Research in Hawaii
Ben Houlton

My projects on Maui, Kauai and across the Hawaiian Islands center on understanding the emergence of broad shifts in forest nitrogen cycles. Hawaiian rainforest ecosystems are ideal for addressing that problem because they exhibit global variations in nitrogen cycling, while often sharing the same bedrock geology and plant community compositions. My approach involves comparing measures of natural changes in nitrogen and oxygen isotopes at the scale of ecosystems against a new generation of isotope models that provide mathematical interpretations of biogeochemical pattern.

Frequently, I take trips to Maui and Kauai to sample streams, soil waters, rainfall inputs and cloud-water. I then analyze these samples for nitrogen chemistry and associated stable isotopes ratios. Since the “imprint” of biogeochemical interactions is encapsulated within such isotopic measures, this approach allows me to ask questions about broad shifts in forest nitrogen cycles without disrupting the feedback loops that form between natural ecological communities. Through this research, I hope to advance our understanding of nitrogen cycling at a basic level, as nitrogen is a macronutrient often in short supply in terrestrial ecosystems, and at an applied level, as human activities have dramatically altered nitrogen in the biosphere yet we don’t understand the effects of such a perturbation. Lastly, and importantly, this work is exciting and fun, too!

Orographic rainfall gradient on Haleakala Volcano, Maui.

O’hia canopy and associated bryophyte mats in the wet, nitrogen poor forest on Maui.

Photograph of “dry” forest on the Maui rainfall gradient.

Giant tree fern on Maui.

Undergraduate researcher, Jon Benner, catches a rare glimpse of the elusive Maui Dinosaur!!!

Ben Houlton conducting a field-experiment on Maui.

Jen Houlton collecting a soil core on Maui.

Beautiful O’hia in full bloom.

The infamous “Cane Spider” at the field-lab facility on Maui.