Bryophyte responses to fragmentation in temperate coastal rainforests: A functional group approach

The species richness and frequency of occurrence of bryophytes within taxonomic and functional groups was examined in relation to the size of 20 old-growth patches (size range: 0.6-63.6 ha) remaining after logging in temperate rainforests of coastal British Columbia. At the centre of each remnant patch, bryophytes were sampled in sixty-three 10 cm × 30 cm microplots on three substrate-types (forest floor, downed logs and tree bases). Generalized linear models demonstrated that the species richness and frequencies of some bryophyte functional groups were related to patch size. In particular, some dispersal-limited groups (perennial stayers) and microclimate-sensitive groups (closed canopy species, epixylic (log-dwelling) species, and liverworts) showed significant declines in either richness or frequency as patch size decreased. In contrast, colonists and open canopy species showed little association with patch size. Many, but not all, of the significant patch size relationships disappeared when the three smallest patches (0.6-1.8 ha) were eliminated from the analysis. These results suggest that patches sized 3.5 ha or larger may provide habitat capable of sustaining a diverse array of bryophyte functional groups in temperate rainforest landscapes.     

Bryophytes on tree trunks in natural forests, selectively logged forests and cacao agroforests in Central Sulawesi, Indonesia

Forest disturbance and transformations into agricultural land alter tropical landscapes at drastic rates. Here, we investigate bryophyte assemblages on trunk bases in natural forest, selectively logged forest and cacao agroforests that are shaded by remnants of natural forest in Central Sulawesi. Overall, bryophyte richness per site did not differ between forest types. However, mosses and liverworts reacted differently in that moss richness was lowest in cacao agroforests, whereas liverwort communities were equally rich in all forest types. In terms of cover, mosses remained unaffected while liverwort cover decreased significantly in disturbed forest. Species composition of bryophytes clearly changed in cacao agroforests as compared to natural forests and selectively logged forests. In particular some drought-sensitive species were rare or absent in cacao agroforests and were replaced by drought-tolerant ones, thus underlining the importance of microclimatic changes. Moreover, differences in bryophyte species composition between large and small trees were only pronounced in cacao agroforests, presumably due to concomitant changes in stemflow of precipitation water. In conclusion, the bryophyte assemblages of selectively logged forests and cacao agroforests were as rich as in natural forest, but species turn-over was particularly high towards cacao agroforests probably due to microclimatic changes. Maintenance of shade cover is crucial to the conservation of the drought-sensitive forest species.     

Spring bryophytes in forested landscapes: Land use effects on bryophyte species richness, community structure and persistence

Many freshwater ecosystems face severe threats from anthropogenic disturbances, yet little is known about the degree to which their biotic communities have been degraded by human activities. We analysed temporal changes and persistence of bryophyte communities in 40 springs in eastern Finland by comparing field surveys conducted in 1986 and 2000. During that period, some springs had remained in a near-pristine state, while others had undergone varying degrees of disturbance from forest management, drainage, and water abstraction. Several spring bryophytes (e.g., Philonotis fontana) declined between the study years, whereas Sphagnum mosses (e.g., Sphagnum warnstorfii) increased in abundance. Species richness of spring bryophytes declined significantly from 1986 to 2000, irrespective of bryophyte group (spring vs. other bryophytes) and spring condition (severely disturbed vs. unaltered springs). Bryophyte cover also decreased dramatically from 1986 to 2000, but this effect was related to both spring condition and bryophyte type. Spring bryophytes lost much of their cover in severely altered springs, while in unaltered springs they remained relatively stable through time. No such trend was observed for other, habitat generalist bryophytes. Persistence and stability of bryophyte communities showed significant, albeit rather weak, relationships with spring condition, with communities in unaltered springs being more persistent than those in altered springs. Given the importance of springs to boreal forest and aquatic biodiversity, restoration of degraded springs is a major challenge to maintaining and conserving biodiversity of boreal landscapes.     

Retention patches as potential refugia for bryophytes and lichens in managed forest landscapes

Leaving small patches of forest intact at harvesting is now a standard procedure to mitigate negative effects on biodiversity. One purpose of the patches is to “life-boat” species over the forest regeneration phase, although the capacity of small forest fragments to do so is very uncertain. We investigated the survival of red-listed and indicator species of bryophytes and lichens in 74 retention patches in boreal Sweden. The patches were between 0.01 and 0.5 ha in size and of six different types with respect to tree species composition and location on the harvested area. Species presence and abundance were recorded shortly after harvest in transects covering the whole patches, and an identical inventory was carried out 6 years after the first. During this time, bryophytes generally decreased, most pronounced for liverworts. The largest decreases were found in buffer zones to streams and lakes and the smallest in tree groups dominated by deciduous trees. By contrast, among the lichens some species decreased while others increased, and there was no difference between retention patch types. Among the species abundant enough to be analyzed individually, the lichens Calicium parvum and Micarea globulosella decreased less in larger patches and the bryophyte Hylocomiastrum umbratum decreased more in patches of irregular shape. The results imply that retention patches of this size might be too small to function as refugia for sensitive bryophytes and lichens until the surrounding forest regenerates, but that some lichens appear to persist or even increase. Retention harvesting is still a young management practice and further studies on its long-term conservation benefits will be valuable.     

Bryophytes in a changing landscape: The hierarchical effects of habitat fragmentation on ecological and evolutionary processes

Testing the myriad predictions associated with the community, demographic and genetic impacts of habitat fragmentation remains a high conservation priority. Many bryophyte taxa are ideal model systems for experimentally testing such metapopulation-based and population genetic predictions due to their relatively fast colonisation-extinction rates, high substrate specificity, dominant haploid condition, and diminutive size. Herein, we review the community, demographic and population genetic impacts of habitat fragmentation on bryophytes, highlight the present knowledge gaps, and offer ideas on how experimental studies utilizing bryophytes may be used to address the broader conservation implications associated with fragmented ecosystems. Previous research suggests that dispersal limitation best explains observed patterns of abundance and distribution of bryophytes in some fragmented habitats. However, edge effects influence bryophyte community structure of border habitats especially where abrupt differences in micro-climatic conditions between the matrix and the forest remnant exist, or where the species pool contains members with inherently restricted ecological amplitudes. Existing studies do not agree on the relationship between basic attributes of bryophyte community structure (i.e., species richness and local density), and habitat area and degree of spatial-isolation. Demographic studies are a critical step in structuring conservation strategies, however surprisingly little empirical information exists as to the impacts of habitat fragmentation on plant population dynamics. We propose that bryophytes offer great potential for testing predictions with respect to plant population persistence in spatially-structured landscapes.     

Does time or habitat make old-growth forests species rich? Bryophyte richness in boreal Picea mariana forests

The relative importance of time since disturbance and habitat variables in creating diversity in old-growth forests will influence conservation strategies. However, the independent roles of these factors are not well understood, as they are rarely examined independently. This study examines the respective roles of habitat variables and time (stand age) in determining bryophyte diversity in Picea mariana (Mill. (BSP)) forests. Bryophytes are frequently used as indicators of old-growth forest, but their true dependence on forest continuity is unknown. Bryophytes were classified into taxonomic-habitat guilds: true mosses (forest), forest liverworts, bog liverworts and sphagna (bog). Diversity increased with age and peaked at approximately 275 years since fire, driven by liverworts. Multiplicative habitat modeling indicated that time and habitat played different roles for the different taxonomic-habitat guilds. True mosses and forest liverworts were primarily influenced by habitat variables, while sphagna and bog liverworts were influenced by time and habitat variables. The models for sphagna were particularly strong, indicating that many important factors were included, while forest liverwort models were particularly weak. This unexplained variability may represent site specific random factors, such as secondary disturbances that create habitat in a fully occupied space. Overall, high richness was created by small species dependent on habitat variables and chance factors for establishment. Therefore, time since disturbance was not the primary factor limiting richness in these forests. These results suggest that in boreal North America, where forest fragmentation is limited and recent, conservation strategies that emphasize habitat variables rather than forest continuity may be effective for some bryophytes.     

The regeneration capabilities of bryophytes for rich fen restoration

Biodiversity in wetland habitats is strongly affected by drainage. In Sweden, rich fens (alkaline fens) have been particularly affected by drainage campaigns for forestry and conversion to agricultural land. Fragmentation of the landscape, invasion of tall vascular plants as well as Polytrichum and Sphagnum mosses and substrate degradation all lead to reduced plant diversity.We evaluated the recolonization potential of four characteristic rich fen bryophyte species that use to decrease rapidly after drainage (Scorpidium scorpioides, Scorpidium cossonii, Pseudocalliergon trifarium and Campylium stellatum) by performing transplantation studies with gametophyte fragments in recently hydrologically restored rich fens. In greenhouse and field experiments 1 cm fragments of all four species had a high survival rate and established well, especially after surface liming of the peat. A protective cover increased the colonization success and the growth potential of the added fragments. Even small alterations of the water level (5 cm) resulted in differences in biomass growth of the fragments of S. cossonii and C. stellatum. Our results show that it is possible to reintroduce bryophyte species lost after drainage using gametophyte fragments as propagules, and that these techniques seem feasible for a number of characteristic rich fen bryophytes. These findings will be of importance when methods for practical restoration of rich fens are developed.     

Resilience of bryophyte communities to clear-cutting of boreal stream-side forests

We asked if short-term changes in bryophyte communities in response to clear-cutting of boreal stream-side forests are persistent and whether species with low resilience may survive in narrow riparian buffer strips. To assess short-term changes and the function of buffer strips we compared the bryophyte community in permanent 0.1 ha plots of mature forest before and after clear-cutting. Persistent changes were inferred by pair-wise comparisons of 0.1 ha plots of mature forests with carefully matched 0.1 ha plots in stands established after clear-cutting 30-50 years earlier. Total bryophyte species richness did not respond significantly to clear-cutting. However, richness changed in many subgroups defined by phylogenetic, habitat or substrate affinity. Numbers of both liverwort and forest species were significantly reduced on clear-cuts and these differences remained significant, although smaller, 30-50 years after clear-cutting. In contrast, there were short-term increases in richness of mosses and of species growing on disturbed mineral soil, but these species numbers returned to mature-forest levels in the young stands. Number of species associated with convex substrates, especially woody debris species, was strongly reduced by clear-cutting and showed no significant recovery after 30-50 years. Hence, most of the negative effects of clear-cutting on bryophyte species persist almost halfway into the next forestry rotation period. However, narrow buffer strips (10 m on each side) prevented most of the short-term extirpations of species with low resilience on clear-cuts. Buffer strips may thus be effective in conserving the bryophyte flora of stream-side forests, but their long-term function as refugia and their contribution to population recovery in other parts of the landscape need further evaluation.     

A survey method for evaluating drought-sensitive bryophytes in fragmented forests: A bryophyte life-form based approach

Drought-sensitive bryophytes are especially vulnerable to edge effects caused by forest fragmentation. Because of increased forest fragmentation, these bryophyte species are declining and are in need of conservation. Considering that a field survey including all bryophyte species is very time consuming, methods that make identification less difficult should be tested for their usefulness in conservation. This paper describes an alternative survey method that utilizes the correlation between bryophyte life-forms and microclimates for evaluating drought-sensitive bryophytes. This survey method was examined using epiphytic bryophyte flora on tree trunks in 27 fragmented forests of Kyoto city, in the western part of Japan. The usefulness of life-forms for this evaluation was discussed based on the correlation of life-forms with species richness and microclimates. The results indicated that, while life-from richness was considered to reflect the heterogeneity of moisture availability and light intensity in bryophyte habitats, a certain life-form category (for example, fans and dendroids) seemed to correlate with drought sensitivity of bryophytes. Considering this correlation, an alternative survey method was proposed that utilizes the richness of hygrophilous life-forms. This survey method seems to be more cost-effective than a traditional all-species survey, and provides an important step toward the conservation of drought-sensitive species.     

Patch size and isolation effects on epiphytic and epiphyllous bryophytes in the fragmented Brazilian Atlantic forest

An inventory of the understory forest epiphyte and epiphyllous bryophyte floras was carried out in eight Atlantic rain forest fragments. The fragments were between 7 and 500 ha in size and belonged to two areas (lowland and submontane) of the state of Pernambuco, northeastern Brazil. The aim of this study was to investigate the effect of habitat fragmentation and changes in the natural landscape on community structure (composition, richness, diversity, and abundance). Although the influence of altitude was noted in this study by increasing richness, diversity, and abundance, it was clear that in some fragments the influence of fragment size and isolation can be more important than this positive environmental factor. Fragment size and isolation affect both communities but the last one seems to be a stronger threatening factor for the epiphylls. The least isolated and the largest fragments housed the richest floras - especially in relation to the epiphylls - and had the greatest proportion of shade species. Habitat fragmentation negatively affected epiphytic and epiphyllous bryophytes and increased the representation of species with larger niches (generalists) while decreasing the representation of species with smaller niches (typically found in shady or in sunny areas). The results suggests that the critical fragment size necessary for bryophyte preservation must be correlated with insularity levels; for epiphytes, however, it is likely that low levels of isolation cannot compensate borderline effects as with the epiphyllous bryophytes.     

Oribatid mite communities and foliar litter decomposition in canopy suspended soils and forest floor habitats of western redcedar forests, Vancouver Island, Canada

Litter decomposition and changes in oribatid mite community composition were studied for 2 years in litterbags collected from arboreal organic matter accumulations (canopy suspended soils) and forest floors associated with western redcedar trees on Vancouver Island, British Columbia. We tested the hypotheses that lower rates of mass loss, higher nutrient levels, and different patterns of oribatid mite richness and abundance in decomposing western redcedar litter would be observed in litterbags associated with canopy suspended soils compared to forest floors. Decomposition, measured by mass loss of cedar litter in litterbags, was not significantly different in canopy and forest floor habitats, although reduced in the canopy. Abundance and richness of oribatid mites inhabiting litterbags were significantly greater on the forest floor compared to the canopy suspended soils. Canopy suspended soils had higher levels of total nitrogen, available phosphorus and potassium than the forest floor, but moisture content was significantly lower in the suspended soils. Higher nutrient levels in the canopy system are attributed to differences in coarse woody debris input (but not foliar litter), combined with reduced nutrient uptake by roots and lower mobilisation rates of nutrients by detritivorous and fungivorous microarthropods. Moisture limitation in the canopy system possibly contributed to lower mass loss in litterbags, and lower abundance and richness of oribatid mites in litterbags placed on canopy suspended soils. Patterns of oribatid mite community composition were related to mite communities associated with the underlying substrate (forest floor or canopy suspended soil) which act as source pools for individuals colonising litterbags. Successional and seasonal trends in oribatid mite communities were confounded by moisture limitation at 24 months, particularly within the canopy habitat.     

Differential effects of lichens and mosses on soil enzyme activity and litter decomposition

In the New Jersey Pinelands, canopy gaps in the pine-dominated forest support patches of lichens, mosses, and caespitose grasses. We tested the hypotheses that non-vascular plants and lichens can affect nutrient cycling processes and that mosses and lichens would differ from each other. We predicted that (1) lichen tissues would decompose more slowly than pine or moss tissues, (2) all plant materials would decompose more slowly beneath lichens than beneath mosses, and (3) soil enzyme activities would be higher under lichens than under mosses or grasses, reflecting greater nutrient limitation. We compared rates of decomposition of the litter of Pinus rigida and moss and lichen tissues, and measured soil enzyme activities responsible for nutrient mineralization from litter (acid and alkaline phosphatases, chitinase, β-glucosidase, aminopeptidase, and phenol oxidase) under three types of groundcover (lichens, mosses, and grasses) and unvegetated soil at two sites. While groundcover affected enzyme activities, the patterns of enzyme activities differed markedly between the two sites. In general, the enzyme activities were uniformly low. Decomposition rates were more strongly affected by the groundcover than by litter materials. While all litters tended to decompose more slowly under lichens than under mosses, supporting one of our initial hypotheses, the rates of decomposition were markedly different between the two sites. These results suggest that while mosses and lichens create patches of different soil function in both sites, the differences between the sites in unknown factors cause the enzyme activities and decomposition rates to differ.     

Urban domestic gardens (XIII): Composition of the bryophyte and lichen floras, and determinants of species richness

Private, residential gardens form a substantial proportion of the undeveloped land in urban areas. Evaluating their role in supporting biodiversity is crucial to (i) predicting which plant and animal species can persist in towns and cities, (ii) understanding the regional impacts of urbanisation, and (iii) guiding sympathetic garden management by owners. To obtain baseline information on a poorly-studied component of garden biodiversity, we measured the size and composition of the cryptogam assemblages in 61 domestic gardens in the city of Sheffield, UK. A total of 67 bryophyte and 77 lichen taxa were recorded. Bryophytes ranged from 3 to 24 species per garden, with a mean richness of 11.3 species; lichens ranged from 2 to 30, with a mean of 14.9 species. Stone substrates supported the highest lichen richness, although minor substrates contributed unique species. Just over one fifth of bryophyte species were recorded in grass lawns, and these were more widespread than those of other habitats. Most cryptogams were scarce, with around one quarter of both bryophytes and lichens occurring in single gardens, and only 10% were found in more than half of the gardens. Garden area - correlated with substrate richness - and garden altitude were the only two factors explaining variation in cryptogam richness (bryophytes 39.1%, lichens 32.4%). Positive correlations existed among bryophyte, lichen and vascular plant richness, and these were only partially mediated by the effect of garden area. Therefore the opportunity remains for garden owners to support cryptogam richness, the most effective action being to enhance substrate diversity.     

Application of body size spectra to nematode trait-index analyses

Current trait-based indices of soil fauna for assessing soil quality rely on extensive knowledge of life history traits for hyper-diverse groups. We look at the effects of clear-cut forest harvesting and subsequent wood ash application on the free-living nematode community using trait-based indices and body size spectra. We test the hypothesis that body size is a unifying trait and that the body size spectra can be used to demonstrate changes in soil quality while overcoming taxonomic impediments. Undisturbed boreal forest floor soils were compared with clear-cut sites amended with zero, one-half calcium equivalent wood ash, equivalent calcium reintroduction, and twice calcium reintroduction. Total abundance, trait-based metrics for the Maturity Index, and two metrics of body size spectra were calculated. Nematode abundance was not a good indicator of soil disturbance, while traditional trait-based approaches (the summed Maturity Index) demonstrated predicted changes in community structure. Analysis of two types of body size spectra elucidated how the community had changed under disturbance, and revealed that smaller bodied organisms were lost under ash amended treatments compared to both clear-cut and undisturbed forest. Using the body size spectra for nematodes is a simple addition to current trait-based approaches that can supplement soil assessments for disturbance and quality without requiring taxonomic expertise.     

Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park

We compared breeding bird communities and vegetation characteristics at paired point locations in primary (undisturbed) and mature secondary forest (70-100 years old) sites in Great Smoky Mountains National Park, USA to understand how sites logged prior to creation of the park compare to undisturbed sites following 70 years of protection from human disturbance. We found that bird and vegetation communities are currently similar, but retain some differences in species composition. Rank abundance curves for primary and secondary forest bird communities showed very similar patterns of species dominance. Species composition was also similar on the two sites which shared 24 of the 25 most frequently recorded species. Nonetheless, comparisons of density estimates derived from distance sampling showed three bird species were more abundant on primary forest sites and that one bird species was significantly more abundant on secondary forest sites. Notably, comparisons based on raw counts (unadjusted for potential differences in detectability) produced somewhat different results. Analyses of vegetation samples for the paired sites also showed relative similarity, but with some differences between primary and secondary forests. Primary forest sites had more large trees (trees greater than 50 cm diameter at breast height) and late successional species. Primary forest sites had a denser tall shrub layer while secondary forest sites had a denser canopy layer. Nonetheless, tree species richness, basal area of live trees and number of standing snags did not differ between primary and secondary forest sites. Results indicate that breeding bird communities on sites within the park that were logged commercially 70 years ago are currently quite similar to bird communities on sites with no history of human disturbance. Similarities between the bird communities on previously disturbed and undisturbed sites in Great Smoky Mountains National Park may exceed those on more fragmented landscapes because large patches of primary forest, adjacent to commercially logged sites, remained in the park when it was established in 1935. These patches of primary forest may have served as source areas for commercially logged sites.     

Diversity of dead wood inhabiting fungi and bryophytes in semi-natural beech forests in Europe

Saproxylic organisms are among the most threatened species in Europe and constitute a major conservation problem because they depend on the most important forestry product - dead wood. Diversity of fungal and bryophyte communities occurring on dead beech trees was analyzed in five European countries (Slovenia, Hungary, The Netherlands, Belgium and Denmark) considering tree level species richness (TLSR), country level species richness (CLSR), frequency distributions of species, occurrence of threatened species and relations between TLSR and decay stage, tree size and countries. Altogether 1009 trees were inventoried in 19 beech dominated forest reserves.The number of fungi in the full dataset was approximately three times larger (456 versus 161 species) and the proportion of low frequent species was higher than among bryophytes. The species richness of bryophytes and fungi was significantly different among countries considering both TLSR and CLSR. In addition the diversity patterns deviated considerably between the two groups of organisms. Slovenian sites appeared to be biodiversity hotspots for bryophytes characterized by high TLSR and CLSR and a high fraction of threatened species. Hungarian sites had somewhat lower bryophyte diversity, while the Atlantic region had deteriorated assemblages. Fungal species richness was very high in Denmark, but the Hungarian and Slovenian sites were richer in threatened and low frequency species. Tree size was better able to explain variation in TLSR in both organism groups than decay stage. TLSR was found to vary significantly between countries but the difference was most considerable in the case of bryophytes.The diversity patterns of both organism groups along the investigated geographical gradient appear to be influenced by both climatic and management related factors (forest history, dead wood availability and continuity, habitat fragmentation). There is no doubt that an increase in the abundance of dead wood in European beech forests will benefit diversity of saproxylic fungi and bryophytes, especially if a continuous presence of large diameter logs are secured within individual stands.     

Are habitat-tracking metacommunities dispersal limited? Inferences from abundance-occupancy patterns of epiphylls in Amazonian forest fragments

In theory, habitat fragmentation alters plant community dynamics by influencing both local (within patch) and regional (among patch) processes. However, the lengthy generation times of plant taxa relative to the short duration of most experiments has precluded studies from assessing the impact of fragmentation at both local and regional scales. Due to their accelerated life cycles, high rates of local extinction, and naturally patchy substrates, epiphyllous bryophyte assemblages are an appropriate plant guild for empirically testing metacommunity-based predictions associated with habitat fragmentation. By examining the local abundance and regional distribution patterns of 67 epiphyllous (leaf-inhabiting) bryophyte species in an experimentally fragmented landscape in Amazonia, we demonstrate that changes in local abundance wrought by habitat fragmentation are best explained by fragment size rather than proximity to forest edge. Furthermore, evidence of a simultaneous inter-specific decline in epiphyll local abundance and regional distribution in small (1- and 10-ha) forest fragments corroborate with metapopulation-based predictions highlighting the importance of immigration in buffering from patch extinction risk (i.e., the rescue effect). Collectively, these results provide indirect evidence that dispersal limitation, rather than compromised habitat quality attributable to edge effects, likely account for species loss from small tropical forest fragments. Whether dispersal limitation is due to increased insularity from regional sources for epiphyll recolonization or rather to lowered within-fragment dispersal potential is unknown; nonetheless, the long-term persistence of these microscopic plant metacommunities depends on the preservation of rain forest reserves of at least 100-ha in size.     

Dependence of bryophyte species on young, mature and old growth wet eucalypt forest

Maintenance of old growth forest has been argued to be important for the future of many bryophyte species, but there has been no empirical test of this proposition. Bryophytes constitute much of the plant biodiversity in Tasmanian tall open-forests dominated by Eucalyptus regnans and Eucalyptus obliqua. These forests have a low level of protection in their old growth stage. We ask whether if there is a concentration of bryophyte species in particular forest age classes and assess its significance for biological conservation. The bryophyte species at 99 forest sites were recorded and related to young, mature and old growth age classes using ANOVA. Only two bryophyte taxa were confined, with statistical confidence, to one of these classes. Succession in bryophyte assemblages takes the relay floristics form, with a few highly frequent species in the young forest, most of which do not persist in later stages, a large number of species establishing in middle-aged forests, some dying out with their short-lived hosts by the time of the old growth forest stage, and liverworts becoming more prominent with age. Species concentrated in the old growth phase of these eucalypt forests have all been recorded from secure reserves in this and other vegetation types. If present patterns of land use continue, and no extensive wild fires occur in the reserved old growth forest, almost all bryophyte species of E. regnans and E. obliqua mixed forest are likely to survive. This may not be the case in other regions of the world, where reservation may be poorer than in Tasmania.     

Moss and lichen decomposition in old-growth and harvested high-boreal forests estimated using the litterbag and minicontainer methods

Bryophytes and lichen are important components of many boreal forest ecosystems, making the quantification of moss and lichen decomposition rates critical to understanding the C cycle of these forests. Cryptogam decomposition has been predominantly studied in wetlands, while few studies exist for forest-habitat mosses and even fewer for foliose ground lichen. We used a) the litterbag and b) the minicontainer (MC) method to quantify the decomposition rates of i) feathermoss, ii) forest peatmoss, iii) foliose ground lichen, and iv) alder leaves (reference litter) in cool, wet high-boreal Labrador black spruce forests. A total of 1560 litter samples (360 litterbags, 1200 MCs) were incubated for two years in six forest stands of different disturbance origin: three old-growth stands of wildfire origin, and three recently clearcut stands. Litter samples were retrieved after 6.5, 13, 47, 57 and 109 weeks of field incubation, and analysed for mass loss, C, N, nutrient, and fibre content.While clearcut harvesting had no significant effect on litter decomposition at all, decomposition rates significantly differed between litter types, with residual mass increasing in the order alder ≤ lichen < feathermoss ≤ peatmoss. Compared to wetlands, forest moss litter was more labile in the studied forest types, with lichen producing especially fast-decomposing litter. Litter type was a better predictor of decomposition rates than individual chemical parameters, indicating that, even in extreme climates like in Labrador, substrate quality is more important in determining decomposition rates than environmental factors. For all litter types, decomposition models accounting for the seasonality of decay dynamics performed better than models assuming constant or continuously decreasing decay rates. Compared to the litter bag method, which yielded decomposition rates comparable to previous studies, the MC method overestimated decomposition rates for alder and lichen due to fragmentation artefacts. The small sample size of the MC method therefore outweighs its statistical advantages arising from ease of replication. In order to derive reliable estimates of litter decomposition, both the field incubation method and the applied decomposition model must therefore be selected to suit the studied litter types.     

Use of remnant boreal forest habitats by saproxylic beetle assemblages in even-aged managed landscapes

Saproxylic Coleoptera are diverse insects that depend on dead wood in some or all of their life stages. In even-aged boreal forest management, remnant habitats left as strips and patches contain most of the dead wood available in managed landscapes and are expected to act as refuges for mature forest species during the regeneration phase. However, use of remnant habitats by the saproxylic fauna has rarely been investigated. Our objective was to characterize the saproxylic beetle assemblages using clearcuts and forest remnants in western Québec, Canada, and to explore the effects of forest remnant stand characteristics on saproxylic beetle assemblages. We sampled both beetle adults and larvae, using Lindgren funnels and snag dissection, in five habitat locations (clearcuts, forest interiors of large patches, edges of large patches, small patches and cut-block separators) from three distinct landscapes. Adult saproxylic beetles (all feeding guilds combined) had significantly higher species richness and catch rates in small patches compared to forest interiors of large patches; the phloeophagous/xylophagous group had significantly higher species richness only. Small patches, cut-block separators and edges of large patches also had the highest snag density and basal area, increasing habitat for many saproxylic beetles. No significant differences in density of saproxylic larvae were found between habitat patches, but snag dissection nevertheless suggests that snags in forest remnants are used by comparable densities of insects. Saproxylic beetles appear to readily use habitat remnants in even-aged managed landscapes suggesting that forest remnants can insure the local persistence of these species, at least in the timeframe investigated in our study.