© 1996 Heron Publishing—Victoria, Canada
Effects of light environment and successional status on lightfleck use by understory trees of temperate and tropical forests
Manfred Küppers (1, 2), Hans Timm (1), Frank Orth (1), Jens Stegemann (1), Robert Stöber (1), Hans Schneider (1), Kailash Paliwal (3), K. S. T. K. Karunaichamy (3) and Rodolfo Ortiz (4)
1. Institut für Botanik, Technische Hochschule Darmstadt, Schnittspahnstrasse 10, D-64287 Darmstadt, Germany / 2. Institut für Geobotanik und Botanischer Garten, Martin-Luther-Universität, Neuwerk 21, D-06108 Halle (Saale), Germany / 3. School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, India / 4. Escuela de Biologia, Universidad de Costa Rica, San José, Costa Rica / Received March 2, 1995
Summary
Utilization efficiency (LUE) of lightflecks by leaves increases with decreasing duration of the lightfleck, and depends on
photosynthetic induction. Sun and shade leaves differ with respect to photosynthetic induction. Shade leaves may become fully
induced by a series of light pulses, whereas photosynthetic induction of leaves from partial shade or full sun depends on
continuous light. Additionally, shade leaves maintain a higher induction state over longer periods in dim light or darkness
than sun leaves. Both features are advantageous to shade leaves in a highly dynamic light environment.
We determined whether pioneer plants and late-successional species differ in photosynthetic induction dynamics and LUE during
the establishment phase when both plant types are growing in the shade of the understory. We also determined the effects of
shade acclimation and successional position of species on photosynthetic induction and LUE. Results from temperate and tropical
rain forests indicate a trade-off between leaf acclimation to shade and the successional position of species. Light acclimation
is important, but in deep shade, late-successional species maintain a higher induction state over longer periods than pioneer
species.
Keywords:
CO2 assimilation, Costa Rica, European beech forest, forest gap, India, photosynthetic induction, successional position, sunfleck,
tropical rain forest, understory, Western Ghats.
