Pourquoi la biodiversité est importante

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What Is Biodiversity?

Biodiversity, which is short for biological diversity, is a term used to describe the variety of life found on Earth and the relationships between living organisms.  This includes diversity among individuals (genetic variation), species (number of species), and ecosystems (variations in ecosystems).

Genetic diversity refers to the variation of genes in a species. Genes are passed from parent to offspring and determine the characteristics of the individual. This genetic diversity allows species to adapt to changing environmental conditions as well as to respond to natural selection. When one species has a large genetic diversity, it will increase the likelihood of species survival.

Species diversity is the most commonly discussed type of diversity. It refers to variation among species. High species diversity tends to mean that an area is healthier than when there is low species diversity.

Community and ecosystem diversity refers to the variation of ecosystem and all of their inhabitants. This is often assessed through a comparison of different ecosystems or sites to determine which have higher or lower levels of diversity. It can be measured on different scales; within  community diversity (alpha diversity), between communities diversity (beta diversity) or diversity over the entire landscape of geographic region (gamma diversity).

How Do We Measure Biodiversity?

There are many ways to measure biodiversity, and scientists do not agree on one method. However, scientists do agree that more than one measurement is necessary to gain an accurate picture of the diversity within an area. These measurements often include species richness and evenness calculations, which are then used within an index, which offers a simple number that can be interpreted with ease.

Species Richness:
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This biodiversity index is commonly used because it is a quick way to differentiate between different locations, ecosystems, or populations of organisms. It is a calculation of the total number of species in a particular place. This method is beneficial because scientists often do not have disagreements about species identification as they do about other taxonomic levels, such as family or genus. It is also easy for the public to understand. However, it does not take into consideration the number of individuals in each species (proportions).

Species Evenness:
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This measure of biodiversity examines the relative quantities, or proportion of the species that have been identified in one area. It looks at how individuals are distributed among a community. For example, a site may be home to many different individuals and seem diverse, but if 99% of those individuals belong to the same species group, the site may actually not be very diverse at all.

Simpson Index:
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This example of one type of biodiversity index is a more complex measure of biodiversity that combines species richness and species evenness to create a measurement. Based on this number, we can determine whether the site has a low or high level of biodiversity. The scale ranges from 0-1, with 1 representing low biodiversity and 0 representing high biodiversity. We can also use this number to compare biodiversity between different sites.

Why Is Biodiversity Important?

There are several important reasons for us to gain an understanding of the dynamic nature of biological diversity, particularly in terms of maintaining ecological balance. It is no secret that humans have an enormous impact on species and ecosystem diversity, yet, throughout our existence, biodiversity has faithfully provided us with enormous economic, medical and social benefits as well as many other natural services.  As such, it is essential that we actively choose to minimize the negative impacts that our actions have on the environment.

How Do We Benefit From Biodiversity?

Natural Services: 
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Ecosystems provide a vast range of services necessary for human survival. The healthier biodiversity is (genetic variation, species diversity and ecosystem diversity), the more services will be provided to us, which in turn will create a healthier human population. We have included a few major examples of these services below:

  • Oxygen production
  • Water purification
  • Climate moderation
  • Removal of greenhouse gasses from the atmosphere
  • Nutrient storage and recycling
  • Pollution breakdown and absorption  
Economic Benefits:
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Almost all aspects of our economy are in some way, or were at some point, directly linked to biological diversity. It is easy for us to forget that basic aspects of our lives such as the food we eat, our jobs, our homes, building materials, medicine and biological resources (past, present and future) are almost entirely dependent on what biodiversity continually offers. This means that the human species is extremely dependant on the survival of biological diversity and vice versa. Below, we have listed a few examples of how biodiversity has provided us with important economic benefits:

  • Employment: Agriculture, forestry, fishing, eco-tourism, outdoor recreation, etc…
  • Industry: Agriculture, fishing, forestry, etc…
  • Medicinal and pharmaceutical resources
  • Food and beverage industries
  • Biotechnology 
Social Benefits:
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For many people, the diversity found within ecosystems and species is a powerful source of emotional, spiritual and individual identity. We would be quite naive not to acknowledge our intrinsic understanding that biodiversity must be respected, understood and protected. On the most basic level it is easy to see that all species depend on biodiversity to survive, however, humans as an entity also depend on biodiversity to thrive beyond the realms of mere instinct. Below, we have listed a few of the very important social benefits which biodiversity provides to us:

  • Recreation and tourism
  • Spiritual and artistic inspiration
  • Cultural identity
  • Research, education and monitoring 

Threats To Biodiversity

Unfortunately, our world’s biodiversity is being challenged. Humans have introduced many new technologies and chemicals to the environment that are harming individuals and entire species who are unable to adapt. We often use the acronym HIPPOC to outline the 6 major threats to biodiversity.

Habitat Loss:
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This occurs when an area is converted from usable to unusable habitat land. Many causes of habitat loss center around human activities, such as industrial activities, deforestation, agriculture, mining, water extraction, among others. When organisms do not have a place to live anymore, they are forced to find a new habitat and adapt, or will be unable to survive in their environment. 
Invasive Species:
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Invasive species also pose a threat to biodiversity. An invasive species is an organism that is not native to a location (an introduced species) and have no natural predators. Because of this they are able to increase their population size rapidly, out competing native species for resources. They may even prey upon native species, negatively affecting their population numbers. 
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Pollution is a well known problem throughout the world. The discharge of toxic synthetic chemicals and heavy metals into the environment has a huge impact on species and can lead to a decrease in biodiversity. Even those substances that we view as natural elements, such as carbon, phosphorus, and nitrogen, can have negative effects on organisms when used in excess. These pollutants are harming organisms, possibly even to the point of extinction or extirpation, having a negative impact on local biodiversity. 
Population Increase:
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The human population has now well surpassed 7 billion individuals. We all need places to live, to grow, and harvest our food, as well as space to create new materials. With our exponentially increasing population, we are using more resources and land to meet our global needs. While the impacts that each single human has on biodiversity vary and depend on a variety of things, it is clear that as a whole, our globally increasing population has led to increasing threats to biodiversity. 
Over Harvesting:
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Over harvesting occurs when humans extract large amounts of resources, often much more than is sustainable, from the planet. This may include hunting, fishing, forestry and other extraction based industries. 
Climate Change:
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Studies have shown that green house gas emissions in our atmosphere are increasing, and are correlated to human activity. This increase in green house gases is contributing to the effects of climate change, such as changing ocean and air temperatures, sea levels, length of seasons, levels of precipitation, oceans and wind current patterns, and so much more. Many species are struggling to adapt to these changing conditions, and if they cannot adapt they may move to a new area, or become extinct, thus decreasing that location’s biodiversity.

If we think of an ecosystem as a woven carpet, these threats become much easier to understand. If we pull on one loose thread in the carpet, several things may happen. This pull may only impact that single thread, or a few  surrounding threads, making them loose as well.  If we continue to pull on these loose threads, the carpet will begin to unravel and at a faster rate each time a thread is pulled. If each and every one of us is pulling on a thread, it will not be long before we completely unravel our woven carpet. This sensitivity represents the biodiversity which is woven around us. We are a part of this carefully woven environment, and with continual pulling, we may “unravel” the planet which we depend on for survival.

Bringing Biodiversity to Canada's Schoolyards