Correct, Trees. The research conducted indicates that these trees (which are naturally drought tolerant to some degree) are able to tolerate slightly drier conditions because they do not need to transpire (and lose water) through as many stomata. The only problem with the research as I see it, is the lack of a baseline. If the study had been attmpted at lower CO2, 200 years ago, and failed, these results would be a little more conclusive. They will need to do a fair bit more work and corroborate thier findings experimentally.
As for whether rainforests become drier with less transpiration... well that's a tricky one. It probably depends on location, as a rainforest such as the Daintree receives it's water through local geography. Wet air comes off the Coral Sea and dumps the moisture when it is pushed up the mountains. Some rainforests rely more on transpired water (local recycling), and these may suffer more. To be honest, climatically driven variation in rainfall is far more likely to be a threat.
