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

Tretiach, Mauro; Pecchiari, Marco

doi:10.1111/j.1469-8137.1995.tb04335.x

Cited by 30 publications

(24 citation statements)

References 24 publications

(20 reference statements)

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“…Saturation was apparently reached at the maximum value compatible to the IRGA used in the experiments (c. 1,300 ppm). Net photosynthesis at 360 ppm was lower than 50% of the rate measured at the upper CO 2 concentration limit; this value is comparable with previous results obtained for other endolithic lichens using the same technique (see Tretiach and Pecchiari 1995).…”

Section: Carbon Dioxide Concentrationsupporting

confidence: 92%

“…1b). At higher water contents photosynthesis was progressively inhibited: at 13 mg cm A2 , when liquid water was present on the lichen surface, it was only 40±50% of the maximum value, although other epi-and endolithic lichens, such as Aspicilia radiosa, Petractis clausa and Rinodina immersa, showed more marked inhibition (Tretiach and Pecchiari 1995).…”

Section: Carbon Dioxide Exchangesmentioning

confidence: 98%

“…Data on the metabolic performance of such organisms are rare (Lange et al 1970;Kappen 1993, 1994;Tretiach and Pecchiari 1995). This is for several reasons (Tretiach 1995): (1) the ecological importance of endolithic lichens has often been underestimated; (2) large, common genera such as Thelidium and Verrucaria are burdened with synonyms (Nimis 1993) and therefore the identi®cation of many infrageneric taxa is uncertain; and (3) the substratum, which cannot be removed without damaging the lichen thalli, is a source of several methodological problems.…”

Section: Introductionmentioning

confidence: 98%

“…One of the commonest species is Verrucaria baldensis Massal., a shade-tolerant species that is particularly common in the darkest parts of abysses and gorges. The chlorophyll content of V. baldensis is the lowest ever found in endolithic lichens (Tretiach and Pecchiari 1995), and therefore its CO 2 gain is presumably very low. Surprisingly, however, the species has a very high biomass, approximately twice that of other endolithic species (Tretiach 1995).…”

Section: Introductionmentioning

confidence: 99%

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CO 2 exchange of the endolithic lichen Verrucaria baldensis from karst habitats in northern Italy

Tretiach

Geletti

1997

Oecologia

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CO exchange of the endolithic lichen Verrucaria baldensis was measured in the laboratory under different conditions of water content, temperature, light, and CO concentration. The species had low CO exchange rates (maximum net photosynthesis: c. 0.45 μmol CO m s; maximum dark respiration: c. 0.3 μmol CO m s) and a very low light compensation point (7 μmol photons m s at 8°C). The net photosynthesis/respiration quotient reached a maximum at 9-15°C. Photosynthetic activity was affected only after very severe desiccation, when high resaturation respiratory rates were measured. Microclimatic data were recorded under different weather conditions in an abyss of the Trieste Karst (northeast Italy), where the species was particularly abundant. Low photosynthetically active radiation (normally below 40 μmol photons m s), very high humidities (over 80%), and low, constant temperatures were measured. Thallus water contents sufficient for CO assimilation were often measured in the absence of condensation phenomena.

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Section: Carbon Dioxide Concentrationsupporting

confidence: 92%

Section: Carbon Dioxide Exchangesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CO 2 exchange of the endolithic lichen Verrucaria baldensis from karst habitats in northern Italy

Tretiach

Geletti

1997

Oecologia

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“…These lichens are generally slowgrowing (Tretiach and Pecchiari 1995), and in many habitats, they are less competitive and often overgrown by epilithic species (Tretiach 1995). However, in extreme environments, interspecific competition is low because few organisms have evolved to survive the environmental extremes of exposed rock surfaces.…”

Section: Introductionmentioning

confidence: 99%

Life in extreme environments: survival strategy of the endolithic desert lichen Verrucaria rubrocincta

Garvie

Knauth

Bungartz

et al. 2008

Naturwissenschaften

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Verrucaria rubrocincta Breuss is an endolithic lichen that inhabits caliche plates exposed on the surface of the Sonoran Desert. Caliche surface temperatures are regularly in excess of 60 degrees C during the summer and approach 0 degrees C in the winter. Incident light intensities are high, with photosynthetically active radiation levels typically to 2,600 micromol/m(2) s(-1) during the summer. A cross-section of rock inhabited by V. rubrocincta shows an anatomical zonation comprising an upper micrite layer, a photobiont layer containing clusters of algal cells, and a pseudomedulla embedded in the caliche. Hyphae of the pseudomedulla become less numerous with depth below the rock surface. Stable carbon and oxygen isotopic data for the caliche and micrite fall into two sloping, well-separated arrays on a delta(13)C-delta(18)O plot. The delta(13)C(PDB) of the micrite ranges from 2.1 to 8.1 and delta(18)O(SMOW) from 25.4 to 28.9, whereas delta(13)C(PDB) of the caliche ranges from -4.7 to 0.7 and delta(18)O(SMOW) from 23.7 to 29.2. The isotopic data of the micrite can be explained by preferential fixing of (12)C into the alga, leaving local (13)C enrichment and evaporative enrichment of (18)O in the water. The (14)C dates of the micrite range from recent to 884 years b.p., indicating that "dead" carbon from the caliche is not a significant source for the lichen-precipitated micrite. The endolithic growth is an adaptation to the environmental extremes of exposed rock surfaces in the hot desert. The micrite layer is highly reflective and reduces light intensity to the algae below and acts as an efficient sunscreen that blocks harmful UV radiation. The micrite also acts as a cap to the lichen and helps trap moisture. The lichen survives by the combined effects of biodeterioration and biomineralization. Biodeterioration of the caliche concomitant with biomineralization of a protective surface coating of micrite results in the distinctive anatomy of V. rubrocincta.

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Weakening of gneiss surfaces colonized by endolithic lichens in the temperate climate area of northwest Italy

Favero‐Longo

Accattino

Matteucci

et al. 2015

Earth Surf Processes Landf

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A role of lithobionts in geomorphological processes is increasingly argued, but the spatio‐temporal scale of their impact is largely unexplored in many ecosystems. This study first characterizes in the temperate zone (northwest Italy) the relationships between lithobiontic communities including endolithic lichens and the hardness of their siliceous rock substrate (Villarfocchiardo Gneiss). The communities are characterized, on humid and xeric quarry surfaces exposed for decades and natural outcrops exposed for centuries, in terms of lichen and microbial constituents, using a combined morphological and molecular approach, and with regard to their development on and within the gneiss. A lichen species belonging to Acarosporaceae (Polysporina‐Sarcogyne‐Acarospora group, needing taxonomic revision) chasmoendolithically colonizes both the humid and xeric quarry surfaces, on which epilithic cyanobacterial biofilms and epilithic pioneer lichens respectively occur. Light and electron microscopic observations show the development of the endolithic thalli within rock microcracks and the hyphal penetration along crystal boundaries down to depths of 1 to 3 mm, more pronounced within the humid surfaces. Such colonization patterns are likely related to biogeophysical deterioration, while no chemical alteration characterizes minerals contacted by the endolithic lichen. By contrast, on natural outcrops, where the endolithic colonization is negligible, a reddish rind below epilithic lichens indicates chemical weathering processes. Schmidt Hammer measurements highlight that the endolithic lichens deeply affect the hardness of the gneiss (down to −60% with respect to fresh controls and surfaces only colonized by cyanobacteria), exerting a significantly higher weakening effect with respect to the associated epilithic lithobionts. The phenomenon is more remarkable on humid than on xeric quarry surfaces and natural outcrops, where epilithic lichens are likely involved in long‐term hardening processes supporting surface stabilization. Endolithic lichens are thus active biogeomorphological agents at the upper millimetric layer of siliceous rocks in temperate areas, exerting their weakening action during the early decade‐scaled stages of surface exposure. Copyright © 2015 John Wiley & Sons, Ltd.

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

Cited by 30 publications

References 24 publications

CO 2 exchange of the endolithic lichen Verrucaria baldensis from karst habitats in northern Italy

CO 2 exchange of the endolithic lichen Verrucaria baldensis from karst habitats in northern Italy

Life in extreme environments: survival strategy of the endolithic desert lichen Verrucaria rubrocincta

Weakening of gneiss surfaces colonized by endolithic lichens in the temperate climate area of northwest Italy

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