Trees that use little water

Royi Frame

Dear tree experts, hope you can help.

I am looking for suggestion for planting small trees ( 20 t0 25 feet )at the back of my garden.
The problem is that some houses in the neighbourhood have had subsidence which has been blamed on local trees using up water in what is predominantly clay soil.

Can you suggest trees that will use up very little water and do not have extensive root systems.

I imagin trees such as OLIVE trees will not use up too much water , is this correct ?

looking forward to a response.

best regards
Royi

Ekka

Hi

We first need to know where you are for climate details. Like in the USA they have Zones and it helps selection. I'm here in Brisbane which is a lot more humid than say Melbourne and we have different trees.

So if we know where you are we'll have a better chance of narrowing down the selection.

We're on heavy clay here too.

Now here's some interesting things, the amount of water a tree uses is pretty much proportional to the volume of canopy as the water is used when the tree transpires (a process used in photosynthesis). So trees with a sparse canopy will use less water than trees with a big full dense canopy.

Take a look at Aussie natives, most are quite sparse in the canopy compared to say a birch or elm. Also a 20' to 25' tree is only small, fruiting trees will tend to use more water than ornamentals as they have fruit to make.

Great question.

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Royi Frame

Hi Ekka

Thank you for the response.

We live in central London, Dartmouth Park a cross the road from Hampstaed heath ( fantastic trees ), and a few blocks away from Higate cemetry where amongst others, Karl Marx is burried. All the houses in the area were built between 1820 and 1880, on what is typically London clay ( most the Thames valley has this substructure ) As the climate changes, we had a rather dramatic drought last year, and a hose pipe ban for several months, the clay has been drying out more excessivly and causing more cases of subsidence. Everything I have read on this matter ( most coimprehensive is a 2004 report by Cambridge University ) says that a tree whould need to be dramatically cut back over 50% to make any real difference to the amount of water it extracts ( they suggest 70%) This corrolates with what you have said above. This is really dramatic for a tree and would need to be done regularly to keep its water usage low.
This is why I am keen to find a tree which inherently uses less water. Thanks for the point about fruit trees, makes a lot of sense.
I was also thinking about a false Acacia. It does not have a heavy canopy, and again I assume that because it originated in the savanas of Africa it would inherently not need or use too much water.

I'm very keen to hear more on this topic.

best regards

Royi

Sean Freeman

Hi Royi, very interesting question, and a lovely spot to live in, magnificent parkland all around you there I know it well, now those planners knew what they were about!!

Please don't try reducing evapotranspiration by reducng the live foliage of your trees by anything like 50% let alone 70%... The effect on even healthy trees of reductions above 25% in the live canopy is very detrimental long term.

If you're thinking of Robinia pseudoacacia it's actually a native of the Appalachian Mountains (below 3500 feet) but it does have a deservedly good reputation as being tolerant of a wide range of soils and conditions, yes it will tolerate drier conditions than its place of origin, however you would need to get the tree to a size able to sustain its system through such poor times, ie established 5-7yrs.

The soils you have in that area of London are fairly reactive clays and you need to bear in mind whatever you plant will change the soil moisture levels and have an impact on both soil plasticity and the potential for ground heave or subsidence..basically ensure the planting is not too close to your foundations, ensure you provide irrigation to the root system, even if its a bucket every week, but maintain that watering pattern. Fluctuations in soil moisture levels are not good in any situation particularly not with reactive clays.

There is no reason why you can't grow beautiful successful trees in your part of central London, but common sense when it comes to the eventual size of the tree and the way you intend to water it are essential.

If fruit trees are the way you decide to go remember that the Bay tree, Laurus nobilis is an excellent companion for citrus and is extremely drought tolerant when established..the leaves aren't half bad either.

For more UK drought resistant plants check out http://www.rhs.org.uk/advice/profile..._resistant.asp

SF

Royi Frame

Hi Boa70

Many thanks for your response its been really helpfull, and I've just checked out the stite you suggested.

again thank you for yourt time and advise.

Royi

Ekka

A suggestion from another member is paper bark maple or weeping copper beech and keep it regularly pruned.

What do you think?

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mdvaden

Who else is familiar with Lavelle Hawthorn?

Have any in your area?

Water needs are average, but its not a big tree.

Has berries about 1/2"

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