New Zealand Journal of Botany abstract
B96022
Received 10 April 1996; accepted 8 May 1997
New Zealand Journal of Botany, 1997, Vol. 35: 493-504
0028-825X/97/3504-0493 $7.00 (c) The Royal Society of New Zealand 1997
Temperate rainforest lichens in New Zealand: light response of
photosynthesis
T. G. A. GREEN
Department of Biological Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
B. BüDEL
Universität Kaiserslautern
Fachbereich Biologie
Allgemeine Botanik
Postfach 3049
D-67653 Kaiserslautern, Germany
A. MEYER
H. ZELLNER
O. L. LANGE
Julius-von-Sachs-Institut für Biowissenschaften
der Universität Würzburg, Lehrstuhl Botanik II
Julius-von-Sachs-Platz 3
D-97082 Würzburg, Germany
Abstract The photosynthetic response to photosynthetically
active photon flux density (PPFD) was measured in the field for nine New
Zealand rain forest lichen species spanning environments from the deep shade
within the forest through the forest margin to outside, open ground sites.
Light compensation (PPFDcomp) and light saturation (PPFDsat) were much higher
for the species of the open sites (over 50 and 500 umol/m
2.s,
respectively). Lichens at forest margin or within the forest had PPFDsat of
64.3-29, and 61-162, umol/m
2.s, respectively, but showed no apparent
adaptive trends for these parameters. PPFD response of photosynthesis was
measured at several thallus water contents (WC) for one species,
Pseudocyphellaria coronata, which showed severe depression of
photosynthesis at high WC because of increased diffusion resistances, at all
PPFD above compensation. PPFDsat was also depressed but not dark respiration,
PPFDcomp, or quantum efficiency. Green algal and cyanobacterial lichens showed
no relationship between nitrogen and chlorophyll contents but green algal
species were always <=0.7% nitrogen. A third group, cephalodiate (nitrogen
fixing) lichens, had nitrogen contents of 1.5-4.4% dry weight with a clear,
positive relationship with chlorophyll content. Chlorophyll and nitrogen
contents both increased at more shaded sites within the forest. It is suggested
that the possession of cephalodia providing a nitrogen source is advantageous
within these evergreen forests by allowing a greater contribution to be made to
photosynthetic machinery. The PPFDsat of forest lichens seems to be too high
for the prevailing PPFD environment and the lichens would rarely be able to
photosynthesise at optimal PPFD. It is suggested that this is a protection
against transient high light in sunflecks.
Keywords lichen; light; photosynthesis; rainforest; shade;
chlorophyll; nitorogen
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