Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservati... more Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservation. Colonization is a two-step process of dispersal and establishment, characterized by the compatibility of plant traits with landscape structure and habitat conditions. Therefore, ecological trait profiling of specialist species is initially required to estimate the relative importance of colonization filters. Old planted parks best satisfy the criteria of a newly created and structurally matured habitat for forest-dwelling plant species. We sampled species in 230 ancient deciduous forests (source habitat), 74 closed-canopy manor parks (target habitats), 151 linear wooded habitats (landscape corridors), and 97 open habitats (isolating matrix) in Estonia. We defined two species groups of interest: forest (107 species) and corridor specialists (53 species). An extra group of open habitat specialists was extracted for trait scaling. Differing from expectations, forest specialists have hig...
The autecology of rare species can be derived using similarities among functional traits and
envi... more The autecology of rare species can be derived using similarities among functional traits and environmental conditions observed for common species, i.e. we employed the ‘matching analogy approach’ with the analytical scheme ‘common species / driver / trait / driver/rare species’.We addressed the driveretrait relationship for common epigeic lichens of thin-soil calcareous grasslands, which are endangered by cessation of traditional land use. Common lichens were suppressed by encroaching herbs and shrubs, and were supported by ground disturbances. The lichens of open low-productivity alvars are predominantly calciphilous, epibryic, crustose-squamulose, sexually reproducing and contain UV-protective pigments. Lichens of encroached alvars are soil-type generalists, fruticose, reproduce vegetatively and contain herbivore-deterring compounds. Rare lichens resemble the species of open lowproductivity alvars, except their more limited niche space, i.e. they are restricted to arcticalpine habitats. The conservation practices on alvars should support the formation of crustforming communities by suppressing the growth of shrubs and herbs, and by promoting recurrent small-scale soil disturbances.
Semi-natural grasslands, among them thin-soil calcareous grasslands (alvars), have great conserva... more Semi-natural grasslands, among them thin-soil calcareous grasslands (alvars), have great conservation value but have become increasingly rare in Europe. The main threat to alvar grasslands is the encroachment by juniper Juniperus communis and therefore it is usually removed during the restoration practice. Juniper can also be a host plant for many epiphytic lichens, but its role as a phorophyte is poorly known. We studied epiphytic lichen diversity on 126 junipers in 17 sites in western Estonia and found 140 lichenized taxa including several rare and red-listed species. Using indirect and direct multivariate analyses (DCA, pCCA) and general linear models we revealed that both habitat and phorophyte properties affect lichen assemblies on juniper. Lichen species richness per site showed a unimodal relationship with compound factors of site productivity and juniper characteristics (stem circumference and juniper width). Lichen species richness per phorophyte was increasing with its siz...
Abstract: Wooded meadows with a history of traditional land use over thousands of years support a... more Abstract: Wooded meadows with a history of traditional land use over thousands of years support a great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows are threatened because of the cessation of traditional management in large areas. We studied lichen communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment of traditional management on epiphytic lichen species composition, considering factors on three spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree diameter, described as much of the compositional variation as geographic location (region) or environmental conditions in wooded meadows. Of the environmental factors studied, woodland canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the community type of semi-open wooded meadows to species-poor communities characteristic of secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently observed lichen species revealed that more than half of them (21) are influenced by site openness (canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open wooded meadows. The results emphasize that the preservation of large old deciduous trees of various species and the maintenance of the semi-open structure of stands are vitally important for the protection of epiphytic lichen communities in wooded meadows.
Abstract: We assessed multiple environmental factors that might influence the population vitality... more Abstract: 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 specificmanagement 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.
Semi-natural calcareous grasslands (alvars) are biodiversity hotspots in Northern Europe, particu... more 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.
ABSTRACT Changes in the forest management practices have strongly influenced the distribution of ... more ABSTRACT Changes in the forest management practices have strongly influenced the distribution of species inhabiting old-growth forests. The epiphytic woodland lichen Lobaria pulmonaria is frequently used as a model species to study the factors affecting the population biology of lichens. We sampled 252 L. pulmonaria individuals from 12 populations representing three woodland types differing in their ecological continuity and management intensity in Estonia. We used eight mycobiont-specific microsatellite loci to quantify genetic diversity among the populations. We calculated the Sørensen distance to estimate genetic dissimilarity among individuals within populations. We revealed that L. pulmonaria populations have significantly higher genetic diversity in old-growth forests than in managed forests and wooded meadows. We detected a significant woodland-type-specific pattern of genetic dissimilarity among neighbouring L. pulmonaria individuals, which suggests that in wooded meadows and managed forests dominating is vegetative reproduction. The vegetative dispersal distance between the host trees of L. pulmonaria was found to be only 15–30m. Genetic dissimilarity among individuals was also dependent on tree species and trunk diameter. Lobaria pulmonaria populations in managed forests included less juveniles compared to old-growth forests and wooded meadows, indicating that forest management influences life stage structure within populations. We conclude that as intensive stand management reduces the genetic diversity of threatened species in woodland habitats, particular attention should be paid to the preservation of remnant populations in old-growth habitats. Within managed habitats, conservation management should target on maintenance of the stand’s structural diversity and availability of potential host trees. KeywordsGenetic dissimilarity–Genetic distance–Epiphytic lichen–Microsatellites–Managed forest–Old-growth forest–Population genetics–Wooded meadow
Abstract. Lobaria pulmonaria is a conspicuous and widely known epiphytic
lichen species which mai... more Abstract. 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 southwestern 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.
Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservati... more Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservation. Colonization is a two-step process of dispersal and establishment, characterized by the compatibility of plant traits with landscape structure and habitat conditions. Therefore, ecological trait profiling of specialist species is initially required to estimate the relative importance of colonization filters. Old planted parks best satisfy the criteria of a newly created and structurally matured habitat for forest-dwelling plant species. We sampled species in 230 ancient deciduous forests (source habitat), 74 closed-canopy manor parks (target habitats), 151 linear wooded habitats (landscape corridors), and 97 open habitats (isolating matrix) in Estonia. We defined two species groups of interest: forest (107 species) and corridor specialists (53 species). An extra group of open habitat specialists was extracted for trait scaling. Differing from expectations, forest specialists have hig...
The autecology of rare species can be derived using similarities among functional traits and
envi... more The autecology of rare species can be derived using similarities among functional traits and environmental conditions observed for common species, i.e. we employed the ‘matching analogy approach’ with the analytical scheme ‘common species / driver / trait / driver/rare species’.We addressed the driveretrait relationship for common epigeic lichens of thin-soil calcareous grasslands, which are endangered by cessation of traditional land use. Common lichens were suppressed by encroaching herbs and shrubs, and were supported by ground disturbances. The lichens of open low-productivity alvars are predominantly calciphilous, epibryic, crustose-squamulose, sexually reproducing and contain UV-protective pigments. Lichens of encroached alvars are soil-type generalists, fruticose, reproduce vegetatively and contain herbivore-deterring compounds. Rare lichens resemble the species of open lowproductivity alvars, except their more limited niche space, i.e. they are restricted to arcticalpine habitats. The conservation practices on alvars should support the formation of crustforming communities by suppressing the growth of shrubs and herbs, and by promoting recurrent small-scale soil disturbances.
Semi-natural grasslands, among them thin-soil calcareous grasslands (alvars), have great conserva... more Semi-natural grasslands, among them thin-soil calcareous grasslands (alvars), have great conservation value but have become increasingly rare in Europe. The main threat to alvar grasslands is the encroachment by juniper Juniperus communis and therefore it is usually removed during the restoration practice. Juniper can also be a host plant for many epiphytic lichens, but its role as a phorophyte is poorly known. We studied epiphytic lichen diversity on 126 junipers in 17 sites in western Estonia and found 140 lichenized taxa including several rare and red-listed species. Using indirect and direct multivariate analyses (DCA, pCCA) and general linear models we revealed that both habitat and phorophyte properties affect lichen assemblies on juniper. Lichen species richness per site showed a unimodal relationship with compound factors of site productivity and juniper characteristics (stem circumference and juniper width). Lichen species richness per phorophyte was increasing with its siz...
Abstract: Wooded meadows with a history of traditional land use over thousands of years support a... more Abstract: Wooded meadows with a history of traditional land use over thousands of years support a great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows are threatened because of the cessation of traditional management in large areas. We studied lichen communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment of traditional management on epiphytic lichen species composition, considering factors on three spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree diameter, described as much of the compositional variation as geographic location (region) or environmental conditions in wooded meadows. Of the environmental factors studied, woodland canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the community type of semi-open wooded meadows to species-poor communities characteristic of secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently observed lichen species revealed that more than half of them (21) are influenced by site openness (canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open wooded meadows. The results emphasize that the preservation of large old deciduous trees of various species and the maintenance of the semi-open structure of stands are vitally important for the protection of epiphytic lichen communities in wooded meadows.
Abstract: We assessed multiple environmental factors that might influence the population vitality... more Abstract: 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 specificmanagement 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.
Semi-natural calcareous grasslands (alvars) are biodiversity hotspots in Northern Europe, particu... more 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.
ABSTRACT Changes in the forest management practices have strongly influenced the distribution of ... more ABSTRACT Changes in the forest management practices have strongly influenced the distribution of species inhabiting old-growth forests. The epiphytic woodland lichen Lobaria pulmonaria is frequently used as a model species to study the factors affecting the population biology of lichens. We sampled 252 L. pulmonaria individuals from 12 populations representing three woodland types differing in their ecological continuity and management intensity in Estonia. We used eight mycobiont-specific microsatellite loci to quantify genetic diversity among the populations. We calculated the Sørensen distance to estimate genetic dissimilarity among individuals within populations. We revealed that L. pulmonaria populations have significantly higher genetic diversity in old-growth forests than in managed forests and wooded meadows. We detected a significant woodland-type-specific pattern of genetic dissimilarity among neighbouring L. pulmonaria individuals, which suggests that in wooded meadows and managed forests dominating is vegetative reproduction. The vegetative dispersal distance between the host trees of L. pulmonaria was found to be only 15–30m. Genetic dissimilarity among individuals was also dependent on tree species and trunk diameter. Lobaria pulmonaria populations in managed forests included less juveniles compared to old-growth forests and wooded meadows, indicating that forest management influences life stage structure within populations. We conclude that as intensive stand management reduces the genetic diversity of threatened species in woodland habitats, particular attention should be paid to the preservation of remnant populations in old-growth habitats. Within managed habitats, conservation management should target on maintenance of the stand’s structural diversity and availability of potential host trees. KeywordsGenetic dissimilarity–Genetic distance–Epiphytic lichen–Microsatellites–Managed forest–Old-growth forest–Population genetics–Wooded meadow
Abstract. Lobaria pulmonaria is a conspicuous and widely known epiphytic
lichen species which mai... more Abstract. 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 southwestern 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.
Uploads
Papers by Jaan Liira
environmental conditions observed for common species, i.e. we employed the ‘matching
analogy approach’ with the analytical scheme ‘common species / driver / trait /
driver/rare species’.We addressed the driveretrait relationship for common epigeic lichens
of thin-soil calcareous grasslands, which are endangered by cessation of traditional land use.
Common lichens were suppressed by encroaching herbs and shrubs, and were supported by
ground disturbances. The lichens of open low-productivity alvars are predominantly calciphilous,
epibryic, crustose-squamulose, sexually reproducing and contain UV-protective pigments.
Lichens of encroached alvars are soil-type generalists, fruticose, reproduce vegetatively
and contain herbivore-deterring compounds. Rare lichens resemble the species of open lowproductivity
alvars, except their more limited niche space, i.e. they are restricted to arcticalpine
habitats. The conservation practices on alvars should support the formation of crustforming
communities by suppressing the growth of shrubs and herbs, and by promoting
recurrent small-scale soil disturbances.
great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows
are threatened because of the cessation of traditional management in large areas. We studied lichen
communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded
meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment
of traditional management on epiphytic lichen species composition, considering factors on three
spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial
Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition
is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree
diameter, described as much of the compositional variation as geographic location (region) or
environmental conditions in wooded meadows. Of the environmental factors studied, woodland
canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the
community type of semi-open wooded meadows to species-poor communities characteristic of
secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently
observed lichen species revealed that more than half of them (21) are influenced by site openness
(canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect
on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open
wooded meadows. The results emphasize that the preservation of large old deciduous trees of various
species and the maintenance of the semi-open structure of stands are vitally important for the
protection of epiphytic lichen communities in wooded meadows.
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 specificmanagement 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.
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.
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 southwestern
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.
environmental conditions observed for common species, i.e. we employed the ‘matching
analogy approach’ with the analytical scheme ‘common species / driver / trait /
driver/rare species’.We addressed the driveretrait relationship for common epigeic lichens
of thin-soil calcareous grasslands, which are endangered by cessation of traditional land use.
Common lichens were suppressed by encroaching herbs and shrubs, and were supported by
ground disturbances. The lichens of open low-productivity alvars are predominantly calciphilous,
epibryic, crustose-squamulose, sexually reproducing and contain UV-protective pigments.
Lichens of encroached alvars are soil-type generalists, fruticose, reproduce vegetatively
and contain herbivore-deterring compounds. Rare lichens resemble the species of open lowproductivity
alvars, except their more limited niche space, i.e. they are restricted to arcticalpine
habitats. The conservation practices on alvars should support the formation of crustforming
communities by suppressing the growth of shrubs and herbs, and by promoting
recurrent small-scale soil disturbances.
great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows
are threatened because of the cessation of traditional management in large areas. We studied lichen
communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded
meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment
of traditional management on epiphytic lichen species composition, considering factors on three
spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial
Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition
is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree
diameter, described as much of the compositional variation as geographic location (region) or
environmental conditions in wooded meadows. Of the environmental factors studied, woodland
canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the
community type of semi-open wooded meadows to species-poor communities characteristic of
secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently
observed lichen species revealed that more than half of them (21) are influenced by site openness
(canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect
on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open
wooded meadows. The results emphasize that the preservation of large old deciduous trees of various
species and the maintenance of the semi-open structure of stands are vitally important for the
protection of epiphytic lichen communities in wooded meadows.
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 specificmanagement 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.
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.
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 southwestern
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.