Principle Causes of Biodiversity Loss
The main causes of biodiversity loss, often described as drivers, are well documented in global assessments. See, for example, the IPBES Global Assessment Report on Biodiversity and Ecosystem Services and the IPCC Sixth Assessment Report which considers the impacts of climate change on biodiversity and extinction.
These reports identify five principal drivers:
- Land and sea use change – conversion of natural habitats into farmland, urban areas, or infrastructure. Examples include deforestation, wetland drainage, and coastal development, leading to habitat loss, fragmentation, and reduced species richness.
- Overexploitation of resources – unsustainable hunting, fishing, logging, and wildlife trade that drive population declines and extinctions.
- Climate change – long-term human-driven shifts in temperature and weather patterns. Examples include range shifts in species, disrupted timing between plants and pollinators, and coral bleaching. These changes increase stress, habitat mismatch, and extinction risk.
- Pollution – introduction of harmful substances or energy into the environment. Examples include pesticides, plastics, and nutrient runoff that cause eutrophication.
- Invasive alien species – non-native species that spread aggressively, displacing or preying on native biodiversity. Zebra mussels (native to the Caspian Sea) and Japanese knotweed in the UK are well-known cases.
Alongside these direct drivers, there are also indirect pressures, such as population growth, unsustainable consumption, weak governance, economic systems that externalise environmental costs, and technological change. A useful overview of these factors, focused on insect declines but relevant more broadly, is given by Sánchez-Bayo and Wyckhuys (2020).
Approaches to Biodiversity Restoration
At present, the barriers to biodiversity restoration are largely social and political. Solutions to the crisis are well known, but they are blocked by economic constraints, social resistance, and lack of political will. Halting climate change or reducing human consumption requires systemic change that would transform how modern societies live. It is not a quick fix.
Even so, many restoration techniques have been developed. These can be grouped into five broad approaches:
- Passive restoration removes pressures such as grazing, logging, or pollution, allowing ecosystems to regenerate without further intervention.
- Rewilding can involve passive recovery, but often includes the active reintroduction of keystone or apex predators. Projects are usually large-scale to enable natural processes and viable populations to re-establish.
- Active restoration uses human intervention to speed or guide recovery. Techniques include tree planting, grassland restoration, peatland rewetting, or reintroducing locally extinct species. Such sites often require ongoing management to shape outcomes.
- Integrating restoration into production systems brings biodiversity into farming and land use. Examples include agroforestry, cover cropping, and wildlife-friendly field margins. Regenerative agriculture is one such approach.
- Landscape-scale restoration reconnects fragmented habitats by creating ecological corridors, buffer zones, or coordinated land-use planning. An example from the UK is Weald to Waves.
