MEXICO CITY - Almost all the world’s tropical forests remain effectively unprotected even though two-thirds have been designated for some sort of preservation over the past two decades, according to a new survey.

The study of tropical forest management by the International Tropical Timber Organization surveyed 2 billion acres — two-thirds of the world’s tropical forests — in 33 countries.

All of those forests were designated by the governments and landowners overseeing them as being under “sustainable management,” meaning they were completely protected as conservation areas, or designated as sites where economic activities such as logging were only allowed if they didn’t destroy the forest.