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What is biodiversity?

Passers-by in the heart of the Square des Freres CharronBiological diversity or biodiversity refers to the variability of living things and the dynamics of their interactions. It applies not only to the diversity of plants, animals and microorganisms but also to the genetic diversity within species and the diversity of ecosystems. It includes all life forms, as well as the interactions between them and their living environment.

Human beings are an integral part of this diversity of living things and are in constant interaction with its components, even in an urban setting!

“Biological diversity” means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems.

(Source: United Nations, Convention on Biological Diversity, 1992)

Why be concerned about biodiversity?

Nature is a complex system in which all the components are interrelated and each one has its place and role. The loss of biodiversity threatens the balance of ecosystems.

The lap owlPhoto credit : Antonio Rizi

Several species depend on a diversity of habitats to complete their life cycle. For example, birds of prey hunt and feed in the open but build their nests in the forest. Some turtles spend most of their time in the water but lay their eggs on land.

Living organisms also depend on one another. One example of this interdependence is the food chain: plants grow by capturing energy from the sun, herbivores feed on plants, carnivores feed on other animals, detritus feeders feed on animal remains and plant debris and small organisms break down organic matter into minerals for plants.

MonarqueThe scattering of seeds by squirrels, birds and other small animals, as well as the pollination of plants by bees, butterflies and other insects, are some other examples of these fascinating interactions.

The more diversified an ecosystem, the more resilient it is to disruptions, such as the introduction of a disease or pest. The prominence of ash trees on the streets and in the parks of Montréal has made the urban ecosystem vulnerable to attacks by the emerald ash borer. All efforts have been mobilized to combat this destructive insect and enable the urban forest to regenerate, including by diversifying new plantings.

Around the world, biodiversity is threatened primarily by the loss and degradation of natural habitats, overexploitation of natural resources, pollution, invasive exotic species and climate change (United Nations Environment Program, Global Environment Outlook 5, 2012).

Admittedly, the challenges in urban settings with densely built multi-use spaces are many. Ville de Montréal’s 2013 Biodiversity Report states that Montréal’s rich flora and fauna face various threats, the most important being habitat loss and fragmentation, as well as invasive species.

How is nature’s presence beneficial to citizens?

Our societies depend on healthy ecosystems, even in cities! At the request of the United Nations Secretary-General, experts from around the world studied the links between the health of ecosystems and the well-being of humans: the Millennium Ecosystem Assessment was completed in 2005.

Four major categories of services provided by nature or ecosystem services were identified by the thousand experts who took part in this assessment:


  • Regulating services: climate regulation, air and water purification, protection against natural disasters, etc.
  • Provisioning services: supply of goods such as food, fresh water, wood for construction, medicinal plants, etc.
  • Cultural services: landscape aesthetics, activities of recreational and educational value, etc.
  • Supporting services: soil formation, photosynthesis, etc.

In Montréal, nature provides a variety of valuable services:

Snowshoeing in nature park

  • Supply of fresh water through major water sources
  • Improvement of air quality, especially thanks to the action of large trees
  • Cooling effect of vegetation and reduction of heat islands
  • Absorption of storm water and load reduction on the waste-water collection system
  • Beautification of urban landscapes and increased attractiveness of neighbourhoods
  • Beneficial effects on psychological health (e.g., reduced stress)
  • Incentive for outdoor sports or relaxation, especially in parks
  • Opportunities to discover/observe nature close to home
  • And many others!

Who can act to support Montréal’s biodiversity?

To enable citizens to benefit from the valuable services provided by nature, the City has implemented a series of initiatives to protect Montréal’s natural heritage (several of these initiatives appear on the various pages of this website). But the City is far from being the only stakeholder contributing to the protection and enhancement of biodiversity in Montréal. Citizens, the scientific community, non-profit organizations, large institutional owners and the business community, among others, have a complementary role to play in maximizing biodiversity in Montréal.

Green StreetCitizens’ efforts are especially important. By revegetating private land, adopting positive attitudes toward nature (keeping to pathways in parks, not feeding wild animals, etc.), taking part in citizen action projects, and staying informed and committed to biodiversity, citizens can make a major contribution. Together, we can do much more!

Is there interesting flora and fauna in Montréal?

Yes! Southern Québec is an area rich in biodiversity; it represents the northern range of several species. Montréal is home to a biodiversity of great interest and can provide a haven for threatened or vulnerable species, both animal and plant, such as the brown snake, the map turtle, the yellow water crowfoot and the black maple. The agglomeration boasts more than 1,000 species of vascular plants, hundreds of species of butterflies and birds, and numerous fish, amphibians, reptiles and mammals.

We invite you to explore the “Biodiversity” section of our website and discover Montréal’s amazing wealth of flora and fauna.