Figure 2: Branch daytime ‘snap-shot’ branch emissions of (a ) acetic acid (AA), (b ) methanol (MeOH), and (c ) the AA/MeOH emission ratio from control (N = 21) and drought stressed (N = 16) poplar trees. In addition, the daily maximum (d ) AA emissions, (e ) MeOH emissions, and (f ) AA/MeOH emission ratios from real-time branch gas exchange measurements on the first day of secession of soil water addition (Day = 0: control) and a subsequent day during the drought response at the time where AA emissions were maximized (N = 5) are also shown. All values are plotted as average +/- one standard deviation (ns indicates no statistical significance between control and drought treatments, * indicates statistically significant differences, P < 0.05).