Forest Ecosystems  

Information provided by Nicholas Pande

Almost a third of the Earth’s land is covered by forest. Forests are defined by Food and Agriculture Organization as “Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10%, or trees able to reach these thresholds in situ. It does not include land that is predominantly under agricultural or urban use” (FAO, 1998).  

Forests aren’t just full of trees – they’re teeming with all kinds of life. They are home to 80% of the world’s land-based animals, insects and plant species, and around 300 million people. They provide people with timber, food, fuel, medicine, jobs and shelter, and are especially important for providing these to the world’s poorest. They recycle the air we breathe and regulate rainfall and climate patterns around the world. Forest ecosystem services include water purification and carbon sequestration (storing carbon) (WWF).   

Forest Biomes  

There are 3 types of forests/forest biomes.  

Tropical Forest

Common to areas near the equator, such as Southeast Asia, Sub-Saharan Africa, and Central America. They include tropical rainforests, subtropical rainforests and mangroves. They are the warmest and often wettest forests on the planet and are some of the most species-rich ecosystems on earth. Even though they cover less than 10% of the world they are host to over half the world’s species. Flora in tropical forests can include mangrove trees, Brazil nut trees, and African rosewood, among others.   

Temperate Forests

These are found across eastern North America, Eurasia and parts of South America. The Temperatures vary throughout the year because of the four distinct seasons at these latitudes. Flora in temperate forests includes coastal redwoods, oaks and birch. 

Boreal Forests

Found across Siberia, Scandinavia, and North America (Alaska and Canada). Temperatures in boreal forests are, on average, below freezing. Flora in boreal forests include conifers, spruce and fir trees. Boreal forests cover huge, remote areas.   

Forest Ecosystem Services  

• Forests regulate the climate and absorb carbon from the atmosphere. Between 2001 and 2019, carbon absorption by forest averaged 49 gigatonnes annually (Harris et al. 2021). 

• Forest ecosystems provide habitat for 80%, 75% and 68% of all amphibians, bird and mammal species, respectively (Hilton-Taylor and Stuart 2009).  

• They contribute to precipitation, regulate streamflow and foster groundwater recharge, providing drinking water to one-third of the world’s largest cities. Food, shelter, energy, medicines and around 86 million associated jobs come from forest products (FAO 2018; FAO 2014).  

Facts about Forests (WWF)

• Forests are home to over 80% of the world’s land-based species of animals, plants and insects. These animals help to keep the forest healthy. For example, elephants distribute seeds from fruits they have eaten. When the seeds pass through their gut, they come out undigested in their dung and germinate in the ground.
• Forests can make rain – Over three-quarters of the world’s accessible freshwater comes from rivers in or around forests. Forests also move so much water from the soil into the atmosphere that they create rain. Parts of the Amazon trigger their own rainy season.
• We still don’t know all there is to know about our forests – We don’t know how many tree species there are on Earth, but scientists estimate there are about 63,000 known species. There could be as many as 9,000 tree species still unknown to science.
• Forests are incredibly good at storing carbon – Most of this carbon storage takes place underground. For example, in UK forests, around 70% of carbon stored is kept in the soil. The rest is stored in the roots, surface litter and the tree above ground.
• Our tropical forests store about one-third as much carbon as is held in the atmosphere – Around 30% of all the carbon reserved in the world’s forests is stored in the forests of South America – around 82 gigatonnes.
• Forests once covered just under half of the earth’s land – The total number of trees has fallen by nearly half since the start of human civilisation and it’s estimated that over 15 billion trees are cut down each year. That’s around 100,000 square kilometres of forest.
• Our food system is the biggest driver of forest loss – Up to 80% of deforestation worldwide happens to make room for crops and livestock. 
• People are responsible for around three-quarters of all wildfires – Between 2001 and 2015, 23% of global forest loss was due to wildfires. 
• Deforestation releases carbon dioxide that has been stored as carbon in trees, roots and soil, making climate change worse  – This creates a feedback loop, as climate change increases the likelihood of deforestation, as the risk of droughts, wildfires and pest infestations increases and stresses the forest ecosystem. It is not possible to fight the climate crisis if we don’t stop deforestation. 

Challenges Forests are Facing  

Forests are globally important in regulating climate and locally important in sustaining communities and supporting biodiversity. But they, and the people who depend on them, are under increasing pressure.  

• Although deforestation has slowed in recent years, the world lost around 10 million hectares of forests per year between 2015 and 2020 (FAO and UNEP 2020). If these rates continue unabated, the global canopy could shrink by 223 million hectares by 2050 (Bastin et al. 2019).  

• Each year, an average of 122 million hectares of forests are affected by fires, pests, diseases, invasive species, drought and adverse weather events.  

• Degradation could affect up to 1.75 billion people who live in or near forests, including indigenous and local communities, smallholders and people who work in formal or informal forest-based enterprises.  

• Degradation increases the risk of flooding and human-wildlife conflicts.  

• Between 2001 and 2019, deforestation, logging and other disturbances resulted in emissions of 8.1 GtCO2e annually (Harris et al. 2021).  

Annex 1 – Definitions