"Data included in the worksheet titled ""PlasticN.moaf"" are individual root life span for the study reported in:" "Kern, C. C., Friend, A. L., Johnson, J. M.-F., Coleman, M.D. (2004). Fine root dynamics in developing Populus deltoides plantation. Tree Physiology 24: 651-660" "The ""PlasticN.moaf"" worksheet includes the following columns." BLOCK Block number. The randomized block design consists of four replicate blocks each containing four fertilizer treatments. PLOT Plot number. Treatment plots were 225 square meters each with 196 trees. A central measurement plot within each treatment plot contained 64 trees (81 m2). TRTMT "Treatment level. Fertilizer treatments were 0, 50, 100, and 200 kg N / ha / yr." TUBE Minirhizotron tube number. Five tubes per plot. FRAME View frame (1.4805 cm2) within each minirhozotron accessed with indexing handle. ROOTID Each root is identified with a unique number within a frame of a specific minirhizotron tube LGTH Root length (mm) DIA Root diameter (mm) born Julian date of observation session in which the root appeared died Julian date of observation session in which the root disappeared. lifespan Root lifespan defined as days between initial appearance and disappearance or last observation for right censored roots. censored Takes a value of 1 if still present at final observation date (right censored) depth Depth in soil (cm) year Year of observation. 1998 or 1999 season "Season of observation. Season was assigned according to solstice and equinox: 1=spring, 2=summer, 3=fall. There were no winter observations."