Maarg Manthan · Topic 7.2

Effects of Loss of Biodiversity

Environment & Ecology › Threats to Biodiversity and Conservation Strategies · Topic 7.2

The loss of biodiversity weakens the ecosystem services that support human life and economies. Ecologically, it reduces the stability and resilience of ecosystems, simplifies food webs, lowers primary productivity, speeds up the spread of pests and diseases, and can trigger cascading effects when keystone species are lost, as happened when sea otters were removed from kelp forests and sea urchins destroyed the kelp. Economically, it threatens food security by shrinking crop and livestock genetic diversity, harms fisheries, timber, pollination and medicines, and raises costs of water treatment and disaster protection. Socially, it hurts the livelihoods and culture of forest-dependent and coastal communities. Climate regulation suffers too, as degraded forests, peatlands and mangroves store less carbon.

5 min read · UPSC Prelims · Environment & Ecology · Threats to Biodiversity and Conservation Strategies

At a Glance

Ecological Less stability and productivity
Economic Food, fisheries, medicine
Health Disease risk
Cascade example Sea otters and kelp
Social Livelihoods
Exam link UPSC Prelims, Environment & Ecology: Threats to Biodiversity and Conservation Strategies

Where Does It Fit?

This topic follows the causes of biodiversity loss. It shows what is at stake before the topics on extinction, the Red List and conservation methods. Previous topic: Causes of Biodiversity Loss. Next topic: Extinction of Species and Mass Extinction.

Type	Effects and examples
Lower ecosystem stability	Species-rich systems resist drought and pests better. David Tilman’s Minnesota grassland experiments showed more diverse plots had higher productivity and recovered better from drought
Trophic cascades	Removal of top predators or keystone species changes whole systems. Wolves in Yellowstone controlled elk and allowed willows to recover; sea otter loss led to urchin barrens
Pollination crisis	Decline of bees and other pollinators threatens crops; over 75 percent of leading food crops depend on animal pollination
Loss of genetic resources	Fewer crop varieties and wild relatives limit breeding for resistance, as with the Irish potato famine
Fisheries collapse	Overfishing and habitat loss reduce catch, as with the Grand Banks cod in 1992
Water and soil	Loss of forests and wetlands cuts water purification, flood control and soil protection
Climate	Loss of forests, mangroves, peat and seagrass adds greenhouse gases and weakens carbon sinks

How Does Biodiversity Loss Affect Health and Livelihoods?

Medicines: loss of species removes potential drugs, with about a quarter of modern drugs derived from plants
Zoonotic disease: habitat disturbance and wildlife trade bring people closer to animals, raising the risk of diseases such as Nipah, Ebola and COVID-19; the One Health approach links human, animal and environmental health
Dilution effect: high diversity can lower disease risk by diluting the number of competent hosts
Food security: reliance on few crops makes systems vulnerable; only a handful of crops give most calories
Livelihoods: fisherfolk, forest dwellers and farmers lose income
Culture: sacred species and landscapes disappear
Disaster protection: loss of mangroves and reefs raises storm damage
Economic cost: the World Economic Forum estimates about half of global GDP depends moderately or highly on nature

What Else Should You Remember?

Resilience: the ability of an ecosystem to recover after disturbance
Insurance hypothesis: diversity buffers ecosystem function against change
Redundancy: many species doing similar roles protect function
Keystone species: have outsize effects, such as starfish Pisaster in intertidal zones (Robert Paine’s experiment)
Sea otter case: fur trade removed otters, urchins boomed, kelp forests vanished
Yellowstone wolves: reintroduced in 1995
Pollinator decline: due to pesticides, habitat loss and disease; colony collapse of honeybees
Pesticide cost: in some regions farmers hand-pollinate fruit trees, as in parts of Sichuan, China
Soil biodiversity: loss reduces fertility
Wetland loss: raises flood risk, as seen in Chennai and Srinagar floods linked to wetland encroachment
Mangrove loss: cyclone damage was larger where mangroves were lost, as in the 1999 Odisha super cyclone
Coral reef loss: lowers fish catch and coastal protection
Genetic erosion: loss of landraces due to modern varieties
Seed banks: such as the Svalbard Global Seed Vault guard crop diversity
Invasive effect: can cause economic losses; India’s cost runs into billions of dollars per year in estimates
Human wellbeing: access to nature improves mental health
Planetary boundary: biosphere integrity is one of the nine boundaries, with genetic diversity already beyond safe limits
Economic assessments: the Dasgupta Review (2021) argued that nature is an asset
TEEB: study to value ecosystem services
Link to previous: see Causes of Biodiversity Loss
Link to next: see Extinction of Species and Mass Extinction
Link to services: see Functions of Biodiversity
Caution: the diversity-stability link is debated for some systems, but most evidence supports it for productivity
Slow effects: some losses show up decades later (extinction debt)
Exam hint: give one example each of ecological, economic and health effects

Why Does It Matter for the Exam?

Cascade: otters, wolves
Health: zoonoses
Economy: pollination, fisheries
Current affairs link: One Health and nature-related finance
Common errors: saying biodiversity loss affects only wildlife

As an analytical point, biodiversity loss is not only a wildlife issue but a risk to food, health, water and economic stability. Treating nature as natural capital moves the debate from sentiment to risk management.

Why Is This Topic Important?

Stability Falls
Cascades Keystone loss
People Food, health

What Came Next?

The next topic covers extinction of species and mass extinction. Next topic: Extinction of Species and Mass Extinction.

Key People and Terms

Trophic cascade Chain effect through food web
Resilience Recovery ability
Zoonosis Animal-to-human disease
One Health Integrated health approach
Genetic erosion Loss of genes
Dilution effect Diversity lowering disease risk

Exam Corner

Points to Remember

Wolves in Yellowstone showed a cascade.
Over 75 percent of food crops use pollinators.
One Health links people, animals, environment.
Mangrove loss raises cyclone damage.
Tilman tested diversity and productivity.

Do Not Confuse With

Trophic cascade and food chain Top-down effect versus energy path
Resilience and resistance Recovery versus staying unchanged
Zoonosis and epidemic Animal origin versus spread

Memory Hook

Lose a species, lose the link: stability, cascade, crops, cure.

Mains Angle

Questions ask for effects and examples. These points help.

Ecology Stability
Economy Services
Health Zoonoses

A Question You May Face

An original practice question, not a past paper question.

“Examine the ecological, economic and health consequences of the loss of biodiversity with suitable examples.”

How to Answer

Ecology Cascades.
Economy Services.
Health Disease.
Society Livelihood.

GS Relevance

Prelims: effects, cascade examples, links to health. GS Paper 3: environment and economy.

Frequently Asked Questions

What are the effects of biodiversity loss on ecosystems?

Loss of biodiversity makes ecosystems less stable and productive, reduces their ability to resist or recover from drought, pests and climate shocks, simplifies food webs and can set off cascading changes when keystone species disappear. Services like pollination, water purification and carbon storage also decline.

What is a trophic cascade?

A trophic cascade is a chain of effects that spreads through a food web when the numbers of a top predator or keystone species change. The reintroduction of wolves to Yellowstone controlled elk grazing and let willow and aspen recover, while loss of sea otters allowed urchins to destroy kelp forests.

How does biodiversity loss threaten food security?

It threatens food security by reducing the pollinators and natural pest controllers that crops need, shrinking the genetic variety of crops, livestock and wild relatives that breeders use, depleting fish stocks and degrading soils. A diet and farming system that relies on few species is more exposed to pests and climate shocks.

How is biodiversity loss linked to disease outbreaks?

Clearing forests, farming expansion and wildlife trade bring humans, livestock and wild animals into closer contact, which raises the chance of animal diseases jumping to humans, such as Nipah, Ebola and COVID-19. Diverse ecosystems can dilute disease risk, which is the basis of the One Health approach.

Why does loss of mangroves matter?

Mangroves protect coasts from cyclones and tsunamis, act as nurseries for fish and prawns, trap sediments, filter pollutants and store large amounts of carbon. Their loss raises storm damage, reduces fisheries and releases stored carbon, as the Odisha super cyclone of 1999 caused heavier damage where mangroves had been removed.

PYQ Practice — Statement Analysis

1 Reintroduction of wolves in Yellowstone is an example of a trophic cascade.

True

Restored vegetation.

2 Loss of biodiversity has no effect on human health.

False

It affects disease risk and medicine.

3 Loss of sea otters led to expansion of kelp forests.