What is biodiversity, and why is it so important?
It’s a word we hear a lot –
Biodiversity encompasses all life on Earth, and the biodiversity we see today is the product of 4.5 billion years of evolution.
Biodiversity is often used to mean the number of individuals and variety of species within an area. However, there are in fact three levels to biodiversity.
The level most of us are most familiar with is the variety and abundance of species – be that plant, animal, fungus, or microorganism – in an area or ecosystem (species diversity). But number of species and individuals is just one
Biodiversity includes a smaller scale, too – the variation in
What is happening to biodiversity?
Biodiversity is in crisis, both in the UK and globally. Biodiversity loss is accelerating at an unprecedented rate, while the average size of wildlife populations worldwide has fallen by 73% between 1970 and 2020.
The latest UK State of Nature report found that “the UK is one of the most nature-depleted countries in the world”. Butterflies have lost 97% of their habitat, and pollinating insects like bees, hoverflies and moths, which play a critical role in food production, are almost all declining in numbers, and have also suffered an average reduction in distribution of 18% since 1970.
Of the 4 billion or so species that are thought to have ever evolved, 99% are now extinct. Many of these have been lost during previous ‘mass extinction’ events caused by huge enviromental upheaval, such as that which wiped out the dinosaurs. Data tracking extinctions over time has shown that we are currently in another period of vastly accelerated extinctions, with rates 10 to 100 times higher than the natural baseline. This has caused some scientists to suggest that we are entering a sixth mass extinction.
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Biodiversity is key to the stability of ecosystems. The higher the biodiversity, with a wide range of species and interactions, the more resilient the ecosystem is, and the more able it is to adapt to and overcome changes, such as changes in climate, outbreaks of disease or pollution, or the arrival of non-native species.A high level of biodiversity forms a complex food web; this is key to resilience as it provides a buffer to knock-on effects of individual extinctions – the more species there are, the more likely that there will be alternative food sources for those higher up the chain should a prey species be lost.
The UN cites biodiversity as being our strongest natural defence against climate change. Healthy ecosystems, and the biodiversity that forms them, are the world’s largest carbon sinks (capture and long-term storage of carbon). Heathy and functional peatlands, seagrass forests, mangrove swamps and terrestrial forests are all critical in limiting climate change.
From a human-centric perspective, biodiversity is crucial to our survival – the species it includes, and the ecosystems and ecosystem processes it creates, provide the basic resources we need to survive, such as food, clean air, rainwater, a stable climate, and medicines.
Beyond survival, biodiversity is important for human wellbeing – it enhances our landscapes, provides recreational and economic opportunities, and contributes to health and wellbeing through interactions with wildlife and ecosystems. It’s also immersed in our cultures, forming the basis of cultural traditions and ways of life, as well as forming the basis of numerous industries worldwide.
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There’s a lot more to biodiversity loss than loss of species. It encompasses loss of genes, populations and ecosystems, too. Losing genetic diversity within a species, through its populations shrinking or disappearing, is as much a loss of biodiversity as losing the species as a whole.
In an ecosystem, different species support different functions in different places at different times. Ecosystem processes such as primary productivity (conversion of sunlight and carbon dioxide into biomass that becomes the foundation of the food web), nutrient cycling, and decomposition of dead material rely on biodiversity.
Loss of biodiversity can lead to ecosystem collapse. With that comes loss of the environmental benefits ecosystems provide and on which we rely (ecosystem services), such as providing clean air, regulating water quality and building healthy soils, as well as pollination, on which we depend for food.
Healthy ecosystems provide 75% of global freshwater resources. Scientists highlighted the value of this service in 2008 when they reported that installing a new water plant to treat New York’s water, to replace a service once provided naturally by the ecosystem in the catchment basin, would cost $8-9bn. Restoring the catchment basin would cost only $1bn, higlighting the economic advantage of nature-based solutions.
In the UK alone, insect
With 50% of modern medicines derived from natural sources, and research of processes in nature frequently informing the development of treatments, biodiversity is likely to hold compounds for cures and clues to medical breakthroughs that we haven’t yet discovered. For example, scientists were studying how a gastric-brooding frog was able to turn off acid production in its stomach in the hope of applying this in human ulcer treatment, when the frog went extinct, taking with it those medical possibilities. With each new extinction, unknown potential is lost.
What are the threats to biodiversity?
Most of the major causes of biodiversity loss are driven by global human population growth: we are simply consuming, and producing, too much. These are widely accepted by scientists as the top threats to biodiversity worldwide:
- Habitat loss: deforestation, destruction of habitat for agricultural land or development, and other land use change is thought to be the biggest driver of biodiversity loss.
- Climate change: scientists have predicted that on the basis of mid-range climate-warming scenarios, by 2050, 15-37% of species will be ‘committed to extinction’. Currently, the rate of climate change is exceeding mid-range scenarios. The UN reports that climate change has already caused the loss of local species, increased diseases, and driven mass mortality of plants and animals.
- Over-exploitation: this is particularly severe in marine environments, where global fish populations have plummeted from overfishing, and sharks have declined by 80% with 39 species listed as Endangered by IUCN, with 26-73 million being ‘harvested’ for fins each year.
- Pollution: contamination of the environment with toxic substances such as pesticides, heavy metals and micro- or nano-plastics, aquatic ecosystem destruction through run-off of fertilisers (eutrophication), and air pollution and the associated acid rain are all detrimental; as well as leaching of compounds such as pharmaceuticals (including the toxic effects of pet flea treatments to waterways and birds). There is no river in the UK that is not polluted and no environment on Earth that is free of nanoplastics.
- Invasive non-native species: the WHO reports that these contribute in some way to 60% of species extinctions, and cause $423 billion in global economic damage each year.
How to conserve biodiversity
The most effective ways to conserve and increase biodiversity on a national and global scale are through 1) enviromental policy such as conventions and treaties, and 2) establishing protected areas, which are effectively policed and managed. The biggest benefit is achieved when protected areas are located to align with hotspots of biodiversity and link up fragmented populations and ecosystems.However, there are also lots of actions that can be taken on a smaller scale – by all of us – to make a positive difference.
What can you do?
Conserving biodiversity really can begin in our own back gardens. With over 2,670 species of plants and animals having been found in one typical UK garden, we know the value they hold for biodiversity – and the potential to make a difference.
- Plant for wildlife – fill your garden with RHS Plants for Pollinators and bird-friendly plants to ensure there is plentiful food available. If you prefer to have more confidence that the plants you buy don’t contain
pesticide - Include a wide range of plants – both natives and non-natives, as these both have value for biodiversity.
- Avoid pesticides and weedkillers – a heathy ecosystem will keep numbers of less desirable species in check. Consider whether ‘weeds’ might actually be bringing benefits for wildlife, and always use non-chemical methods of control.
- Be less tidy – long grass, fallen leaves, and piles of ‘woody waste’ such as logs and brush all provide habitat, and chop and drop is a great way to help wildlife while saving yourself work. Once you’ve optimised natural habitat, you can supplement that by providing accommodation such as bird boxes, bat boxes, hedgehog houses and bee posts (as simple as drilling deep, narrow holes into fence posts to create nesting sites for solitary bees).
- Create a pond – this is probably the single garden feature that supports the most biodiversity, and is easy to make.
- Embrace a flower-rich lawn – wild plants that naturally arrive in lawns, such as dandelions, clover, buttercups, yarrow and self-heal, are all fantastic for biodiversity.
- Leave perennials standing over winter – the vegetation provides shelter for small mammals and a range of other wildlife, while the hollow stems provide hibernacula for invertebrates and the seeds provide food for birds. Wait until March to cut back instead.
- Make a compost heap – these support high levels of biodiversity in themselves, and spreading the finished product on beds improves the health of the soil ecosystem.
- Go peat-free – peatlands are unique and vulnerable ecosystems rich in flora and fauna, as well as the most efficient carbon sink on land, and their depletion for horticultural use destroys habitats and exacerbates climate change. By going peat-free you are helping to preserve biodiversity elsewhere and limit climate change.
- Influence your friends, family and neighbours – each outdoor space that is made more biodiversity-friendly boosts our cumulative positive impact.
