ECOLOGICALLY‐LINKED VARIATION IN MORPHOLOGY, ACETYLENE REDUCTION, AND WATER RELATIONS IN <i>PSEUDOCYPHELLARIA DISSIMILIS</i>

Snelgar, W. P.; Green, T. G. A.

doi:10.1111/j.1469-8137.1981.tb03211.x

Cited by 54 publications

(32 citation statements)

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“…Ptychomnion aciculare also shows this photosynthetic pattern (unpublished data). Similar external storage of water may occur in some species of Pseudocyphellaria (Snelgar & Green 1980). …”

Section: Resultsmentioning

confidence: 99%

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

Snelgar

Brown

Green

1980

New Zealand Journal of Botany

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The effect of water content on photosynthetic and respiratory rates in eight lichen species and one bryophyte species were studied using an injection infrared gas analyser technique. All species showed a strong relationship between net assimilation rate (NAR). respiration rate. and water content similar to relationships reported in published studies overseas. Species from moist habitats showed negative NAR at low water contents. Species from high-light areas showed a depression in NAR at high water contents which could be alleviated by higher light intensities. The experiments confirmed the suitability of New Zealand species for these studies.Keywords bryophytes; lichens; Stictaceae; photosynthesis; respiration; water content INTRODUcnONIn the last decade considerable advances have been made in the understanding of gas exchange and productivity of lichens and bryophytes. Research has concentrated on species from relatively open habitats such as Canadian open woodland (Kershaw 1971(Kershaw , 1977a(Kershaw . 1977bKershaw & Smith 1978;Harris 1971;Busby & Whitfield 1978). deserts (Lange 1969). maritime Antarctica (Collins 1976). Canadian tundra (Kershaw & Rouse 1971). and English woodlands (Dilks & Proctor 1979). There is a paucity of research on species from dense forest. particularly rain forest in subtropical and tropical areas. In New Zealand a considerable biomass of lichens and bryophytes exists in rain forests and. to date. there appear to have been no physiological studies on the productivity or gas exchange of these plants. An initial study of nitrogen fIXation by New Zealand lichens has been carried out and demonstrates the suitability of the plants for physiological studies.In this work the relationship between carbon dioxide exchange and water content of eight lichens and one bryophyte was studied using the il\iection infrared gas analyser technique pioneered by Larson & Kershaw (1975). This technique provides considerable time advantages over a gas flow system When many samples are involved. Received 12 September 1979Seven of the lichens studied are members of the Peltigerinae (six in the Stictaceae) and were chosen to represent the ecological range found within this group. One lichen species (Usnea sp.) was included to provide the contrast of a lichen that does not fix nitrogen ~d occurs in an exposed habitat. Similarly. one species of bryophyte was included so that a comparis~n ~f the water relations of a different plant type growing In the same area could be made. It was considered that these comparisons would be of interest in this preliminary study of New Zealand species.The lichens fOrming the central part of this study may be of great importance in New Zealand forests. particularly in their ability to fix nitrogen. This work is part of a mlijor study on the productivity and ecology of this group in an attempt to assess their role in the nutrient cycles of forests. MATERIALS AND METHODSLichens and bryophytes were collected from the localities listed in Table I. The date of collection ...

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“…Ptychomnion aciculare also shows this photosynthetic pattern (unpublished data). Similar external storage of water may occur in some species of Pseudocyphellaria (Snelgar & Green 1980). …”

Section: Resultsmentioning

confidence: 99%

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

Snelgar

Brown

Green

1980

New Zealand Journal of Botany

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“…Positive gas exchange rates, for exatnple, ranged from 0003 to 0-012 g H.,O cm'^ in Petractis clausa, and from 0-2 to 0-8 g H^O cm ' in A. calcarea. Such a difference could be owing to difTerent thickness of the medulla, which is important for water storage, at least in some toliose species (Snelgar & Green, 1981). Endolithic lichens have only a very thin layer of hyphae penetrating into the substratum, their biomass being quite low (c. 5 mg cm ^ unpublished); A. calcarea has, on the contrary, a very thick medulla, and a greater biomass (c. 50mgcm ^).…”

Section: Discussionmentioning

confidence: 99%

Gas exchange rates and chlorophyll content of epi‐ and endolithic lichens from the Trieste Karst (NE Italy)

Tretiach

Pecchiari

1995

New Phytologist

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SUMMARYThe photosynthetic activity of calcicolous endo-and epilithic lichens from the Trieste Karst area (NE Italy) was investigated. The data consist of: (a) gas exchange rates oi Acrocordia conoidea, Petractis clausa, Rinodina immersa ' h~' at optimal conditions; (2) the relation between thallus water content and photosynthesis differs from that of foliose and fruticose lichens; the optimum water content of endolithic lichens is particularly small, when expressed in g H^O cm""; (3) the algae of endolithic lichens, which belong to different systematic groups, are light-saturated at a small radiation flux; (4) chlorophyll contents of endolithic lichens are rather large, being similar to those of some parmelioid lichens. The ecological implications of the endolithic growth-form are briefly discussed. Endolithic lichens should be regarded as slowgrowing, stress-tolerant organisms, which are rather similar in their physiology to epilithic crustose lichens; they have a high resistance to CO.^ diffusion, saturation being reached only at a very large CO^ concentration.

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“…Evaporation rate (ugcm~2s~'), calculated from Piche evaporimeters over a 12-day period. Although not likely to be identical this rate is expected to be similar for wet lichen thalli, which have often been referred to as having the water relations of filter paper (Snelgar & Green 1981a). §The faveolate depressions on the upper thallus surface are full of water.…”

Section: Rainforest Lichensmentioning

confidence: 99%

“…Normal is the mean value for other Pseudocyphellaria and Sticta lichens (Snelgar 1981). §Terminology and dimensions from Snelgar & Green (1981a). jfData from Demmig-Adams et al (1990a).…”

Section: Physiological Adaptations To the Rainforest Environment Adapmentioning

confidence: 99%

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Ecophysiological Adaptations of the Lichen Genera Pseudocyphellaria and Sticta to South Temperate Rainforests

Green

Lange²

1991

The Lichenologist

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Temperate rainforests are a poorly researched habitat with respect to lichen ecophysiology in comparison to desert and polar regions. The evergreen, broadleaf forests provide a dim, moist environment that is relatively stable throughout the year. Lichens are abundant in both quantity and species diversity with the large foliose genera Sticta and Pseudocyphellaria normally being dominant, visually and in terms of biomass. These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1 (imolm" 2 s"', PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity. Photobiont versatility is also a feature of these genera. Photosymbiodemes occur, i.e. a single thallus containing both green algal and cyanobacterial sectors. Because the different sectors have the same fungal partner and grow in the same habitat, it is possible to investigate whether particular physiological traits are photobiont determined. The ability to recover photosynthetic activity in humid air is confined to thalli with green algal photobionts whilst the inability of thalli containing cyanobacterial photobionts to tolerate high light stress may be related to their lack of a protective xanthophyll cycle.

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ECOLOGICALLY‐LINKED VARIATION IN MORPHOLOGY, ACETYLENE REDUCTION, AND WATER RELATIONS IN PSEUDOCYPHELLARIA DISSIMILIS

Cited by 54 publications

References 14 publications

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

Gas exchange rates and chlorophyll content of epi‐ and endolithic lichens from the Trieste Karst (NE Italy)

Ecophysiological Adaptations of the Lichen Genera Pseudocyphellaria and Sticta to South Temperate Rainforests

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