Inga Jüriado

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.

Influence of tree stand age and management on the species diversity in Estonian eutrophic alvar and boreo-nemoral Pinus sylvestris forests

Abstract The influence of tree stand age, silvicultural management and several habitat variables on species diversity was analysed in Calamagrostis site type alvar forests and Hepatica site type boreo-nemoral forests. On the community scale, the herb-layer species richness appeared to be determined mostly by forest soil and light conditions. However, the number of bryophyte species growing on tree stem bases and on decaying wood was dependent on management intensity and forest site quality class. On the same substrate types the number of lichen species was promoted only by tree species diversity. On the 1 m2 quadrat scale, diversity and density of tree layer, species richness of bush layer and soil pH have significant layer-specific effects on species richness. Bryophyte diversity increases together with increasing shade and moisture in forest ground vegetation, while an increase of herb-layer diversity is connected with lightness. Therefore, maintenance of the small-scale species richness of forest ground vegetation cannot be achieved by uniform management practice.

Diversity of epiphytic lichens in boreo-nemoral forests on the North-Estonian limestone escarpment: the effect of tree level factors and local environmental conditions

The species richness and composition of lichens was quantified for four temperate broad-leaved tree species ( Acer platanoides, Fraxinus excelsior, Tilia cordata and Ulmus glabra ) in boreo-nemoral forests on the talus slope of the North-Estonian limestone escarpment (North-Estonian Klint). Thirteen study sites were distributed along the klint on a west to east gradient. The effects of tree and stand characteristics and geographical location of a stand on composition and diversity of epiphytic lichens were evaluated by multivariate analyses (DCA, CCA, pCCA) and by general linear mixed models (GLMM). Tree level variables (e.g. bark pH, bryophytes cover and host tree species) explained the largest fraction of the variation in lichen species composition. However, species richness and composition were significantly influenced also by the unique habitat conditions of klint forest (length of the forest fragment, proximity of the stand to the sea and height of the escarpment). A significant correlation between stand locality and lichen diversity on the tree bole was found which is most likely related to local air pollution gradients caused by alkaline cement dust and acid pollutants in the north-eastern part of Estonia.

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

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. Nomenclature: Randlane & Saag (1999, 2004) and Santesson et al. (2004) for lichens; Leht, M. (ed.) 1999 for vascular plants. Abbreviations: AIC = Akaikes information criterion; GLIM = Generalized linear model; TLC = Thin layer chromatography.

The conservation of ground layer lichen communities in alvar grasslands and the relevance of substitution habitats

Semi-natural calcareous grasslands (alvars) are biodiversity hotspots in Northern Europe, particularly for herb layer plants. In the last century, traditional management has ceased, and the area of grasslands has declined due to extensive encroachment. We were interested in the drivers of ground layer (alias terricolous or epigeic) lichen communities. Our survey consisted of 86 habitat fragments in western Estonia, covering four types of historic alvar grasslands and three types of alvar-like habitats. We found that the ground lichen communities were primarily soil-type-specific, but were also affected by historic disturbances and land use change. In contrast to knowledge about herb layer communities, for which shrub encroachment has been shown to be main driver, the increased density of the herb layer and the reduced diversity of microhabitats were major drivers for the ground layer lichen community. These drivers caused a decrease in species richness, but only within the species of conservation value, and also led to a shift in the composition of lichen growth form from the dominance of squamulose and crustose towards fruticose lichens. We conclude that the traditional practice of restoring alvars by cutting shrubs is insufficient to maintain ground layer lichen biodiversity. Alvar maintenance practices should include grazing, which creates various small-scale ground disturbances and increases microhabitat heterogeneity. Alvar-like habitats originating from large-scale historic disturbances appeared to be suitable for calcicolous epigeic lichens, and can therefore be considered to be temporary substitution habitats, i.e. refugia for the regional species pool.

Habitat conditions and host tree properties affect the occurrence, abundance and fertility of the endangered lichen Lobaria pulmonaria in wooded meadows of Estonia

We assessed multiple environmental factors that might influence the population vitality of the epiphytic lichen Lobaria pulmonaria at the individual tree and habitat levels in partially overgrown wooded meadows in Estonia. A total of 301 trees of four species were sampled at nine study plots, using a stratified factorial scheme, 151 colonized by L. pulmonaria and 150 not colonized by L. pulmonaria forming the control group. We used the Generalized Linear Models (GLZ) to identify a complex of factors which predicts the probability of the lichen occurring on tree trunks and the presence of apothecia on its individuals. We employed the General Linear Mixed Model (GLMM) to study the relationship between cover of L. pulmonaria and environmental factors. The occurrence probability of L. pulmonaria on tree trunks increased with increasing light availability and height of deciduous shrubs near the trunk, and decreased with increasing distance to the nearest colonized tree. The host tree species and its trunk properties were also of importance, particularly the facilitating effect of the cover of bryophytes upon L. pulmonaria. The probability of occurrence of apothecia increased with maximum values of bark pH and cover of L. pulmonaria on the trunk. We conclude that partially overgrown wooded meadows are suitable habitats for L. pulmonaria. However, to maintain the vitality of these populations, a specific management scheme, preventing development of a dense stand, should be applied. Management requirements would include 1) selective cutting of overgrowing coniferous trees (particularly spruce), 2) preservation of adult and younger potential host trees within 10–20 m of colonized trees, 3) preservation of scattered deciduous shrubs in the vicinity of the host trees.

Threatened forest lichen Lobaria pulmonaria - its past, present and future in Estonia

Threatened forest lichen Lobaria pulmonaria - its past, present and future in Estonia Lobaria pulmonaria is a conspicuous and widely known epiphytic lichen species which mainly occurs on mature hardwood trees in old forests. The distribution of L. pulmonaria has become highly fragmented, showing a decline across Europe. Lobaria pulmonaria is unevenly distributed among ca. 600 localities in Estonia. Most localities are in north-eastern and south-western Estonia (50% and 21% of records respectively). 86% of L. pulmonaria localities are in nature reserves, national parks or woodland key habitats (WKH). In 81% of historical localities known until 1992, L. pulmonaria could be considered extinct. 6% of L. pulmonaria localities have become destroyed in the period from 1993 to 2010 due to clear cutting; in 19% of localities the species could be considered endangered, as its neighbourhood is affected by forest management activities. 40% of destroyed localities are located in forests designated as WKHs in north-eastern Estonia, and most of the endangered populations are also within WKHs. In forest management and conservation planning, WKHs should be preserved with surrounding buffer areas in order to avoid abrupt changes in environmental condition and natural disturbance regimes. There is also a necessity to develop specific management methods to recover reforested wooded meadows, to ensure that species of semi-open habitats are retained, e.g. by reducing the density of spruce. Harilik kopsusamblik (Lobaria pulmonaria) - ohustatud metsasamblik Eestis minevikus, tänapäeval ja tulevikus Harilik kopsusamblik (Lobaria pulmonaria) on iseloomulik liik Euroopa vanade laialehiste metsade samblikukooslustele, seetõttu on teda laialdaselt kasutatud looduskaitselise väärtusega metsade indikaatorliigina. Harilik kopsusamblik on Euroopas ohustatud ja mitmes regioonis isegi hävinud, seda eelkõige intensiivse metsamajanduse ja õhusaaste tõttu. Siiski on harilik kopsusamblik veel üsna sage näiteks Põhja-Euroopas ja Baltimaades. Seda samblikuliiki on siinkandis leitud eelkõige väikestes ja fragmenteeritud vanametsalaikudes, kus ta kasvab peamiselt suurediameetrilistel puudel. Puudest eelistab ta hea puhverdusvõimega lehtpuude koort, mille pH on vahemikus 5-6, nagu näiteks harilikul saarel (Fraxinus excelsior) ja harilikul haaval (Populus tremula). Et saada ülevaadet hariliku kopsusambliku levikudünaamikast Eestis 19. sajandi lõpust kuni tänapäevani, kasutasime erinevatesse andmebaasidesse koondatud levikuandmeid ja analüüsisime puistute seisundit kasutades erinevaid Maa-ameti kaardikihte. Korduvvaatluste eemaldamisel koosnes meie andmestik 75 ajaloolisest hariliku kopsusambliku leiukohast ajavahemikus 1897 kuni 1992 (intensiivsete metsain-venteerimiste eelse perioodi kirjed on sageli ebatäpsete leiuandmetega) ja 621 kirjest, mis on üles märgitud aastatel 1993 kuni 2010 (leiukohad registreeritud GPS-iga metsaeraldise täpsusega). Harilik kopsusamblik on Eestis ebaühtlaselt levinud, kasvades eelkõige metsades, kuid ka poollooduslikes kooslustes nagu puisniidud ja vanad pargid. Tänapäeval on hariliku kopsusambliku leiukohtade tihedus suurim Kirde-Eestis (50%; Ida- ja Lääne-Virumaa) ja Edela-Eestis (21%; Pärnumaa). Ülejäänud 12-s Eesti maakonnas varieerub leidude arv üldkogumist 0,5-6%. Leidudest 86% on teada looduskaitsealadelt, rahvusparkidest või vääriselupaikadest. 81% ajaloolises leiukohas (periood 1897-1992) on harilik kopsusamblik ilmselt hävinud, kuna seal puuduvad uuemad leiud. Liik on hävinud näiteks Tallinna ja Tartu linnast ja nende lähiümbrusest ning Kesk- ja Lõuna-Eesti parkidest, mis on ümbritsetud põllumajandusmaastikuga. Aastatel 1993 kuni 2010 on harilik kopsusamblik puistu lageraiete tõttu hävinud 6% leiukohtades. 19% kopsusambliku leiukohtadest on ohustatud, kuna metsaosa, kus samblik kasvab, piirneb vähemalt kahest küljest lageraielankidega. Hävinud leiukohtadest 40% ja enamus ohustatutest on Ida- ja Lääne-Virumaa metsade vääriselupaigad. Metsade majandamise planeerimisel tuleb rõhku panna vääriselupaikade kaitsele ning nende ümber peaks planeerima puhverala, et tagada sobivad keskkonnatingimused metsades kasvavatele vanametsasamblikele. Vanade kinnikasvanud puisniitude hooldamisel ja taastamisel tuleb kasutada majandusvõtteid, mis säilitaksid poolavatud kooslustele iseloomulikud kasvukohatingimused ja kasvupinnad. Eelkõige tuleks vähendada kuuskede järelkasvu ja tihedust.