My travel mate and I had the privilege to re-visit Tomohiro Masumi at the Koju-en shohin-bonsai nursery in Kyoto. We had a very pleasant time as always with Tomohiro. One of the important lessons at this visit was always to keep your shohin in as much light as possible. I think we from time to time hear about keeping some trees in semi-shade to protect them from the sun, but this is wrong according to Tomohiro.
Keeping shohin from getting all the light they can get, will make them grow longer branches with greater distance between the internodes (leaf pairs), and make it difficult to achieve a compact tree wanted when growing shohin especially. All kind of trees needs full sun to be able to make a compact image.
This of course demands that we are careful watering thoroughly when the heat dries out the small volume of soil available. The net seen at some nurseries placed above the trees have two purposes, depending on the aim of it. At Koju-en a large net is covering the whole nursery to keep birds away from the trees, often seeking food by taking of the fertilizer pellets and risking to tip the trees off the tables.
At Mansei-en nursery in Omiya we observed a big open building constructed with a net over it, and also at a nursery in Angyo. There the purpose of the net was to provide shade for weaker trees, that needed less sun for a period to recover. Often these trees are brought in from customers who have made mistakes or because of deceases. Therefore the bonsai needs slight protection when they are taken into care and recovering from the stress applied to them.