Graeme P. Berlyn

E. H. Harriman Professor of Forest Management and Physiology of Trees

Research Overview


Our main goal is to deepen knowledge of the ways in which plants respond to the environment in terms of different traits (genetic, physiological, anatomical, and morphological). We examine these traits at different levels of biological organization, viz., molecular, cellular, organ, organismal and at the forest level. We look at different modes of response such as phenotypic plasticity, the capacity of an organism to change in morphology and physiology in response to environmental signals, and genetic mechanisms as revealed in common garden experiments and DNA analysis. The techniques we have used are cellular (cytophotometry, DNA microsatellites & microarrays, and image analysis of cellular and tissue level changes), light and carbon processing (photosynthesis, spectral reflectance, chlorophyll fluorescence, stable isotopes, etc), water relations, and growth analysis. One of the ways we investigate these responses is to use natural gradients of environmental stress such as along elevational gradients in mountains. High elevation sites are indicator ecosystems for a variety of stressors such as acid rain, global warming, grazing by domestic animals and wildlife, recreational use, commercial development, and pollution by toxic chemicals. We also study changes along microtopographic transects such as ridge tops, midslope and bottomland sites. Even these finer environmental differences are recorded in the structure, optical properties, and function of leaves, enabling determinations on such problems as what species are optimally adapted to each of these types of habitats under various conditions. Within the crowns of trees and in cross sections of the forest canopy there are environmental gradients, which are reflected in the way these aggregate structures process light. In turn structural changes mirror these gradients and can be studied using invasive and non-invasive techniques. We, along with colleagues and students, have conducted studies in New England, Canada, Sri Lanka, Panama, Peru, Mexico, Costa Rica, Puerto Rico, Africa, and India. In addition to the field components we also conduct controlled experiments in the Greenhouse and controlled growth rooms in order to more precisely isolate effects of environmental factors such as light quantity and quality, nutrition, competition, and water relations. Additional interests are plant embryology, biotechnology, genetic stability, interaction of environment and nuclear genome, biostimulants and mineral nutrition, cytochemistry, quantitative microscopy and microtechnique.

My current research includes anatomical, physiological, and optical properties of leaves in relation to: (a) light intensity and quality, (b) distribution in tree crowns, (c) nutrient status, and (d) ecology and silviculture. The second current project concerns the development and use of organic biostimulants to maintain optimum plant growth while reducing fertilizer requirements and increasing natural stress resistance with respect to water, disease, insects, and toxic substances. I was one of the originators of the biostimulant concept for amplifying plant growth and stress resistance. Current work involves adding beneficial microbes (or their byproducts) to the biostimulant such as mycorrhizas and organisms that inhibit pathogenesis and increase the natural resistance of the plant using chemical signaling to stimulate the production of protective compounds and protective tissues.