Biological diversity, or biodiversity, is defined as ‘the number, variety and variability of living organisms’.
Biodiversity is considered at three levels:
Each of these types of diversity are essential for life on earth.
1. Genetic diversity
Each individual within a population usually has slightly different forms of the genes that give them their unique traits. You have probably heard the term ‘gene pool’, which is the total array of genes within a population.
Genetic diversity is necessary for any species to maintain reproductive viability, resistance to disease, and the ability to adapt to changing conditions. Those individuals that are better able to survive and reproduce pass on these favourable genes. This is known as natural selection.
In these times of changing climate and increasing human pressure, the ability to adapt and survive is vital for a species’ continued existence. And if a species disappears, an entire ecosystem can start to unravel.
2. Species diversity
Species diversity is a measure of the number of different species and their relative abundance in an ecological community. The identification and classification of species is known as taxonomy.
Each species has its role in the ecosystem, be as predator, prey, pollinator or seed disperser, amongst many others. If one species goes extinct, there are repercussions throughout the whole ecosystem. For example, if bees went extinct, fruits and vegetables could be next, and then the animals that feed off them.
We are not separate from nature either – the consequences for people are just as serious. Take the current pollinator crisis for example. The abundance and diversity of native bee species are declining around the world and 75% of leading global food crops depend on animal pollination. This has serious implications for future food security.
3. Community diversity
This is the number of different species assemblages within a particular area. For example at the coast you may have the beach and sand dunes, then further inland heath and woodland. Each of these has its characteristic vegetation and different animals associated with it.
Community diversity supports the continuity of proper ecosystem functioning, which provides crucial services to people. These include clean water for drinking and agriculture, flood control, protection from soil erosion, filtering of air, climate stability, pollution absorption, medicinal resources, and more.
Besides the benefits of biodiversity described above, there are also additional benefits to society. For example, new research has shown that greater species richness in videos shown to participants leads an increase in their mental well-being. For many people, it is simply important that biodiversity continues to exist and is around for future generations.
The Woodland Trust is contributing to biodiversity conservation at all three levels. We preserve community diversity through protecting woodlands and associated open habitats, we conserve species diversity through planting a diverse mix of native trees, and we protect genetic diversity through using only UK-sourced and grown trees of local provenance.
We are also part of the UK National Tree Seed project with Kew, collecting seeds that are genetically representative of UK populations for the Millennium Seed Bank for long-term conservation and research.