Genetic diversity of reintroduced tree populations in restoration plantations of the Brazilian Atlantic Forest

Long‐term ecological success of large‐scale restoration programs planned for the next decades will rely on genetic diversity (GD) of reintroduced or colonizing species, a limiting factor in highly fragmented landscapes. In small and isolated natural remnants or restoration areas, substantial reduction in population's size or connectivity may lead to local extinctions due to the accumulation of deleterious recessive alleles and ongoing reduction of fecundity, plant vigor, recruitment success, and adaptive potential. Despite the paramount role of GD for species persistence, its levels in restoration programs are poorly known. We assessed the GD of four model tree species (different succession stages, dispersal, and pollination syndromes) from the Brazilian Atlantic Forest, comparing two high‐diversity restoration plantations, one forest fragment and one conserved remnant. Contrary to the expectation that the plantation strategies adopted in the restoration programs could result in genetic composition homogenization, we found that restoration areas established heterogeneous genetic groups with similar levels of neutral GD and inbreeding to those observed in natural forest remnants. This pattern was consistent across the four functionally different tree species, despite some species idiosyncrasies. For instance, we observed lower allelic richness in early successional species in restoration sites, suggesting that some species may be more prone to reintroduction with lower GD. Thus, we advocate the use of high GD levels in restoration to support biodiversity conservation in human‐modified landscapes, thus reinforcing the role of ecological restoration for recovering the diversity of genes—the basic constituent of biodiversity.     

Biotechnological efforts for preserving and enhancing temperate hardwood tree biodiversity,health, and productivity

Hardwood tree species in forest, plantation, and urban environments (temperate regions of the world) are important biological resources that play a significant role in the economy and the ecology of terrestrial ecosystems, and they have aesthetic and spiritual value. Because of these many values of hardwood tree species, preserving forest tree biodiversity through the use of biotechnological approaches should be an integral component in any forestry program in addition to large-scale ecologically sustainable forest management and preservation of the urban forest environment. Biotechnological tools are available for conserving tree species as well as genetic characterization that will be needed for deployment of germplasm through restoration activities. This review concentrates on the biotechnological tools available for conserving, characterizing, evaluating, and enhancing hardwood forest tree biodiversity. We focus mainly on species grown for lumber and wood products, not species grown mainly for fiber (pulp and paper production). We also present a brief summary of the importance of non-wood forest products from temperate hardwood tree species (a research area that needs further development using biotechnological techniques) and a few case studies for preserving forest tree biodiversity.     

Achieving Restoration Success: Myths in Bottomland Hardwood Forests

Restoration of bottomland hardwood forests is the subject of considerable interest in the southern United States, but restoration success is elusive. Techniques for establishing bottomland tree species are well developed, yet problems have occurred in operational programs. Current plans for restoration on public and private land suggest that as many as 200,000 hectares could be restored in the Lower Mississippi Alluvial Valley alone. The ideal of ecological restoration is to reestablish a completely functioning ecosystem. Although some argue that afforestation is incomplete restoration, it is a necessary and costly first step but not an easy task. The 1992 Wetlands Reserve Program in Mississippi, which failed on 90% of the area, illustrates the difficulty of broadly applying our knowledge of afforestation. In our view, the focus for ecological restoration should be to restore functions, rather than specifying some ambiguous natural state based on reference stands or pre‐settlement forest conditions. We view restoration as one element in a continuum model of sustainable forest management, allowing us to prescribe restoration goals that incorporate landowner objectives. Enforcing the discipline of explicit objectives, with restoration expectations described in terms of predicted values of functions, causal mechanisms and temporal response trajectories, will hasten the development of meaningful criteria for restoration success. We present our observations about current efforts to restore bottomland hardwoods as nine myths, or statements of dubious origin, and at best partial truth.     

Regeneration of tropical dry forests in Central America,with examples from Nicaragua

Abstract. This paper focuses on the management potential of natural forests in the tropical dry zones of Central America, particularly Nicaragua. Distribution and status of dry forest formations are reviewed. Two case studies from the Pacific coast of Nicaragua are presented to illustrate the disturbance created by traditional utilization, and to show the relatively high potential for natural forest management, with many of the tree species having economic value. Natural forest management, together with conservation and reforestation, is viewed as the main management option for the tropical dry forest areas. In spite of its importance, this option has received little attention or promotion from the governmental forestry sector. Four complementary options which can be devised for silvicultural work in production forests are: encouragement of advanced growth of desirable tree species, inducement of natural regeneration, coppice management, and compensatory planting. These options form different strategies for rehabilitation of the production and conservation functions of the forest and may well be combined in the same area. Research applied to better utilization of the forest resources should form an intrinsic part of rural development programs. Research work in tropical dry forest areas should focus on ecological, as well as socio-cultural and economical aspects related to the management options. Experimental sites are important enabling and securing long-term basic and applied biological research. They may also serve as units for demonstration, training and extension.     

Short-distance gene flow in <Emphasis Type="Italic">Populus nigra</Emphasis> L. accounts for small-scale spatial genetic structures: implications for in situ conservation measures

The European black poplar (Populus nigra L.) is a major species of riparian softwood forests. Due to human influences, it is one of the most threatened tree species in Europe. For restoration purposes, remaining stands may act as source populations. We analysed a natural population of P. nigra for genetic diversity and spatial genetic structure using seven microsatellite markers. For the first time, paternity analysis of seedlings as well as juveniles from a restricted area of natural regeneration was used to quantify pollen- and seed-mediated gene flow, respectively. In both cases, cultivated P. x canadensis trees in vicinity could act as potential parents. Spatial genetic patterns of the adult tree population suggest small-scale isolation by distance due to short-distance gene flow, the major part of which (i.e. 70%) takes place within distances of less than 1 km. This helps to explain the reduced diversity in the juveniles. It has implications for the spatial management of natural regeneration areas within in situ conservation measures.     

Improving Planting Stocks for the Brazilian Atlantic Forest Restoration through Community‐Based Seed Harvesting Strategies

High‐diversity reforestation can help jumpstart tropical forest restoration, but obtaining viable seedlings is a major constraint: if nurseries do not offer them, it is hard to plant all the species one would like. From 2007 to 2009, we investigated five different seed acquisition strategies employed by a well‐established tree nursery in southeastern Brazil, namely (1) in‐house seed harvesters; (2) hiring a professional harvester; (3) amateur seed harvesters; or (4) a seed production cooperative, as well as (5) participating in a seed exchange program. In addition, we evaluated two strategies not dependent on seeds: harvesting seedlings from native tree species found regenerating under Eucalyptus plantations, and in a native forest remnant. A total of 344 native tree and shrub species were collected as seeds or seedlings, including 2,465 seed lots. Among these, a subset of 120 species was obtained through seed harvesting in each year. Overall, combining several strategies for obtaining planting stocks was an effective way to increase species richness, representation of some functional groups (dispersal syndromes, planting group, and shade tolerance), and genetic diversity of seedlings produced in forest tree nurseries. Such outcomes are greatly desirable to support high‐diversity reforestation as part of tropical forest restoration. In addition, community‐based seed harvesting strategies fostered greater socioeconomic integration of traditional communities in restoration projects and programs, which is an important bottleneck for the advance of ecological restoration, especially in developing countries. Finally, we discuss some of the limitations of the various strategies for obtaining planting stocks and the way forward for their improvement.     

Use of microsatellite data and pedigree information in the genetic management of two long-term salmon conservation programs

In this paper, we describe the utility of microsatellite data and genetic pedigree information to guide the genetic management of two long-term conservation programs for endangered populations of salmon: Snake River Sockeye Salmon, Oncorhynchus nerka, and inner Bay of Fundy Atlantic Salmon, Salmo salar. Both programs are captive broodstock (live gene banking) programs for endangered populations of salmon. In order for these programs to be successful for recovery efforts, genetic change, including accumulation of inbreeding, loss of genetic variation, and adaptation to captivity, must be minimized. We provide an overview of each program, describe broodstock selection and pairing for spawning, and discuss how pedigree data are being used to evaluate different management practices. While there are inherent species and programmatic differences, both of these programs use widely accepted genetic conservation strategies (minimize mean kinship, reduce variance in family size, minimize inbreeding in the next generation, maintain large census and effective population size) to potentially mitigate some unintended side-effects associated with the rearing of small populations in captivity. These case studies highlight the benefits and practical limitations of applying these strategies in the genetic management of salmon, and may be used to inform other conservation programs.     

Transformational restoration: novel ecosystems in Denmark

Restoring the estimated 1 billion hectares of degraded forests must consider future climate accompanied by novel ecosystems. Transformational restoration can play a key role in adaptation to climate change but it is conceptually the most divergent from contemporary approaches favoring native species and natural disturbance regimes. Here, we review concepts of novelty in ecosystems with examples of emergent/neo-native and designed novel ecosystems, with application to transformational restoration. Danish forests have a high degree of novelty and provide a realistic context for discussing assisted migration, one method of transformational adaptation. Deforestation and impacts of past land use created a highly degraded landscape dominated by heathland in western Denmark. Restoration with non-native species began 150 years ago because the native broadleaves could not establish on the heathlands. Danish forestry continues to rely extensively on non-native species. Preparing for transformational adaptation requires risky research today to prepare for events in the future and refugia from the last glaciation may provide genetic material better adapted to future climate. A new project will test whether species and provenances from the Caspian forests in Iran possess greater genetic diversity and superior resistance (physiological adaptability) and resilience (evolutionary adaptability) and possibly a gene pool for future adaptation.     

Identifying effective tree planting schemes to restore forest carbon and biodiversity in Shiretoko National Park,Japan

Growing interest in ecosystem restoration has recently turned the focus on tree planting, one of the most widely used restoration tools globally. Here, we study the restoration potential of tree planting in a cool-temperate forest in Shiretoko National Park, northern Japan. We used simulation modeling to investigate the long-term success of tree planting in restoring biodiversity and the climate change mitigation function relative to intact natural forests. Specifically, we investigated 31 different restoration scenarios, consisting of five planting densities (1,000–10,000 trees/ha) × six levels of planted tree species richness (one to six species) + one no-planting scenario. We examined these scenarios at different distances from natural forests serving as a seed source (0–300 m) to quantify the potential for natural regeneration. In restoration areas in close proximity to a natural forest, species-rich high-density planting scenario performed best, reaching >50% of the reference values from intact natural forests within 33 years for both restoration goals. However, variation in restoration outcomes was small when >2,500 trees/ha of more than four species were planted, regardless of distance to seed source. In contrast, biodiversity restoration was considerably delayed in scenarios where planted species richness was low as well as in restoration areas that were far from a seed source yet relied solely on natural regeneration. We here demonstrate how forest landscape simulation can be used to identify viable restoration options for managers across multiple restoration goals as an important step to bridge the research–implementation gap in forest restoration.     

Sustainable management of planted landscapes: lessons from Japan

In Japan, 42?% of forests are planted forests, and most of them were established after World War II (1950–1980) to meet increased wood demands. Although Japanese planted forests are now reaching their planned harvest age, they have not been managed, and their restoration is now being discussed. Japanese foresters have not cut their own forests, and the country’s high wood demands have been met by imports during recent decades. The decline of young forests due to the stagnation of forestry activity is suggested to be partly responsible for the nation-wide decline in early-successional species, which is referred to as the “second crisis of biodiversity.” As a timber-importing nation, it is suggested that Japan has underused the nation’s own forests and has overused forests elsewhere. A revival of Japanese plantation forestry may contribute to the restoration of early-successional species because young planted forests are likely to provide suitable habitats. Furthermore, only 30?% of the current planted forests in Japan will be needed to meet the expected future domestic demand for lumber and plywood without imports. The remaining 70?% of the current planted forests may be restored to natural forests with or without harvesting. The history of Japanese planted forests suggests that some natural trees/forests should be retained, even in the landscapes that specialize in wood production, because part of the planted forests may be economically marginalized in the future, and their restoration to natural forests would then be needed.     

First-Generation Forests Are Not Necessarily Worse than Long-Term Managed Forests for Lichens and Bryophytes

For biodiversity, natural afforestation is generally more favorable than plantation-based afforestation, but the difference may be less important if both methods fail to provide habitats for sensitive old-forest species. Given that some conditions, such as substrates, can be actively restored in new forests, their effect on biodiversity should be separated from dispersal limitation. We asked whether, and to what extent, lichen and bryophyte vegetation is impoverished on old-forest substrates in non-intensively afforested lands of the twentieth century compared with similar substrates in managed long-term forestlands. We measured the diversity and abundance of all lichens and bryophytes as well as the cover of human-sensitive (hemerophobic) species on large deciduous trees, logs, snags, and windthrows on 30 random 2-km transects in a 900-km² forest landscape in Estonia, hemiboreal Europe. Altogether, 235 species, including 39 hemerophobic species, were detected on 781 structural elements. New forests were not significantly worse than long-term forests in any of the cryptogam community characteristics, which was explained by the predominance of natural afforestation (many native tree species present), time for substrate development and cryptogam dispersal (most stands >40 years old), few cuttings in the new forests (only about 20% of stands thinned), and short distances to long-term forests (67% of substrates within 250 m). Under such conditions, afforested areas appeared to be as suitable as traditional managed forests both for developing multifunctional forestry and as starting points for habitat restoration for threatened species.     

Genetic consequences of trumpeter swan (Cygnus buccinator) reintroductions

Relocation programs are often initiated to restore threatened species to previously occupied portions of their range. A primary challenge of restoration efforts is to translocate individuals in a way that prevents loss of genetic diversity and decreases differentiation relative to source populations—a challenge that becomes increasingly difficult when remnant populations of the species are already genetically depauperate. Trumpeter swans were previously extirpated in the entire eastern half of their range. Physical translocations of birds over the last 70 years have restored the species to portions of its historical range. Despite the long history of management, there has been little monitoring of the genetic outcomes of these restoration attempts. We assessed the consequences of this reintroduction program by comparing patterns of genetic variation at 17 microsatellite loci across four restoration flocks (three wild-released, one captive) and their source populations. We found that a wild-released population established from a single source displayed a trend toward reduced genetic diversity relative to and significant genetic differentiation from its source population, though small founder population effects may also explain this pattern. Wild-released flocks restored from multiple populations maintained source levels of genetic variation and lacked significant differentiation from at least one of their sources. Further, the flock originating from a single source revealed significantly lower levels of genetic variation than those established from multiple sources. The distribution of genetic variation in the captive flock was similar to its source. While the case of trumpeter swans provides evidence that restorations from multiple versus single source populations may better preserve natural levels of genetic diversity, more studies are needed to understand the general applicability of this management strategy.     

Will genomics guide a greener forest biotech?

Forest biotechnology has been increasingly associated with wood production using plantation forestry, and has stressed applications that use pedigreed material and transgenic trees. Reasons for this emphasis include limitations of available technologies to conform to underlying genetic features of undomesticated forest tree populations. More recently, genomic technologies have rapidly begun to expand the scope of forest biotechnology. Genomic technologies are well suited to describe and make use of the abundant genetic variation present in undomesticated forest tree populations. Genomics thus enables new research and applications for conservation and management of natural forests, and is a primary technological driver for new research addressing the use of forests trees for carbon sequestration, biofuels feedstocks, and other 'green' applications.     

The role of land-use history in driving successional pathways and its implications for the restoration of tropical forests

Secondary forests are increasingly important components of human-modified landscapes in the tropics. Successional pathways, however, can vary enormously across and within landscapes, with divergent regrowth rates, vegetation structure and species composition. While climatic and edaphic conditions drive variations across regions, land-use history plays a central role in driving alternative successional pathways within human-modified landscapes. How land use affects succession depends on its intensity, spatial extent, frequency, duration and management practices, and is mediated by a complex combination of mechanisms acting on different ecosystem components and at different spatial and temporal scales. We review the literature aiming to provide a comprehensive understanding of the mechanisms underlying the long-lasting effects of land use on tropical forest succession and to discuss its implications for forest restoration. We organize it following a framework based on the hierarchical model of succession and ecological filtering theory. This review shows that our knowledge is mostly derived from studies in Neotropical forests regenerating after abandonment of shifting cultivation or pasture systems. Vegetation is the ecological component assessed most often. Little is known regarding how the recovery of belowground processes and microbiota communities is affected by previous land-use history. In published studies, land-use history has been mostly characterized by type, without discrimination of intensity, extent, duration or frequency. We compile and discuss the metrics used to describe land-use history, aiming to facilitate future studies. The literature shows that (i) species availability to succession is affected by transformations in the landscape that affect dispersal, and by management practices and seed predation, which affect the composition and diversity of propagules on site. Once a species successfully reaches an abandoned field, its establishment and performance are dependent on resistance to management practices, tolerance to (modified) soil conditions, herbivory, competition with weeds and invasive species, and facilitation by remnant trees. (ii) Structural and compositional divergences at early stages of succession remain for decades, suggesting that early communities play an important role in governing further ecosystem functioning and processes during succession. Management interventions at early stages could help enhance recovery rates and manipulate successional pathways. (iii) The combination of local and landscape conditions defines the limitations to succession and therefore the potential for natural regeneration to restore ecosystem properties effectively. The knowledge summarized here could enable the identification of conditions in which natural regeneration could efficiently promote forest restoration, and where specific management practices are required to foster succession. Finally, characterization of the landscape context and previous land-use history is essential to understand the limitations to succession and therefore to define cost-effective restoration strategies. Advancing knowledge on these two aspects is key for finding generalizable relations that will increase the predictability of succession and the efficiency of forest restoration under different landscape contexts.     

Historical Stem‐Mapped Permanent Plots Increase Precision of Reconstructed Reference Data in Ponderosa Pine Forests of Northern Arizona

Forest structural reference conditions are widely used to understand how ecosystems have been altered and guide restoration and management objectives. We used six stem‐mapped permanent plots established in the early twentieth century to provide precise structural reference conditions for ponderosa pine forests of northern Arizona prior to Euro‐American settlement. Reference conditions for these plots in 1873–1874 included the following historical attributes: tree densities of 45–127 trees/ha, mean tree diameter at breast height (dbh) of 43.8 cm with a corresponding quadratic mean diameter range of 41.5–51.3 cm, and a stand basal area of 9.2–18.0 m²/ha. The reconstructed diameter distributions (for live ponderosa pine trees with dbh ≥9.14 cm) prior to fire exclusion varied in shape but generally displayed an irregular unimodal distribution. We suggest that management objectives for the structural restoration of ponderosa pine forests of northern Arizona emphasize: (1) conservation and retention of all pre‐settlement (>130 years) trees; (2) reduction of tree densities with a restoration objective ranging between 50 and 150 trees/ha having a large‐tree component between 25 and 50% of the total trees per hectare, respectively; (3) manipulation of the diameter distribution to achieve a unimodal or irregular, uneven‐aged shape (possibly targeting a balanced, uneven‐aged shape on cinder soil types) through the use of harvest and thinning practices that mimic gap disturbances (i.e., individual tree selection system); and (4) retention of 3–11 snags and logs per hectare resulting from natural mortality.     

Large‐scale assessment of regeneration and diversity in Mediterranean planted pine forests along ecological gradients

Aim There is increasing concern regarding sustainable management and restoration of planted forests, particularly in the Mediterranean Basin where pine species have been widely used. The aim of this study was to analyse the environmental and structural characteristics of Mediterranean planted pine forests in relation to natural pine forests. Specifically, we assessed recruitment and woody species richness along climatic, structural and perturbation gradients to aid in developing restoration guidelines. Location Continental Spain. Methods We conducted a multivariate comparison of ecological characteristics in planted and natural stands of main Iberian native pine species (Pinus halepensis, Pinus pinea, Pinus pinaster, Pinus nigra and Pinus sylvestris). We fitted species‐specific statistical models of recruitment and woody species richness and analysed the response of natural and planted stands along ecological gradients. Results Planted pine forests occurred on average on poorer soils and experienced higher anthropic disturbance rates (fire frequency and anthropic mortality) than natural pine forests. Planted pine forests had lower regeneration and diversity levels than natural pine forests, and these differences were more pronounced in mountain pine stands. The largest differences in recruitment – chiefly oak seedling abundance – and species richness between planted and natural stands occurred at low‐medium values of annual precipitation, stand tree density, distance to Quercus forests and fire frequency, whereas differences usually disappeared in the upper part of the gradients. Main conclusions Structural characteristics and patterns of recruitment and species richness differ in pine planted forests compared to natural pine ecosystems in the Mediterranean, especially for mountain pines. However, management options exist that would reduce differences between these forest types, where restoration towards more natural conditions is feasible. To increase recruitment and diversity, vertical and horizontal heterogeneity could be promoted by thinning in high‐density and homogeneous stands, while enrichment planting would be desirable in mesic and medium‐density planted forests.     

Allelopathy: a tool for weed management in forest restoration

Forest restoration uses active management to re-establish natural forest habitat after disturbance. However, competition from early successional species, often aggressively invasive exotic plant species, can inhibit tree establishment and forest regeneration. Ideally, restoration ecologists can plant native tree species that not only establish and grow rapidly, but also suppress exotic competitors. Allelopathy may be a key mechanism by which some native trees could reduce the abundance and impact of exotic species. Allelopathy is a recognized tool for weed management in agriculture and agroforestry, but few studies have considered how allelopathic interactions may aid restoration. Here we introduce the “Homeland Security” hypothesis, which posits that some naïve exotic species may be particularly sensitive to allelochemicals produced by native species, providing a tool to reduce the growth and impacts of invasive exotic species on reforestation. This article explores how exploiting allelopathy in native species could improve restoration success and the re-establishment of natural successional dynamics. We review the evidence for allelopathy in agroforestry systems, and consider its relevance for reforestation. We then illustrate the potential for this approach with a case study of tropical forest restoration in Panama. C₄ grasses heavily invade deforested areas in the Panama Canal watershed, especially Saccharum spontaneum L. We measured the effect of leaf litter from 17 potential restoration tree species on the growth of invasive C₄ grasses. We found that leaf litter from legume trees had a greater inhibitory effect on performance of S. spontaneum than did litter from non-legume trees. However, allelopathic effects varied greatly among species within tree functional groups. Further evaluation of intra- and inter-specific interactions will help to improve our selection of restoration species.     

Genetic structure and mating system of Manilkara huberi (Ducke) A. Chev., a heavily logged Amazonian timber species

In this work, we report on the population genetic structure of the endangered tree species Manilkara huberi, an Amazonian tree species intensely exploited due to the high density and resistance of its wood. We investigated the patterns of spatial distribution, genetic structure, and mating system using 7 microsatellite loci and here discuss the consequences for conservation and management of the species. To examine the population genetic structure, 481 adult trees and 810 seedlings were sampled from an area of 200 ha from a natural population in FLONA Tapajós, PA, Brazil. We found relatively high and consistent inbreeding levels (intrapopulation fixation index [f] 0.175 and 0.240) and a significant spatial genetic structure up to a radius of approximately 300 m, most likely due to a limited seed and pollen flow. The multilocus (tm) population outcrossing rate was high (0.995), suggesting that the species is predominantly allogamous with a pollen flow restricted to 47 m. These results suggest that M. huberi is spatially structured, consistent with a model of isolation by distance. Fragmentation may therefore cause the loss of subpopulations, suggesting that management programs for production and conservation should include large areas. The genetic data also revealed that for ex situ conservation, seeds should be collected from more than 175 maternal trees, in order to keep an effective population size of 500. Furthermore, as the species is widely distributed across the Amazon Forest, samples should include several populations in order to represent the highest genetic diversity possible. These results provide a blueprint to guide the production and conservation management policies of this valuable timber species.     

Neotropical rainforest restoration: comparing passive,plantation and nucleation approaches

Neotropical rainforests are global biodiversity hotspots and are challenging to restore. A core part of this challenge is the very long recovery trajectory of the system: recovery of structure can take 20–190 years, species composition 60–500 years, and reestablishment of rare/endemic species thousands of years. Passive recovery may be fraught with instances of arrested succession, disclimax or emergence of novel ecosystems. In these cases, active restoration methods are essential to speed recovery and set a desired restoration trajectory. Tree plantation is the most common active approach to reestablish a high density of native tree species and facilitate understory regeneration. While this approach may speed the successional trajectory, it may not achieve, and possibly inhibit, a long-term restoration trajectory towards the high species diversity characteristic of these forests. A range of nucleation techniques (e.g., tree island planting) are important restoration options: although they may not speed recovery of structure as quickly as plantations, their emphasis on natural regeneration processes may enable greater and more natural patterns of diversity to develop. While more work needs to be done to compare forest restoration techniques in different environmental contexts, it appears that nucleation and, at times, passive restoration may best preserve the diverse legacy of these forested systems (both with lower costs). An integrated approach using both plantation productivity but also the natural functions associated with nucleation may develop composition and diversity trajectory desired in Neotropical conservation efforts.     

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.