Environment Controls Seasonal and Daily Cycles of Stem Diameter Variations in Portuguese Oak (Quercus faginea Lambert)

Tree growth takes place at different time scales ranging from hours to days. To understand responses climate, continuous high-resolution measurements of tree diameter variations are needed, which usually obtained with automatic dendrometers. Here, we monitored stem increment Quercus faginea Lambert growing in central Portugal determine the effect climate on daily and seasonal dynamics during 2013 season. Stem variation presented a unimodal pattern characterized by an exponential phase spring followed plateau summer, interrupted abrupt increase autumn caused rainfall. started March when temperature was above 10 °C. showed double climatic constrain, limiting precipitation summer. The amplitude cycles higher as well expansion length, meaning that trees needed longer replenish water lost through transpiration day. absence pronounced shrinkage summer suggests Q. has access over whole Our results indicate this species relies deep soil reserves can be physiologically active drought.