Assessing Wood from Hurricane-Downed Trees in Puerto Rico

After Hurricane Maria made landfall in September 2017, the storm left hundreds of thousands of downed trees in its wake. Many of the trees were species with commercially valuable wood, but which ones?

A huge pile of logs from hurricane-downed trees in Puerto Rico.
Wood from hurricane-downed trees in Puerto Rico. Species identification was needed to decide how to best use or dispose of the material.

To find out, an assessment of the post-hurricane wood, stored at 21 different locations around the island, was requested by Puerto Rico’s Department of Natural and Environmental Resources, or DNER. The Federal Emergency Management Agency supported this request through the Natural and Cultural Resources Recovery Support Function.  The Department of the Interior contacted the USDA Forest Service, and scientists Mike Wiemann of the Forest Products Laboratory and William Gould from the International Institute of Tropical Forestry developed an assessment of the species mix and log quality of the downed trees.

A technical team was assembled, including personnel from the Forest Service’s Southern Research Station Forest Inventory and Analysis, the USDA Caribbean Climate Hub, the Pinchot Institute, and arborists from the company Siempre Verde to conduct a rapid, two-week assessment.

Identifying the species in the log piles was complicated by the fact that the most common and reliable characters for tree identification, flowers and leaves, were no longer present. But wood can last a long time and it can be used for identification.

Visits were made to some twenty sites where logs had been piled. Intact wood was removed from logs using chain saws and chisels, a field identification was made using a hand lens, and samples were brought to the Forest Service’s International Institute for Tropical Forestry for closer examination, using microscopic features when necessary.

Because the storage sites were concentrated along the urban coasts, the species mix consisted of both native and introduced tree species, complicating the identification process. In all, some 135 samples were collected and identified, representing 40 different species. Of these, about three quarters produce commercially important wood; the others are of strictly ornamental value.

The most common commercially important species identified included guanacaste, mahogany, mango, pine, and tropical almond. There were also many street ornamentals, such as African tulip tree and flame tree, whose wood has no value.

A report on the assessment was compiled and provided to DNER, to inform officials as decisions are made about the use or disposal of the wood.