Q:

Does a Japanese maple require special care when a post-hole is dug in the root system?

I need to put a post down to support a carport. The post would be embedded in a concrete block approx. 60cm x 60cm. This is 3 metres from the trunk of a Japanese Maple about 5 metres tall.
Is there a likelihood of damage to the tree if we are careful in digging the hole, and how can I help it?

A:

It's anybody's best guess really - where the roots of a tree spread to is very much down to local conditions, and the only way you're going to find out is to start digging the hole. At a distance of three metres from the trunk, it's likely you will come across some root material, and losing a little of it shouldn't cause too much damage, particularly at this time of year (assuming you're in the northern hemisphere), but if the whole area is a solid mass of roots, both large, woody ones and fibrous ones, then yes, your tree will suffer and may even die. 
Ultimately, if you need to put in a post, then you need to do it, and you may have to replace your tree if putting up a carport is a priority, but you might find it's not an issue when you start to dig out.

A:

It partly depends on the size of the tree (some Japanese maples mature far larger than others, and at 5m tall, there are a lot of possibilities.), but at 3 meters from the trunk, you are more likely to damage a larger tree than a smaller one. In any case, you are unlikely to kill the tree, even if you do cut some roots. That will be such a small percentage of the root system. Sometimes if I feel I've cut back more root than normal I'll prune the top-growth a little, to balance the systems. If you do this, wait until spring, so you don't get winter burn from it.

