Collecting Data (IMAGE) Penn State Caption Researchers conducted fieldwork in the eastern Sierra Nevada Mountains in 2017. They measured tree diameters and litter depth, counted the number of seedlings and saplings and identified tree species at the research sites. Credit Lucas Harris / Penn State Usage Restrictions non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.