Biodiversity is the variety of life on Earth, in all its forms and all its interactions. This includes everything from microorganisms, plants and animals to the natural systems that support them. Biodiversity describes our natural wealth, which makes up the living landscape around us, sustains ecological systems and enhances our quality of life.
Biodiversity enables our natural systems to function properly by providing many important services such as soil formation and nutrient recycling, and pollution breakdown and absorption, as well as biological resources such as the water we drink, the air we breathe and the food we eat.
In short, human survival is dependent upon these vital ‘ecosystem services’. Ecosystem services can be defined as the benefits that people derive from nature. The Millennium Ecosystem Assessment (1) categorised these as: provisioning, regulating, supporting and cultural services.
A really good example of how nature provides valuable ecosystem services to humans is by showing the importance of trees in towns and cities (2).
Trees cool the surrounding environment through shading and evapotranspiration, a process where trees take up water from the ground and release it through the surfaces of their leaves, cooling the surrounding air. This helps to reduce the heat island effect in urban areas (built-up areas with temperatures higher than surrounding rural areas).
Trees also play an important role in combating climate change by capturing and storing carbon from the atmosphere. The roots of trees help improve soil quality through protection from erosion and aeration. They also increase infiltration of rainwater into the soil, reducing runoff from floods.
The leaves of trees improve urban air quality by removing harmful pollutants and filtering dust from the air whilst also providing a barrier to noise. They provide nesting, shelter and food for local wildlife such as birds and invertebrates.
The presence of trees in urban areas provides people in towns and cities with daily access to nature on their doorstep, helping to relieve stress, improve emotional well-being and strengthen their connections to nature (3).