Root pressure
We estimated root pressure with bubble manometers on five individuals of
each liana species (n=80) as described by Ewers et al. (1997). During
the night prior to measurement, we cut one lateral branch and we
attached a manometer with a tight-fitting vinyl tube. Each manometer
consists of a glass tube of 1 mm internal diameter closed at the distal
end, filled with distilled water in basal half and air bubble in the
distal part. We measured the length of bubble at pre-dawn
(Lpd, in m) and then we immediately cut the vinyl tubing
and we measured the bubble length again, representing the atmospheric
pressure (Latm, in m). We estimated root pressure
(PR, in kPa) using the ideal gas law (Ewers, et al.
1990; Tibbetts & Ewers, 2000) as:
PR= 100 [(Latm / Lpd)
- 1] Equation 3.
We estimated the maximum height for reverting embolism (hc) by a given
root pressure near the stem base (PRb, in kPa) (Ewers et
al., 1997; Tibbetts & Ewers, 2000) as follows:
hc= (Pr -Pc)/10 Equation
4.