Chlorophyll fluorescence emission: scaling from the leaf to satellite remote sensing - Chlorophyll, the green pigment in leaves, exhibits the unusual feature of re-emitting a small fraction of the light it absorbs; that is, it fluoresces. For decades, physiologists examining individual leaves have used the strength of fluorescence emission to probe the inner workings of photosynthesis and leaf responses to environmental stress. Only recently, instruments capable of measuring chlorophyll fluorescence have been mounted on towers and satellites, allowing for remote sensing of the fluorescence of whole forests. We partner with collaborators at Boston University, Caltech, UC - Davis, the University of Utah, and elsewhere to understand how remotely sensed chlorophyll fluorescence might deepen our understanding of forests and their response to global climate change. This work is supported by grants from NASA, NIST, and the NSF.
The ecophysiology of eastern dwarf mistletoe infection - Eastern dwarf mistletoe, a diminutive parasitic plant, can fell a mature white spruce in a matter of years. Curiously, a closely related host growing in adjacent forest stands, red spruce, tolerates infection and even succeeds in killing the parasite. Students, collaborators, and I seek to determine the causal chain of events leading to white spruce mortality and contrast it against the mechanism of red spruce tolerance, drawing upon observations at scales from gene expression and hormone metabolism through whole–tree growth and stand dynamics. The host-parasite interactions we study are shaped by 19th-century removal of red spruce/fir-dominated forests to create pastureland that was subsequently abandoned and recolonized by white spruce. We conduct this work at several sites along the Maine coast, including Monhegan Island.
Jaret Reblin, Laboratory Instructor in Biology, is a close collaborator on many aspects of these and other projects.