Professor Howard Griffiths, Professor of Plant Ecology
Physiological Ecology and Stable Isotopes
The Plant Physiological Ecology Group was established in the Department of Plant Sciences at Cambridge in 2000 to measure the physiological determinants of plant distribution, from tropical forest epiphytes to crop water use and biomass allocation. We are intrigued by the photosynthetic physiology of the organismal awkward squad, and how diffusional and carboxylation co-limitations interact across epidermis and mesophyll by day or night. Such processes have engendered a variety of carbon dioxide concentrating mechanisms (CCM), which enhance the operating efficiency of Rubisco, including the biochemical C4 pathway (in maize, miscanthus and sugar cane), crassulacean acid metabolism, (CAM, in succulents such as Agave, Orchids and Bromeliads), or the biophysical CCM (in algae, cyanobacteria and hornworts). Using stable isotopes (13C and 18O) as markers of photosynthetic gas exchanges, both in real time and in organic material, we seek to evaluate the biophysical and biochemical constraints which may have shaped the evolution of photosynthesis in terrestrial and aquatic plants. We are currently working on the structure, function and origins of the chloroplast pyrenoid, so often associated with the activity of a biophysical CCM in aquatic organisms and hornworts. We also use the isotope signatures to characterise water use and exchange by plants (vascular epiphytes, bryophytes and now insects!), and to infer niche differentiation and habitat preference. Having led several expeditions to Trinidad, Venezuela and Panama to study forest canopies and epiphytes, the Physiological Ecology Group will continue to 'put plants in their place' - sustaining diversity, responding to a changing climate and providing fascinating molecular and ecological insights.
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Department of Plant Sciences
University of Cambridge
Downing Site Downing Street
CAMBRIDGE CB2 3EA
Email: hg230@cam.ac.uk
Office +44 (0)1223 333946
Lab +44 (0)1223 330218
The stable isotope composition of epiphytes in cloudforests may provide a sensitive indicator of climate change processes (here viewed on Morne Bleu Ridge, Trinidad).