"Why do some trees live while others die"? The answer is important because fires, insects, and disease are killing increasing numbers of trees over the last few decades. Sometimes we can answer this question by doing field experiments (Pub. 41, 55, 120). More often we use process-based models to assess how changes in the environment affect trees over a period of years (Pub.117,119). At larger geographical scales, models projections can be tested using information gathered from orbiting satellites (Pub. 115), although to date, ground-based observations are required to confirm predicted shifts in forest structure, composition, and productivity (Pub. 123). A National Aeronautics and Space Admininstration's program in Biodiversity and Ecological Forecasting supports my group's research to  predict mortality of different tree species across western North America (Pub. 121).  The array of techniques available to assess the health of trees and their ability to adapt to new situations has increased significantly over the course of my career (Pub. 77). A summary of our most recent NASA-funded research with links to individual publications can be downloaded. pdf.