Supertrees- The role Woodland can play in the fight against floods



Newly planted trees beside the river Muick, Aberdeenshire

© Copyright Gwen and James Anderson and licensed for reuse under this Creative Commons Licence.

Since Christmas 2013, the UK has experienced the worst winter weather of the century, with January being the wettest since records began in 1766. High winds, heavy rainfall and tidal surges have battered the country, with Western and Southern counties bearing the brunt of the low pressure systems moving across from the Atlantic Ocean.

Much has been made of the government’s lack of action in both responding to and preventing flooding in sensitive low-lying areas such as the Somerset Levels. In particular, many have criticised the Environment Agency for not spending enough money on hard-defences such as Dykes and the dredging of river-beds.

Although appropriate in some circumstances, such defences are often ineffective (and expensive) in the long-term due to the increased threat from Climate Change. For example, the Holderness coast in the North-east of Britain, is one of the fastest eroding areas in Europe. On average, two metres of land is being lost to the sea annually. Placing hard-defences along this long-stretch of coast would do very little in the way of preventing erosion or protecting homes from storm-surges. Stormy weather contains high levels of energy and as such, this energy is often better dissipated through our natural systems.

Models produced by the Forest Research Organisation show that placing Woodland strategically on a floodplain can significantly reduce the size and speed of a flood event. This is because trees absorb water and stabilise the soils. These two effects reduce the size of the flood and also delay the release of water into the river.

A further study commissioned by The Woodland Trust indicated that placing tree belts on upland farmland, can mitigate flooding in adjacent low-lying land, potentially reducing peak stream flow by upto 40%. This is a significant reduction and highlights the role that Woodland can play in alleviating future flooding events.

Despite the success of the above studies, it is imperative that further research is undertaken on how trees and woodland can best reduce flooding. For instance, one study conducted by the Environment Agency found that the tactic of damming rivers with trees to prevent flooding in an area was haphazard and could cause worse flooding downstream, as the water was able to bypass river-bends and flow through neighbouring fields.

In short, policy-makers must look carefully into the ways in which Woodland and other natural systems can mitigate flooding. This winter has demonstrated the variability and strength of Atlantic weather systems. Climate change is likely to cause more extreme weather and as such, it is important that the UK puts into practice the most sustainable and effective flood-management policies. As a result, we will be better prepared and able to protect the things that are most precious to us; our homes, family and way of life.

The Death Of The Ash Tree?

Image courtesy of: Matthew Common- http://instagram.com/mattycbeme.  

There are an estimated 80 million Ash trees in the UK (the third most populous species after Birch and Larch). However, recent findings from environmental organisations suggest that 90% of the current Ash population will be eradicated within the next decade.

A shadow is looming - the fungal disease Chalara fraxiena has made its way across mainland Europe to the shores of the British Isles. The changing season makes it more difficult to spot for signs of disease, but if you look closely - in certain parts of the country - you will be able to spot trees with dark lesions, dying leaves. The disease affects mature trees by reducing the numbers of twigs and branches at the crown, giving them a strange spiky-topped appearance.

The loss of Ash Trees on our landscape will have a severe and long-lasting impact. In some areas of the country, Ash Trees dominate as 'hedgerow trees'. They are the main species of tree planted in hedgerow's along our farmland. Such trees provide a valuable habitat for plants and animals. In particular, it is thought that certain species of Ash-dependent Lichen (an organism consisting of fungus and algae) could disappear altogether. These impacts, of course, would deeply hamper the government's post-2010 targets of conserving and enhancing the UK's biodiversity.

On a positive note: scientists in Denmark and the UK have found that not all Ash Trees succumb to the disease. In fact, 2% of the British Ash Tree population are estimated to be genetically resistant to the strain. At present, scientists in Denmark are collecting the seeds of trees which have not been infected and are hoping to plant new, disease-resistant trees.

Regardless, the disease is spreading fast within the UK, with incidences having increased rapidly since the outbreak was first discovered in areas of East Anglia in October 2012. As of the 15th November, there have been 200 confirmed cases of Chalara fraxiena reported to the Forestry Commission. Of this total, 116 were cases of the disease occurring in natural woodland. Moreover, the disease is thought to have spread not just from infected imports but also through wind-borne spores; which can survive for extended periods of time and move up to 20-30 km per year (Forestry Commission, 2012).

The rapid pace and character of the disease could mean that, despite the best efforts of the government and environmental bodies to control and stop the spread of the disease, many Ash Trees (particularly younger trees) will leave a large, empty space in our countryside. It will likely be many years before woodland and Ash-dependant plant, animal and insect populations are able to recover.


If you want to know more about the disease and what solutions are being put forward then please head to The Woodland Trust's specialist prevention website- www.treedisease.co.uk.

There is also information available from The Forestry Commission: http://www.forestry.gov.uk/chalara. 

Lincolnshire's Missing Woodland

Statistics from The Woodland Trust show that Lincolnshire is one of the least wooded counties in the United Kingdom, with there being an average of 4.2% coverage. This is less than half the national average of 10% and below the recommended average of 15%.

These are worrying figures as woodland has a vital role to play in our environment. This includes: limiting the damage caused by floods, supporting local wildlife, preventing soil erosion and - perhaps most significantly - acting as a sink for our carbon emissions, thus lessening the impacts of global climate change.

Lincolnshire is a county in which the economic livelihood is dependent on agricultural output. Estimates from the Lincolnshire Research Observatory (LRO) show that the food and farming industry employs 10% of people who live in the county and that the economic reliance on this sector is four times the national average (LEFM, 2006). From this it is difficult to see how enough land could be spared to meet the recommended target of 15% without local farmers and communities suffering.

Nevertheless, a recent report by the Forestry Commission has suggested one way in which economic and environmental concerns could be equated. The Forestry Commission puts forward the idea that we should create and encourage the planting of small woodland areas on arable land. This includes: planting trees and other shrubbery (around farm buildings), tracks, storage yards and water courses. This proposal would not encroach upon available crop-planting land and, instead, could  increase the arability and profitability of the land.

This is because wooded areas help stabilise the soil, thus protecting land from soil erosion and nutrient run-off into rivers and streams. In areas prone to flooding, woodland can also protect against crop damage by soaking up excess water. This may be particularly relevant to agricultural areas near the coastline, who face the risk of storm surges due to the changing climate.

With the additional threats posed to Woodland by the fungal disease Chalara Franxiena (Ash dieback), it is essential that the Forestry Commission and other government bodies work together to advance all current Farm Woodland Schemes (FWS) and the English Woodland Grant Scheme (EWGS) in Lincolnshire and across the rest of the UK.