There is a critical issue facing the world concerning environmental decline and the future of life on earth. The issue is the loss of biodiversity on earth, basically the accelerating reduction in the number and population of species, including plants, microbes and animals. Most scientists agree that the rate of species decline is the highest it’s been since at least the last ice age, and that it is caused by a variety of human activities. Reversing the decline is critical to maintaining a healthy planet, but as is usual in cases where change creates winners and losers, it is complicated. Let’s look at the terminology, the causes and examples of species decline, why it is important, and how home gardeners can help.
Meanings and Relationships of Species, Biodiversity, Ecosystems and Ecosystem Services?
These definitions explain the relationships of key mutually-dependent elements and why reversing species decline is so important:
Species: the principal classification unit of organisms. Individual species are a group of organisms that can reproduce naturally and create fertile offspring. Current population studies estimate that there are 8.7 million species on earth, 6.5 on land and 2.2 in oceans. About 1.1 million have been identified to date.
Biodiversity: the variety of plant, animal and microorganism species on earth and the ecosystems they form. It includes diversity within species and between different species. It covers species in terrestrial, freshwater and marine ecosystems, local and global.
An ecosystem is the combination of different species that live together to form a stable community, interacting with one another and the physical environment, relying on diversity and balance to thrive. The interrelationships between plants, animals and microorganisms, and their essential contributions to building and maintaining healthy water, land and air to support life on earth are what makes maintaining biodiversity so critical.
Ecosystem services are the elements of nature that contribute to human health and well-being. They include photosynthesis, pollination, water and air purification, soil formation and health, nutrient cycling and moderating weather extremes. The decline of biodiversity and ecosystem health causes a similar decline in ecosystem services that adds risk to human health and welfare.
Some Examples of Species Decline
Here are some well-documented examples of species population declines. The links connect to publications that add detail:
- Worldwide:
- A 2/3 loss of worldwide wildlife in the past 50 years
- 1 million species and 40% of the earth’s plants at risk of extinction
- In the US
- A reduction in our bird population by 3 billion since 1970
- A 30% reduction in our pollinator network, affecting food production and flowering plant survival.
- Known population declines for a huge number of species. For example, the 80% decline of the Eastern Monarch butterfly since the 1990s, affected by reduced milkweed supply, their major larval food source, and deforestation in Mexico, their adult wintering location.
Dr. EO Wilson, biologist, naturalist and writer, a lifelong advocate for biological diversity, once said: “If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos.”
We need to take this issue seriously. Let’s review what it means and what we can do about it.
Causes and Impacts of Biodiversity Decline
Worldwide, human population has increased from about 1 billion in 1800 to 8 billion today. During this period, the US population has grown from 5.3 million to 331 million. The similar rapid growth of technology and fossil fuel use has changed the way we live. While it has helped to improve the feeding, housing and life choices of some of earth’s growing population, it has negatively impacted the environment and biodiversity, harming others, human and non-human. Major changes include:
- Habitat loss due to urban growth and deforestation for construction and agriculture
- Pollution from fossil fuel and chemical use by agriculture, manufacturing and consumers
- Climate change due to the increase in atmospheric carbon from 277 parts per million (ppm) in 1750 to 414 ppm today, a 49% increase that is 100 times faster than prior recorded increases. The result is higher air and water temperatures leading to major weather changes including floods, droughts and wildfires, rising ocean levels due to glacial melting impacting coastal and low-lying areas world-wide, and a 30% increase in ocean acidity that is destructive to marine life including coral reefs.
- Wildlife declines due to poaching, exotic pet trading and overfishing
- The spread of invasive species, of plants, animals and microbes, that outcompete and reduce native species.
The Debate Around Causes and Significance
Over 99% of peer reviewed scientific papers agree that humans are the primary cause of climate change and related issues. The science says it is an existential issue that we need to deal with to preserve life as we know it. There are some who disagree, both that humans are the cause and that it is something we need to address.
Those who doubt that humans are the cause argue that climate and species changes have occurred since the planet was formed and this is simply another series of natural changes. But human dominance, and the correlation of changes linked to human population growth, fossil fuel use, industrial growth, technology and chemical use make that denial difficult if not impossible to believe.
Doubters of the importance of the loss of diversity argue that as the dominant species on the planet, humans should manage nature to suit our needs rather than work to preserve natural evolution. This view fails to acknowledge that the human focus has improved life for some, but damaged it for many, human and non-human, and its self-focus ignores the benefits we receive from diverse natural ecologies.
With the rate of diversity loss increasing rapidly, following the science and seeking to rebuild biodiversity to achieve a natural ecological balance, while supporting healthy existence for all life forms, seems like the best approach. Optimizing change by finding the best path from current practices to proposed solutions and committing to moving forward makes sense. Failing to act doesn’t.
How Can Home Gardeners Help?
The general population can engage in thoughtful study and debate what to do and how to do it. Urging representatives at all levels to do the same, separating fact from emotion, is essential.
Gardeners and homeowners can adopt sound ecological practices in our own yards and gardens, and perhaps influence neighborhoods and communities to join the effort.
Suggested approaches for homeowners and gardeners include:
- Following regenerative farming practices in our edible gardens by:
- Limiting tillage by using cover crops, solarization vs herbicides and broadforking rather than tilling
- Keep living roots in the soil through dense crop planting and off season cover crops
- Diverse planting by rotating crops and using multi-species cover crops
- Building soil health by adding organic amendments like compost to the soil surface
- Minimize use of pesticides and synthetic fertilizers
About 15% of US cropland now follows these principles. It is a small start to repair the damage done by past practices. Data indicates that the changes can be made economically and productively. Home gardeners and commercial growers can join this movement.
- Build pollinator habitat including native trees, shrubs and perennials, to increase populations of insects, birds and other species. In my garden, adding pollinator plants that flower throughout the growing season has increased insect and bird populations and eliminated serious damage from garden pests through the summer.
- Use mostly native plants to support native pollinators. Some professionals in the field think the push to native plantings is not as critical as many believe, but it is certainly a good thing. The question isn’t whether native plants are bad, rather how fast native pollinators adapt to new plant species. Dr Doug Tallamy, a highly respected, much published entomologist from the University of Delaware, recommends a 70% native plant base, leaving room for 30% exotics. This seems like a reasonable approach.
- Reduce lawn: Turfgrass lawns are an established element of home landscapes but provide no significant ecological benefit. Regular mowing prevents deep root growth while the fertilizers and herbicides used contribute to polluting our waterways. Reducing lawn area and substituting native pollinator plants is a great way to help local ecology.
- Manage invasive plants which aggressively overtake established natives and spread uncontrollably. By displacing natives, they deny food to the insects we want to encourage. They are relentless, but control is essential. In the Charlottesville/Albemarle area Blue Ridge Prism is the leading resource for information on identifying and treating harmful invasive plants.
- Learn to love insects: Many of us go through life instinctively fearing or swatting any insects we meet. In fact, we need them if we want to have a healthy environment. They pollinate our food, feed our birds and beneficial insects help control insect pests. We can help by getting rid of bug zappers, making exterior lights motion sensitive, using yellow bulbs which don’t attract insects, reducing insecticide use and providing food for them through pollinator plants. For information about invasive insects refer to Invasive Insects | University of Maryland Extension (umd.edu)
- Minimize Chemical Use: Chemical fertilizer and pesticides have become the go-to method of managing soil and controlling unwanted plant disease and insect pests over the past century. While they have helped increase agricultural output, they have provided a short-term benefit at a long-term cost. Much of the damage to soil, soil microbes, insects and marine life is traceable to the use of various chemicals. Regenerative soil building and increasing pollinator populations to reestablish a natural balance, can help reduce the need for chemicals. Following IPM principals is another sensible practice.
Doug Tallamy’s Home Grown National Park (HGNP)
Doug Tallamy advocates for increasing insect and pollinator populations via many of the techniques noted. He has formed a non-profit to encourage home, commercial and agricultural property owners to change landscaping and land management practices, to increase biodiversity. It is called Homegrown National Park. For homeowners, it advocates reducing our turfgrass lawns by 50% and replacing them with native plants (trees, shrubs, perennials). This action, with help from wood lot and agricultural landowners, can make a significant contribution to restoring the decades long species decline in the US.
Tallamy’s basic premise is that all life is better off if humans and nature coexist. HGNP’s emphasis is to provide ways to enable nature to move back into human dominated landscapes. A few key points are:
- 78% of unprotected land in the US is privately owned. Private landowners can have a huge impact.
- In 2005, the US had 40 million acres of lawn that offers virtually no ecological benefit, and the negative effects of regular mowing and fertilizer/herbicide use are significant. Converting half of this to a diverse ecology would provide a huge benefit to struggling plant, animal and microbial species, as well as the environment.
- Key goals are to create a food web to support all life including pollinators, sequester carbon through photosynthesis and manage water sheds.
- Focus on keystone plants, those that provide the most food and habitat benefit to local wildlife.
- While insects are needed to pollinate food sources, they also pollinate 80% of all plants and 90% of flowering plants.
- Practical actions for farmers, relating to roadsides, hedgerows and prairie strips and eliminating neonicotinoid insecticide
- This YouTube video of Dr Tallamy’s presentation to the National Garden Club adds detail.
The Takeaways
Biodiversity and related topics are complex and emotional. This article underscores its importance to the future of life, human and otherwise, on planet earth. It is essential to find a balance with nature, rather than simply control it for our benefit. Climate change and loss of diversity are undeniably happening. We owe it to ourselves and our descendants to act seriously to manage its environmental impacts, in a thoughtful, fact-based, responsible way, for the benefit of all living things.
As Dr Seuss wrote in his surprisingly controversial book “The Lorax”, published in 1971, “…UNLESS someone like you cares a whole awful lot, nothing is going to get better. It’s not.”
The list of sources that follows includes books and articles that I found informative, including the Albemarle County Biodiversity Action Plan (BAP) and Biodiversity Stewardship webpage and the Charlottesville Environmental Sustainability webpage.
Sources:
Books by noted authors:
Sustaining Life: How Human Health Depends on Biodiversity, Edited by Eric Chivian MD and Aaron Bernstein MD, Oxford University Press, 2008.
Half Earth: Our Planet’s Fight for Life, Edward O Wilson, Liveright Publishing Corporation, 2016.
The Sixth Extinction: An Unnatural History, Elizabeth Kolbert, Henry Holt and Company, 2014.
Science based publications from reputable sources:
The importance of Biodiversity, Matthew R. Fisher and Editor, University of Minnesota
Why We Should Care About Biodiversity, Arizona State University, December 7, 2020.
The Statistics of Biodiversity Loss (2020 WWF Report), Owen Mulhern, Earth.Org, Dec 4, 2020.
Articles presenting conflicting views:
Doug Tallamy speaks…Art Shapiro responds, Million Trees fills in the gaps, March 22, 2020.
They Fought the Lawn. And the Lawn’s Done, Cara Buckley, NY Times, 12/14/2022.
40 year old Dr Seuss book that tried to bring attention to the species loss evident 50 years ago: The Lorax, by Dr Seuss, Random House, Inc., NY, 1971
Albemarle County Biodiversity Action Plan (BAP)
Informative County webpage: Environmental Stewardship in Albemarle County
Charlottesville Environmental Sustainability Division website
Featured image: World-wide Biodiversity Illustration: Duke University
