Trees are important in our lives, but how do we secure their continued health in a changing world?

By Nick Marsh ǀ Forest Creation Officer, Forest of Marston Vale

It is generally accepted that the era of modern-day global warming started with the industrial revolution in the 19th century, when the burning of fossil fuels began in earnest - this marked a pivotal moment in history when our modern economy and global trade expanded significantly. Manufacturing processes set in motion a situation where gases including carbon dioxide started being released into the atmosphere in huge quantities. This contributed to so-called ‘greenhouse effect’: where heat becomes trapped, warming the earth’s surface.

In the UK, the industrial revolution coincided with woodland cover at its lowest in recorded history. Only with the establishment of the Forestry Commission in the early 20th century to establish the domestic conditions for a strategic resource of timber did woodland cover begin to increase.

From the Government Forestry and Woodlands Policy Statement - January 2013, Defra.

150 years later and we now know how this process has contributed to climate change and what needs to be done to reduce its effects. Trees are playing a vital role in this recovery.

Trees are the ‘lungs’ of the earth and provide many benefits to us and our lives

Trees draw in carbon dioxide and store this within their fibrous structure and within the surrounding soil throughout their life. Even when they eventually die and decompose, the process takes decades and carbon is only slowly released. Timber in itself locks away carbon potentially for centuries, particularly when used within building construction.

Trees are natural regulators of air quality, absorbing chemicals from traffic fumes such as sulphur dioxide, nitrogen dioxide, metals and particulates which can affect lung and cardiovascular function. They are particularly important in helping to improve air quality within our towns and cities

Trees can also reduce heat concentration within urban areas where solar energy is absorbed by surfaces such as concrete (so called urban heat island effect). They provide shading, filtering heat and adding water to surrounding air (a process known as evapotranspiration) as a method of cooling. They also control water movement through the soil and can play an important role in flood management.

But trees  cannot counteract emissions released from fossil fuel burning alone.

In order for trees to work efficiently  in combatting climate issues and improve environmental conditions, reducing our reliance on coal, oil and gas is imperative - it was one of the main discussion points at COP26 in Glasgow. Governments around the world have made pledges to find ways of using renewable energy resources and achieving carbon net zero (where emissions balance absorption) supported by the cessation and reversal of deforestation.

Planting trees to create wooded habitats whilst managing existing woodland is important in helping to support these goals. However, trees need to thrive and survive in order to deliver maximum benefits for the environment.

But which trees and where?

Photo of a Ginkgo biloba (Maidenhair tree)

Gingko biloba (Maidenhair tree)

Planting the right tree in the right place is important. We know through research that different species work in different ways to combat the effects of climate change. Diversity is the key however, both in managing disease and ensuring the most beneficial result for nature and the environment. We refer to native species as those that have been with us since the last ice age (10,000 years), but we also know that trees such as Gingko biloba (maidenhair tree), native to China has been found within fossil records in the UK so clearly was once an integral part of our ecosystem, albeit at a different time and within a different climate.

Our key aim at Forest of Marston Vale is to plant UK sourced and grown native species, using a proportion of local provenance. Such species have become integral to our ecosystem and are often host to many species so they play a key role in our natural environment. Although research on the introduction of non-native trees is being undertaken, this must be balanced with a clear understanding of their individual characteristics and any negative effects on habitats.

With global effects on climate, future trees whose natural range are limited by latitude and altitude may be able to grow in other regions of the world. Conversely, some trees may suffer as they may not readily adapt to this rapidly changing scenario. For example, beech trees are generally found on thinner soils and have a shallow root structure making them more susceptible to drought, particularly in southern England. When trees are under such stress, they can also be especially vulnerable to pests, pathogens and disease. Given time, beech may naturally migrate northwards.

Photo of a beech tree with roots exposed

Beech tree

Other trees such as wild service (Sorbus torminalis) which has been a minor species in the UK and generally only found within the confines of ancient woodland may become more widespread, having a deep rooting system and able to withstand extremes of weather. Preferring warmer climes (called thermophilic species), they occupy a large geographic range from the Mediterranean to Cumbria and could expand further.

Species such as silver birch, yew and elder have been found to be particularly y effective at capturing particulates within urban areas. Hairs on their leaves and needles gather liquid and solid  matter and silver birch are particularly efficient when planted as buffers between roads and residential areas.

Photo of an area of silver birch planted along a track

Silver birch planting

Pioneer species including  birch and wild cherry may have the advantage of being able to quickly colonise open land, but given that some seeds require chilling within the soil to trigger germination, this could affect their level of success as warming continues. 

For carbon capture, long-lived, broadleaved species including oak, hornbeam and field maple are considered to be valuable, but at a time when we have a proliferation of tree disease, planting a diverse range of species with the ability to naturally regenerate within woodland and colonise open ground will give us the best chance of creating highly resilient and adaptable habitats, able to sustain themselves and create genetically strong trees able to withstand disease and other vectors.

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