Forests: a tool in the fight against climate change

Climate change is having profound effects on Earth’s systems. Its effects can be seen on every continent, with some areas being affected more severely than others. Now, researchers are looking more seriously at forests to be a tool in the fight against climate change, writes Kathleen Conroy, of Trinity College Dublin.

Climate change is having profound effects on Earth’s systems. Its effects can be seen on every continent, with some areas being affected more severely than others (e.g., permafrost melting in Greenland, island nations such as Tuvalu threatened by sea level rise).

The climate on Earth naturally fluctuates over time. It has experienced periods of cold (glacial periods, also known as Ice Ages) and periods of warmth (interglacial periods). We are currently in an interglacial period. However, the accelerated rate in which this warming is occurring is unprecedented and is a cause for great concern. This warming trend origin has been linked to the onset of the Industrial Revolution of the late 19th Century.

Since that turning point, humanity has advanced on a number of fronts including medicine, technology and mechanics. In reaching these milestones, fossil fuels have been and continue to be consumed in unsustainable quantities. Fossil fuels (e.g., coal, oil) are great energy sources, however, when they are burned to release this energy, they also produce large amounts of greenhouse gases, most notably carbon dioxide.

There are a number of different gases that contribute to the greenhouse effect, but carbon dioxide is the most abundant, stays in the atmosphere for an exceedingly long time (estimates between 300-1000 years) and is very good at insulating. As the amount of carbon dioxide in the atmosphere increases, a greenhouse effect occurs which traps heat on Earth. The heat from the Sun penetrates the atmosphere in the form of visible light. Normally, the Earth reflects much of the light back into space in the form of infrared light. However, the extra carbon dioxide blocks the infrared light from reflecting and traps the heat on Earth. This is the premise of climate change.

Carbon dioxide is naturally in the atmosphere. Animals respiring, oceanic gas balancing, forest fires, volcanos, are all examples of carbon dioxide production. Although there is disagreement, generally, it is acknowledged that 350 parts per million is a safe amount of carbon dioxide to have in the atmosphere. At the time of this writing, there are 422 parts per million carbon dioxide in the atmosphere. According to the EEA Europa, the last time that the Earth had a safe level of carbon dioxide was 1986.

What Climate Change Means?

Climate change is so much more than just warmer temperatures. It means increased number and intensity of storms. Climate change increases the number and intensity of droughts, leading to water scarcity and food shortages. It causes glacial melting and sea level rise, threatening coastal communities. It is a leading factor in the biodiversity loss crisis, shifting habitat conditions rapidly causing extinction in many species. The range of some tree species is shifting, as their current range is becoming inhabitable to the species. The temperature of the Earth will increase as well. As of 2015, it is 1C higher than pre-industrial times. The consequences of climate change will only get worse as that temperature increases.

What Can Be Done?

A number of things can still be done to manage climate change. Education, lowering consumption of fossil fuels, policies and increased use of alternative energies (e.g., wind) are all important measures to combat climate change. However, most measures are to prevent new carbon from accumulating in the atmosphere. To begin to really fight climate change, carbon dioxide needs to be removed from the atmosphere (carbon sequestration) and it needs to be stored for long periods of time and not allowed to re-enter the atmosphere

(carbon storage). A great way to remove carbon dioxide is by planting trees.

All plants require carbon dioxide to photosynthesize. The carbon dioxide is transformed into glucose which the plant uses as its energy source. Carbon dioxide can be stored away as biomass (the living part of the plant). As trees grow larger, they require more carbon dioxide to generate enough glucose and can store larger amounts of carbon away. Forest soils are

also great carbon sequesters, with estimates of 50% of forest carbon being stored below ground. A well functioning, healthy forest would be known as a carbon sink, pulling in large amounts of carbon and storing it for long periods of time. However, if a forest is mismanaged, unhealthy and greatly disturbed (by forest fires, logging, etc) then it can become a carbon source, emitting large amounts of carbon into the atmosphere. In this regard, forests must be closely monitored and managed to make sure they are acting as a sink and not as a source.

Different tree species can sequester carbon at different rates. In general, faster growing conifers are able to sequester more carbon quickly, especially when they are young. However, in general, hardwoods are often able to store carbon longer as they are growing more slowly. The use of the forest is important as well. If trees are cut down for timber processing then they should be used in construction, furniture or some other type of

long-term storage. If immediately used as firewood, then all that carbon is released back into the atmosphere.

Climate change can be overwhelming and can make some people feel hopeless. However, by taking small steps and using nature-based solutions like forestry as carbon sinks, the effects of climate change can be slightly mitigated. Forestry is also multifunctional. While sequestering carbon dioxide, it can also provide habitat to endangered species, regulate water flow and prevent flooding during the more intense storms seen in climate change. Not only can forests help fight climate change directly, but it can also alleviate some of the problems that climate change causes.

New paper: A decision methodology for site-level ecosystem accounting

The ForES team, in collaboration with the Nature + Energy project and the IDEEA group, published a discussion paper on the application of the System of Environmental-Economic Accounting Ecosystem Accounting (SEEA EA) at site-level, led by Dr. Courtney Gorman. Here, co-author Francesco Martini, Trinity College Dublin postdoc, outlines some key findings...

The SEEA EA (System of Environmental-Economic Accounting Ecosystem Accounting) is the internationally recognised standard to report extent and condition of ecosystems, and the flow of ecosystems services. It provides a consistent framework to monitor the state of our natural capital and its connections to society and the economy.

So far, the SEEA EA has been mostly applied at national or regional scale. Now the ForES project and Nature + Energy are exploring its application at small spatial scales, where typically environmental decisions are taken and management actions implemented. Nature+Energy is developing new ways of accounting for the value of nature on wind farms, while ForES is working at Coillte forestry sites in Ireland.

In this paper, the authors describe the steps involved in developing ecosystem accounts at site-level for both projects and discuss the different decisions and approaches between them (see Figure 1, above).

Their main conclusions are:

•  Site-level ecosystem accounting is highly context-dependent.

•  Close collaboration with stakeholders is key to develop accounts that can support their objectives.

• The availability of high-quality data is a limitation that needs to be overcome in the future.

As ecosystem accounting continues to develop and grow in uptake globally, this article provides a timely perspective and recommendations to all practitioners and stakeholders interested in developing accounts at local level.

Read the full article 'A decision methodology for site-level ecosystem accounting' Courtney E. Gorman, Francesco Martini, Kathleen Conroy, Emma King, Reiss Mcleod, Carl Obst, Jane C. Stout, Ian Donohue, Yvonne M. Buckley: https://doi.org/10.1016/j.jenvman.2024.121814

The ForES project is funded by the Department of Agriculture, Food and the Marine’s Competitive Research Funding Programme.

Responsible forestry can pull us back from a 'carbon cliff' - Yvonne Buckley, The Irish Times

The ForES project was mentioned in an Irish Times column by team member Prof Yvonne Buckley, co-director of the Co-Centre for Climate + Biodiversity + Water, about the importance of well-managed forests to provide critical woodland ecosystem services including carbon sequestration and storage. Read more...

We have had a bumpy relationship with trees. Our landscapes were largely treeless at the beginning of the 20th century, with just 1 per cent of Ireland’s land covered by forest.

The native forests that used to cloak more than 80 per cent of the land were gradually removed, from the Stone Age onwards, for timber and agricultural land. Now just tiny pockets of ancient forests remain. Forests have increased from 1 per cent to over 11 per cent over the past 120 years, with most of the increase due to plantations of non-native conifer species. One single conifer species from the west coast of North America, Sitka Spruce, occupies 45 per cent of Ireland’s forest area.

Our current forest landscapes are like mosaics with a single colour predominating. While Sitka Spruce is a very productive timber tree that also sequesters and stores carbon, it can be negative for native biodiversity if planted in monocultures and clear-cut without appropriate protection of watercourses from sediments eroded from the newly uncovered land.

Poorly sited and badly managed forests can be damaging to biodiversity. Forests make many different contributions to our economy, health and wellbeing, including wood, water filtration, flood mitigation, habitats for plants and animals, climate regulation and psychological benefits.

These benefits can be provided by different kinds of forests in different areas, the “mosaic” approach, or from a single forest, the “multifunctional” approach. For example, forests close to urban areas are likely to be more heavily visited by people, providing many recreational benefits, whereas forests in the uplands provide water holding capacity that can improve water quality and reduce flooding downstream.

Well-managed forests on the right kinds of soil sequester and store carbon, pulling damaging carbon dioxide from the atmosphere. If trees are harvested and the wood is used in long-lived products such as building materials and furniture that carbon can be stored for decades to centuries. Other trees can then be replanted or regenerate naturally on the same land sequestering more carbon, and so on.

Given the tempo of forest planting in Ireland, we are now approaching a “carbon cliff” where from 2025 to 2030 our forests are projected to be a source of greenhouse gas (GHG) emissions rather than a sink. There are a range of reasons for this reversal, more forests are reaching maturity and being harvested than are being planted, many forests planted in the 1980s were planted on peat soils which, when drained, emit GHGs and older trees grow more slowly than younger trees.

There are many solutions to our forest conundrums. Ireland’s Forest Strategy promotes multifunctional forests and more diverse forest mosaics. More broadleaf trees will be planted and open non-forest ecosystems will be maintained within the forest footprint. Continuous cover forestry, or close-to-nature forest management, maintains a forest canopy while small numbers of trees are harvested regularly rather than the entire forest being clear-felled.

This type of forest management protects the soil, maintains carbon within the ecosystem and allows for the best timber to be extracted and replaced through planting or natural regeneration. A more complex forest structure arises, with trees of many sizes and several different species can be included. Structural diversity is good for nature. We need to plant at least 8,000 hectares of forest per year to achieve 18 per cent of our land area covered by forest by 2050. Our new forests will be around for decades, and they must deliver for climate, nature, wood, people, and economic and rural development. This will require investment in the public and private forestry sectors to encourage and speed up the planting of diverse multifunctional and mosaic forests.

Confidence in the forestry sector is important given that it is a long-term investment and government support for the many ecosystem services, not just timber, that are produced from forests will be needed.

In the Fores research project, we are developing tools to map, measure and model the ecosystem services provided by different kinds of forests under different management regimes. Many of these ecosystem services are invisible but critical - as we expand our forests, we need to be able to demonstrate their many values.

• Yvonne Buckley is professor of Zoology at Trinity College Dublin and co-director of the Co-Centre for Climate + Biodiversity + Water

This article first appeared in The Irish Times on 27/06/2024.