Blog - Energy, sustainability & economics
How many trees are there in the UK? Will tree planting help much?
How many trees are there in the world? When Thomas Crowther and Henry Glick used geospatial data in 2015 to estimate the number of trees in the whole world there was good news and bad news. Good news that there were several times as many trees as anyone had previously realised (total is about 3 trillion) and bad news that the number was declining faster than expected. The calculation was done partly to establish a baseline so that tree-planting efforts could be put into perspective - the UN's Billion Tree Campaign managed to plant about 15 billion trees over 10 years in virtually all countries across the world (193). But whilst these numbers sound large this has only added 0.5% of trees so much more needs to be done if we want to reduce the damage humans have done to tree numbers - before humans emerged there were about twice as many trees as there are now. Perhaps that's why the Trillion Tree Campaign was launched in 2018 in Monaco - a principality covering only two square kilometres and almost bereft of trees. More locally, the UK has a tree count of about 3 billion trees - about 45 trees per person - calculated by analysing aerial photos and estimating tree numbers as was done under the UN's Plant for the Planet project. There is some flexibility on the definition of what counts as a tree - and this assumes you don't count all the self-sown seedlings or bushes, which some might consider as trees. This number is dominated by a few species - of the commercially grown plantations in Scotland, for example, 60% of the trees are Sitka Spruce so they don't add as much to biodiversity as a wider species mix would do. And those 45 trees per person is a bit misleading in that there may be nearer to 400 trees per person in Scotland - it is more sparsely populated with less than a tenth of the UK's population but almost half the trees. The UK's tree-planting is put into perspective by comparing the relative numbers - the UK's 3 billion trees amounts to one thousandth of the global total whereas nearer to 1% of the world's population is British - so by comparison with the world's average, on a per-person-basis a Briton has a tenth as many trees as the average citizen of the world. The most densely tree-ed parts of the world are the tropics where 43% of the world's trees are growing. At a recent general election (2019) the political parties were competing to promise how many new trees they would ensure were planted - the Liberals and SNP each promised 60 million a year, whereas Labour said they would do 100 million every year. A more realistic Conservative party promised 30 million trees every year which would equate to about 15,000 hectares (or 6,000 acres). Despite this lower manifesto promise, the government is really struggling to achieve even that amount - but if they did reach that target every year for 10 years it would add 10% to the UK's tree cover. There is ample scope for more trees with the UK having only 13% tree cover, but are there are other ways to increase the numbers beyond tree planting? Trees will naturally establish themselves if they are not cut or grazed - perhaps one thing the government could do would be to reduce the number of wild grazers - mostly deer and sheep.
Why plant trees?
There’s a seemingly endless stream of bad news in the world: the coronavirus pandemic has forced us stay inside more than we’ve ever had to in our lifetimes, and there’s the ever-impeding threat of the climate crisis. Our collective mental health is suffering, and more than ever we’re looking for anything that can provide some alleviation from this. The government recently found that almost half of the UK’s population say they are spending more time outside than they did before the pandemic, so it’s clear that green spaces are more important than they have ever been for both our own wellbeing and the wellbeing of our planet, which really begs the question ‘why not plant more trees?’ Why is tree planting good for the environment? Forest ecosystems are one of the world’s greatest carbon sinks in existence. They hold up to 45% of all the carbon stored on land, as well as being home to 80% of the animal and plant life on land. Maintaining our forest ecosystems could be one very large step towards solving the climate crisis; and though this won’t be enough on its own, it’s definitely a good place to start. On a smaller scale, one hectare of young woodland has the ability to lock up over 400 tonnes of carbon. Imperial College estimates that a tree planting initiative on a worldwide scale could capture the equivalent to one decade’s worth of carbon emissions (at current rates) by the time these forests reach maturity, or up to 1/3 of all emissions from human activities that remain in the atmosphere since the Industrial Revolution. How can tree planting can benefit you? Local tree planting initiatives are an excellent means of drawing a community together. Forest For Peterborough, a tree planting organisation in the UK, started in 2010 with the aim to plant 230,000 trees by 2030, and at the same time provides a space where the community can come together and learn how to make responsible and sustainable choices. In 1980 Edward O Wilson, American biologist, popularised the term biophilia to describe the innate connection people have to the natural world, and it’s true that we as humans seek and crave the comfort of the natural world, particularly in times of stress. The UK government estimates that visits to UK woodlands have saved an estimated £185 million in mental health treatment and costs. At the same time, street trees in rural areas are thought to have avoided £16 million in antidepressant costs, so why are there not more trees being planted in rural and urban areas? More local tree initiatives like Forest For Peterborough could both help save people’s mental health and help the UK government reach their target of becoming carbon neutral by 2050. Planting trees can also help with our physical health. It goes without saying that having poor mental health can begin to have an impact on our physical health, and vice versa (in fact, loneliness has the same affect as smoking 15 cigarettes per day), and having green spaces near our living areas helps to improve our attention and creativity. Walking amongst trees even boosts our immune system and reduces our cortisol levels. It’s also been shown that in areas affected by tree loss, women have a higher risk of cardiovascular disease (222,000 hectares of green space have been lost to urban sprawl between 2006 and 2012 in the UK) and senior citizen’s survival rate is 17% higher if their residence is within walking distance of a green space. Planting trees can even help your wallet, too (maybe money does grow on trees!). Aside from saving the UK government millions of pounds in mental health costs and the projected costs that could come with the climate crisis in future, planting trees next to buildings can reduce the buildings’ energy consumption by up to 26%. This lowers the buildings’ internal temperature by 4 degrees in the summer and increases it by 6 degrees in the winter, so there’s less of a need for central heating and cooling systems (and of course prevents further emissions into our atmosphere). House prices rise by 9 to 15% if they’re near trees: they add to the aesthetic value of a neighbourhood, make people feel safer, and have been proven to lower crime rates. Why not plant trees? So, why plant trees? If planting trees for the sake of the planet isn’t enough of a reason, then there are plenty of ways tree planting can help you and your community. If you’re looking for tree planting opportunities there are plenty of events coming up, such as National Tree Day, which this year will be celebrated on July 31st. For the Queen’s Platinum Jubilee a tree planting initiative - The Queen’s Green Canopy- will encourages people across the UK to 'Plant a Tree for the Jubilee.’ Tree planting land for sale is available through the Woodlands website- let’s get planting!
A problem with plastic.
In the C19th, many objects were made from ivory. The ivory came from the slaughter of elephants. As elephant populations fell, so the search for a suitable substitute began. Celluloid was one of the first materials used but it was easily combustible. It was soon replaced by other materials like Bakelite, this was the first entirely synthetic plastic. It was made from phenol and formaldehyde. It was used for toys, radios, telephones etc. Bakelite was tough, heat resistant and did not conduct electricity. Other materials followed, and many different plastics are produced today; for example, polyethylene (which is widely used in product packaging) and polyvinyl chloride [PVC] (which is used in construction and pipes because of its strength and durability). The trouble is that plastics are just so useful. Plastics are cheap, lightweight and durable. Durability is a good quality when the plastic is being used but not when it is discarded, for example, into landfill where it may take centuries to degrade. Sadly, many consumers leave empty bottles / containers / wrappers in the streets, on the beach, at picnic sites etc. As most plastics are made from fossil fuels / oil, the manufacture of plastic is also a driver of climate change. Since the middle of the twentieth century, it is estimated that some 8.3 billion tonnes of plastic has been produced. Sadly much of this has ended up in landfill, in rivers, the soil, and the oceans - with significant effects of wildlife. Plastic pollution is ubiquitous. For example, the Great Pacific Garbage Patch, which is a collection of large areas of plastic and other debris in the North Pacific Ocean. It has been estimated that it contains some 1.8 trillion pieces of plastic . It is a serious threat to marine life such as whales, sea turtles, fish, and birds. Plastic items are discarded with little thought to the consequences. Bottles etc can end up as traps for many animals and a few years back we (at woodlands) found a child’s plastic boat dumped in a woodland (see featured image above). Sometimes, we see the distorted remains of plastic tree guards ‘strangling’ young trees. Plastic carrier bags (sometimes filled with dog faeces) can end ups suspended from trees / shrubs in woodland, or caught on wire fencing, waving n the wind. Discarded plastic items come in all shapes and sizes; those that are 5mm or smaller are termed “microplastics.” Microplastics come in part from larger plastic pieces that degrade into smaller pieces; but also from microbeads. Microbeads are very small pieces of polyethylene plastic that are added to health and beauty products, such as some skin cleansers and toothpastes. Now microplastics are to be found everywhere from deep oceans, to Arctic snow and Antarctic ice. They are found in foodstuffs and drinking water. One investigation found that if parents prepare baby formula by shaking it up in hot water inside a plastic bottle, their child might swallow tens of thousands of these microplastic particles each day. The movement of these particles through ecosystems is graphically summarised in this article. There is currently much discussion and research about how these microplastics will impact on the environment and different organisms, including us. Because they are so small and to be found widely in the environment, they enter organisms and food chains. Apart from the plastic in these particles, they may also contain chemical residues of plasticisers, drugs, and pharmaceuticals, and heavy metals may stick to them. Sometimes, sewage sludge may be used as fertiliser and this can contain nanoplastics. Also, treated wastewater is used for irrigation purposes and this again may be a source of plastic. Research indicates that earthworms in microplastic ‘enriched’ plant litter grow more slowly and have a shorter life span, and there is evidence that the gut of earthworms becomes inflamed after exposure to microplastics. Earthworms are important in aerating the soil and transporting materials such as dead leaves from the surface to deeper in the soil, they also 'inadvertently' transport micro-plastics. Springtails, a group of soil micro-arthropods (Collembola) can also help move micro-plastics in the soil. The movement of microplastics through the soil makes these materials ‘accessible’ to other soil dwellers but it is not clear if they pass along food chains (as has been the case with pesticides). Whether nano-plastics are taken up by or affect plants - again is not yet clear. However, the chemicals released by plastics such as phthalates may taken up by plants. There is a significant risk of physical and physiological damage to organisms and ecosystems by these micro-plastics *. The particles also get into the human body and the consequences for our health are, as yet, unknown. further information on nanoparticles etc : https://www.sciencedaily.com/releases/2022/04/220420133533.htm
The lost trees of Dartmoor
Certain upland areas of the UK , such as Dartmoor, have experienced long term grazing. This has lead to soil compaction, which in turn means that water run-off is greater. Instead of percolating into the soil, rain water runs over the surface and into rivers. This can lead to flooding during extreme weather events. Dartmoor (National Park) is a large upland area, which historically was dominated by oak woodland. Oak woodland now covers a very small area. The region is now dominated by blanket bog, heathland and acid grassland. The number of grazing animals (sheep, cattle and ponies - deer) increased significantly between the 1950s and 2000, resulting in soil compaction. Researchers at the University of Plymouth have investigated areas of upland pasture on Dartmoor, and the potential for the establishment of native oak saplings. Working with test sites, they were able to show that significant improvements in soil properties could be observed with 15 years of sapling establishment. The most effective location (in terms of flood prevention) for sapling / tree planting was on steep hillside on the edge of upland areas. Their initial work on the planting of woodland has since been expanded to determine the factors that affect the establishment of the tree (oak) saplings. Their most recent paper notes that the presence of livestock meant that fewer oak saplings survived and those that did were smaller. However, the effects of cattle and ponies was not always negative in that their trampling could reduce the growth of bracken - allowing more light to reach young tree saplings. [caption id="attachment_34391" align="aligncenter" width="650"] A southern upload moorland - Exmoor[/caption] The research team formulated a number of recommendations relating to the creation / establishment of woodlands in such upland pastures. Livestock should be excluded in areas where there are seedlings and young saplings (1 - 3 years). This exclusion should last for some 12 years. Larger oak (4 - 7 yrs) saplings can be planted into areas of dense vegetation, as this protects the saplings from livestock. Livestock could be allowed to graze in the vicinity of mature oak trees as this would reduce dense, competitive vegetation, allowing seedlings to grow / develop. Strategic planting and management should be considered / encouraged for upland slopes where drainage is poor - to allow for soil recovery and development of ecosystem services (flood mitigation). Whilst natural tree colonisation is a low-cost and environmentally sensitive mechanism to promote woodland expansion (working towards government targets on climate mitigation, carbon sequestration etc.), it is likely that the expansion of oak woodland into upland pasture systems will require strategic planting and informed livestock management. [caption id="attachment_37920" align="aligncenter" width="650"] Exmoor Ponies.[/caption] Full details of their paper can be found here : https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12126 (Thanks to Art for images of exmoor and ponies).
Nurture the soil
We tend not to think about soil very much, except perhaps when digging over a tough patch of weeds in the garden or if we see it being stripped from dry fields in a strong wind. We take soil for granted though we rely on it for our food - almost totally. Soil is a very thin layer covering the outer surface of the Earth. The earth’s crust varies in thickness from 3 miles in oceanic regions to 30 miles in continental areas - by comparison most soils are shallow and have little depth. Sadly, the earth’s soils have been neglected and squandered throughout history. In America and Canada, deep ploughing of the prairies and subsequent drought left the ‘unanchored soil’ exposed to wind erosion. Read more...
“tropical nights’ and greening our cities
Much of England experienced a series of ‘tropical nights’ last summer, when night time temperatures were 20oC or above. These tropical nights were associated with the heat wave that affected most of south east England. Central London experienced its longest stretch of extreme daytime temperatures since the 1960’s - temperatures of 30+oC were recorded on six consecutive days. A number of experts have said that such heatwaves and associated tropical nights are likely to become more common as a consequence of climate change. We were not alone in experiencing high temperatures by day and night, much of western Europe sweltered in the heat this August. The problem was most marked in urban areas and large cities. Some three-quarters of the population of Europe now live in urban areas. Extreme heat affects our health causing general discomfort, malaise, respiratory problems, headaches, heat stroke, heat cramps and heat-related mortality. Read more...
“The Scottish Uplands: how to revive a degraded landscape” a talk by Dr Helen Armstrong
Checking through my emails, I came across a link sent by a friend to one of the winter talks in the program offered by the Botanical Society of Scotland - specifically “The Scottish Uplands: how to revive a degraded landscape” by Dr Helen Armstrong. The talk was live-streamed but was also recorded and is available here. Dr Armstrong spent 24 years at the Nature Conservancy Council, the Macaulay Land Use Research Institute, Scottish Natural Heritage and Forest Research carrying out research and advisory work. The following is an attempt to summarise some of the key features of her informative and enlightening talk. Read more...
AI technology harnessing the hoverflies.
The loss of pollinators, particularly honey bees, may bring about a synergy between pollinators such as hover flies and artificial intelligence technology. Honey bees (and indeed bumblebee)s have been hit hard by habitat loss, pollution, the extensive use of pesticides and the spread of viruses and varroa. Bees provide an important ecosystem service, namely pollination. bees provide the majority of plant pollination world-wide but the bees are fighting a losing battle and this represents a threat to food supplies. In the United States, bee hives are 'bussed around' in a somewhat 'cavalier manner', indeed "Hives may be moved multiple times and several thousand miles per year" Read more...