In Hawaii, numerous lava flows can create forest fragments that are called kipuka (Lit. ‘Image of a Forest’) in Hawaiian. These forest fragments can suffer from edge effects as the surrounding matrix habitat starts out being barren, and then is colonized by an assemblage of pioneer species. Edge effects can cause forest canopy to decrease in density nearer to the edge, and the size of the kipuka strongly dictates the severity of the edge effects with smaller kipuka being more affected. The presence of certain understory species may be affected by the density of the canopy and the subsequent effects of light, and moisture.
In this presentation, we show that the presence of ‘uluhe ferns are significantly affected by the canopy density. ‘Uluhe ferns are a predominantly matrix species, but are present in kipuka with a lower average canopy density and smaller size, suggesting that they have an affinity for light which makes sense in light of their growth habits, and that they take advantage of the edge effects of smaller kipuka to colonize them.
Their invasive growth habit and status as an early successional native species suggests that they may have a role in community assembly to prevent the invasion of other less desirable invasive species by crowding out their niche space. This could be a valuable tool in restoring degraded ecosystems.Kipuka Project 1
Understory Composition and Edge Effects on Canopy Density in Hawaiian Forest Fragments