Forest Biodiversity

Examples of forests

Tropical forests: found around the Equator, these vertically layered forests experience high temperatures and precipitation. Animal diversity is incredibly high. Scientists estimate that tropical forests are home to over 5 million undiscovered species.

Northern coniferous forests: found in northern Eurasia and America, these forests generally experience low precipitation and extreme seasonal differences in temperature. Mammals are diverse, whilst some birds migrate depending on the seasons.

Temperate broadleaf forests: found in mid-latitude regions, these vertically layered forests have year-round precipitation and seasonal temperature differences. Mammals typically hibernate and birds migrate during colder months.

Why is biodiversity so high in forests?

Forests are home to thousands of different species of animals, plants, and fungi. Tropical forests are the most diverse terrestrial ecosystems – home to 62% of the world's terrestrial vertebrates. Nearly half of these are endemic.

The lowland forests of the Amazon are home to 14,000 plant species, including 6000 trees.

But why are these tropical forests hotspots for biodiversity?

Energy Availability

Tropical rainforests are found close to the Equator, where temperatures are high year-round.

Consistent heat and sunlight provide more energy than we get here in the UK! Plants can photosynthesise throughout the year, enabling growth and an increase in biomass.

High Biomass and Resources

The high biomass of tropical rainforests provides many resources. Food, nutrients, and shelter will always be available to support many species.

Additionally, the layered forest structure supports biodiversity. Light, plants, and nutrient levels vary between the top of the canopy and the forest floor, creating different habitats. Thus, different species will inhabit each layer.

Effects of Forests on Biodiversity

As well as being biodiversity hotspots themselves, forests play a key role in maintaining biodiversity in different parts of the world.

Atmospheric Regulation

Forests act as a carbon sink – absorbing more CO₂ than they emit.

This atmospheric regulation minimises temperatures rising elsewhere in the world. Rising temperatures affect species distributions, forcing them to move to a higher altitude or latitude. Habitats will be damaged, causing population decline. Endemic species are particularly at risk, because of their small range size.

Forests provide oxygen to the atmosphere through photosynthesis. The Amazon Rainforest alone produces 20% of the world's oxygen, earning its nickname 'Lungs of the Earth'.

Photosynthesis

All plants, including trees, are autotrophs. This means that they make their own food using sunlight via the process of photosynthesis:

carbon dioxide + water ⇾ glucose + oxygen

Plants release oxygen as a by-product; an unneeded waste product. But without atmospheric oxygen, animals wouldn't be able to survive. As well as oxygen production, plants remove carbon dioxide from the atmosphere, reducing the effects of climate change.

Hydrological Regulation

Trees have a higher leaf area than other vegetation types, making them more effective at intercepting rain and preventing soil erosion. Trees also have high water productivity, making them efficient biomass producers. Deep, large roots allow increased evapotranspiration (water loss) from leaves. More energy is used to evaporate this water, resulting in a cooling effect. The root systems contribute to soil infiltration, improving water retention and groundwater recharge. This helps regulate the water cycle, providing water to other ecosystems and humans.

The Importance of Forests on Biodiversity

Regulating the atmosphere and the hydrological cycle are essential to maintain a high level of global biodiversity. Changing climate and fluctuating water availability can make species survival very difficult. This is because ecosystems and Earth's physical systems are closely connected. The loss of biodiversity in one ecosystem can have knock-on effects all over the world.

Deforestation

Unfortunately, forests are under threat.

Forests provide important provisioning resources to humans: such as timber, food, fuel, fibres, and medicines. These resources are being harvested unsustainably, leading to forest loss. Furthermore, deforestation is taking place. Huge areas of land are being cleared for alternative uses such as mining and cattle grazing.

Deforestation has a range of adverse effects on forests.

Conservation of Forest Biodiversity

Conserving forests helps reduce the impacts of deforestation, and maintain high levels of biodiversity.

Conservation isn't always a straightforward process. It may conflict with people's jobs, homes, and livelihoods. Because of this, it is important to always consider people when it comes to making conservation strategies.

Methods to Aid Forest Conservation

• Forest Restoration: examples of restoration methods include planting trees, improving soils and protecting wildlife corridors. Restoration is most effective when experts and conservationists engage with local communities and national governments.
• Establish Protected Areas: This is most useful when combined with supporting initiatives to ensure long-term success.
• Payments for Ecosystem Services: these provide strong incentives to conserve forests by creating a market for intact, functioning forest ecosystems. They can also offset costs borne by land-owners, whose land value is reduced by conservation projects.
• Agricultural Reforms: these are most useful where protected areas and payments are less effective due to weak governance or private land.
  • Agroforestry is a farming technique incorporating crops alongside trees or natural pasture.

I hope that this article explained forest biodiversity to you. Remember that forests are diverse ecosystems, that provide important atmospheric and hydrological regulation!

^{1. Andrew Guttierez, Climate change effects on poikilotherm tritrophic interactions, Climatic Change, 2008}

^{2. AQA, Environmental Science Specification, 2017}

^{3. Bart Muys, What role do forests play in the water cycle?, 2022}

^{4. Domingos Cardoso, Amazon plant diversity revealed by a taxonomically verified species list, Biological Sciences, 2017}

^{5. Eckehard Brockerhoff, Forest biodiversity, ecosystem functioning and the provision of ecosystem services, Biodiversity and Conservation, 2017}

^{6. Jason Scullion, Conserving the Last Great Forests: A Meta-Analysis Review of the Drivers of Intact Forest Loss and the Strategies and Policies to Save Them, Frontiers in Forests and Global Change, 2019}

^{7. Kevin Gaston, Global patterns in biodiversity, Nature, 2000}

^{8. Neil Campbell, Biology: A Global Approach, 2018}

^{9. One Tree Planted, Amazon Rainforest Facts, 2022}

^{10. Rajeev Pillay, Tropical forests are home to over half of the world’s vertebrate species, Frontiers in Ecology and the Environment, 2021}

^{11. Thomas Haaland, Generalists versus specialists in fluctuating environments: a bet-hedging perspective, Oikos, 2020}

^{12. WWF, Jumping marvels of the Amazon, 2022}

^{13. WWF, What is forest restoration and how do we do it well?, 2022}

^{14. WWT, Amphibians, 2022}

^{15. Yude Pan, Forest biodiversity, relationships to structural and functional attributes, and stability in New England forests, Forest Ecosystems, 2018}