Epixylic Species Research Articles

Altitude is a better predictor of the habitat requirements of epixylic bryophytes and lichens than the presence of coarse woody debris in mountain forests: a study in Poland

Key messageIn order to preserve the continuity of epiphytic and epixylic cryptogamic flora, two things are essential: maintaining the near-natural character of a forest community in relation to the montane zonation and more sustainable forest management in relation to deadwood.ContextLichens and bryophytes are common species that inhabit dead wood. The relationship between their habitat requirements, which can be expressed by their Ellenberg indicator values and the characteristics of dead logs, are not yet known.AimsWe formulated the hypothesis that altitude is positively correlated with the demands of species for higher light and lower temperature, while the decomposition stage of deadwood is positively correlated with species’ requirements for nutrients and moisture. Moreover, we assumed that there would be differences in the habitat requirements among specific groups of species, i.e., lichens, liverworts, and mosses.MethodsA total of 629 logs that were colonized by bryophytes and lichens were analyzed in terms of their mean Ellenberg indicator values in order to determine whether there is a link between the location, decomposition of logs and the species’ environmental requirements.ResultsAltitude correlated with the moisture and nutrients in the habitats of liverworts and mosses and light and soil acidification only in mosses.ConclusionsThe obtained results demonstrate that the altitudinal distribution of epixylic species in a montane region is of greater importance than the deadwood properties like decomposition stage and moisture content.

DaLiBor

Digital data on the distribution of species are crucial for vegetation studies, monitoring and nature protection. Despite the existence of databases, the majority of bryophyte and lichen occurrences in the Czech Republic are not widely available in a standard and machinereadable form. Therefore, we created a Database of Lichens and Bryophytes (DaLiBor; dalibor.ibot.cas.cz) under Creative Commons license (CC-BY-SA). DaLiBor provides an infrastructure for recording standardizing, validating and enhancing data, e.g. neural network record classification. The database is also a tool for sharing and analyzing records. Here, a descriptive analysis of 596,935 DaLiBor records, composed of 473,690 (79.4%) bryophytes and 123,245 (20.6%) lichens, is presented. There are bryophyte records for the whole the Czech Republic, but there are no lichen records for large areas. The records of the spatial distribution of bryophytes and lichens in the Czech Republic were evaluated, which confirmed the importance of protected areas for biodiversity. There were more records of epiphytic and epixylic species at high altitudes than of saxicolous and terricolous species, which are mainly recorded at low altitudes. Fagus sylvatica was the tree with the highest number of recorded taxa for both bryophytes and lichens. The highest number of records, including red-listed species, originates from natural beech and managed coniferous forests. Three cases that benefited from DaLiBor standardized data are presented: (i) the species distribution model helped find six new localities for Dicranum majus and Polytrichastrum alpinum within a single field visit; (ii) Analysis of bryophyte and lichen species abundances in time revealed a high percentage of acidophilous species and spread of nitrophilous species in current bryophyte and lichen communities; (iii) DaLiBor is the main source of data for the online interactive Atlas of Czech lichens (dalib.cz).

Mchy i wątrobowce rezerwatu Molenda (Polska środkowa)

The paper presents the results of studies on bryophyte flora of the Molenda forest reserve located in the Central Poland. Fifteen species of liverworts and 73 species of mosses were found. Twenty one of these species are considered to be partially protected by law, three endangered and ten rare in the region. Epigean bryophyte constitute the largest ecological group in the bryophyte flora, consisting of 55 species (62% of total flora), followed by epixylic species which are represented by 48 species (54%). The most interesting were taxa threatened and regionally rare, such as Nowellia curvifolia (Dicks.) Mitt., Callicla­dium haldanianum (Grev.) H.A. Crum, Dicranoweisia cirrata (Hedw.) Lindb., Orthodicranum tauricum (Sapjegin) Smirnova, Orthodontium lineare Schwägr., Orthotrichum pulchellum Brunt., O. stramineum Hornsch. ex Brid., Sciu­ro-hypnum refle­xum (Starke) Ignatov & Huttunen, Ulota bruchii Hornsch. ex Brid. and U. crispa (Hedw.) Brid.

Lichens and allied non-lichenized fungi of virgin forests in the Caucasus State Nature Biosphere Reserve (Western Caucasus, Russia)

Urbanavichus, G., Vondrák, J., Urbanavichene, I., Palice, Z. & Malíček, J. 2020. Lichens and allied non-lichenized fungi of virgin forests in the Caucasus State Nature Biosphere Reserve (Western Caucasus, Russia). – Herzogia 33: 90 –138.We report on 659 epiphytic and epixylic species recorded from seven one-hectare plots established along an altitudinal gradient in a virgin forest of the Caucasus State Nature Biosphere Reserve. A total of 564 species are lichens, 61 are lichenicolous fungi and 34 are allied non- or facultatively lichenized fungi. one hundred forty – nine species (116 lichens, 17 lichenicolous and 16 saprophytic fungi) are new to the Northern Caucasus, including 133 species (104 lichens, 15 lichenicolous and 14 saprophytic fungi) that are new to the Caucasus Mountains. Fifty species are reported from Russia for the first time: 37 lichens (Andreiomyces obtusaticus, Bacidina mendax, Biatora aegrefaciens, B. bacidioides, B. chrysanthoides, Biatorella dryophila, Buellia iberica, Cliostomum haematommatis, Endohyalina ericina, Fellhanera christiansenii, Gyalidea minuta, Japewia aliphatica, Lecanora barkmaniana, L. subravida, Lecidea strasseri, Leptogium hibernicum, Lithothelium hyalosporum, L. phaeosporum, L. septemseptatum, Loxospora cristinae, Melanelixia epilosa, Micarea nowakii, M. perparvula, Opegrapha trochodes, Orcularia insperata, Parvoplaca servitiana, Phylloblastia inexpectata, Psoroglaena stigonemoides, Ptychographa xylographoides, Ramonia dictyospora, R. luteola, Rinodina polysporoides, Thelopsis flaveola, Topelia jasonhurii, Verrucaria hegetschweileri, Wadeana minuta, Waynea giraltiae), nine lichenicolous fungi (Arthonia vorsoeensis, Didymocyrtis melanelixiae, Epigloea urosperma, Muellerella polyspora, Phacographa zwackhii, Pronectria pilosa, Rhymbocarpus pubescens, Taeniolella friesii, Unguiculariopsis acrocordiae) and four non-lichenized saprophytic fungi (Cyrtidula major, Karschia cezannei, Kirschsteiniothelia recessa, Pseudotryblidium neesii).The ratio of macrolichens ranges between 26.5 – 40 % and rises with elevation. Lichens with a trentepohlioid photobiont are represented by 15 –51 species per plot and their species richness decreases with elevation. The species richness of cyanolichens is substantial in all plots (15 –28 species) reflecting a negligible effect of acidification/air pollution. Low species richness and low abundances of nitrophilous species indicate insignificant uptake of nitrogen emissions. Beech and fir are the most preferred phorophytes, but the vast majority of lichen species have low substrate specificity. Species richness per plots ranged between 236 and 379. The highest richness was found in a plot outside the Caucasian Reserve and we recommend its inclusion into the protected area.

Bryophyte flora of selected historical parks and gardens of Slovakia

In a cultural landscape, old historical parks feature important biodiversity refuges not only for vascular plants but also for bryophytes. Here, we surveyed a total of 14 historical parks and gardens in urban and rural areas of Slovakia to evaluate their bryophyte diversity and to find out possible correlations between species richness and habitat characteristics. Overall, 104 bryophyte species (12 liverworts and 92 mosses) were identified. Most frequently occurring species were Amblystegium serpens, Brachythecium rutabulum, Bryum argenteum and Tortula muralis, present at all studied sites. Generally, small urban parks hosted less bryophyte species compared to rural areas. In terms of substrate preference, most frequent were epigeic species, followed by epilithic, epiphytic and epixylic species. At most sites, species’ indicator values showed a dominance of semi-heliophilous, semi-heliophobic, hygrophilous, weakly acidophilous to basiphilous bryophyte taxa. Spearman rank correlation test showed that the species richness correlated with the park location (urban vs. rural area) and the number of settlement inhabitants showing that green areas in urban landscape are more isolated from each other which decreased species richness. Our results show that old parks and gardens can provide suitable habitats for some rare species such as Osculatia bornholmensis (reported recently as new for Slovakia) but even for common forest and meadow species and the study of their diversity should be given an increased attention.

Response of Bryophytes to Disturbances in Managed Forests. A Case Study from a Polish Forest

Forest management practices fundamentally impact the structure of a forest (relatively young stage of forest development, dominating stands with only one or two species of trees, planting coniferous tree species on habitats of deciduous forests, introducing alien tree species, very limited volume of dead wood). Bryophytes are especially sensitive to silvicultural practices. The aim of this study was to examine the importance of particular substrates for maintaining bryophyte species diversity in the Murckowski Forest (Silesian Upland S Poland), which is at present a managed forest. In 100 sampling plots, the structure of the forest and the species composition, frequency and abundance of bryophytes on different types of substrates (ground, tree base, tree trunk and dead wood) were analysed. In total, 54 bryophyte species were recorded (five liverworts and 49 mosses). The largest number of species was observed on dead wood (42), while the lowest number was of typical epiphytes growing on tree trunks bark more than 30 cm above the ground (18). This study confirms that dead wood is a key habitat and determines not only the number of epixylic species, but also the whole richness of bryophyte species. Maximal diameter of trees and presence of old tree stands were significant factors for species that were colonizing the tree bases.

What factors influence colonization of lichens, liverworts, mosses and vascular plants on snags?

The dead standing trees i.e. snags are known as habitat for epiphytic and epixylic species including first of all lichens and bryophytes. The vascular plants are much rarer on this type of coarse woody debris (CWD). The eighty snags (CWD elements higher than 1.5 m) of Norway spruce Picea abies and beech Fagus sylvatica in the Karkonosze Mts. were examined for the presence of lichens, liverworts, mosses and vascular plants. The height of snags, their decomposition stage, cover of bark, diameter at breast height (DBH) as well as site conditions (elevation, slope and aspect, presence in forest community) were measured and noted. The percent cover of plants and lichens were estimated on each snag. Totally 99 taxa were recorded. There lichen species were dominant (44), followed by mosses (34), liverworts (13) and there were only 8 vascular plants. The total species richness varied from 1 to 22 taxa. The species composition growing on snags was subjected to canonical correspondence analysis and statistical analyses. They revealed that the species identity of snag is one of the most important factors influencing species composition. The number of species is positively correlated with DBH whereas decomposition stage, presence of bark, snag height are not significant factors. The species richness increases also with altitude what is connected with higher abundance of spruce snags. The occurrence of snags in this area is mainly associated with forest management practices in the past. Despite of some observed patterns in colonization of snags they are important habitat especially for lichens.

Epixylic vegetation abundance, diversity, and composition vary with coarse woody debris decay class and substrate species in boreal forest

Although the importance of coarse woody debris (CWD) to understory species diversity has been recognized, the combined effects of CWD decay and substrate species on abundance and species diversity of epixylic vegetation have received little attention. We sampled a wide range of CWD substrate species and decay classes, as well as forest floors in fire-origin boreal forest stands. Percent cover, species richness, and evenness of epixylic vegetation differed significantly with both CWD decay class and substrate species. Trends in cover, species richness, and evenness differed significantly between nonvascular and vascular taxa. Cover, species richness, and species evenness of nonvascular species were higher on CWD, whereas those of vascular plants were higher on the forest floor. Epixylic species composition also varied significantly with stand ages, overstory compositions, decay classes, substrate species, and their interactions. Our findings highlight strong interactive influences of decay class and substrate species on epixylic plant communities and suggest that conservation of epixylic diversity would require forest managers to maintain a diverse range of CWD decay classes and substrate species. Because stand development and overstory compositions influence CWD decay classes and substrate species, as well as colonization time and environmental conditions in the understory, our results indicate that managed boreal landscapes should consist of a mosaic of different successional stages and a broad suite of overstory types to support diverse understory plant communities.

Short-term effects of alternative thinning treatments on the richness, abundance and composition of epixylic bryophytes, lichens, and vascular plants in conifer plantations at microhabitat and stand scales

Abstract Epixylic (log-dwelling) flora contribute much to forest biodiversity, but have been shown to decline with intensive management, perhaps through the reduced supply of coarse woody debris, their preferred substrate, and the altered mesoclimate of the understory. Such declines might be ameliorated through modifying the plantation management practices. This study examined the response of epixylic flora to commercial thinning treatments in 6 mid-rotation conifer plantations of northwestern New Brunswick, Canada. Treatments included an unthinned control, and thinning with: moderate debris, moderate debris with added snags, or no-debris. Epixylic flora were surveyed in the first and third year after thinning, on 30 logs in each of the 4 treatments, using both 10 × 20 cm quadrats (%-cover) and a presence-absence census of whole-logs. Treatments were evaluated at log and stand scales, based on the putative disturbance-sensitivity of different epixylic functional groups. Analyses included indicator species analysis, ANOVA of functional group richness and cover, NMS ordination, and PERMANOVA. Thinning with no-debris or moderate-debris reduced species richness at the stand scale, and increased cover at the log-scale. Composition shifted towards chlorolichens, vascular plants, and forest floor or asexually-reproducing bryophytes in thinned treatments, whereas liverworts and bryophytes with desiccation-sensitivity or those lacking asexual reproduction showed slight declines; most bryophyte groups showed no change. Moderate debris with snags and unthinned treatments showed the fewest compositional differences, and maintained many of the same sensitive groups, but all thinned treatments showed similar trajectories of compositional change. Additional monitoring is required to determine whether thinning with moderate debris and snags offers effective conservation of epixylic species, but debris removal (e.g., for biomass harvest) should be discouraged.

Retention patches maintain diversity of epiphytic and epixylic indicator lichens more effectively than solitary trees

ABSTRACTThe effectiveness of retention trees and patches in preserving diversity of nine epiphytic and epixylic old-growth forest lichens was studied in north boreal spruce forests in Finland. We compared (1) 7–8-year-old retention cuts, with at least 5–10 living or dead retention trees per hectare, (2) 10–12-year-old clear-cuts, with some scattered living and dead retention trees on the sites, (3) old-growth spruce forests, and (4) 7-8-year-old retention patches (0.06–0.45 ha) representing the original tree species composition of old-growth forests. The occurrence of indicator lichens was studied on 150 deciduous trees and snags in each forest category. The species richness was significantly higher in old-growth forests than in the clear-cuts and retention cuts, but did not differ between old-growth forests and retention patches. Only three species were found in clear-cuts and two in retention cuts. Foliose cyanolichens Leptogium saturninum and Nephroma bellum thrived on solitary retention trees, whereas humidity-requiring pin lichens from the genus Chaenotheca were found only in old-growth forests and retention patches. Our results suggest that the ability of epiphytic and epixylic species to survive on retained trees depends on several factors: (1) substrate quality (tree species, tree type and diameter of a tree), (2) environmental factors (e.g. humidity, slope exposition), and (3) morphological and physiological characteristics of species. Besides of substrate trees, the retained conifers (esp. spruce) seem to be important in retention patches to provide the shading necessary to maintain humidity.

Epiphytic Lichens of Stužica (E Slovakia) in the Context of Central European Old-Growth Forests

Vondrák, J., Malíček, J., Šoun, J. & Pouska, V. 2015. Epiphytic lichens of Stužica (E Slovakia) in the context of Central European old-growth forests. — Herzogia 28: 104–126.Based on recent lichen inventories, we report 230 epiphytic and epixylic species in the Slovakian old-growth beech-dominated Stužica forest. Microlichens represent 75% of species. By comparison, lichen lists of only three other Central European forests exceed 200 species, and none of them reached 230. Lichen diversity is very unequally distributed in Stužica; the extensive south-facing slopes are poor in species, whereas damp brook valleys and upper parts of slopes above 1000 m alt. are rich. Some rare macrolichens were collected in Stužica about 50 years ago but could not be relocated during the present survey.Twelve species are new to Slovakia: Epigloea urosperma, Graphis macrocarpa, Kirschsteiniothelia recessa, Lecidea sanguineoatra, Lepraria ecorticata, Micarea nigella, Opegrapha trochodes, Parmotrema arnoldii, Pertusaria waghornei, Ramonia chrysophaea, Sclerophora amabilis and Tetramelas chloroleucus. Three recorded species were considered regionally extinct in Slovakia: Arthonia byssacea, Sclerophora coniophaea and Sclerophora farinacea.

Porosty Beskidów Wyspowego i Żywieckiego, Pasma Jałowca i Masywu Babiej Góry [The lichens (Lichenized Fungi) occurrence in the Beskid Wyspowy, Beskid Żywiecki and Pasmo Jałowca Ranges, and the Babia Góra Massif

The work presents lichenological materials collected in the years 1964–1969 in the area of the Beskid Wyspowy, Beskid Żywiecki and Pasmo Jałowca Ranges and the Babia Góra Massif in the Western Carpathians. In the years 1996–1997 comparative studies of those mountain ranges were undertaken again. However, the author managed to reinvestigate the lichens of the Beskid Wyspowy Rangę only, he will probably not be able to continue the research in the other ranges. The check-list of the lichen species occurring there in the sixties, published nów for the first time, can be the reference for the lichenologists who would carry out this project in the same way as the author referenced to the former investigations (STEIN 1872; REHMAN 1879; BOBERSKI 1886; MOTYKA 1934; ZSHACKE 1934; SUZA 1951). In the Beskid Wyspowy Range 342 species of lichens were found, among them 112 epiphytic species, 30 epixylic species, 6 epibryophytic species, 55 epigeic species and 139 epilithic species were recorded. One species of lichenicolous fungus was also found <em>Epilichen scabrosus</em>. In the Beskid Żywiecki and Pasmo Jałowca Ranges, and Babia Góra Massif 543 species of lichens occurred, among them 183 epiphytic species, 43 epixylic species, 21 epibryophytic species, 69 epigeic species and 194 epilithic species. The check-list includes also lichenicolous species: <em>Carbonea vitellinaria, Chaenothecopsis consociata, Microcalicium arenarium, Sphinctrina turbinata, Stenocybe pullatula</em>. In the Babia Góra Massif 27 species previously published from there were not found again: <em>Catolechia wahlenbergii, Cliostomum corrugatum, Phaeographis dendritica, Polyblastia cupularis, P. sendtneri, Solorina crocea, Sticta syhatica</em> (comp. STEIN 1872), <em>Ramalina calicaris</em> (REHMAN 1879), <em>Usneaflorida, U. longissima, U. scrobiculata</em> (MOTYKA 1934), <em>Polyblastia pallescens</em> (ZSCHACKE 1934), <em>Arthrorhaphis alpina, Cladonia amaurocrea, C. bellidiflora, C. cyanipes, C. macrophylla, Evernia divaricata, Hypotrachyna sinuosa, Mycobilimbia berengeriana, Nephroma laevigatum, Peltigera malacea, P. venosa, Solorina saccata, Sphaerophorus fragilis, Sporastatia polyspora, Thamnolia vermicularis</em> (comp. SUZA 1951).

Contribution to the knowledge of lichen flora of inland sand dunes in the western Po Plain (N Italy)

This paper describes the lichen flora surveyed in inland sand dunes, called dossi, in the western Po Plain (Lombardy region, Italy). Here, lichens were marginally known in comparison with the epigaeous component, but they were never studied before in relation to the epiphytic, epixylic and epilithic components. The floristic list includes 50 species; ecological and chorological analyses were carried out. Thirteen lichen species observed on various substrata were not reported in the lichen list of the Ticino Natural Park, which distances only few kilometres from our study area. Nine species are new for the Po phytoclimatic region and one species, Cladonia portentosa, is new for Lombardy. Particularly interesting are some species related to the Corynephorus grasslands, such as Cladonia sp. pl. and Stereocauloncondensatum, and three species usually absent, at our latitudes, beneath the montane belt: Cladonia digitata, Hypocenomyce scalaris and Parmeliopsis ambigua. These data confirm the importance of inland sand dunes for lichen diversity of the Po Plain. Some preliminary remarks concerning the management of the habitats hosting lichens are given, with particular emphasis to their conservation. Suggested actions include the possibility to keep woody coarse debris, to favour epixylic species, and mechanical disturbance, dispersal of lichen fragments and sheep grazing, to favour epigaeous species.

Effects of variable canopy retention harvest on epixylic bryophytes in boreal black spruce – feathermoss forests1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems.

Modification of forest attributes and structural components like downed wood (DW) during forest harvest can lead to local species loss. Epixylic bryophytes have been proposed as good indicators of such changes. Unharvested control, variable canopy retention, and single pass harvest represent a gradient in forest harvest impact and can be used to test the response of epixylic bryophytes to different levels of environmental change. The objective of this study was to see if variable canopy retention attenuates environmental change associated with harvesting, consequently maintaining an epixylic community more similar to unharvested stands than single pass harvesting. Environmental conditions and DW characteristics were sampled on 225 DW pieces distributed in 45 permanent plots. Results showed that treatment affected epixylic richness through its impact on canopy openness and DW diameter and decomposition class. Fewer species were found in more open habitats and more species were found on bigger and more decomposed DW. Most epixylic species were more commonly found on the forest floor than on the DW. In conclusion, variable canopy retention harvest offered microclimatic conditions and DW availability and quality more suitable for epixylic species than single pass harvest, which was less suitable for epixylic species.

Immediate Effects of Logging, Mounding, and Removal of Logging Residues on Epixylic Species in Managed Boreal Norway Spruce Stands in Southern Finland

The immediate effects of bioenergy harvesting methods on epixylic species were studied in mature managed Norway spruce dominated forests in southern Finland. The treatments included logging, residue harvesting, and soil preparation as either mounding or mounding combined with stump harvesting. Altogether, 110 logs and 440 species sample plots on logs were inventoried before and after logging, and after soil preparation treatments. Logging decreased the cover and species richness in all epixylic species groups. The soil preparation decreased the cover of macrolichens, while stump harvesting was significantly most devastating both for cover and richness in bryophytes. We suggest that bioenergy harvesting critically affects the epixylic species, and therefore the use of less devastating methods and compensation for the loss of coarse woody debris is recommended on a landscape level.

Structures determining bryophyte species richness in a managed forest landscape in boreo-nemoral Europe

Forest patches with high biological value are protected as woodland key habitats (WKH), which are identified by the presence of forest structures and indicator species. However, management for conservation needs to consider also managed forests as habitats for species. In this respect, there is a need to set quantitative targets for species and structures at different landscape scales. Due to non-intensive methods of forest management used prior to 1940 in Latvia, it might be expected that large areas of forest have developed structures that can support many species characteristic of natural forests. The aim of the study was to create a model that best described the richness of bryophyte species that are characteristic of natural forests, using forest structures as explanatory factors. The structures and bryophyte communities on living trees and coarse woody debris (CWD) were described in plots along transects blindly placed in areas dominated by State forests under commercial management. Explanatory variables related to tree species composition and tree size explained 54% of the variation in WKH indicator species richness on living trees. The best explanatory factors were maximum diameter of deciduous tree species and CWD. Low richness of total bryophyte and indicator species was found on dead wood, and the amount of variation in bryophyte species richness on CWD explained by explanatory variables was low. The study indicates the importance of deciduous tree substrate in managed forests in maintaining the spatial continuity of epiphytic species diversity. However, the forests in the managed forest landscape did not support high diversity of epixylic species, even in the WKHs, due to low diversity of suitable dead wood substrate.

Effects of Retention Felling on Epixylic Species in Boreal Spruce Forests in Southern Finland

We studied the effects of patch retention felling and soil scarification by harrowing on the coverage and species richness of epixylic species in boreal Norway spruce (Picea abies) forests in Southern Finland. The epixylics were investigated from both the retention tree groups (RTGs) and the surrounding felling areas before and after fellings and after scarification on consecutive years. The cover percentage of all included species groups was shown to decrease after the felling, especially in the felling areas (vascular plants, −0.4%; mosses, −27.8%; liverworts, −4.0%; and lichens,−2.1%). The decrease was considerable also in the RTGs. The amount of dead moss increased in both the areas indicating microclimatic changes. Species richness also declined rapidly after the first year, especially in the felling areas (vascular plants, −2.2%; mosses, −27.3%; liverworts, −30.3%; and lichens, −22.9%). Scarification also decreases covers and species richness of bryophytes. After the second year, the covers of the species groups generally started to regain, especially in the untreated RTGs. The size of RTG was in positive correlation with the total species number. Another main result indicates that it is possible to maintain much higher initial vegetation abundance and diversity in the RTGs than in the felling areas. Coarse woody debris formed by the frequent tree uprootings may also enhance the long-term survival of epixylics over forest regeneration period. RTGs should be at least 10 times larger than the size used in current Finnish forestry, so that they could function as species refugia.

Colonization-extinction dynamics of epixylic lichens along a decay gradient in a dynamic landscape

Metapopulation models are often used for understanding and predicting species dynamics in fragmented landscapes. Several models have been proposed depending on e.g. the relative importance of patch dynamics on the metapopulation dynamics. Dead wood is a dynamic substrate patch, and species that are confi ned to such patches have experienced a high degree of habitat loss in managed forests. Little is, however, known about how the population dynamics of epixylic species are aff ected by the fast dynamics of their substrate patches. We quantifi ed the eff ect of local patch conditions and metapopulation processes on colonizations and extinctions of epixylic lichen species in a managed boreal forest landscape. Th is was done by twice surveying seven lichen metapopulations on 293 stumps in 30 stands of ages covering the duration of the dynamic patches (stumps). We also investigated the relative importance of local stochastic extinctions from stumps that remained available, and deterministic extinctions due to stump surface disappearance . We found importance of a decay gradient, surrounding metapopulation size, and local population sizes, in driving the colonization – extinction dynamics of epixylic lichens. Th e species were sorted along the stump decay gradient. Increasing surrounding metapopulation size was associated with increased colonization rates, and increasing local population size decreased lichen extinction rates. Finally, both local stochastic extinctions and deterministic extinctions due to patch disappearance occur, confi rming that the longterm persistence of epixylic lichens depends on colonization rates that compensate for stochastic population extinctions as well as deterministic extinctions.

Succession of bryophyte assemblages following clear-cut logging in boreal spruce-dominated forests in south-central Sweden — Does retrogressive succession occur?

The recovery process of boreal bryophyte communities after clear-cutting was studied in a chronosequence in south-central Sweden. We hypothesized that high initial grass cover on clearcuts, high litter cover and low light levels during canopy closure, and shortage of coarse woody substrates would constrain recovery in different ways. Instead, both epigeic and epixylic guilds (i.e., species growing on forest floor and deadwood) displayed a gradual increase in similarity over time from the clear-cut phase, perhaps because of the absence of distinct peaks in needle litter and canopy cover. Epixylic species started to recover long before the accumulation of deadwood, indicating that microclimate rather than substrate availability was the most constraining factor during the first 50 years. Since we did not find any other bottlenecks during the succession after clear-cutting, conservation measures aiming at decreasing local extinction rates during clear-cutting may also increase long-term persistence. On the other hand, as the results from the epixylic guild suggest, other factors during the forest succession, such as the development of a suitable microclimate, might be more important for some organisms, thus possibly mitigating such long-term positive effects of adjusted management during the clear-cutting operation.

The effects of stand structure on ground-floor bryophyte assemblages in temperate mixed forests

The effect of tree species composition, stand structure characteristics and substrate availability on ground-floor bryophyte assemblages was studied in mixed deciduous forests of Western Hungary. Species composition, species richness and cover of bryophytes occurring on the soil and logs were analysed as dependent variables. The whole assemblage and functional groups defined on the basis of substrate preference were investigated separately. Substrate availability (open soil, logs) was the most prominent factor in determining species composition, cover and diversity positively, while the litter of deciduous trees had a negative effect on the occurrence of forest floor bryophytes. Besides, bryophyte species richness increased with tree species and stand structural diversity, and for specialist epiphytic and epixylic species log volume was essential. Sapling density and light heterogeneity were influential on bryophyte cover, especially for the dominant terricolous species. Many variables of the forest floor bryophyte community can be estimated efficiently by examining stand structure in the studied region. Selective cutting increasing tree species diversity, stand structural heterogeneity and dead wood volume can maintain higher bryophyte diversity in this region than the shelter-wood system producing even-aged, monodominant, structurally homogenous stands.