Abundance Of Bryophytes Research Articles

Influence of bark chemistry on distribution of epiphytic mosses on basal trunk of <i>Cryptomeria japonica</i>

Epiphytic mosses are integral parts of forest community structure in the Darjeeling Hills of the Eastern Himalayan region with remarkable contributions to the ecosystem functionality. The study was framed to assess the richness and spatial distribution of epiphytic mosses growing on the basal trunk of Cryptomeria japonica (Thunb. ex. L.) D.Don, and also to evaluate the explanatory host traits for shaping the moss assemblage. Field measurements and sampling were performed near Lamahatta village within Darjeeling district on 270 microplots placed on tree trunks. A total of twelve mosses represented by the members of Dicranales and Hypnales were recorded. Low species diversity was observed with dominance and maximum cover of Syrrhopodon confertus. Canonical correspondence analysis predicted a distinct combination of chemical requirements for local colonization of each moss. The results also demonstrated influence of bark acidic inputs on abundance and co-existence of bryophytes. The outcome can be potentially helpful in depicting the community structure of non-vascular epiphytes, which may further be considered while developing forest management strategies.

Multiple global change factors cause declines of a temperate bryophyte

ABSTRACT Background Climate change, nutrient enrichment and land use have been predicted to alter bryophyte abundance and performance; we expect these factors to interact, yet experiments addressing their joint effects are missing. Aims We tested the responses of Brachythecium rutabulum, a common temperate moss species, to single and combined effects of future climatic conditions, grazing, light limitation and nutrient enrichment. We predicted that future climatic conditions, intense grazing, light limitation and nutrient enrichment have all negative effects on the survival and photosynthetic condition of B. rutabulum, and their joint effects become strong even if individual factors have only weak effects (multiple stress hypothesis). Methods We measured after two growing seasons biomass and chlorophyll fluorescence of transplanted moss colonies in full-factorial treatments of fertilisation, exclusion of sheep grazing and light amendment by LED lamps, replicated in ambient and future climatic conditions. Results Future climate and fertilisation had negligible effects on colony biomass and chlorophyll fluorescence of bryophyte colonies, whereas light amendment had positive effect on chlorophyll fluorescence and grazing exclusion had positive effect on colony biomass. Colony biomass and chlorophyll fluorescence decreased with increasing number of global change factors. Conclusion Supporting the multiple stress hypothesis, individually weak global change factors can combine to strong joint effects.

Vegetation mosaic shaping bryophyte diversity in a threatened ecosystem: A case study of Brazilian Cangas (ferruginous rupestrian fields)

The Canga vegetation in Brazil is a unique ecosystem found on ironstone outcrops, known as ferruginous rupestrian fields, and is considered one of the most diverse in the world. This mosaic landscape, comprised of trees, shrubs, and herbaceous vegetation, is home to a diverse range of plants, including angiosperm, bryophytes, and lichens. To understand the effect of Cangas' patchy landscape, here called mesohabitats, on bryophyte communities, we asked the following questions: Do the diversity parameters such as richness, abundance and composition of bryophytes differ along the different Cangas’ mesohabitats? Do bryophyte assemblages group by functional traits and filter per mesohabitat? We surveyed eight sites in the Quadrilátero Ferrífero (Iron Quadrangle), southeast Brazil. We collected and analysed data on bryophyte diversity and functional traits in three different mesohabitats: exposed areas (EA), shrub associations (SA), and tree associ ations (TA). The diversity of both groups was tested using one-way ANOVA; and functional traits were addressed with a Factorial Analysis of Mixed Data (FAMD). There are significant differences in the diversity of bryophytes among the mesohabitats, with TA having the highest diversity and abundance of liverworts and mosses, followed by SA and EA. The study also found bryophyte assemblies with similar functional traits in similar mesohabitats across the Brazilian Quadrilátero Ferrífero. The research revealed that the different mesohabitats provided important and distinct niches for bryophytes in Cangas, and this threatened ecosystem's high diversity must be considered when developing conservation strategies. This entails land managers adopting effective approaches aimed at improving both the quality and connectivity of habitats, fostering biodiversity, and bolstering the resilience of the ecosystem.

Epigeic bryophytes of Bryansk parks and prospects for their use in landscape architecture

Studies of epigeal bryophytes growing on the territory of public facilities in Bryansk have been carried out and the prospects of using mossy ones for the landscape organization of an urbanized environment have been considered. The studies were conducted under conditions of different levels of insolation and with different soil conditions. The species composition of the living ground cover was determined, the general projective cover of the living ground cover, the general projective cover of bryophytes, and the projective cover of each bryophyte species were established. The general and particular projective coverage of mosses was determined according to the methodology developed by us using information technology. The conducted studies have shown that the abundance and occurrence of epigeic bryophytes, as well as the dominance of mossy species in urban parks depends on the growing conditions. Bryophytes are less demanding on soil fertility, which leads to their dominance in conditions of serious disturbance of the soil cover or in its absence. Epigeic bryophytes of the parks Bryansk has a number of decorative characteristics, due to which they have a beneficial effect on the aesthetic appearance of green areas.

Frost damage measured by electrolyte leakage in subarctic bryophytes increases with climate warming

Abstract Observed climate change in northern high latitudes is strongest in winter, but still relatively little is known about the effects of winter climate change on tundra ecosystems. Ongoing changes in winter climate and snow cover will change the intensity, duration and frequency of frost events. Bryophytes form a major component of northern ecosystems but their responses to winter climate changes are largely unknown. Here, we studied how changes in overall winter climate and snow regime affect frost damage in three common bryophyte taxa that differ in desiccation tolerance in a subarctic tundra ecosystem. We used a snow manipulation experiment where bryophyte cores were transplanted from just above the tree line to similar elevation (i.e. current cold climate) and lower elevation (i.e. near‐future warmer climate scenario) in Abisko, Sweden. Here, we measured frost damage in shoots of Ptilidium ciliare, Hylocomium splendens and Sphagnum fuscum with the relative electrolyte leakage (REL) method, during late winter and spring in two consecutive years. We hypothesized that frost damage would be lower in a milder climate (low site) and higher under reduced snow cover and that taxa from moister habitats with assumed low desiccation tolerance would be more sensitive to lower temperature and thinner snow cover than those from drier and more exposed habitats. Contrary to our expectations, frost damage was highest at low elevation, while the effect of snow treatment differed across sites and taxa. At the high site, frost damage was reduced under snow addition in the taxon with the assumed lowest desiccation tolerance, S. fuscum. Surprisingly, frost damage increased with mean temperature in the bryophyte core of the preceding 14 days leading up to REL measurements and decreased with higher frost degree sums, that is, was highest in the milder climate at the low site. Synthesis Our results imply that climate warming in late winter and spring increases frost damage in bryophytes. Given the high abundance of bryophytes in tundra ecosystems, higher frost damage could alter the appearance and functioning of the tundra landscape, although the short and long‐term effects on bryophyte fitness remain to be studied.

Mixed evidence of a commensal relationship between a rare epiphytic orchid and cohabiting bryophytes

AbstractThe co-occurrence of orchids and bryophytes at occupied sites on host trees has been documented on several occasions, particularly in the tropics, and it may represent an important symbiotic relationship that supports epiphytic orchid populations. Despite continuing interest from ecologists, the specific life history traits that are affected by associations of orchids with bryophytes, and how they are affected, remain unclear. Clarifying the nature of the association will improve our understanding of orchid ecology and have practical implications for applied conservation efforts, particularly for rare species in restricted habitats. In this study, we explored the relationship between the abundance of bryophyte cover on host trees and various life history traits related to size, survival and reproduction of a rare tropical epiphytic orchid, Lepanthes caritensis. The results demonstrated that bryophyte abundance on host trees had variable effects on individual aspects of an orchid’s life history. Orchid recruitment was positively correlated with the abundance of bryophyte cover, but survival and flower production were negatively correlated with bryophyte abundance. Our findings revealed that an apparent commensal symbiotic relationship between L. caritensis and bryophytes exists at the recruitment stage, but this is lost during later life stages, when the abundance of bryophytes appears to negatively affect this species.

Rock‐climbing shifts cliff‐face vegetation community composition based on site characteristics

AbstractQuestionsWhat are the effects of rock‐climbing on diversity, abundance and composition of cliff‐face vegetation along environmental gradients? Does site variability influence cliff vegetation more than the presence of climbing?LocationLinville Gorge Wilderness Area, NC, USA.MethodsWe compared species richness, Shannon’s diversity, abundance and species composition of lichens, bryophytes and vascular plants within 334 plots, each 1 m2. We compared climbed plots with unclimbed plots using Non‐metric Multidimensional (Distance) Scaling ordination, means comparison and regression analysis.ResultsEighty‐five species were observed within 334 m2 of cliff‐face plots, including one North Carolina state (Canoparmelia alabamensis) and 21 Burke County collection records. Climbing altered cliff plant communities: unclimbed cliffs supported more diverse and different species than did climbed cliffs. However, site was more important than was climbing in differentiating cliff community composition. Variation in species composition was driven mostly by variation in cliff aspect and surface heterogeneity. Cliffs with the highest surface heterogeneity had the highest species richness, diversity and abundance of all three vegetation types (lichens, bryophytes and vascular plants). Unclimbed areas had similar richness, diversity and abundance compared with easy climbing routes, whereas harder climbing routes supported lower species richness and abundance of all vegetation types.ConclusionsDifferences in cliff‐face vegetation in Linville Gorge were due more to site variability than to climbing impact. Therefore, management of climbing areas and decisions for future route development should be site‐specific and include a thorough biological survey.

Effects of stand structure and ungulates on understory vegetation in managed and unmanaged forests.

Conventional conservation policies in Europe notably rely on the passive restoration of natural forest dynamics by setting aside forest areas to preserve forest biodiversity. However, since forest reserves cover only a small proportion of the territory, conservation policies also require complementary conservation efforts in managed forests in order to achieve the biodiversity targets set up in the Convention on Biological Diversity. Conservation measures also raise the question of large herbivore management in and around set-asides, particularly regarding their impact on understory vegetation. Although many studies have separately analyzed the effects of forest management, management abandonment, and ungulate pressure on forest biodiversity, their joint effects have rarely been studied in a correlative framework. We studied 212 plots located in 15 strict forest reserves paired with adjacent managed forests in European France. We applied structural equation models to test the effects of management abandonment, stand structure, and ungulate pressure on the abundance, species richness, and diversity of herbaceous vascular plants and terricolous bryophytes. We showed that stand structure indices and plot-level browsing pressure had direct and opposite effects on herbaceous vascular plant species diversity; these effects were linked with the light tolerance of the different species groups. Increasing canopy cover had an overall negative effect on herbaceous vascular plant abundance and species diversity. The effect was two to three times greater in magnitude than the positive effects of browsing pressure on herbaceous plants diversity. On the other hand, a high stand density index had a positive effect on the species richness and diversity of bryophytes, while browsing had no effect. Forest management abandonment had few direct effects on understory plant communities, and mainly indirectly affected herbaceous vascular plant and bryophyte abundance and species richness and diversity through changes in vertical stand structure. Our results show that conservation biologists should rely on foresters and hunters to lead the preservation of understory vegetation communities in managed forests since, respectively, they manipulate stand structure and regulate ungulate pressure. Their management actions should be adapted to the taxa at stake, since bryophytes and vascular plants respond differently to stand and ungulate factors.

Bryophyte Diversity in Mount Prau, Blumah Village, Central Java

Bryophytes are a major component of the ecosystem in Indonesia. Due to their sensitiveness, the abundance and diversity of bryophytes in an ecosystem are influenced by environmental conditions. This study aimed to determine the diversity of bryophytes based on ecological parameters in the village of Blumah Kecaman Plantungan, Kendal Regency which is directly adjacent to the Mount Prau protected forest, Central Java. The data collection method used was the exploratory method and the descriptive exploratory method with survey techniques. Observation was carried out by exploring an area of 3 kilometers, every 1 km distance. An observation station was made consisting of station 1 Jiwan hamlet, station 2 Garung, and station 3 at Cengkek and Gondan springs. The specimens were identified based on taxonomic literature. Each species was collected as a specimen for further identification in the laboratory. Abiotic environment parameters such as temperature, humidity, altitude, light intensity, pH and slope were observed. The results showed that Blumah village still has high plant diversity, especially bryophytes. The more humid, the higher the place, the lower the temperature and light intensity, the more species diversity. Based on the identification results, 21 species were recorded, which includes 15 species of mosses, 4 species of liverworts, and 2 species of hornworts. The index value of bryophyte species diversity was in the medium category, and the index value of species richness and species dominance were at low levels.

Habitat determines plant community responses to climate change in the High Arctic

Plant climate responses may depend on site-specific environmental context. Using fences and open-top chambers, we enhanced snow depth (creating Ambient, Medium, and Deep regimes) over an 11-year period and increased temperatures for two summers in dry heath and mesic meadow habitats on Svalbard, Norway. Comparison of plant growth form abundance and diversity responses in these two habitats showed that the response was more limited in the dry heath than in the mesic meadow. Common to both habitats was a decrease in shrub abundance and vascular plant species richness in the Deep snow regimes. Bryophyte abundance increased with enhanced snow cover in both habitats, but only up to a certain extent of snow depth in the meadow. However, for many growth forms, the effects of snow enhancement were habitat specific. In the mesic meadow, the abundance of forbs and bryophytes increased with snow enhancement, but the effect was stronger when combined with summer warming. The “bryofication” — that is, an increased abundance of bryophytes in response to snow enhancement and summer warming — also influenced overall plant diversity in the mesic meadow. Bryophytes are species-rich taxa and may respond differently than vascular plants to environmental change. We show that the inclusion of even the most common bryophytes in measures of diversity may determine overall plant diversity responses to environmental change in the Arctic.

Ambient and experimental warming effects on an alpine bryophyte community

Alpine and Arctic bryophytes have been found to respond negatively to climate change, but as they are often analysed as one functional group, there is limited knowledge on species-specific responses. In this study, we examine how nearly two decades of experimental warming by open-top chambers and ambient warming have affected the bryophyte community structure in an alpine Dryas octopetala L. heath in Finse, southwest Norway. In contrast to what we expected, we found that bryophyte abundance, species richness, and evenness increased over time in the control plots, indicating a positive response to ambient warming. However, the increase in bryophyte abundance and cover was suppressed in experimentally warmed plots compared with control plots. Bryophyte community composition changed in a similar direction in response to both ambient and experimental warming. Acrocarpous mosses were not affected stronger by warming than pleurocarpous mosses, but individual species and taxa showed contrasting responses. Our study highlights the importance of studying bryophyte responses to environmental change, as well as combining long-term observations with experimental warming.

Impacts of rock climbing on cliff vegetation: A methods review and best practices

AbstractQuestionsCliff vegetation is diverse, understudied, and threatened by increased human disturbance. The growing popularity of rock climbing heightens the need for science‐based management to balance recreational use and conservation of cliff ecosystems. What has existing research revealed about the impact of climbing on vegetation? Are the conclusions consistent across the literature? If not, how can research methods be streamlined and standardized to produce more consistent results and reliable conclusions?MethodsWe present a review of vegetation‐focused climbing‐impact studies written in English. We compare study design and climbing‐specific considerations in 19 studies and report the impact of rock climbing on richness and abundance of lichens, bryophytes, and vascular plants. We then propose a set of best practices to guide design of future studies.ResultsOur work reveals that existing studies have employed widely differing methods for data collection and analysis. The effects of climbing on vegetation also varied among studies. Standardizing methods, such as pairing climbed and unclimbed transects or including a metric for climbing use, will generate more reliable and useful conclusions about the effect of climbing on vegetation.ConclusionsClimbing will increasingly disturb cliff ecosystems. Our proposed best practices for climbing study methods are one way to produce more accurate information to inform climbing management plans, ultimately enhancing cliff conservation.

Nowhere to escape – Diversity and community composition of ferns and lycophytes on the highest mountain in Honduras

AbstractIPCC predictions for Honduras indicate that temperature will increase by up to 3–6°C and precipitation will decrease by up to 7–13% by the year 2050. To better understand how fern and lycophyte communities might be affected by climate change, we comprehensively surveyed the community compositions of ferns and lycophytes at Celaque National Park, the highest mountain in Honduras. We surveyed a total of 80 20 × 20 m2plots along an altitudinal gradient of 1249–2844 m a.s.l., identifying all species and estimating their abundances. We recorded a total of 11,098 individuals from 160 species and 61 genera. Community composition was strongly influenced by changes in altitude, precipitation and the abundance of bryophytes (a proxy for air humidity). Of the 160 species, 63 are expected, under a RCP2.6 scenario for the year 2050, to shift their range fully or partially above the maximum altitude of the mountain. Of these, 65.1% are epiphytes. We found that species with narrow altitudinal ranges at high altitudes were more at risk. Our study indicated that conservation efforts should prioritise higher altitudinal sites, focusing particularly on preserving the vulnerable epiphytic fern species, which are likely to be at greater risk.

Riparian forests can mitigate warming and ecological degradation of agricultural headwater streams

Abstract Riparian forests are commonly advocated as a key management option to mitigate the effects of agriculture on headwater stream biodiversity and ecosystem functions. However, the benefits of riparian forests might be reduced by uninterrupted catchment‐scale pollution. We studied the effects of riparian land use on multiple ecological endpoints in headwater streams in an agricultural landscape. We studied stream habitat characteristics, water temperature and algal accrual, and macrophyte, benthic macroinvertebrate and fish communities in 11 paired forested and open agricultural headwater stream reaches that differed in their extent of riparian forest cover but had similar water quality. Hydromorphological habitat quality was higher in forested reaches than in open reaches. Riparian forest had a strong effect on the summer water temperature regime, with maximum and mean water temperatures and temperature variation in forested reaches substantially lower than in open reaches. Macrophyte communities differed between forested and open reaches. The mean abundance of bryophytes was higher in forested reaches but the difference to open reaches was only marginally significant, whereas graminoids were significantly more abundant in open reaches. Within‐stream dissimilarity of benthic macroinvertebrate community structure was significantly related to the difference in riparian land use between reach pairs. The relative DNA sequence abundance of pollution‐sensitive Ephemeroptera, Plecoptera, and Trichoptera species tended to be higher in forested reaches than in open reaches. Finally, fish densities were not significantly different between forested and open reaches, although densities were higher in forested reaches. This unequivocal evidence for the ecological benefits of forested riparian reaches in agricultural headwater streams suggests that riparian forest can partly mitigate the adverse impacts of agricultural diffuse pollution on biota. The strong effect of forests on stream water temperature suggest that riparian forest could also mitigate harmful effects on headwater stream biodiversity and ecosystem functions of the predicted more frequent high summer temperatures.

Разнообразие лиственничных лесов и редколесий западного макросклона Приполярного и Северного Урала

Разнообразие лиственничных лесов и редколесий западного макросклона Приполярного и Северного Урала

Impacts of alien tree species on the abundance and diversity of terricolous bryophytes

Bryophytes comprise an important element of temperate forest biodiversity and functioning. Although numerous studies reported impacts of alien tree species on understorey vegetation, few focused on impacts on bryophytes. Here we checked whether three invasive tree species in Europe (Prunus serotina Ehrh., Quercus rubra L. and Robinia pseudoacacia L.) influence terricolous bryophyte communities, alpha and beta diversity, and cover. We used a set of 186 study plots in western Poland with data on the cover of bryophytes species, as well as light availability, soil C:N ratio and pH. We found that light availability was the main driver of bryophyte species richness, cover and composition. Poor Pinus sylvestris L. forests invaded by P. serotina hosted more species and higher species richness than non-invaded P. sylvestris forests, while forests invaded by Q. rubra and R. pseudoacacia hosted fewer species than native forest types. Low differences among forest types studied resulted from small pools of species and the presence of generalist species. Fagus sylvatica L. forest, Q. rubra and R. pseudoacacia forests hosted the smallest number of species, while the most species rich stands were poor P. sylvestris forest invaded by P. serotina and non-invaded P. sylvestris forests. We concluded that light limitation by invasive species might be more important than dominant tree species identity in limiting terricolous bryophyte species richness and abundance. This requires further studies, accounting for varied abundances of invasive tree species. Therefore, the conservation of sites with high terricolous bryophyte biodiversity needs to be focused on canopy cover.

Bryophyte cover and richness decline after 18 years of experimental warming in alpine Sweden.

Climate change is expected to affect alpine and Arctic tundra communities. Most previous long-term studies have focused on impacts on vascular plants, this study examined impacts of long-term warming on bryophyte communities. Experimental warming with open-top chambers (OTCs) was applied for 18 years to a mesic meadow and a dry heath alpine plant community. Species abundance was measured in 1995, 1999, 2001 and 2013. Species composition changed significantly from original communities in the heath, but remained similar in mesic meadow. Experimental warming increased beta diversity in the heath. Bryophyte cover and species richness both declined with long-term warming, while Simpson diversity showed no significant responses. Over the 18-year period, bryophyte cover in warmed plots decreased from 43 % to 11 % in heath and from 68 % to 35 % in meadow (75 % and 48 % decline, respectively, in original cover), while richness declined by 39 % and 26 %, respectively. Importantly, the decline in cover and richness first emerged after 7 years. Warming caused significant increase in litter in both plant communities. Deciduous shrub and litter cover had negative impact on bryophyte cover. We show that bryophyte species do not respond similarly to climate change. Total bryophyte cover declined in both heath and mesic meadow under experimental long-term warming (by 1.5–3 °C), driven by general declines in many species. Principal response curve, cover and richness results suggested that bryophytes in alpine heath are more susceptible to warming than in meadow, supporting the suggestion that bryophytes may be less resistant in drier environments than in wetter habitats. Species loss was slower than the decline in bryophyte abundance, and diversity remained similar in both communities. Increased deciduous shrub and litter cover led to decline in bryophyte cover. The non-linear response to warming over time underlines the importance of long-term experiments and monitoring.

Restoration of rare bryophytes in degraded rich fens: The effect of sod-and-moss removal

Rich fens are known as biodiversity hot spots among peatlands encompassing many endangered bryophytes. In some European regions, specialised rich-fen bryophytes, including red-listed species, have been outcompeted by expansive Sphagnum species and competitively strong vascular plants. One of the main causes of the rapid succession was a cessation of traditional management such as scything, raking, or occasional grazing. Most of the current rich fens in Central and Western Europe depend on such management-related disturbances because they have been initiated or altered by humans. Removal of expansive Sphagnum species together with tussocks of graminoids is occasionally suggested to reverse the succession to previous rich fen stage before re-establishing the traditional management or its imitation. We carried out such treatment on 31 sites to restore microhabitats for fen-specialised bryophytes. Expansive Sphagnum species declined after the sod-and-moss removal. After one and a half years, the treated plots showed a gradual increase in species richness and abundance of fen-specialised bryophytes, which, however, only slightly increased in total cover. In regions where no Sphagnum species are endangered or legally protected, a sod-and-moss removal is a possible tool for restoration of rich fen vegetation that developed to poor fens because of modern anthropogenic interventions in the agricultural landscapes. However, its repetition after approximately a decade might be required due to the rapid regeneration of expansive Sphagnum species. Yet, further research is needed on the effectiveness and applicability of sod-and-moss removal over a longer period.

Seventy-year history of management using low-intensity harvesting methods: weak impact on biodiversity of hemiboreal Scots pine forests

Less intensive harvesting methods (e.g., selection cutting, shelterwood cuttings) are recommended as alternatives to clearcutting for maintaining mature forest biodiversity in the process of forest regeneration. However, the long-term impact of low-intensity harvesting methods has rarely been studied. Our aim was to clarify the long-term effects of repeated selective cutting, thinning, and shelterwood cutting on the richness, abundance, and species composition of vascular plants, bryophytes, and lichens in Scots pine forests (Pinus sylvestris L.). Data were collected from 25 mature stands located in dry Podzols in southwestern Estonia with a known management history for the last 70 years. Altogether, 35 vascular plant, 41 bryophyte, and 78 lichen species were recorded, including five species with conservational value. Generally, the management history was not related to species richness, except a negative correlation with the species number of epiphytic lichens on conifer trees. In addition, the abundance of two lichen species from the genus Chaenotheca was lower in more frequently managed stands. Species richness and composition were most strongly affected by soil pH and light conditions. We conclude that long-term, low-intensity harvesting of Scots pine forests on nutrient-poor Podzols maintains suitable habitats for vascular plants, bryophytes, and lichens, confirming its suitability for sustainable forest regeneration.

Aquatic bryophytes play a key role in sediment-stressed boreal headwater streams

Forestry-related land use can cause increasing instream sedimentation, burying and eradicating stream bryophytes, with severe ecological consequences. However, there is limited understanding of the relative roles and overall importance of the two frequently co-occurring stressors, increased fine sediments and loss of bryophytes, to stream biodiversity and ecosystem functions. By using random forest modeling and partial dependence functions, we studied the relative importance of stream bryophytes and fine sediments to multiple biological endpoints (leaf-decaying fungi, diatom, bryophyte, and benthic macroinvertebrate communities; leaf decomposition) using field survey data from headwater streams. Stream bryophyte abundance and richness were negatively related to fine sediment cover, highlighting the detrimental effect of sedimentation on bryophytes. However, bryophyte abundance was consistently more important a determinant of variation in community composition than was fine sediment cover. Leaf decomposition was influenced by shredder abundance, water temperature and, to a lesser degree, stream size. Our results suggest that the loss of stream bryophytes due to increasing sedimentation, rather than fine sediments per se, seems to be the key factor affecting multiple biological responses. Enhancing the re-establishment of bryophyte stands could partly compensate for the negative impacts of sedimentation on bryophytes and, consequently, on several other components of boreal stream ecosystems.