Commodity prices eased back last month after a record high in April, but were still at the second highest level the index has recorded.
The ANZ commodity price index fell 1.6% in May, though that was after a 12.6% surge in the previous month.
Nine commodity prices strengthened on May, led by an 11% increase in log prices due to demand from China.
Prices for six commodities fell, including dairy and beef.
ANZ economist Steve Edwards says in the last 18 months there have been rises in exports of milk powder, logs, sheep, beef and seafood to China.
He says judging by prices in the forestry sector it's a sign that things are starting to turn around in the global markets, particularly Asia, which weathered the downturn quite well.
Mr Edwards says the forestry component of the index hit a 23 month high, driven by the price of sawn lumber which hit a five year high.
He says forestry prices in general have increased for nine consecutive months.
Mr Edwards says horticulture prices have also hit new highs as the new season's crop reaches the northern hemisphere markets.
"So it's a seasonal thing - it happens every year - but we have seen apple prices hit a 20 year high and kiwifruit prices hit a five year high."