Monitoring changes in lichen resources for range management purposes in reindeer husbandry

Mat-forming lichens are important as food source for reindeer during the winter, and thus a vital resource to manage in reindeer husbandry. In this paper we suggest a method for monitoring of changes in lichen height with the purpose to early detect changes in lichen abundance in reindeer grazing areas. The method is intended for measuring geographically uniform lichen areas, evenly used for reindeer grazing. We analysed spatial variations in lichen height at the meter and 100 m scales, and calculated sample size requirements, and estimated effects of forest density and age, lichen moisture and lichen density on lichen height, and assessed the correspondence between lichen height and biomass. The variation in lichen height differed considerably between sites and, hence, the required sample size to detect a 5 mm change in lichen height with a power of 0.95 ranged from 200 to 2000, depending on the standard deviation of measured heights. Based on the autocorrelation in lichen height found between adjacent measurement points, a minimum distance of 4 m between measurement points is also recommended. Lichen height was significantly affected by lichen moisture, and the results suggest that this effect of moisture might vary with lichen density. Lichen height varied spatially within the study sites, and the spatial variations were partly caused by forest age and density. Thus, gradual changes in the forest characteristics are likely to alter the spatial variation in lichen height and it is therefore important to regularly re-evaluate the locations of measurement points within the monitored area. This study provides suggestions for a variable that could be used as an indicator of changes in the lichen resource, and aspects that should be considered when designing a monitoring program. The accuracy of detecting changes depends on the monitoring efforts, i.e. the number and distribution of measurement points and how often an area is monitored. In conclusion, our results indicate that measurements of lichen height have considerable potential for monitoring of changes in lichen resources within reindeer husbandry.     

中国地衣学现状综述

本文对中国地衣学在多样性、系统性及其物种与基因资源生物学研究方面进行了综述。文中强调了多样性和系统性研究在自然界地衣资源与研究开发之间的桥梁作用。论述了地衣结皮固沙、固碳及其基因资源在沙漠生物地毯工程中的意义。揭开了不产次生代谢产物的地衣秘密及其破解途径。     

The weight of the crust: Biomass of crustose lichens in tropical dry forest represents more than half of foliar biomass

In recent years, our ecological knowledge of tropical dry forests has increased dramatically. However, the functional contributions of whole ecosystem components, such as lichens, remain mostly unknown. In these forests, the abundance of epiphyte crustose lichens is responsible for the characteristic white bark on most woody plants, conspicuous during the dry season, but the amount of resources that the lichen component represents remains unexplored. We estimated lichen biomass in a Mexican tropical dry forest using the bark area of trees, the dry mass of lichens per unit area and the percentage of bark covered by lichens, together with previously known tree densities. The lowest 2.5 m of the forests main trunks contained 188 kg/ha of lichen biomass, with lichens covering 85% of the available bark for trees <12 cm DBH and 38% for trees >12 cm. Total epiphytic lichen biomass was 1.34–1.99 Mg/ha. Lichen biomass represented 61% of the foliar biomass in the forest. To our knowledge, this is the first time that a lichen biomass estimate is provided for an ecosystem in which crustose lichens are the dominant lichen growth form. Crustose lichens are typically considered to contribute little to the total lichen biomass and to be difficult to include in ecological analyses. The high lichen biomass in this ecosystem implies a significant ecological role which so far is unexplored. We suggest the crustose lichen component should not be underestimated a priori in ecological studies, especially in ecosystems with abundant lichen cover.     

Herbivore grazing—or trampling? Trampling effects by a large ungulate in cold high‐latitude ecosystems

Mammalian herbivores have important top‐down effects on ecological processes and landscapes by generating vegetation changes through grazing and trampling. For free‐ranging herbivores on large landscapes, trampling is an important ecological factor. However, whereas grazing is widely studied, low‐intensity trampling is rarely studied and quantified. The cold‐adapted northern tundra reindeer (Rangifer tarandus) is a wide‐ranging keystone herbivore in large open alpine and Arctic ecosystems. Reindeer may largely subsist on different species of slow‐growing ground lichens, particularly in winter. Lichen grows in dry, snow‐poor habitats with frost. Their varying elasticity makes them suitable for studying trampling. In replicated factorial experiments, high‐resolution 3D laser scanning was used to quantify lichen volume loss from trampling by a reindeer hoof. Losses were substantial, that is, about 0.3 dm³ per imprint in dry thick lichen, but depended on type of lichen mat and humidity. Immediate trampling volume loss was about twice as high in dry, compared to humid thin (2–3 cm), lichen mats and about three times as high in dry vs. humid thick (6–8 cm) lichen mats, There was no significant difference in volume loss between 100% and 50% wetted lichen. Regained volume with time was insignificant for dry lichen, whereas 50% humid lichen regained substantial volumes, and 100% humid lichen regained almost all lost volume, and mostly within 10–20 min. Reindeer trampling may have from near none to devastating effects on exposed lichen forage. During a normal week of foraging, daily moving 5 km across dry 6‐ to 8‐cm‐thick continuous lichen mats, one adult reindeer may trample a lichen volume corresponding to about a year's supply of lichen. However, the lichen humidity appears to be an important factor for trampling loss, in addition to the extent of reindeer movement.     

Experimental lichenology

Experimental methods in lichenology are summarized, the most attention being paid to the synthetic and cultural methods. Synthetic methods are based on the several stages: induction of dissociation of the natural lichen thallus to the monocultures of symbionts, culturing of these symbionts, and subsequent resynthesis under controlled conditions. Synthesis of the model association is based on monocultures of one of the symbionts and free-living organisms. These methods allow studying specificity and selectivity of interactions among symbionts, morphogenesis of the lichen thallus, and the role of minor components of the symbiotic system. Cultural methods involve development of dedifferentiated cell aggregates of lichen thallus ("lichen tissue cultures") on the solid and liquid media. At present, the methods of maintenance of lichen tissue cultures on the solid medium are worked out only. However, the lichen tissue cultures on the liquid medium are much more interesting because this method can be introduced in biotechnology. Cultural methods allow to achieve lichen biomass that contain specific lichen compounds. Induction of morphogenesis in lichen tissue cultures is possible.     

Surface hydrophobicity causes SO2 tolerance in lichens

BACKGROUND AND AIMS: The superhydrophobicity of the thallus surface in one of the most SO(2)-tolerant lichen species, Lecanora conizaeoides, suggests that surface hydrophobicity could be a general feature of lichen symbioses controlling their tolerance to SO(2). The study described here tests this hypothesis. METHODS: Water droplets of the size of a raindrop were placed on the surface of air-dry thalli in 50 lichen species of known SO(2) tolerance and contact angles were measured to quantify hydrophobicity. KEY RESULTS: The wettability of lichen thalli ranges from strongly hydrophobic to strongly hydrophilic. SO(2) tolerance of the studied lichen species increased with increasing hydrophobicity of the thallus surface. Extraction of extracellular lichen secondary metabolites with acetone reduced, but did not abolish the hydrophobicity of lichen thalli. CONCLUSIONS: Surface hydrophobicity is the main factor controlling SO(2) tolerance in lichens. It presumably originally evolved as an adaptation to wet habitats preventing the depression of net photosynthesis due to supersaturation of the thallus with water. Hydrophilicity of lichen thalli is an adaptation to dry or humid, but not directly rain-exposed habitats. The crucial role of surface hydrophobicity in SO(2) also explains why many markedly SO(2)-tolerant species are additionally tolerant to other (chemically unrelated) toxic substances including heavy metals.     

荒漠地衣结皮研究进展

微型生物结皮在干旱、半干旱荒漠地区广泛分布,对维持荒漠生态系统的稳定性具有重要作用。地衣结皮是微型生物结皮的重要组成部分及主要类型之一,在固沙、固碳和固氮能力方面独具优势。本文从区域尺度和局部尺度综述了国内外荒漠地衣分布、群落组成及其影响因素,从微尺度探讨了荒漠地衣在形成过程中可能相关的生物因子的作用与功能。虽已有研究发现气候类型、降水量、土壤理化性质、微地形和温度会对荒漠地衣生长型、种类、丰度及盖度产生影响,来自地衣体、地衣结皮和地衣结皮土壤中的生物因素与维持地衣正常生命活动及分布之间存在相关关系,但上述结论尚具有一定的局限性,主要表现在区域尺度仍缺乏专门对荒漠地衣的研究,微尺度缺乏对地衣相关生物功能的实验性探索及验证。上述局限在一定程度上限制了通过人工手段大规模应用荒漠地衣结皮的研究。本文基于国内外研究进展及存在问题,对荒漠地衣结皮应用进行了展望,以期为人工构建荒漠地衣结皮和干旱、半干旱荒漠治理及生态恢复提供新的思路和参考。     

Commercial and ethnic use of lichens in India

The diversity of Indian lichen flora has undergone a considerable decline in the last five decades. Among the various anthropogenic activities, overexploitation and selective removal of economically important lichens have become major threats to the lichen flora of the country. Commercial samples of lichens collected from different states of India were studied for their source and commercial use. Among samples offered for sale, 38 different lichen species were identified. The western Himalayas proved to be the main area for lichen collection, while some lichen species also come from the central and Western Ghats. Local traders coordinate the lichen collection and then sell the material to traders in the foothills, and from there it is processed and distributed to other parts of the country and abroad. Because lichens belonging to the families Parmeliaceae and Physciaceae are the ones most exploited commercially, they are recommended for inclusion in the CITES list.     

Non-dominant trees significantly enhance species richness of epiphytic lichens in subtropical forests of southwest China

Host species has an important influence on the distribution of epiphytic lichens in forests. However, the importance of non-dominant trees in shaping lichen communities has been poorly studied owing to the relative rarity of individuals. The importance of dominant and non-dominant trees for distribution of epiphytic lichens was determined in eight subtropical forests in southwestern China. Dominant trees supported more abundant total and exclusive lichen species only in secondary forests. The occurrence of non-dominant trees promoted lichen diversity within forest types and influenced lichen communities on both tree groups. The effects of total tree species on lichen distribution largely resulted from the presence of non-dominant trees. Dominant and non-dominant trees supported distinct lichen assemblages within forest types, and ordination analyses showed a clear separation. Our study, therefore, reinforces the importance of non-dominant trees for conserving epiphytic lichens, and highlights that lichen assemblages are shaped by both dominant and non-dominant trees.     

Epiphytic and epixylic lichen species diversity in Estonian natural forests

The epiphytic and epixylic lichen flora of natural forests was recorded in different parts of Estonia. Altogether 232 taxa of lichens, lichenicolous fungi, or non-lichenized fungi were recorded, 10 of them listed in the Estonian Red Data Book. We found regional differences in lichen species composition and diversity caused by differences in the forest types. The tree-species-rich boreo-nemoral forests had the most diverse lichen flora, while the boreal forest dominated by coniferous trees or birch had the lowest diversity. The stand age proved to be significant in regard to the number of lichen species in a forest. The most remarkable effect on the diversity of forest lichen species was caused by the presence of Populus tremula. Aspen had the highest number of lichen species on the basal trunk and twigs, and also the highest number of host-specific lichen species.     

Lichen growth

A theory of the growth of a lichen is presented, based upon the production of a carbohydrate by photosynthesis, partial consumption of it to thicken the lichen, diffusion of the remainder toward the outer edge, and its consumption there to increase the lichen radius. The mathematical formulation of the theory leads to a free boundary problem for the determination of the carbohydrate concentration, and of the lichen radius as a function of time. For the realistic case of slow growth the problem is solved approximately. The result for the growth rate is shown to fit Proctor's data fairly well.     

地衣标本的采集、制作与保存

详细论述了地衣标本的采集、制作和保存方法及注意事项,同时阐明了在采集标本的同时进行共生菌和光合共生物分离培养的重要性。     

The influence of multi‐scale environmental variables on the distribution of terricolous lichens in a fog desert

Question: How do environmental variables in a hyper‐arid fog desert influence the distribution patterns of terricolous lichens on both macro‐ and micro‐scales? Location: Namib Desert, Namibia. Methods: Sites with varying lichen species cover were sampled for environmental variables on a macro‐scale (elevation, slope degree, aspect, proximity to river channels, and fog deposition) and on a micro‐scale (soil structure and chemistry). Macro‐scale and micro‐scale variables were analysed separately for associations with lichen species cover using constrained ordination (DCCA) and unconstrained ordination (DCA). Explanatory variables that dominated the first two axes of the constrained ordinations were tested against a lichen cover gradient. Results: Elevation and proximity to river channels were the most significant drivers of lichen species cover in the macro‐scale DCCA, but results of the DCA suggest that a considerable percentage of variation in lichen species cover is unexplained by these variables. On a micro‐scale, sediment particle size explained a majority of lichen community variations, followed by soil pH. When both macro and micro‐scale variables were tested along a lichen cover gradient, soil pH was the only variable to show a significant relationship to lichen cover. Conclusion: The findings suggest that landscape variables contribute to variations in lichen species cover, but that stronger links occur between lichen growth and small‐scale variations in soil characteristics, supporting the need for multi‐scale approaches in the management of threatened biological soil crust communities and related ecosystem functions.     

To eat or not to eat—relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its relationship to lichen frequency are poorly understood. Therefore, we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen frequency in the field.Methods In a no-choice feeding experiment, we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing. Then, we related experimental lichen consumption with the frequency of lichen species among 158 forest plots in the field (Schw?bische Alb, Germany), where we had also sampled snail and lichen species.Important findings In five lichen species, snails preferred treated samples over untreated controls, indicating chemical feeding defense, and vice versa in two species, indicating chemical feeding stimulus. Interestingly, compared with less frequent lichen species, snails consumed more of untreated and less of treated samples of more frequent lichen species. Removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately. However, the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa, indicating that our results were robust and that lumping the species to two taxa was justified. Our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound recognition. This supports the idea that consumers adapt to the most abundant food source.     

Tree Species Composition Predicts Epiphytic Lichen Communities in an African Montane Rain Forest

The ecology of many tropical rain forest organisms, not the least in Africa, remains poorly understood. Here, we present a detailed ecological study of epiphytic lichens in the equatorial montane rain forest of Bwindi National Park (331 km²), Uganda. We evaluated all major lichen growth forms, including selected groups of crustose lichens. In 14 transects at elevations of 1290 m to 2500 m, we sampled 276 trees belonging to 60 species. We recorded all lichen species on each tree trunk between ground level and 2 m above the ground, yielding 191 lichen species in 67 genera, with a mean of 4.7 species per tree. We used non‐metric multi‐dimensional scaling to separate epiphytic lichen assemblages according to tree species composition and elevation. Structural equation modeling indicated that elevation influenced tree species composition and that tree species composition largely determined lichen species composition. Thus, elevation acted indirectly on the lichen assemblages. Further studies examining factors such as bark properties and lichen colonization ecology may clarify what determines the association between tree species and lichen assemblages. The link between lichen assemblages and large‐scale elevation patterns, as well as disturbance and regrowth histories, warrants further study. An analysis of lichen species composition on individual tree species that occur over large elevation ranges would distinguish the effect of tree species on lichen assemblages from the effect of elevation and thus climate. Our study highlights the limited extent of our knowledge of tropical epiphytic lichens.     

Edge and land-use effects on epiphytic lichen diversity in the forest-steppe ecotone of the Mongolian Altai

Epiphytic lichen diversity was studied in forests of Siberian larch (Larix sibirica) in the forest-steppe ecotone of the Mongolian Altai. These forests are utilized for livestock grazing, fuelwood collection and occasional logging by pastoral nomads. The density of nomad households in the proximity of the forests influences epiphytic lichen diversity more strongly than the position of sample trees in the forest interior or at the forest line to the steppe. This suggests that land use exerts a stronger effect on lichen diversity than the distinct gradient in microclimate between the forest interior and the forest edge. The co-occurrence of nitrophytes with anitrophytic acidophytes on a small spatial scale as well as higher N and Ca concentrations and pH values in the bark of larch trees at the forest edge than in the forest interior indicate that moderate livestock grazing increases the epiphytic lichen diversity due to an increase of the diversity of chemically different microhabitats. Preference of many lichen species (and of rare species in particular) for overmature and decaying trees suggests that logging and fuelwood collection has adverse effects on epiphytic lichen diversity. This adverse effect is likely to be more crucial for lichen diversity than the putatively positive effect of livestock grazing, since more lichens with a preference for old and decaying trees than for nitrogen-enriched bark were found. The present study is the first one investigating the impact of pastoral nomadism in Central Asia on epiphyte diversity.     

Large beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>) trees as ‘lifeboats’ for lichen diversity in central European forests

The forest management practices used in central Europe in the last several centuries have led to loss of lichen diversity that may be largely attributed to a loss of substrate variability and quantity. In an attempt to obtain information enabling us to mitigate this process, we surveyed affinity of lichen species to the substrates they currently occupy in six forest areas in the Czech Republic, located between 200 and 1000 m a.s.l. Tree bases and stems represented the most important substrate for lichen species, and especially so for threatened (i.e. red-listed) species. Lichen species richness per individual tree generally increased with stem diameter, especially for beech. Stems and tree bases of large-diameter beeches provide habitats that have enabled the survival of a crucial component of the red-listed lichen species in central Europe, far outweighing other tree species. The deciduous tree species that are commonly considered as favourable for lichen diversity (e.g. maples, ash, elms) were inhabited by only a few other lichen species additional to those associated with beech. This may be due to the low frequency of these tree species in most managed forests, and also some forest reserves, at the present time. Similarly, low incidence of dead wood in managed forests has likely limited its contribution to the lichen diversity, despite the high potential for lichen diversity associated with such substrates. It is thus apparent that bark of large-diameter live beech trees comprises a keystone habitat element in the provision of lichen diversity in central European forests.     

Nd-YAG laser irradiation damages to Verrucaria nigrescens

Epilithic and endolithic microorganisms and lichens play an important role in stone biodeterioration. The structural and physiological damage caused by nanosecond pulsed laser of 1064 nm from Nd:YAG laser to Verrucaria nigrescens lichen as well as to endolithic algae and fungi were investigated in the present study. Ultrastructural laser effects on lichen and endolithic microorganisms were study without disturbing the relationship between lichen and lithic substrate by taking lichen-containing rock fragments and processing both together. SEM-BSE, LT-SEM and FM were used to determine cell integrity and ultrastructure, which reflect microorganism viability. Photobiont vitality was determined using a PAM chlorophyll fluorescence technique. The lichen thalli were completely removed by irradiation with 5 ns pulses at a fluence of 2.0 J/cm² with no stone damage as showed by micro-Raman spectroscopy. The fungal and algal endolithic cells located below were completely destroyed or presented a high plasmolysis degree resulting from heating their microenvironment. The lichen and endolithic mycobiont near the irradiated zone were also damaged. Algal photosynthetic damage prevents fungal survival and lichen viability. This is the first report of laser removal and inactivation of lichen and lithic microorganisms, and thus provide an environmentally friendly and efficient method to control stone biodeterioration.     

中国石蕊科地衣研究之三 中国新记录属:扇盘衣属

本文报道了主要分布于澳洲的扇盘衣属地衣,缝裂扇盘衣在中国的首次发现,从而为中国地衣区系增加了一个新记录属。文中报道的该属的地衣不仅在中国,即使在世界范围也十分珍异。因而,对于该属及种的特征从形态学、解剖学与化学方面给以简要描述。     

Lichen biota of Khakassia

The diversity of Khakassia lichen biota inhabiting the central part of the Altai-Sayan mountain region and the general regularities in the lichen distribution on substrates and along vertical belts have been studied. The lichen composition of 1330 species, 262 genera, and 82 families was determined via generalization of the lichenological data available for this republic. The main lichen synusia in high mountain, mountain steppe, and mountain forest belts were recorded.