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Watershed Protection

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Biodiversity

What is biodiversity?

Biodiversity is the natural variety found in living systems and individuals. The term can refer to different levels of organization. Genetic diversity is the variation in genetic characteristics of a species. Species diversity refers to the number and types of different species that inhabit an area or ecosystem. Ecosystem diversity is the variety of habitat types or ecosystems found within a landscape.

The exact number of species on earth is not known: estimates range from 2 million to 100 million. Of these, only about 1.8 million have been identified by biologists. In particular, a large percentage of organisms, such as bacteria, insects and crustaceans, are largely unknown. We are fortunate to live in the province with the most biodiversity in Canada. Insect species alone number between 50,000 and 70,000. Other species in B.C. include (at least) 143 mammals, 454 birds, 20 amphibians, 19 reptiles, 2,850 vascular plants, 1,600 lichens, 522 attached algae, and over 10,000 fungi.

The great abundance of life found in many of B.C.’s marine areas rivals the biodiversity of tropical rain forests. Around 7000 marine species have been identified in the region off the coast of B.C., and at least as many unidentified species are believed to exist.

Numbers aside, all types of biodiversity are essential to the function of ecosystems and to the continuation of life on earth. As humans, we are part of, and dependent on, the earth’s ecosystems. Biodiversity is therefore directly important to our own survival.

What threatens biodiversity?

Unfortunately, biodiversity is currently declining around the world. This is apparent in the rate of species extinction; every day, one species is lost to the world forever. Mass extinctions have occurred before, due to global catastrophes such as climate change and meteor impacts. The difference today is that humans appear to be the cause. Furthermore, the rate of extinction is 1,000 to 10,000 times greater than what would naturally occur. In British Columbia, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has identified over 150 species that are at considered endangered, threatened or of “special concern.”

Ecosystem diversity is also threatened. For example, in southeastern Vancouver Island, over 92% of the land base consists of “modified,” landscapes. These include urban and agricultural areas, as well as forests less than 100 years old. Sensitive ecosystems such as wetlands, coastal bluffs and older forests are disappearing. Some of the main threats to biodiversity fall under the following categories:

  • Habitat Loss and Degradation: activities such as urban expansion, logging and shoreline modification modify the landscape so that fewer organisms can survive there.
  • Invasive Species: non-native species that aggressively compete with native plants and animals can drastically alter the landscape. Dense plant monocultures, for example, provide little habitat or food for local animals.
  • Pollution: chemical and sewage pollution can be directly toxic to many plants and animals, and can modify the oxygen and nutrient content of the air and water.
  • Climate change: The Intergovernmental Panel on Climate Change (IPCC), a consortium of hundreds of climate scientists around the world, believe that humans are likely contributing to an overall increase in global temperature.(5) This threatens many animal and plant species that will probably not be able to adapt fast enough.
  • Excessive hunting, fishing and “pest control”: some of the animals threatened by these actions include bison, whales, seals, wolves, ground squirrels and a large percentage of the world’s fish species. Chemicals used to control pest can often harm non-target species, and contaminate food and water.

Why is biodiversity important to ecosystems?

Ecosystems are composed of complex relationships between organisms and their physical environment. These relationships are constantly fluctuating, and are rarely predictable. This relatively simple concept has eluded western scientists until quite recently. Ecosystems have been treated like machines that will supply our needs as long as some basic conditions are optimized. For example, species deemed to be undesirable are removed and replaced by commercially valuable species that are “harvested” at constant rates. This practice ignores the complex relationships in ecosystems and the importance of biodiversity, and has had some catastrophic consequences.

Different species fulfill important functions within the ecosystem. For example, they may be photosynthesizers, decomposers, herbivores, carnivores or pollinators (see figure below). In ecosystems that have many species that can fulfill a given function, the ecosystem is more resilient. In other words, it is able to respond to disturbances such as disease or fire without collapsing. This apparent redundancy is very effective insurance, for if one species succumbs to a disease, its “function” in the ecosystem is taken over by another species. Ecosystems with limited diversity, including monocultures (areas entirely dominated by a singe species, as in most agricultural crops), are much more prone to disease than diverse natural systems.
image - common ecosystem functional groups
A few common functional groups within ecosystems (6)

Why is biodiversity important to people?

Humans depend on functions performed by the world’s ecosystems. Ecosystems produce oxygen, purify and detoxify the air and water, store and cycle freshwater, regulate the climate, form topsoil, prevent erosion and flood damage, and produce raw materials, foods and medicines. Most of these ecosystem services cannot be replaced by human technology, at any cost. Biodiversity is the “library” of species and genetic information that allows the Earth’s systems to function.

Some economic and social arguments further illustrate the importance of biodiversity:

  • The value of the world’s ecosystem services has been (conservatively) estimated at $33 trillion per year.
  • The state of New York discovered that wetlands and other natural systems in the watershed accomplished water purification and filtration that would require an $8 billion water treatment plant to replace. Protecting and remediating these natural systems cost much less.
  • Over 75% of staple food crops and 90% of flowering plants worldwide depend on pollination by insects and other animals. Between 100,000 and 200,000 species of animals act as pollinators, and their populations are declining.
  • Crop diversity is substantially falling as agri-business is taking over food production from small family operations that once supplied our population. The practice of saving seeds is being abandoned in favour of hybrid varieties that require reseeding every year, as well as large amount of chemicals. This trend affects the self-sufficiency of farmers worldwide. Reduction of genetic diversity of food crops makes these crops more susceptible to disease and pest outbreaks.
  • Non-timber forest products such as wild foods, floral greens, herbal medicines and edible and medicinal mushrooms may be sustainably harvested from a healthy forest. If carried out with respect for the environment and for First Nations knowledge, this emerging industry may be worth many millions of dollars to the economy in BC. These plants and fungi are part of natural diversity in forests, and are less abundant in areas that have been clear-cut.
  • Virtually all natural and pharmaceutical medicines are composed of (or derived from) natural compounds of plants, fungi, microbes and animals. In areas of severe environmental degradation, many species with known or undiscovered healing properties are threatened with extinction.
  • The highly biodiverse coastal environment of BC contributes 4.5% to the provincial GDP.

Many people also believe that plants and animals have the right to exist, that they have value in and of themselves. This intrinsic value does not depend on any utility for human benefits.

In summary, the known and unknown species of the world may one day provide us with answers to questions we do not yet know how to ask. Given how little we know about how nature functions, preserving biodiversity is an important investment in our future, and a priceless gift to future generations.

What can I do to help preserve biodiversity?

For information on preserving biodiversity, please visit our How Can I Help section.

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