New Zealand forest owners are cutting back on their harvest on the back of tumbling log prices.

Cheaper logs from Russia and Scandinavia are flooding into China, leaving Kiwi logs piling up on Chinese wharves.

"A" grade logs have fallen from about 140 US dollars a tonne - to 110 US dollars.

Collapsing demand in China for New Zealand logs, combined with economic effect of the trade war between China and the United States have been pointed to as two of the main reasons behind the price fall.