I have a Japanese black pine that I would love to eventually train as bonsai. The needles are too long and wouldn't appear to be a miniature tree. How would I train it to have shorter needles?

Smaller pots, root prunning, less fertilizer building ramification and candle pinching. All techniques used on pine bonsais will shorten neadles and internodes.

The main technique here is candle pruning. Japanese black pine can re-flush in summer, if at the right time this years' growth is clipped off. The needles on that growth do not have a lot of time to develop. As such, they are shorter. This is combined with the reduction of the number of needles left on each branch over winter, so that less energy is captured to grow the next year.

Harry has a few good articles on this: bonsai4me.com/AdvTech/ATPine%20Pruning%20Page2.html