Excess CO2 and other greenhouse gases in the atmosphere have always been an issue of global concern. This is due to their profound contribution to accelerating climate change. CO2 is produced from diverse sources, such as burning fossil fuels, conventional agricultural practices, and industrial processes, and released into the atmosphere. When these gases move freely in the atmosphere, they enhance the greenhouse effect, or global warming. The consequences of this are seen as rising temperatures, melting glaciers and ice caps, rising sea levels, and altered weather patterns. So many attempts have been made by various bodies globally to capture and reduce further global CO2 emissions, and one of the most promising approaches is agroforestry.

To reach EU’s climate neutrality goal by 2050, the European Parliament adopted the European Climate Law, a part of the European Green Deal, which raises the EU’s target of reducing net greenhouse gas emissions: from 40% to 55% to be reached by 2030. 

In the fourth quarter of 2022, EU economy greenhouse gas emissions totalled 939 million tonnes of CO2 equivalents, a 4 % decrease compared with the same quarter of 2021 (-39 million tonnes of CO2 equivalents). Agriculture-related emissions account for around 13% of the overall EU GHG emissions.

Agroforestry has proven to be a major tool in combating both global food insecurity and climate change. Its ability to meet the demands for food crops and forest products through polyculture systems has earned it global recognition. Forests play a vital role in stabilizing the climate. They help to slow the rate of climate change by removing excess carbon dioxide from the atmosphere and storing it for a long period of time. Also, trees present in a forest perform other vital functions, such as releasing enough oxygen into the environment and regulating the hydrological cycle. An agroforestry system mimics the functions of a natural forest in order to meet human needs while also stabilizing the environment.

Sequestering carbon through agroforestry

Trees are natural carbon sinks. They absorb carbon dioxide (CO2) from the atmosphere during photosynthesis and store it in their trunks, branches, leaves, and roots. The global transition to regenerative agriculture and agroforestry therefore helps to slow the increase in atmospheric CO2 concentrations, thereby reducing the rate of climate change. Forests have the ability to store carbon for extended periods of time. The carbon is stored in the trees and in the soil and can last for hundreds of years. Forests are important for reducing the effects of climate change because of their long-term storage capacity. Every year, forests absorb about 2.6 billion tonnes of carbon dioxide, or about one-third of the CO2 generated by burning fossil fuels. 

Natural carbon sequestration in the EU could be increased to 350 megatons (Mt) per year, mainly through reforesting 12 million hectares of land and enhancing efficiency in the agriculture sector. Furthermore, 62 million hectares of land are currently unused or abandoned and lack high biodiversity value.

Over time, forests’ trees build up biomass as they develop and reach maturity. Biomass is the term used to describe the organic material found in living or recently living things, including soil, plants, and trees. Carbon is stored in the soil and vegetation of this biomass in considerable quantities. Cellulose, lignin, and other substances found in woody tissues are the main forms in which carbon is stored. In contrast to smaller or younger trees, large, older trees typically store more carbon. When trees lose their leaves, branches, and other organic material, it decomposes and adds to the soil’s accumulation of organic carbon. The decomposing plant matter and other organic materials found in forest soils can contain significant amounts of carbon.

Trees actively maintain and renew their woody tissues throughout their lives. As a result of this, the carbon is locked away inside the structure of the tree and cannot be released back into the atmosphere as carbon dioxide. When a tree dies, its wood can degrade and release the carbon that was locked up in it back into the environment, although more slowly than other organic matter. However, when preserved properly, the carbon that was stored in trees is still locked inside the wood even after they are cut down to make furniture. Depending on the lifespan of the furniture and how it is used, the carbon that is stored in wood products like furniture can stay there for many years or even decades.

The role of trees in the hydrological cycle

The water cycle is continuously maintained by forests, which serve as massive storage for water that is slowly released into the ecosystem. Through a process called evapotranspiration, trees play a significant role in the water cycle. During transpiration, they remove water from the earth via their leaves. The water is absorbed through the roots of these trees. The moisture released into the atmosphere increases the air’s total humidity, which raises the likelihood of rain. Because trees have deeper roots than other plants, they are able to access and pump up greater amounts of soil water for delivery to the leaves for transpiration and growth. For instance, during the vegetation phase, a large oak tree can transpire up to 1600 liters of water each day. 

By disrupting the transpiration process, deforestation disturbs the water cycle. When forests are cleared, the rate of transpiration declines. This causes a drop in the amount of water vapor in the atmosphere, which reduces the development of rain clouds and may result in a decrease in rainfall. So, drought and desert expansion are the results of continuous deforestation. However, transitioning into agroforestry promotes the rate of transpiration, thereby supporting the water cycle.

Additionally, tree leaves serve as interceptors, trapping falling precipitation that later evaporates and precipitates rain elsewhere. Forests and tree cover can also modify airflow or act as windbreaks to change wind patterns. In turn, changes in wind speed and direction can have an impact on how clouds and rainfall travel and are distributed. Trees have higher interception and transpiration rates than other vegetation types, which leads to higher evapotranspiration. By providing shade and cooling benefits, trees have the power to produce specialized microclimates in certain areas. Under the shade of trees, cooler temperatures can slow evaporation and support higher humidity levels. This creates conditions that are appropriate for rainfall by reducing the possibility of humid air being carried away by hot, dry winds.

Agroforestry creates suitable microclimates for crops to survive

Different crops require different climates to thrive or perform to their maximum potential. This has been a limiting factor in conventional farming systems. Temperate crops find it difficult to survive in tropical regions, and vice versa. Agroforestry has the potential to create new microclimates for crops within agricultural landscapes. Through the integration of trees in crop fields, agroforestry gives associated crops an advantage, especially in regions different from their native environment. For instance, a low-temperature crop will find it easier to survive in a tropical environment if the weather parameters mimic those of a temperate zone. 

Integrating trees in crop fields can create cooler temperatures in tropical regions through adequate shade and high humidity as a result of evapotranspiration. Lower temperatures can be good for livestock and crops, especially in hot, dry places where heat stress can be a serious problem. Also, adequate shading from trees in an agroforestry system enables the establishment of plant nurseries. Young seedlings enjoy suitable microclimates for their growth and survival. Tree shade helps to balance temperature extremes, shielding plants from too much heat or cold. Since seedlings are more susceptible to temperature changes in the early stages of establishment, this can be especially crucial. Additionally, the shade aids in lowering evaporation, which preserves soil moisture and gives seedlings a constant water source. For agricultural production, biodiversity, and general ecosystem resilience, these microclimates can provide a number of advantages.