When coconut trees attack . . . other treesS

On the atoll of Palmyra, south of the Hawaiian Islands in the Pacific, the coconut trees are literally bombing the local flora into extinction. How can trees be destroying trees?

Apparently by dropping coconuts on them.

USGS blogger Ben Young Landis writes:

A USGS report released in January [by researchers] Stacie Hathaway, Kathryn McEachern and Robert Fisher recommended habitat management strategies for Palmyra. One finding casts the coconut palm in a villainous role.

Coconut palms, a species that was being farmed in local plantations, are taking over the island landscape. The palms are driving out a rare, native tree species called Pisonia grandis — which create immense forests that act as a key foundation of the Palmyra Atoll's terrestrial ecosystem.

As McEachern recently described to Greenwire, "In the most mature state, you'd be walking through a forest that has big trunks widely spaced apart, but it would be like looking up in a cathedral with a green roof, all the leaves knit together."

This canopy cathedral also provides valuable nesting habitat for vast numbers of seabirds, such as red-footed boobies, which can perch on and create stable nests in the maze-like branches of Pisonia trees. In turn, feces from the nesting seabirds delivers important nutrients to the island ecosystem, fertilizing trees and sustaining the local food web.

In contrast, the long, slick coconut palm fronds provide no such nesting structure, and seabirds tend to avoid them. Coconut fronds and nuts themselves also crush Pisonia saplings when they fall to the ground.

"As a result, coconut palms are quickly replacing the native forest, bird nesting sites have shrunk and ecosystem dynamics are changing," says Hathaway.

Environmental scientists are working on ways to remedy the situation, which will (hopefully) include cutting those evil coconut bullies down and making room for birds and smaller trees. Or maybe the coconuts can be transplanted and rehabilitated elsewhere.

via WERC From the Field