 – 104 ], fewer studies have explored the association between biodiversity and social dimensions of health [ 68 , 105 •]. Engaging in nature conservation volunteering can facilitate social interaction [ 106 ]. Biodiverse environments, such as in neighbourhoods with more trees, may provide a setting for social interaction with others, which is likely to increase social cohesion [ 101 , 107 ]. No relationship, however, was found between the vegetation complexity of a visited greenspace and social cohesion [ 108 ]. In contrast, neighbourhood well-being, a measure of self-reported satisfaction living with one’s neighbourhood environment, was positively associated with the species richness and abundance of birds as well as vegetation cover [ 89 , 109 ].

Given that contact with nature can increase social interactions, social cohesion and prosocial behaviour [ 110 , 111 ], future work should examine the relationship between social well-being and the biodiversity of different types of natural environments. Such insights into the social impact of biodiversity could contribute to efforts to facilitate pro-environmental behaviour change [ 110 ], contribute to sustainability [ 112 ] and mitigate the potential negative impacts of increased urbanisation.

Future Research Directions

This brief review demonstrates some of the evidence that biodiversity contributes to better health and well-being in urban areas. This is important because of the increasingly urbanised character of human populations and the greater health and well-being stresses which come with urban living, such as air pollution and extreme temperatures, despite the greater proximity of health services. While several reviews already reported direct relationships between biodiversity and human health outcomes [ 30 , 68 , 105 , 113 •, 114 , 115 •], they do not shed light on the causal pathways through which biodiversity may work to establish those relationships. This lack of mechanistic understanding of pathways linking biodiversity to human health limits the application of nature-based solutions in public health [ 26 ]. In order to facilitate cross-sector integration between biodiversity conservation and public health [ 9 ], it is necessary to better identify and characterize the causal pathways linking biodiversity to human health.

Consequently, a key research challenge is to investigate the causal pathways linking specific elements of biodiversity to human health [ 17 , 105 , 113 •] and test theoretical frameworks [ 18 ••, 116 •]. How exactly does biodiversity influence human physical, mental and social health? Four domains of pathways have been proposed by Marselle et al. [ 18 ••]: (1) reducing harm (e.g. provision of medicines, decreasing exposure to air and noise pollution), (2) restoring capacities (e.g. attention restoration, stress reduction), (3) building capacities (e.g. promoting physical activity, transcendent experiences) and (4) causing harm (e.g. dangerous wildlife, zoonotic diseases, allergens). These four domains highlight the effects—both beneficial and harmful—that biodiversity can have on human health. Future research should empirically test this theoretical framework by investigating the causal mechanisms underlying biodiversity’s influence on human health.

Another key topic for biodiversity-health research is to understand which aspects of biodiversity matter and their perception. It is not clear to what extent perceived biodiversity measurements [ 91 , 92 ] coincide with actual, scientifically recorded, biodiversity measurements. While some studies show a relationship of actual biodiversity with health and well-being measures [ 73 , 91 , 97 , 117 ], other studies have found no relationship [ 76 , 118 ]. When measures of actual and perceived do not coincide, this suggests that different things are being measured in the perceived biodiversity assessment, rather than actual biodiversity [ 98 ]. As such, perceived biodiversity measures cannot replace a measure of actual biodiversity [ 92 ] and vice versa. Future studies could usefully investigate whether perceived biodiversity mediates the effect of actual biodiversity on human health [ 68 •].

A third key research frontier is the exploration of contact with biodiversity, which is defined as both exposure to and experience of biodiversity [ 18 ••]. Exposure is defined as the amount of contact that an individual or population has with biodiversity [ 18 ••, 20 ], and can be measured in two ways. The first is actual exposure to biodiversity, based on the frequency (how often) and duration (how long) a person or population has had contact with biodiversity [ 108 , 119 ]. The second is a proxy measure of actual exposure, where the proximity or availability of biodiverse habitats, species communities or specific species within a geographical area near to a person’s location (e.g. neighbourhood, state, country) is used as an indicator for exposure [ 19 , 20 ]. But, the vicinity of biodiversity and potential accessibility does not always equate to actual accessibility and actual exposure, i.e. that a person will come in contact with biodiversity. Approaches to exposure measurement do not capture the experiential aspects of contact with biodiversity—the experience of biodiversity. As people may experience biodiversity differently [ 74 , 120 ], one’s experience of contact with biodiversity may be highly relevant for individual health effects [ 10 ]. For example, humans experience biodiversity through the five senses, which could account for differential impacts on health outcomes [ 121 ]. There are four types of biodiversity experiences based on whether we are exposed to the specific elements of biodiversity directly (e.g. in a park) or indirectly (e.g. through a window) and whether we interact with biodiversity intentionally or incidentally as a by-product of another activity [ 18 ••]. The type of experiences people have with biodiversity may influence health outcomes and mediating pathways [ 18 ••]. Future studies need to investigate actual exposure to biodiverse environments or species in order to unravel ‘dose-response’ relationships [ 122 ]. Investigating how the senses in which we can experience biodiversity and the specific types of experiences with biodiversity elements affect health outcomes is an urgent research need for understanding biodiversity-health relationships [ 18 ••, 20 ].

Biodiversity Loss Is a Public Health Issue

Biodiversity is essential for the survival of the human species. Therefore, those whose role is to protect the public’s health should join the campaign against climate change and other threats to biodiversity [ 123 ]. At the global and government levels, cross-sector efforts should ensure that biodiversity, climate and health considerations are jointly integrated into government-wide and worldwide strategies. A good example of this is the UK environment strategy, which incorporates human health as a central goal [ 124 ]. Likewise, health strategies should also emphasise the importance of a healthy natural environment.

The biodiverse natural environment should be considered as a foundation for public health. Modern public health must also address health inequalities, whereby low socio-economic status can lead to up to 10 years life lost [ 125 ]. However, there is also inequality in access to natural environments, with more socially and economically deprived people living more likely in urban areas that are denuded of biodiversity [ 126 ], confounding efforts to establish the relationship between access to biodiverse environments and health. In analyses that control for social deprivation, health outcomes are shown to be related to several characteristics of greenspace (e.g. [ 61 ]). Although it is not possible to prove causality, the precautionary principle would suggest that investment in creating and maintaining natural environments in socially deprived areas will benefit public health and reduce health inequalities.

A key role of a public health professional is as a commissioner for health interventions. Such ‘green interventions’ should support lifestyles that benefit both humans and the environment, such as investments in cycling and walking infrastructure. Some of these ‘green interventions’, such as volunteering conservation projects, can have the dual impact of enhancing natural environments while simultaneously bringing human health benefits [ 127 •]. Such health interventions are based on the concept of ‘salutogenesis’ whereby the emphasis is on supporting well-being before it becomes necessary to treat disease [ 128 ]. ‘Social prescribing’ connects people to holistic interventions, and green interventions fit very well within this salutogenesis model [ 127 •].

However, to promote green health interventions with funding and embedding in strategies requires evidence of their effectiveness. As these interventions are complex and difficult to evaluate, those who fund research and interventions must understand and embrace this complexity. Research that quantifies the human health benefits and cost savings from investing in public greenspaces is needed to build persuasive evidence for investment. To foster the evidence base, cost-benefit analyses can assess the effectiveness of nature-based solutions on human health outcomes, such as reducing health care costs for noncommunicable diseases like depression [ 20 , 86 •], nature conservation and climate change mitigation. Scenario building and statistical modelling can assist in forecasting the effects of further biodiversity losses or gains for human health and thereby inform management priorities. This will help foster informed decision making as well as appropriate indicator development to monitor biodiversity and health trends to adapt integrated management and policy accordingly.

Policy Support for Biodiversity and Health

The increasing relevance of biodiversity for health and well-being is increasingly recognised in global and regional policy development [ 9 , 129 , 130 ], such as the UK Government report on the economics of biodiversity [ 131 ], the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment [ 2 ] or the IPBES pandemic report [ 132 ]. Since 2012, the WHO has collaborated with the CBD to raise awareness of the interconnections between biodiversity and human health [ 9 •, 115 ]. While progress is being made linking the biodiversity and public health sectors [ 133 ], ‘silo-thinking’ is still common, and cross-sectoral approaches still need to be embraced by policy [ 123 ]. The current COVID-19 pandemic has highlighted the severe health consequences of unsustainable biodiversity management, as well as the importance of urban greenspaces for fostering physical and mental health and well-being and reducing health inequalities [ 134 , 135 ]. The PBES has recently published a workshop report on biodiversity and pandemics [ 132 ] and integrates wider human health considerations in their current IPBES Nexus Assessment on the interlinkages among biodiversity, water, food and human health ( https://ipbes.net/nexus ).

Biodiversity-related public health threats as well as opportunities can only be addressed by integrating public health and environmental perspectives [ 127 •]. To implement actions, policy frameworks are needed to assure that human health is included as integral to biodiversity conservation policies [ 9 •]. Likewise, biodiversity should be considered in public health policies as well as spatial and urban planning [ 136 ]. The international policy discussions on the post-2020 global biodiversity framework of the CBD, the European Biodiversity Strategy and the European Green Deal [ 137 ] provide pertinent leverage points to strengthen the biodiversity-health policy agenda.

Designing Cities for Both People and Nature

Urban planning decisions, such as fostering nature-based solutions in cities, can form proactive solutions to tackle both human health challenges and biodiversity loss while mitigating and adapting to climate change [ 7 , 20 , 138 ]. While urban planning policies explicitly consider nature conservation and climate change, the impacts of city planning decisions on human health is often considered implicitly [ 136 ]. Addressing health issues in urban planning is necessary for the creation of sustainable healthy cities that are able to cope with future developments, such as rising rates of mental health and cardiovascular diseases, future pandemic lockdowns and increasing climate change–related impacts. For this reason, interdisciplinary cooperation between urban planning, biodiversity experts, climate modellers and the health sector should be strengthened.

Conclusions

With this review, we provide an overview of the rapidly developing research field of biodiversity and human health linkages with a focus on urban areas. We discuss the importance of exposure and experience of biodiversity for attaining health effects and develop a research agenda to quantify health benefits and unravel the specific causal mechanisms through which biodiversity affects human health. This understanding will enable urban planners and policy makers to harness opportunities for linking biodiversity, climate and public health agendas and to invest into biodiversity as foundation of our health.

Acknowledgments

We thank the following funding agencies for supporting the work reported here: Volkswagen Foundation (grant number 96 067) and the German Federal Agency for Nature Conservation (BfN) BIOCLIM project (funding code 3514 80 020A). AB gratefully acknowledges the support of iDiv funded by the German Research Foundation (grant number DFG–FZT 118, 202548816). SL and PC are supported by the UK Natural Environment Research Council, the Arts and Humanities Research Council and the Economic and Social Research Council under the Valuing Nature Program (grant number NE/N013530/1).

Declarations

Melissa Marselle, Sarah Lindley, Penny Cook, and Aletta Bonn declare that they have no conflict of interest.

This article does not contain any studies with human or animal subjects performed by any of the authors.

This article is part of the Topical Collection on Built Environment and Health

The original online version of this article was revised: Following the publication of the original article, the publisher regrets a mistake in co-author, Aletta Bonn's affiliation.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Change history

A Correction to this paper has been published: 10.1007/s40572-021-00321-9

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Sarah J. Lindley, Email: [email protected] .

Penny A. Cook, Email: [email protected] .

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Nicholas Kristof

The Case for Saying ‘I Do’

By Nicholas Kristof

Opinion Columnist

With little notice, the United States may be crossing a historic milestone in family structure, one that may shape our health, wealth and happiness.

Historically, most American adults were married — more than two-thirds as recently as 1970. But the married share has crept downward , and today only about half of adults are married. Depending on the data source, we may already have entered an epoch in which a majority are not married.

“Our civilization is in the midst of an epochal shift, a shift away from marriage,” Brad Wilcox, a sociologist who directs the National Marriage Project at the University of Virginia, writes in his new book, “ Get Married .” “In place of marriage, many Americans are remaining single or simply living together without wedding rings. And to be clear, it’s more of the former than the latter.”

Wilcox believes that perhaps a third of today’s young Americans will never marry. As a long-married romantic myself, I find that troubling, but it’s not just soggy sentimentality. Survey data indicates that married couples on average report more happiness, build more wealth, live longer and raise more successful children than single parents or cohabiting couples, though there are plenty of exceptions.

“Fixing what ails America starts with renewing marriage and family life, especially in poor and working-class communities where the fabric of family life is weakest,” Wilcox argues.

He’s up against a counter view that one should dodge family responsibilities, relish freedom and play hard. Many boys and men flock to the online rantings of Andrew Tate , the misogynistic influencer facing human trafficking charges, who has argued, “There is zero advantage to marriage in the Western world for a man.”

Some women have likewise celebrated freeing themselves from an institution that often shackled them to cooking, laundry and second-class status at a cost to their careers. As women have enjoyed more economic opportunities, they’re less often forced to marry some oaf who gets violent after a few drinks — and, anyway, what self-respecting woman with independent means would want to marry, say, a fan of Andrew Tate?

Yet even as marriage has receded, the evidence has grown that while it isn’t for everyone, in many cases it can improve our lives more than we may appreciate.

“Marriage predicts happiness better than education, work and money,” Wilcox writes. For example, survey data indicates that getting a college degree increases the odds of describing oneself as “very happy” by 64 percent. Earning a solid income lifts the odds by 88 percent. Being “very satisfied” with one’s job raises them by 145 percent. And marriage increases the odds of being very happy by 151 percent — while a “very happy” marriage boosts the odds by 545 percent.

I’ve long been interested in family structure for two reasons. First, I believe the left made a historic mistake by demonizing the Moynihan Report, which 59 years ago this month warned about the consequences of family breakdown. Daniel Patrick Moynihan was prescient, for we now know that households headed by single mothers are five times as likely to live in poverty as those with married couples.

Second, loneliness and social isolation are growing problems. One poignant example: Perhaps 100,000 or more dead bodies in America go unclaimed each year, often because there are no loved ones to say farewell. It’s a topic explored in another recent book, “The Unclaimed,” by sociologists Pamela Prickett and Stefan Timmermans.

Marriage doesn’t solve loneliness and social isolation, but it helps. And there is good news on the family front: The divorce rate has dropped to a 50-year low , and the share of children raised in an intact family with married parents has increased slightly in recent years. Today about 51 percent of American kids reach adulthood with the same two parents they started out with.

But it’s also true that the marriage rate has collapsed, particularly for working-class Americans. Of those without a high school diploma, more than two-thirds are unmarried.

Wilcox writes that “the American heart is closing,” but I wouldn’t put it that way. I think many Americans want to marry but don’t feel sufficiently financially stable, or they can’t find the right person.

I’m staggered by the interest in virtual boyfriends and virtual girlfriends. One virtual boyfriend app offers an assortment of possibilities such as “polite and intelligent Edward” or “romantic and cute Daniel.”

“Don’t be shy, he’ll definitely like you,” the app advises. “He knows how to cheer you up, so you won’t feel sad or lonely.”

Just reading that makes me achingly sad. Virtual mates feel like an elegy for civilization.

One reason for the decline in marriage in working-class communities may be a lack of economic opportunity, particularly for men, and another may be culture and changing norms. That’s worth pondering. In polls, majorities of college-educated liberals seem diffident about marriage, unwilling to criticize infidelity and disagreeing with the idea that children do better with two married parents. Perhaps this liberal lack of enthusiasm for marriage also accounts for the marriage penalties built into benefit programs like Medicaid, in turn disincentivizing marriage for low-income Americans.

Wilcox scolds elites for clinging to traditional values themselves — in the sense that they get married and have kids for the most part — even as they are reluctant to endorse marriage for fear of seeming judgmental or intolerant. Elites “talk left but walk right,” he says.

We are social animals, Aristotle noted more than two millenniums ago, and it’s still true. Spouses can be exasperating (as my wife can attest), but they also can cuddle, fill us with love and connect us to a purpose beyond ourselves. They are infinitely better, for us and for society, than virtual lovers on an app, and that seems worth celebrating openly.

Update: I have the final figures for my 2023 holiday giving guide , so I owe readers a follow-up and a “thank you.” More than 5,400 readers contributed a total of $7.2 million to the three nonprofits I recommended , and here’s what the donations will mean in practical terms: 12,150 girls in rural Africa will be supported for a year of high school through Camfed ; 1,645 young people in the United States will be supported for a year of instruction and mentoring to succeed in college or technical school through OneGoal ; and 4,218 low-income Americans will get free training in information technology through Per Scholas so that they can start better-paying careers in the tech world. All three organizations do excellent work. In addition, 671 readers volunteered to help refugees settle in the United States through my recommended volunteer opportunity, Welcome.US . Thanks so much to all who donated and volunteered: People are benefiting here and abroad from your generosity.

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Nicholas Kristof became a columnist for The Times Opinion desk in 2001. He has won two Pulitzer Prizes, for his coverage of China and of the genocide in Darfur. @ NickKristof