The status of Puerto Rico's forests, 2003
Puerto Rico’s forest cover continues to increase and is now 57 percent for mainland Puerto Rico, 85 percent for Vieques, and 88 percent for Culebra. Subtropical dry forest occupies 50 346 ha, 6832 ha, 2591 ha, and 6217 ha on the islands of Puerto Rico, Vieques, Culebra, and Mona, respectively. Subtropical moist forest, the most prevalent forested life zone on mainland Puerto Rico, had 49 percent forest cover or 258 861 ha of forest. Subtropical wet and rain forest occupies 161 503 ha, lower montane wet and rain forest occupies 11 723 ha at the highest elevations, and mangrove forest occupies 7920 ha in coastal areas. Puerto Rico’s forests were found to have over 1,602,378,689 trees over 2.5 cm in diameter and 10 607 847 m2 of basal area, and to hold 36.6 million Mg of sequestered carbon. There were 3,112 trees, 19.2 m2 of basal area, 68.25 m3 of merchantable stem volume, and 80 Mg of aboveground biomass in an average hectare of forest. The subtropical moist and wet and rain secondary forests inventoried in 1990 are still young and increasing in average basal area, which rose from 13.2 mm2/ha in 1980, to 15.2 m2/ha in 1990, to the current level of 20.9 mm2/ha.
The most important tree species were the African tuliptree [Spathodea campanulata] Beauv., American muskwood  (L.) Sleumer, cabbagebark tree [Andira inermis] (W. Wright) Kunth ex DC., and pumpwood [Cecropia schreberiana] Miq. Few unhealthy, stressed trees werenoted and widespread pest and disease problems were not observed. Only 12.9 percent of live trees had some type of damage or disease. Average per-hectare amounts of down woody material, forest floor duff, and forest floor litter generally increased as the forest environment became more humid. Small-to-medium forest fire fuels were most common in subtropical dry forests, while medium-to-large fuels were most common in more humid forest life zones.