Species richness of vascular plants,bryophytes, and lichens along an altitudinal gradient in western Norway

Species richness patterns of ground-dwelling vascular plants, bryophytes, and lichens were compared along an altitudinal gradient (310–1135 m a.s.l.), in western Norway. Total species richness peaked at intermediate altitudes, vascular plant species richness peaked immediately above the forest limit (at 600–700 m a.s.l.), bryophyte species richness had no statistically significant trend, whereas lichen richness increased from the lowest point and up to the forest limit, with no trend above. It is proposed that the pattern in vascular plant species richness is enhanced by an ecotone effect. Bryophyte species richness responds to local scale factors whereas the lichen species richness may be responding to the shading from the forest trees.     

Bryophyte and vascular plant species richness in boreo-nemoral moist forests and mires

We compare species richness of bryophytes and vascular plants in Estonian moist forests and mires. The material was collected from two wetland nature reserves. Bryophyte and vascular plant species were recorded in 338 homogeneous stands of approximately 1 ha in nine forest and two mire types. Regional species pools for bryophytes and vascular plants were significantly correlated. The correlations between the species richnesses of bryophytes and vascular plants per stand were positive in all community types. The relative richnesses (local richness divided by the regional species pool size) were similar for bryophyte species and for vascular plant species. This shows that on larger scales, conservation of the communities rich in species of one taxonomic plant group, maintains also the species richness of the other. The minimum number of stands needed for the maintenance of the regional species pool of typical species for the every community type was calculated using the species richness accumulation curves. Less stands are needed to maintain the bryophyte species pools (300–5300 for bryophytes and 400–35 000 for vascular plants).     

High plant species richness indicates management-related disturbances rather than the conservation status of forests

There is a wealth of smaller-scale studies on the effects of forest management on plant diversity. However, studies comparing plant species diversity in forests with different management types and intensity, extending over different regions and forest stages, and including detailed information on site conditions are missing. We studied vascular plants on 1500 20 m × 20 m forest plots in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). In all regions, our study plots comprised different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests, which resulted from clear cutting or shelterwood logging), various stand ages, site conditions, and levels of management-related disturbances. We analyzed how overall richness and richness of different plant functional groups (trees, shrubs, herbs, herbaceous species typically growing in forests and herbaceous light-demanding species) responded to the different management types. On average, plant species richness was 13% higher in age-class than in unmanaged forests, and did not differ between deciduous age-class and selection forests. In age-class forests of the Schwäbische Alb and Hainich-Dün, coniferous stands had higher species richness than deciduous stands. Among age-class forests, older stands with large quantities of standing biomass were slightly poorer in shrub and light-demanding herb species than younger stands. Among deciduous forests, the richness of herbaceous forest species was generally lower in unmanaged than in managed forests, and it was even 20% lower in unmanaged than in selection forests in Hainich-Dün. Overall, these findings show that disturbances by management generally increase plant species richness. This suggests that total plant species richness is not suited as an indicator for the conservation status of forests, but rather indicates disturbances.     

The effects of windthrow on plant species richness in a Central European beech forest

The effects of soil disturbance caused by the uprooting of a single or a few canopy trees on species richness and composition of vascular plant species and bryophytes were examined in a temperate beech forest (Fagus sylvatica) in northern Germany. We recorded the vegetation in 57 pairs of disturbed and adjacent undisturbed plots and established a chronosequence of mound ages to study the effect of time since microsite formation on plant species richness and composition. We found significant differences in plant species richness and composition between disturbed and adjacent undisturbed plots. Species richness of both vascular plants and bryophytes was higher in the disturbed than in the undisturbed plots, but these differences were more pronounced for bryophytes. We suggest that three main factors are responsible for this differential response. The availability of microsites on the forest floor that are suitable for the recruitment of bryophytes is lower than for vascular plants. Establishment of bryophytes in disturbed microsites is favoured by a greater abundance of propagules in the close vicinity and in the soil of the disturbed microsites, as well as by a greater variety of regeneration strategies in bryophytes than in vascular plants. Time since mound formation was a major factor determining plant species richness and composition. A significant decrease in the mean number of species was found from young mounds to intermediate and old mounds. However, differences were observed between vascular plants and bryophytes in the course of changes through time in species richness and composition. A large number of exclusive and infrequent vascular plant species was observed on young mounds, among them several disturbance specialists. We suggest that the establishment of many vascular plant species was infrequent and short-lived due to unfavourable light conditions and a low abundance of propagules. By contrast, the development of a litter layer was the main reason for the decreased mean number of bryophytes on old mounds. Our study supports the view that groups of species differing in important life history traits exhibit different responses to soil disturbance.     

Long-Term Impacts of Forest Ditching on Non-Aquatic Biodiversity: Conservation Perspectives for a Novel Ecosystem

Artificial drainage (ditching) is widely used to increase timber yield in northern forests. When the drainage systems are maintained, their environmental impacts are likely to accumulate over time and along accompanying management, notably after logging when new forest develops on decayed peat. Our study provides the first comprehensive documentation of long-term ditching impacts on terrestrial and arboreal biodiversity by comparing natural alder swamps and second-generation drained forests that have evolved from such swamps in Estonia. We explored species composition of four potentially drainage-sensitive taxonomic groups (vascular plants, bryophytes, lichens, and snails), abundance of species of conservation concern, and their relationships with stand structure in two-ha plots representing four management types (ranging from old growth to clearcut). We found that drainage affected plot-scale species richness only weakly but it profoundly changed assemblage composition. Bryophytes and lichens were the taxonomic groups that were most sensitive both to drainage and timber-harvesting; in closed stands they responded to changed microhabitat structure, notably impoverished tree diversity and dead-wood supply. As a result, natural old-growth plots were the most species-rich and hosted several specific species of conservation concern. Because the most influential structural changes are slow, drainage impacts may be long hidden. The results also indicated that even very old drained stands do not provide quality habitats for old-growth species of drier forest types. However, drained forests hosted many threatened species that were less site type specific, including early-successional vascular plants and snails on clearcuts and retention cuts, and bryophytes and lichens of successional and old forests. We conclude that three types of specific science-based management tools are needed to mitigate ditching effects on forest biodiversity: (i) silvicultural techniques to maintain stand structural complexity; (ii) context-dependent spatial analysis and planning of drained landscapes; and (iii) lists of focal species to monitor and guide ditching practices.     

Is vascular plant species diversity a predictor of bryophyte species diversity in Mediterranean forests?

This study aimed to (i) investigate the congruence among the species composition and diversity of bryophytes and vascular plants in forests; (ii) test if site prioritization for conservation aims by the maximization of the pooled number of vascular plant species is effective to maximize the pooled number of bryophyte species. The study was performed in six forests in Tuscany, Italy. Four-hundred and twenty vascular plant species (61 of which were woody) and 128 bryophyte species were recorded in 109 plots. Despite the good predictive value of the compositional patterns of both woody plants and total vascular with respect to the compositional pattern of bryophytes, the species richness of the latter was only marginally related to the species richness of the former two. Bryophyte rare species were not spatially related to rare plant species and neither coincided with the sites of highest plant species richness. The species accumulation curves of bryophytes behaved differently with respect to those of woody plants or total vascular plants. Reserve selection analysis based on the maximization of the pooled species richness of either woody plants or total vascular plants were not effective in maximizing the pooled species richness of bryophytes. This study indicates that species diversity of vascular plants is not likely to be a good indicator of the bryophyte species diversity in Mediterranean forests.     

基于地形汇流值的东北天然次生林主要树种的生态位

以不同汇流值梯度作为资源轴,以树种重要值为生态位计测的资源状态指标,在集水区尺度上分析了东北天然次生林群落中主林层和演替层11个主要树种(水曲柳、胡桃楸、黄檗、紫椴、糠椴、山杨、白桦、枫桦、春榆、色木槭、蒙古栎)的生态位。提出相对汇流值生态幅和汇流值竞争指数的概念来丰富生态位的测度指标。研究结果显示:在各项生态位指标计算中,主林层以色木槭、蒙古栎以及先锋树种山杨和白桦为主,演替层则以色木槭、春榆、水曲柳、紫椴等原始阔叶红松林的主要阔叶伴生树种占优;另一方面,以群落分层为资源位,主林层和演替层各树种生态位的差异揭示了主要乔木树种在该地区天然次生林群落的演替系列中对资源的占有与利用的情况及其发展变化趋势。在集水区尺度上采用汇流值作为生态位的空间维度能够较好地反映植物种群在不同地形和水分梯度上生态位的时空分布特性。     

Lichens and bryophytes as indicators of old‐growth features in Mediterranean forests

Abstract

This study is focused on the selection of variables affecting lichen and bryophyte diversity in Mediterranean deciduous forests. Plots representing two forest types (Fagus sylvatica and Quercus cerris forests) and two forest continuity categories (old‐growth (OG) and non‐OG forests) were selected in the Cilento and Vallo di Diano National Park (Italy). The presence and the abundance of bryophytes and epiphytic lichens were recorded. Structural variables of the forests and vascular plant species richness have been used as predictors. A strong positive correspondence between the two groups of organisms was found. Higher species richness and the distribution of rare species are related to OG stands, while a qualitative (species composition) rather than a quantitative (species richness) difference between the two forest types was observed. Some species elsewhere considered as indicators of forest continuity, such as Lobaria pulmonaria, Antitrichia curtipendula, and Homalothecium sericeum, are associated with OG forests, independently from forest type, suggesting that they can be regarded as suitable indicators also in Mediterranean forests. Finally, our results suggest that old trees, high levels of basal area, a broad range of diameter classes, and high understory diversity are the main structural features affecting cryptogamic communities, while no correlation was found with the occurrence of deadwood.     

Does cross-taxon analysis show similarity in diversity patterns between vascular plants and bryophytes? Some answers from a literature review

The objective of this study was to clarify the taxon surrogacy hypothesis relative to vascular plants and bryophytes. A literature review was conducted to obtain papers that met the following criteria: (i) they examined species richness values; or (ii) they evaluated the species richness within the same study sites, or under the same spatial variation conditions. Twenty-seven papers were accessed. The richness of the two taxa, compared in 32 cases, positively co-varied in about half of the comparisons. The response to the spatial variation in environmental or human-induced factors of the two taxa in terms of species richness was rather variable. Based on current knowledge, the main documented findings regard forest habitats and nival gradients. In forest habitats, co-variation in species richness is likely when similar environments are analysed and seems to be strengthened for boreal forests. Along the nival gradient, a different response in terms of richness of the two taxa suggests that vascular plants cannot be considered good surrogates for bryophytes.     

Multi‐taxon and forest structure sampling for identification of indicators and monitoring of old‐growth forest

Abstract

The most commonly used old‐growth forest indicators are structural attributes; nevertheless, they do not necessarily represent the biodiversity value of old‐growth forests. The aim of this study is to analyse the relationships between species richness data of different taxa and structural indicators of old‐growth and to identify taxonomic/functional groups, species and structural attributes that may be used as indicators of old‐growth. To achieve this goal we sampled forest structure, vascular plants, lichens, bryophytes, fungi, saproxylic beetles and birds in mature and old‐growth stands in southern Italy. We calculated Spearman’s correlation coefficients between species richness data and structural attributes. Analyses of indicator species, co‐occurrences and two‐way clusters were performed on the multi‐taxonomic list. The group of vascular plants most significantly correlated with other groups in terms of species richness; furthermore, it displays the highest proportion of between‐group co‐occurrences. The resulting multi‐taxonomic list of potential indicators may serve as an effective means of detecting and monitoring forest ecosystems; however, for this goal, structure‐based indicators, such as forest structural attributes and vascular plant species composition, are of primary importance.     

Tree and stand-scale factors affecting richness and composition of epiphytic bryophytes and lichens in deciduous woodland key habitats

Conservation and sustainable forestry are essential in a multi-functional landscape. In this respect, ecological studies on epiphytes are needed to determine abiotic and biotic factors associated with high diversity. The aim of the present study was to evaluate relative sensitivity of conservation targets (epiphytic bryophytes and lichens) in relation to contrasting environmental variables (tree species, tree diameter at breast height, bark crevice depth, pH, tree inclination, pH, forest stand age, area and type) in boreo-nemoral forests. The study was conducted in Latvian 34 woodland key habitat (WKH) boreo-nemoral forest stands. Generalized linear mixed models and canonical correspondence analysis showed that tree species and tree bark pH were the most important variables explaining epiphytic bryophyte and lichen composition and richness (total, Red-listed, WKH indicator species). Forest stand level factors, such as stand size and habitat type, had only minor influence on epiphytic species composition and richness. The results of the present study indicate a need to maintain the diversity of tree species and large trees, particularly Acer platanoides, Carpinus betulus, Fraxinus excelsior, Populus tremula, Tilia cordata, Ulmus glabra and Ulmus laevis in conservation of epiphytic bryophyte and lichen communities in the future.     

The role of regional and local scale predictors for plant species richness in Mediterranean forests

Abstract

Both local and regional predictors play a role in determining plant community structure and composition. Climate, soil features as well as different local history and management affect forest understorey and tree species composition, but to date their specific role is relatively unknown. Few studies have addressed the importance of these predictors, especially in the Mediterranean area, where environmental conditions and human impacts have generated heterogeneous forest communities. In this study, the relationships between environmental variables and species richness of different groups of vascular plants (vascular species, woody species and open habitat species) and bryophytes were investigated in Tuscan forests. A total of 37 environmental variables were used by generalised linear model fitting in order to find parsimonious sub-sets of environmental factors (predictors) that are able to explain species diversity patterns at the local scale. Moreover, the role of regional and local variable groups on species richness of the considered plant groups was estimated by using the variance partitioning approach. We found that local variables, such as forest management and structure, explained more variance than regional variables for total species richness, open habitat species richness and bryophyte species richness. On the other hand, regional variables (such as elevation) played a central role for woody species richness.     

Change in the bryophyte diversity and species composition of Central European temperate broad-leaved forests since the late nineteenth century

The diversity and species composition of the bryophyte flora colonizing the forest floor, live trees and deadwood in semi-natural broad-leaved forests of northern Germany was compared between a recent survey in 2013 and historical records from around 1900. The survey was based on the comparison of presence/absence data and their interpretation with help of ecological indicator values. Total species richness has declined in bryophytes growing on the forest floor but not in the other guilds, whereas a dramatic species turnover was found for all three guilds. This turnover was apparently primarily driven by the increased atmospheric load of reactive nitrogen from anthropogenic emissions. Sensitive species were replaced by more eutrophication-tolerant bryophytes; liverworts are overrepresented among the sensitive and thus declining species. Promotion of the competitive strength of vascular plants due to increased nitrogen levels is the likely cause of the reduction of bryophyte species richness on the forest floor. Former acidification by high atmospheric sulfur dioxide loads has left an imprint in the bryophyte vegetation by having favored acidophytic species and discriminating against basiphytic species. An increase in the mean indicator value for temperature suggests a beginning effect of climate warming on the bryophyte vegetation. Change in forest structure had an apparently smaller imprint on the bryophyte diversity of the studied semi-natural forests than atmospheric chemistry and climate. In this respect, bryophytes differ from the ecologically similar lichens, where published studies from the same region showed a dramatic decline of species richness and a stronger susceptibility to forest management.     

Tree and stand level variables influencing diversity of lichens on temperate broad-leaved trees in boreo-nemoral floodplain forests

Tree and stand level variables affecting the species richness, cover and composition of epiphytic lichens on temperate broad-leaved trees (Fraxinus excelsior, Quercus robur, Tilia cordata, Ulmus glabra, and U. laevis) were analysed in floodplain forest stands in Estonia. The effect of tree species, substrate characteristics, and stand and regional variables were tested by partial canonical correspondence analysis (pCCA) and by general linear mixed models (GLMM). The most pronounced factors affecting the species richness, cover and composition of epiphytic lichens are acidity of tree bark, bryophyte cover and circumference of tree stems. Stand level characteristics have less effects on the species richness of epiphytic lichens, however, lichen cover and composition was influenced by stand age and light availability. The boreo-nemoral floodplain forests represent valuable habitats for epiphytic lichens. As substrate-related factors influence the species diversity of lichens on temperate broad-leaved trees differently, it is important to consider the effect of each tree species in biodiversity and conservation studies of lichens. Nomenclature Randlane et al. (2007) for lichens; Leht (2007) for vascular plants.     

Distribution patterns of flora and fauna in southern Chilean Coastal rain forests: Integrating Natural History and GIS

Knowledge of species richness centers is necessary for the design of conservation areas. In this study, we present a GIS analysis of two years of field data on animal and plant diversity distributions in evergreen, coastal rain forests of southern Chile (39°30′–41°25′ S). Despite their high endemism, these forests have remained largely unprotected. Field records were complemented with data from museum collections and scientific literature. We used selected environmental variables (evapotranspiration, altitude) and, in some cases, forest types as predictors of species distributions. Our study focused on the distribution of forest bryophytes, vascular plants, soil invertebrates, amphibians and birds. We generated distributional maps for each taxa based on their field records in the study area, complemented by natural history information, except in the case of bryophytes and soil invertebrates. In general, species richness was lower at 600 m elevation or above for all the taxa studied. Species richness tends to increase in the northern sector of the study area. We observed a greater richness of vascular plants near rivers and streams, and noted important floristic differences between west and east-facing slopes of the Coastal Range, with more species in the oriental side. Because species in high altitude forests are not a subset of those found at lower elevations, we propose that conservation strategies should prioritize the protection of the entire altitudinal gradient of the southern Coastal Range, especially in the more diverse oriental and northern sectors.     

Edge effect in different groups of organisms: vascular plant, bryophyte and fungi species richness across a forest-grassland border

Six transects were established on the edges of two deciduous forests near Krosno (Carpathian Foothills) to compare the species richness pattern of vascular plants, bryophytes and fungi. The transects had the shape of a cross with one arm 10 m along the forest edge and the other across the edge, 50 m into the forest interior and 12 m into the grassland. They consisted of 2×2 quadrats. The strongest edge effects were recorded for bryophyte, shrub and tree species richness, the weakest for herbaceous plant species richness. Overall vascular plant species richness and herbaceous species richness were higher in grassland than in the forest and peaked in grassland, 3 m from the forest edge. The shrub species richness was highest 1 m from the edge (in the forest) and the tree species richness 3 m from edge. Bryophyte species richness had roughly the same level across the grassland and within the first several meters of the forest, except for the 2 m zone on the edge itself where species richnes was as low as in the forest interior. Fungi species richness was low in the grassland and on the forest edge and rose dramaticaly a few meters from the edge, ramaining at the same level within the forest. The species composition across the forest-grassland border was analysed using detrended correspondence analysis. It revealed that in the case of bryophytes the increase in species richness did not correspond to a change in species composition, such as might have been caused by a general increase in bryophyte density.     

Bole epiphytic bryophytes on <Emphasis Type="Italic">Lithocarpus xylocarpus</Emphasis> (Kurz) Markgr. in the Ailao Mountains,SW China

Epiphytic bryophytes growing on Lithocarpus xylocarpus (Kurz) Markgr. trunks of different diameter classes in primary (132 plots) and secondary (84 plots) Lithocarpus forests in the Ailao Mountains, SW China, were surveyed and analyzed to determine species composition and richness, and to identify environmental variables that may affect it. Among the 65 species (belonging to 32 genera, 19 families) found, 28 occurred in both forests, with Syrrhopodon gardneri (Hook.) Schwaegr. predominanting. Species richness and total coverage in primary forest were significantly higher than in secondary forest. We suggest that a period of perhaps much more than 110 years is necessary for the recovery of epiphytic bryoflora in montane forest of SW China. Fan, turf, and smooth mat are the most important life forms, with high occurrences in both forests. The life form composition of epiphytic bryophytes is determined mainly by microhabitat and host age. Tree age, the presence of primary forest, bark pH, and plot exposure are the environmental variables that have significantly influenced the composition of epiphytic bryophytes. Tree age explained most variations in epiphytic bryoflora. Bark pH is another important parameter that significantly influenced the epiphytic bryophyte community, but seemed indirectly correlated with tree age. Primary forest is a favorable habitat for epiphytes, due mainly to its diversified canopy structure and the presence of large diameter hosts. Moisture-laden southwest trade winds and forest structure could differentiate microclimate and impel a distinct composition of epiphytes in windward and leeward exposures.     

Diversity of dry forest epiphytes along a gradient of human disturbance in the tropical Andes

Question: Disturbance effects on dry forest epiphytes are poorly known. How are epiphytic assemblages affected by different degrees of human disturbance, and what are the driving forces? Location: An inter‐Andean dry forest landscape at 2300 m elevation in northern Ecuador. Methods: We sampled epiphytic bryophytes and vascular plants on 100 trees of Acacia macracantha in five habitats: closed‐canopy mixed and pure acacia forest (old secondary), forest edge, young semi‐closed secondary woodland, and isolated trees in grassland. Results: Total species richness in forest edge habitats and on isolated trees was significantly lower than in closed forest types. Species density of vascular epiphytes (species per tree) did not differ significantly between habitat types. Species density of bryophytes, in contrast, was significantly lower in edge habitat and on isolated trees than in closed forest. Forest edge showed greater impoverishment than semi‐closed woodland and similar floristic affinity to isolated trees and to closed forest types. Assemblages were significantly nested; habitat types with major disturbance held only subsets of the closed forest assemblages, indicating a gradual reduction in niche availability. Distance to forest had no effect on species density of epiphytes on isolated trees, but species density was closely correlated with crown closure, a measure of canopy integrity. Main conclusions: Microclimatic changes but not dispersal constraints were key determinants of epiphyte assemblages following disturbance. Epiphytic cryptogams are sensitive indicators of microclimate and human disturbance in montane dry forests. The substantial impoverishment of edge habitat underlines the need for fragmentation studies on epiphytes elsewhere in the Tropics.     

Epiphytic lichen synusiae and functional trait groups in boreo‐nemoral deciduous forests are influenced by host tree and environmental factors

Deciduous forests with temperate broad‐leaved tree species are particularily important in terms of biodiversity and its protection, but are threatened habitats in northern Europe. Using multivariate analyses we studied the effect of forest site type, environmental variables and host tree properties on epiphytic lichen synusiae as well as on the composition of species‐specific functional traits. Epiphytic lichens were examined on Acer platanoides, Fraxinus excelsior, Quercus robur, Tilia cordata, Ulmus glabra and U. laevis in two types of forests: Humulus‐type floodplain forests and Lunaria‐type boreo‐nemoral forests on the talus slopes of limestone escarpment (klint forests). Klint forests located near the seashore were under greater maritime influence compared to floodplain forests located in inland Estonia which experience stronger air temperature contrasts. In addition to stand level and climatic variables, tree level factors (bark pH, trunk circumference and cover of bryophytes) considerably affected the species composition of the lichen synusiae. Overall, 137 lichen species were recorded, including 14 red‐listed species characteristic of deciduous trees. We defined 13 lichen societies and showed their preference to forests of a specific site type and/or host tree properties. In forests of both types, most of the epiphytic lichens were crustose, and had apothecia as the fruit bodies and chlorococcoid algae as the photobiont. However, the proportion of lichens with a foliose or fruticose growth form, as well as the proportion of lichens with vegatative diaspores, were higher in floodplain forests. In klint forests with a stronger influence from the wind, crustose species completely dominated, while species with vegetative diaspores were rare and most species dispersed sexually. Lichens with Trentepohlia as the photobiont were characteristic of these forests, and lichens with lirellate ascomata were prevailing, indicating the great uniqueness of the kint forests for epiphytic lichens in the boreo‐nemoral region.     

Bryophyte species richness and composition in young forests regenerated after clear-cut logging versus after wildfire and spruce budworm outbreak

The disturbance regime in mixed-wood forests of eastern Canada is characterized by both natural disturbances including wildfires and insect outbreaks as well as forestry. The understanding of how understorey plant assemblages respond to different disturbances is mostly limited to short-term wildfire-logging comparisons of vascular plants. Here, we compare patterns of species richness and composition of four bryophyte guilds in young forests (approx. 40 years old) regenerating after clear-cut logging, wildfire, and spruce budworm outbreak. In addition, young forests were compared with mature spruce-fir dominated stands (approx. 90 years old). Although similar in overall species richness at the scale of 1,000 m² all young forest types were compositionally distinct with fewer species than mature forests. Stands developed after spruce budworm outbreaks had the highest canopy cover values and the highest surface area of coarse woody debris. These stands had similar numbers of woody debris species as mature forests and were closest to mature forests in species composition. Wildfire-disturbed sites were dominated by deciduous trees and a high number of treebase species. Finally, young managed forest had the highest number of forest floor bryophytes at the scale of 100 m² among the three young forest types, but was compositionally far from mature forests in their woody debris flora. In conclusion, young forests regenerating after natural disturbances are distinctly different from young forests regenerated after clear-cutting and if natural disturbances are eliminated certain species (e.g., epixylic and treebase species) might become more restricted to older stands in the landscape.