Trees in Hampstead

What's really causing your subsidence?

Hampstead has large amounts of three of the ingredients that contribute to subsidence:
1) London Clay
2) Water
3) Trees

Trees however only have a ‘walk-on’ part: they do not contribute to subsidence without the primary role of water acting on clay first. Since they will be part of the solution and give us great pleasure, taking them out is not only an immediate waste of money, it means much more needs to be spent later when the true cause is discovered.

Tree saved from felling

Sadly, a ‘blame the tree’ culture, a lack of understanding of the true action of water on clay and trees, and an insufficiently strong legal protection for trees in situations where subsidence is occurring in the presence of trees, are all contributing to the gradual denuding of Hampstead’s magnificent canopy cover.

Hampstead Geology

This part of the south east has a thick layer of marine ‘London’ clay laid down 60-50 million years ago when this area lay under a warm tropical sea. A layer consisting of a mix of clays, silts and sands - Claygate Beds - overlies the London clay, with a top layer of sand deposited by the enormous Bagshot river that ran from west to east across the whole of Wessex 50 million years ago. Hampstead is on the top and southerly slopes of one of London’s sandy hills.These hills remained after glacial melt water from the last ice ages washed away much of the surrounding areas down to the London clay. The top of Hampstead’s hill consists of this Bagshot sand through which water passes easily. The next Claygate Beds layer provides a semi-permeable barrier that checks the water and sends it out as springs at the boundary zone - for example those on the meadow below Kenwood House - and provided the water for the many surface wells around Hampstead and the rivers of north London – the Fleet, Tyburn and Westbourne rivers.

Trees on private land

Street trees, of course, are only a percentage of those trees that make Hampstead distinctive; hence, it is no surprise that every tree in every garden in the conservation area is subject to a tree preservation order. What is surprising is how many of these trees continue to disappear despite their protected status.
Read more...

Under Threat

Trees Hampstead's trees are under an increasing threat from a variety of factors, both environmental and man-made, and its leafy inheritance is no longer something we can take for granted. So in 2006 the Tree Policy Group was set up to counter that threat.

Chopping down a tree at the first sign of decay keeps the Council's insurers happy. But that tree might live for another 250 years! New research about tree safety has led other London Boroughs to adopt a far more tree-friendly approach. And now, thanks to pressure from the TGP, Camden has been brought into line and its felling policy curtailed, it gives more notice about its proposed street tree programme, and provides post-felling photographs and data for decayed trees.

The Heath and Hampstead Society

Hampstead Geology