[Callum McCutcheon]

Hi Boilerplater

Thanks for the book recomendation.That looks like one for the christmas list (counting down the days!).

I would agree that there is sufficient precipitation in most parts, but how much of that is actually available to the tree?. Compared to uncompacted loamy soil, the water infiltration rate through asphalt is zero, paving stones and paving bricks only 5-10% and even the best semi permeable asphalt only 50%.

Much of the water is diverted away through drains, and compacted urban soils often have low holding capacity. At the same time urban trees are subjected to higher temperatures, lower humidity, and increased wind speeds compared to a rural environment.

Once a tree is well established then it is able to cope as long as the tree pit has enough soil volume, but in the first 2 or 3 years following transplantation then suplementary watering to the root zone during the growing season is very beneficial.

Callum

[Callum McCutcheon]

Hi Steve

You make some very good points.

I agree totally with idea that you need good quality stock and that the species has to match the site conditions. Also that this is a better way to go than trying to artificially improve the soil conditions with amendments. Although the soil structure may be completely destroyed and amendments may be essential.

I was wondering how many of the percolation tests you do show poor drainage, and do you find that this occurs more often in city streets than in more rural sites?.

From my own experience and from what I’ve read most of the soils in urban environments suffer from poor drainage because of all the pedestrian and vehicular compaction.

This comes back to what Thomas was saying about allowing enough space in the tree pit for future root growth.
If the tree pit has enough volume to accomodate future root growth and there is a drainage system installed then poor drainage within the pit would only be a problem in heavy clay soil.

Your Sketch-up programme sounds very interesting. I’ve only just started to get into sketch-up, and i had been thinking of using it to produce 3d tree planting schemes.

My computer programming skills are very much at beginner levels. One of the things that attracted me to the Android smart phone operating system was the easy of programming. I’ll be having a look at the sketch-up forum because I think it has great potential (and it’s free)

Thanks

Callum

[Callum McCutcheon]

Hi Thomas

Thanks for the comments.

I can see your point, and to some extent it’s all about education.

The tree itself and the way it is planted (depth, size of pit, quality of stock, formative pruning etc) definately has a big impact on the success of a planting scheme but I think most people are fairly familiar with these issues (maybe with the exception of pit size !). Watering is seen as almost an optional thing.

Your comment about cost of maintainence is also very valid, however in the UK the mortality of trees in the first two years is about 30-50% so we’re obviously doing something wrong and spending a lot on replanting.

I suppose the point I’m trying to make is that all trees need water and the amount of water varies greatly for different sizes of tree, different sizes of pit, different soil type and climate. So it makes sense to give the tree as much water as it requires but avoid watering to much which adds to the cost of maintenance.

If the app could give you an accurate figure and be very easy to use, it could allow a planner or contractor to assess the maintence cost in the planning phase so that schedules and budgets could be included in the project plan.

An effective watering schedule could lead to a higher survival rate which would reduce replanting costs. Avoiding to much or to frequent watering which is unavailible to the tree due to soil field capacity could help conserve water.

Thanks
Callum

An app which identifies trees would be the ‘holy grail’. Maybe in the future someone will invent a pocket DNA analyser , that would be cool !

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