By Thomas Giambelluca

Anecdotal evidence suggests that, besides impacting biodiversity, the invasive tree Miconia calvescens is causing landslides and other soil erosion problems in Tahiti, where it has displaced native forest. As miconia takes hold in Hawai‘i, local scientists and environmental organizations have voiced concerns about its potential hydrological impacts: increased flooding, diminished groundwater supply, loss of topsoil, and siltation of coral reefs.

Miconia invasions lead to dense, monotypic stands with little or no ground-covering vegetation. Miconia’s large, dark leaves reduce light levels beneath the canopy, thereby inhibiting the germination and growth of other plant species. Large leaves also produce relatively large throughfall drops during and after rain events.

“Throughfall” refers to rainwater that reaches the forest floor. Some throughfall consists of raindrops that fall through the forest canopy without hitting any leaves or branches. The rest comes from drops that splash or drip from wetted vegetation. Water that drips…