Light response curves of PSII (ETR_II) and PSI (ETR_I) electron transport rates in fronds of <i>H</i>. <i>cruentum</i> and <i>H</i>. <i>dentatum</i>.

<p>Detached fronds were fully hydrated overnight and then dark adapted during 30 min. PPFD response curves were programmed using the scripting facility of the Dual-PAM 100 control software. Each frond was exposed to successively increasing actinic light levels (0 to 436 μmol photons m^-2 s^-1), with 3 min equilibration time at each light level before the application of saturating pulses. Values correspond to the mean ± SE (<i>n</i> = 4).</p

Changes in partitioning of absorbed excitation energy with increasing PPFD.

<p>This was measured at PSI (a, b) and PSII (c, d) level in fronds of <i>Hymenoglossum cruentum</i> and <i>Hymenophyllum dentatum</i>. A dashed line indicates the portion of the curve where comparisons between species were made. These points correspond to the light saturation points of <i>H</i>. <i>cruentum</i> at 24.6 μmol photons m^-2 s^-1 (Is_{<i>H</i>.<i>cru</i>}) and of <i>H</i>. <i>dentatum</i> at 40.5 μmol photons m^-2 s^-1 (Is_{<i>H</i>.<i>den</i>}), both obtained from gas exchange measurements. Values are shown as mean ± SE (<i>n</i> = 4).</p

Light availability across a vertical gradient in the natural habitats of Hymenophyllaceae species in the Katalapi Park.

<p>Frequency of observed photosynthetic photon flux density (PPFD, μmol photons m^-2 s^-1) measured at three trunk heights: <1, 4.5 and 9 m using data collected by two different data-loggers from 01 October 2010 until 01 February 2011.</p