Lichen Species (lichen + species)

Distribution by Scientific Domains

Selected Abstracts

Host preference and performance of lichenivorous Eilema spp. larvae in relation to lichen secondary metabolites

Heikki Pöykkö
Summary 1We compared the larval host preference of four lichenivorous Eilema (Lepidoptera, Arctiidae) species on four common epiphytic lichen species including Hypogymnia physodes, Melanelia exasperata, Vulpicida pinastri and Xanthoria parietina. Survival and growth of larvae on different species were monitored and correlation to qualitative and quantitative variation in lichen secondary compounds was analysed. 2All moth species preferred M. exasperata, which does not contain polyphenolic substances, over other lichens, but also foraged on other lichens in the food preference experiment. All larvae reared on V. pinastri and H. physodes died during the growth and survival experiment. Survival of larvae on X. parietina and M. exasperata were equal. Larvae grew faster and and bigger on M. exasperata than on other lichens. 3Consumption and utilization measurements also revealed that M. exasperata was of the highest quality, although the relative consumption rate was highest on X. parietina. Our results indicate that different secondary chemicals have different effect against lichenivores or that larvae are either well adapted to certain chemicals or that these chemicals may have other roles than antiherbivore function for lichens. 4It is suggested that lichenivorous lepidopteran species may have different adaptations, such as dietary mixing to receive nutrients in optimal proportions or compensatory feeding ability to ensure the maximal growth efficiency on a suboptimal host. [source]

Lichen acclimatization on retention trees: a conservation physiology lesson

Kadi Jairus
Summary 1.,Green-tree retention (GTR) has been suggested as a means to effectively support epiphytic lichen species in managed forests, given the low lichen mortality on retention trees in the short term. However, a long-term perspective requires a physiological understanding of lichen responses to logging. This study compares anatomical, morphological and physiological traits of lichens on retention trees and on intact forest trees. 2.,Thalli of nine taxa (Buellia griseovirens, Cladonia digitata, Hypogymnia physodes, Lecanora allophana, Lecanora pulicaris, Lepraria spp., Peltigera praetextata, Pertusaria amara and Phlyctis argena) were sampled from birch Betula spp. and aspen Populus tremula in GTR cuts, where they had previously been reported to survive well, and in adjacent managed forests. In the laboratory, chlorophyll fluorescence parameter Fv/Fm, thickness of the upper cortex, photobiont to mycobiont ratio and (in Lecanora species) the relative area of the apothecia were measured. 3.,All the lichen samples collected from GTR cuts appeared alive, but their Fv/Fm was significantly lower, relative areas of the apothecia were larger and the upper cortices of thalli were thicker compared with the samples from adjacent forests. No difference in photobiont to mycobiont ratio was found. These patterns were broadly consistent among species, indicating a common mechanism: while suffering from photoinhibition, the lichens had acclimatized to the open conditions and increased their investment to sexual reproduction in a few years. 4.,Synthesis and applications. The study highlights the value of a morpho-physiological framework for conservation management by pointing out that, in GTR areas, lichen survival is high-irradiation limited and heavily dependent on phenotypic plasticity. A thin upper cortex may be a common feature of the most sensitive species. To sustain epiphyte populations in managed forests, precautionary harvesting strategies (gradual felling; group-retention; extended rotations) should be preferred and large-enough populations should be preserved, even though short-term studies suggest a high survival of lichens in cut areas. [source]

Local extent of old-growth woodland modifies epiphyte response to climate change

Christopher J. Ellis
Abstract Aim, To quantify the interaction between climate and woodland continuity in determining the bioclimatic response of lichen epiphytes. Location, Northern Britain (Scotland). Methods, Indicator-species analysis was used to pre-select lichen epiphytes along parallel gradients in climate and the extent of old-growth woodland. Nonparametric multiplicative regression was used to describe in a predictive model the individualistic response of selected species, which were projected based on climate-change scenarios and contrasting patterns of simulated woodland loss or gain. Species with a similar response were grouped using a novel application of cluster analysis to summarize the potentially huge number of projected outcomes. Projected patterns of occurrence under climate-change scenarios were examined for different levels of old-growth woodland extent. Results, Forty-two lichen species were statistically significant indicator species in oceanic woodlands, and old-growth indicators under suboptimal climatic conditions. Responses to climate-change scenarios were contrasting, with one group comprising species projected to increase in extent in response to climate warming, and other response groups projected to decrease in occurrence, possibly in response to shifting rainfall patterns. The occurrence of all response groups had a positive relationship with old-growth woodland extent. Main conclusions, An ,oceanic' biogeographical group of epiphytes identified using the baseline climatic and present-day woodland setting comprised species with a cyanobacterial photobiont or tropical phytogeographical affinities. However, within this group the individual species responses to climate-change scenarios were contrasting. Additionally, group responses may be poorly matched with simple ecological traits. However, the studied interaction between climate and habitat continuity suggests that the impact of climate change might be offset for certain lichen epiphytes by appropriate management of woodland resources, for example, expansion of native woodland around remnant old-growth stands. [source]

Aspen succession and nitrogen loading: a case for epiphytic lichens as bioindicators in the Rocky Mountains, USA

Paul C. Rogers
Abstract Question: Can lichen communities be used to assess short- and long-term factors affecting seral quaking aspen (Populus tremuloides) communities at the landscape scale? Location: Bear River Range, within the Rocky Mountains, in northern Utah and southern Idaho, USA. Method: Forty-seven randomly selected mid-elevation aspen stands were sampled for lichens and stand conditions. Plots were characterized according to tree species cover, basal area, stand age, bole scarring, tree damage, and presence of lichen species. We also recorded ammonia emissions with passive sensors at 25 urban and agricultural sites throughout an adjacent populated valley upwind of the forest stands. Nonmetric multidimensional scaling (NMS) ordination was used to evaluate an array of 20 variables suspected to influence lichen communities. Results: In NMS, forest succession explained most variance in lichen composition and abundance, although atmospheric nitrogen from local agricultural and urban sources also significantly influenced the lichen communities. Abundance of nitrophilous lichen species decreased with distance from peak ammonia sources and the urban center in all aspen succession classes. One lichen, Phaeophyscia nigricans, was found to be an effective bioindicator of nitrogen loading. Conclusions: Lichen communities in this landscape assessment of aspen forests showed clear responses to long-term (stand succession) and short-term (nitrogen deposition) influences. At the same time, several environmental factors (e.g. tree damage and scarring, distance to valley, topography, and stand age) had little influence on these same lichen communities. We recommend further use of epiphytic lichens as bioindicators of dynamic forest conditions. [source]

Biogeographical determinants of lichen species diversity on islets in the West-Estonian Archipelago

Inga Jüriado
Abstract Questions: Do islet area, number of biotopes and distance from the mainland shape lichen species richness on islets? Are there any species- or substrate group-specific trends associated with these factors? Location: Islets of the west Estonian Archipelago, Estonia. Methods: A species list was compiled for each of the 32 islets and the relative abundance of each species was estimated. The lichens were divided into seven groups according to their substrate preferences. Generalized linear model (GLIM) analysis was applied to test the effect of the islet traits on the number of lichen species on the islets and in the substrate groups. The probability of presence/absence and abundance of the most frequent species according to the islet traits were tested with GLIM and general linear mixed model. Results: The lichen flora of the islets consisted of 326 taxa, the number of lichen species per islet varied from 2 to 197. Total number of species per islet and within the substrate groups was positively correlated with islet area and with number of biotopes, and negatively correlated with distance from the mainland; however, these relationships varied among the substrate groups. Although individual lichen species showed variation in responses, general trends in island biogeography were evident. Conclusions: The distribution pattern of lichens on the studied islets follows the theory of island biogeography: the number of species per islet depends on isolation, area and biotope diversity. Species specific traits, such as dispersal strategy and growth form, as well as availability of a particular substrate are important for formation of the lichen flora on islets. [source]

Rapid breakdown of exogenous extracellular hydrogen peroxide by lichens

Richard P. Beckett
All organisms, even highly stress-tolerant lichens, produce a variety of reactive oxygen species (ROS) during and after stress. Furthermore, the cell walls of some lichens in Suborder Peltigerineae contain laccases, and therefore can produce quinone radicals that can break down to yield ROS. While the extracellular ROS produced by these enzymes probably play important roles in the biology of these lichens, they may also be potentially harmful and need to be rapidly broken down. To test this, rates of breakdown of exogenously supplied H2O2 were measured in a range of lichen species. Considerable diversity existed in rates of H2O2 breakdown but rates were on average almost double in members of Suborder Peltigerineae. While all lichens tested appeared to lack extracellular peroxidases and catalases, enzymes normally involved in breaking down H2O2, extracellular tyrosinase activity could be readily detected in the Peltigerineae. A role for tyrosinases in H2O2 breakdown was supported by the results from experiments involving inhibitors, and demonstration of the simultaneous release into an incubation solution of tyrosinase activity and the ability to breakdown H2O2. Rates of breakdown were very high, and tyrosinase appeared to break down H2O2 by a catalase-like mechanism. However, significant rates of breakdown of H2O2 also occurred in species that did not possess cell wall redox enzymes. These species probably took up the exogenously supplied H2O2 intracellularly and then broke it down by the usual catalases and peroxidases. The importance of H2O2 degradation is discussed in terms of its possible role in defence against the harmful effects of ROS. [source]

Comparison of antioxidant activity and phenolic content of three lichen species

Fehmi Odabasoglu
Abstract The antioxidant activities (AA), reducing powers (RP) and total phenolic contents (TPC) of methanol and water extracts of three lichen species, Usnea longissima Ach., Usnea ,orida (L.) Weber ex Wigg. and Lobaria pulmonaria (L.) Hoffm. were determined in vitro. Of the extracts tested, the methanol extracts of Lobaria pulmonaria and Usnea longissima showed potent antioxidant activities. The methanol extract of L. pulmonaria also had the highest total phenolic contents (87.9 mg/g lyophylisate). For the methanol extract of this species, there was also a strong correlation between antioxidant activity and total phenolic contents. However, a similar correlation was not observed for U. longissima. Although the methanol extract of U. longissima had a lower phenolic content (38.6 mg/g lyophylisate), it exhibited potent antioxidant activity. On the other hand, there was a strong correlation between the reducing powers and the total phenolic contents of the extracts. The highest reducing power was determined for the methanol extract of L. pulmonaria. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Photobiont Selectivity and Interspecific Interactions in Lichen Communities.

PLANT BIOLOGY, Issue 4 2003

Abstract: Lichen communities are characterised by interspecific interactions that not only include interactions between different lichen species but also between the symbionts within a single lichen species. The community "Bunte Erdflechtengesellschaft", growing on weathered calciferous rocks known as Gravel Alvar on Gotland (Baltic Sea, Sweden), shows a high complexity of inter- and intraspecific interactions, including Fulgensia bracteata, F. fulgens, Toninia sedifolia, Squamarina cartilaginea, Psora decipiens and Lecidea lurida. F. bracteata and F. fulgens are the dominant species of this community, showing a tendency to overgrow the other species involved and even parasitic behaviour. Culture experiments have been performed to investigate the selectivity of the mycobiont of F. bracteata towards a variety of potential photobionts. The results provide evidence for the selectivity of the mycobiont and varying compatibility of the respective symbionts that can be interpreted as a cascade of interdependent processes of specific and non-specific reactions of the symbionts involved. [source]