J.P. Grimes, The Role of Plasticity in Exploiting Environmental Heterogeneity. D. Baldocchi, The Physical Nature of Solar Radiation in Heterogeneous Canopies: Spatial and Temporal Attributes. C.L. Ballare, Light Gaps: Sensing the Light Opportunities in Highly Dynamic Canopy Environments. M. Kuppers, Light Gaps: Rapidly Filling Space and Intercepting Light-A Whole-Plant Perspective. D.J. Sims and R.W. Pearcy, Photosynthetic Acclimation to Varying Light: A Leaf to Whole-Plant Perspective. R.W. Pearcy, R.L. Chazcon, and K.A. Mott, Photosynthetic Utilization of Light Variations on the Time Scale of Seconds to Minutes. C. Vazquez-Yanes, Signals for Seeds to Rapidly Sense and Respond Rapidly to Light Gaps. G.P. Robertons and K.L. Gross, Assessing the Heterogeneity of Belowground Resources: Quantifying Pattern and Scale. J. Stark, Causes of Soil Nutrient Heterogeneity. P.S. Nobel, Root-soil Response to Water Pulses in Dry Environments. A.H. Fitter, Architecture and Biomass Allocation as Components of the Plastic Response of Root Systems to Soil Heterogeneity. M. Caldwell, Exploiting Nutrients in Fertile Soil Microsites. F.A. Bazzaz, Coping with Multiple Environmental Gradients in Gaps. G. Bell and M.J. Lechowicz, Spatial Heterogeneity at Small Scales and How Plants Respond to It.