Professor Berlyn’s interests are the morphology and physiology of trees and forests in relation to environmental stress. Leaves are the most responsive and vulnerable organs of trees, and Professor Berlyn studies the ways that leaf structure and function reveal the effects of environmental change such as global warming or altitudinal and latitudinal gradients. In addition, these studies can help determine the optimum range of habitats for individual species and thus be of use in reforestation and aforestation. Some of the techniques used to study these problems are: light processing by leaves in relation to environmental factors as measured by chlorophyll fluorescence, photosynthesis, spectral reflectance, absorption, and transmission; and image analysis of leaf and tree structure. Professor Berlyn has also pioneered in the development of organic biostimulants that can help plants resist insect, disease, and other environmental stressors while reducing fertilizer use. Thus the Berlyn lab focuses on how to measure the stress of plant life and also on how to ameliorate it. Students in the Berlyn lab are currently working on such topics as structural and functional change along elevational gradients in mountains, molecular control of sun/shade leaf phenotypic plasticity, response of tropical pioneer species to gaps in tropical forests, and the role of antioxidants, stress vitamins, and mycorrhizas in organic biostimulants.