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Moss Cover (moss + cover)
Selected AbstractsFunctional biodiversity of macroinvertebrate assemblages along major ecological gradients of boreal headwater streamsFRESHWATER BIOLOGY, Issue 9 2005JANI HEINOArticle first published online: 3 AUG 200 Summary 1. Biodiversity,environment relationships are increasingly well-understood in the context of species richness and species composition, whereas other aspects of biodiversity, including variability in functional diversity (FD), have received rather little rigorous attention. For streams, most studies to date have examined either taxonomic assemblage patterns or have experimentally addressed the importance of species richness for ecosystem functioning. 2. I examined the relationships of the functional biodiversity of stream macroinvertebrates to major environmental and spatial gradients across 111 boreal headwater streams in Finland. Functional biodiversity encompassed functional richness (FR , the number of functional groups derived from a combination of functional feeding groups and habit trait groups), FD , the number of functional groups and division of individuals among these groups, and functional evenness (FE , the division of individuals among functional groups). Furthermore, functional structure (FS) comprised the composition and abundance of functional groups at each site. 3. FR increased with increasing pH, with additional variation related to moss cover, total nitrogen, water colour and substratum particle size. FD similarly increased with increasing pH and decreased with increasing canopy cover. FE decreased with increasing canopy cover and water colour. Significant variation in FS was attributable to pH, stream width, moss cover, substratum particle size, nitrogen, water colour with the dominant pattern in FS being related to the increase of shredder-sprawlers and the decrease of scraper-swimmers in acidic conditions. 4. In regression analysis and redundancy analysis, variation in functional biodiversity was not only related to local environmental factors, but a considerable proportion of variability was also attributable to spatial patterning of environmental variables and pure spatial gradients. For FR, 23.4% was related to pure environmental effects, 15.0% to shared environmental and spatial effects and 8.0% to spatial trends. For FD, 13.8% was attributable to environmental effects, 15.2% to shared environmental and spatial effects and 5% to spatial trends. For FE, 9.0% was related to environmental variables, 12.7% to shared effects of environmental and spatial variables and 4.5% to spatial variables. For FS, 13.5% was related to environmental effects, 16.9% to shared environmental and spatial effects and 15.4% to spatial trends. 5. Given that functional biodiversity should portray variability in ecosystem functioning, one might expect to find functionally rather differing ecosystems at the opposite ends of major environmental gradients (e.g. acidity, stream size). However, the degree to which variation in the functional biodiversity of stream macroinvertebrates truly portrays variability in ecosystem functioning is difficult to judge because species traits, such as feeding roles and habit traits, are themselves strongly affected by the habitat template. 6. If functional characteristics show strong responses to natural environmental gradients, they also are likely to do so to anthropogenic environmental changes, including changes in habitat structure, organic inputs and acidifying elements. However, given the considerable degree of spatial structure in functional biodiversity, one should not expect that only the local environment and anthropogenic changes therein are responsible for this variability. Rather, the spatial context, as well as natural variability along environmental gradients, should also be explicitly considered in applied research. [source] Correlates of biological soil crust abundance across a continuum of spatial scales: support for a hierarchical conceptual modelJOURNAL OF APPLIED ECOLOGY, Issue 1 2006MATTHEW A. BOWKER Summary 1Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen-moss-microbial community that can be used toward these goals, as (i) bioindicators of desertification damage and (ii) promoters of soil stability and fertility. 2We identified environmental factors that correlate with soil crust occurrence on the landscape and might be manipulated to assist recovery of soil crusts in degraded areas. We conducted three studies on the Colorado Plateau, USA, to investigate the hypotheses that soil fertility [particularly phosphorus (P), manganese (Mn) and zinc (Zn)] and/or moisture limit soil crust lichens and mosses at four spatial scales. 3In support of the soil fertility hypothesis, we found that lichen,moss crusts were positively correlated with several nutrients [Mn, Zn, potassium (K) and magnesium (Mg) were most consistent] at three of four spatial scales ranging from 3ˇ5 cm2 in area to c. 800 km2. In contrast, P was negatively correlated with lichen,moss crusts at three scales. 4Community composition varied with micro-aspect on ridges in the soil crust. Three micro-aspects [north-north-west (NNW), east-north-east (ENE) and TOP] supported greater lichen and moss cover than the warmer, windward and more xeric micro-aspects [west-south-west (WSW) and south-south-east (SSE)]. This pattern was poorly related to soil fertility; rather, it was consistent with the moisture limitation hypothesis. 5Synthesis and application. Use of crusts as desertification bioindicators requires knowledge of a site's potential for crust cover in the absence of desertification. We present a multi-scale model of crust potential as a function of site properties. Future quantitative studies can use this model to guide sampling efforts. Also, our results suggest new directions in restoration research: enhancement of moisture residence time and fertilization with key nutrients (Mn, Zn, K and Mg). Re-establishment of soil crusts in desertified lands will help regain lost soil stability and fertility, and facilitate plant re-establishment. [source] Plant community properties predict vegetation resilience to herbivore disturbance in the ArcticJOURNAL OF ECOLOGY, Issue 5 2010James D. M. Speed Summary 1.,Understanding the impact of disturbance on vegetation and the resilience of plant communities to disturbance is imperative to ecological theory and environmental management. In this study predictors of community resilience to a simulated natural disturbance are investigated. Responses to disturbance are examined at the community, plant functional type and species level. 2.,Field experiments were set up in seven tundra plant communities, simulating disturbance based on the impact of grubbing by an increasing herbivore population of pink-footed geese (Anser brachyrhynchus). The short-term resilience of communities was assessed by comparing community dissimilarity between control plots and plots subject to three disturbance intensities based on the foraging impact of these geese. Potential for long-term recovery was evaluated across different disturbance patch sizes. 3.,Resilience to disturbance varied between communities; those with higher moss cover and higher soil moisture, such as wetlands and mires, were most resilient to disturbance. 4.,The wetter communities demonstrated greater long-term recovery potential following disturbance. In wetland communities, vegetative recovery of vascular plants and moss was greater in smaller disturbed patches and at the edges of patches. 5.,The response of vegetation to disturbance varied with intensity of disturbance, plant community and plant species. The use of functional type classifications only partially explained the variation in species responses to disturbance across communities, thus their use in predicting community changes was limited. 6.,Synthesis. The impact of disturbance is shown to be plant-community specific and related to the initial abiotic and biotic properties of the community. By showing that resilience is partly predictable, the identification of disturbance-susceptible communities is possible, which is of relevance for ecosystem management. [source] Density and habitat associations of Henslow's Sparrows wintering in saline soil barrens in southern ArkansasJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2008William C. Holimon ABSTRACT Although the habitat requirements of breeding populations of Henslow's Sparrow (Ammodramus henslowii) have been examined, less is known about their habitat requirements and ecology during the nonbreeding season. We estimated population densities and quantified habitat associations of Henslow's Sparrows wintering in saline soil barrens in southern Arkansas. Densities of Henslow's Sparrows in the saline soil barrens were similar to those in the Longleaf Pine (Pinus palustris) Ecosystem of the southeastern United States, considered by many to be their primary wintering habitat. Henslow's Sparrows were closely associated with open areas with greater cover of Aristida spp. and globe beaksedge (Rhynchospora globularis), greater stem density at 11,20 cm above ground, more lichens, more herbaceous cover, more bare ground, greater occurrence of little bluestem (Schizacyrium scoparium) as the tallest vegetation, less moss, and less shrub cover than randomly selected sites. In contrast to the results of studies conducted in the Longleaf Pine Ecosystem, the presence of Henslow's Sparrows in our study was not correlated with the height of the tallest vegetation. Our results indicate that saline soil barrens of southern Arkansas support a high density of wintering Henslow's Sparrows and do so for longer postdisturbance periods than longleaf pine savanna. We also found that stem density near the ground was similar to that reported from longleaf pine savanna, but only about half that observed on their breeding grounds. Areas used by Henslow's Sparrows had more lichen and less moss cover, suggesting that those areas were drier than random sites within the barrens. Further research is needed to determine if large populations of Henslow's Sparrows winter in other saline soil barrens and if fire influences habitat associations and densities in the barrens. SINOPSIS Aunque los requisitos de hábitat para las poblaciones reproductivas de Ammodramus henslowii han sido determinadas, se conoce muy poco sobre su ecología y requerimientos de hábitat durante la temporada no-reproductiva. Estimamos la densidad poblacional y cuantificamos el hábitat asociado a Gorrión de Henslow que pasan el invierno en un salitral con suelo empobrecido en el sur de Arkansas. La densidad de las aves en el salitral resultó similar a lo encontrado en Ecosistemas de Pinos (Pinus palustris) en el sureste de los EUA, considerado por muchos como el principal hábitat invernal para la especie. Los gorriones estuvieron altamente asociados a áreas abiertas con covertura de Aristida spp. y Rhynchospora globularis, con mayor densidad de tallos, altura entre 11,20 cm sobre el suelo, mayor cantidad de líquenes, mayor cubierta herbácea, más suelo desnudo, mayor presencia de Schzacyrium scoparium (como la vegetación de mayor tamańo), menos musgos, y menos arbustos que localidades seleccionadas al azar. En contraste a los resultados de estudios conducidos en Ecosistemas de Pinos, la presencia del gorrión en nuestra área de estudio no estuvo correlacionada con la altura de la vegetación de mayor tamańo. Nuestros resultados indican que las salinas en Arkansas sostienen una alta densidad de aves invernales, y lo hacen por periodos más largos, después de disturbios, que en las savanas de pinos. También encontramos que la densidad de tallos, cerca del suelo, era similar a la informada en savanas de pinos, pero tan solo la mitad de lo indicado para lugares en donde las aves se reproducen. Las áreas utilizadas tienen más líquenes, pero menos musgos, lo que sugiere que dichas áreas son más secas que lugares con suelo empobrecido muestreados al azar. Se necesitan más trabajos para determinar si otras grandes poblaciones del gorrión de Henslow pasan el invierno en otras salinas con suelos empobrecidos y si eventos como fuegos incluyen en la asociación del hábitat y densidades en los lugares con suelo empobrecido. [source] Spatial patterns of microsite colonisation on two young lava flows on Mount Hekla, IcelandJOURNAL OF VEGETATION SCIENCE, Issue 2 2008N.A. Cutler Abstract Questions: How does vegetation first establish on newly-formed lava substrates? Do very small (cm) and meso-scale (m) variations in the physical environment influence this process and subsequent vegetation development? Location: Mount Hekla, southern Iceland (64°00' N, 19°40' W). Methods: Data on vegetation structure and the incidence of ,safe sites' suitable for colonisation were collected from high and low points on the surfaces of lava flows emplaced during the 1991 and 2000 A.D. eruptions of Mount Hekla. Effects of flow age and meso-topographic position on vegetation structure (moss cover, patch density, stem length) were assessed by two-way analyses of variance. The distributions of colonisation events and available safe sites were analysed using point pattern techniques. Results: Rapid colonisation of the lava surface was observed, despite stressful environmental conditions. The 1991 and 2000 flows differed significantly in vegetation structure, but there were no significant differences in moss cover, patch density and stem length between ,high' and ,low' sites. Conclusions: Colonisation events are invariably associated with small-scale irregularities on the surface of the lava. The colonisation process appears to be spatially random. Development of the moss ,carpet' proceeds by vertical thickening and lateral growth and coalescence of moss patches that establish in ,safe sites'. This process is rapid, with close to 100% of available safe sites exploited within 20 years. Topographic position makes no difference to the very early stages of vegetation development and cannot be used to ,forecast' the later stages of development. [source] Effects of bryophytes and lichens on seedling emergence of alvar plants: evidence from greenhouse experimentsOIKOS, Issue 3 2000Manuela Zamfir Emergence of seedlings of four alvar grassland species (Arenaria serpyllifolia, Festuca ovina, Filipendula vulgaris and Veronica spicata) in bryophyte and lichen carpets was analysed in a series of greenhouse experiments. The aspects investigated were: the influence of thickness of moss mats, both in dry and moist conditions, the effects of thick Cladonia spp. clumps, and of living vs dead moss shoots and lichen podetia. Overall, Festuca seedlings emerged best whereas the small-seeded species, Arenaria and Veronica , had the lowest emergence. Moisture had a significant effect only on the emergence of Festuca seedlings, which emerged better in the dry treatment than in the moist. A thick moss cover negatively affected seedling emergence of Arenaria and Veronica but did not affect the emergence of Festuca. Filipendula showed lower seedling emergence in both thick and thin moss than on bare soil only in the dry treatment, whereas in the moist treatment emergence did not differ among the three substrates. Arenaria seedlings emerged less in thick and thin moss than on bare soil in the dry treatment, whereas in the moist treatment emergence in the thin moss was not different from bare soil. Thus, in relatively dry environments even a thin moss cover may inhibit rather than facilitate seedling emergence. The lichen clumps inhibited only the emergence of the forbs. Both living moss shoots and lichen podetia inhibited emergence of Veronica seedlings but did not affect Festuca. In contrast, emergence in the presence of dead mosses and lichens did not differ from emergence in their absence for both species. Hence, inhibition of seedling emergence by bryophytes and lichens of at least some vascular plant species may be mediated by some biotic factor. However, the effect of differences in substrate properties on germination cannot be excluded [source] Tree age is a key factor for the conservation of epiphytic lichens and bryophytes in beech forestsAPPLIED VEGETATION SCIENCE, Issue 1 2009Örjan Fritz Abstract Questions: What factors limit the distribution of epiphytic lichens and bryophytes at plot and tree level in beech forests? At what ages do epiphytic species, and species of conservation concern in particular, occur along a chronosequence of beech? Location: South-west Sweden. Method: Five hundred and seventy-one age-determined trees from 37 plots distributed among 29 beech-dominated stands were surveyed along with a number of environmental (16) and substrate (seven) variables in a landscape of ca. 550 ha. Non-metric multidimensional scaling (NMS) and indicator species analysis (ISA) were used for data analysis. Results: Plots containing old trees, confined to the base of slopes and with low impacts of recent forestry (thinning), generally had a high richness of species of conservation concern. Richness of common species and red-listed bryophytes were mostly related to the surveyed bark area. At tree level, primary factors explaining both species richness and composition were age, diameter at breast height and moss cover. There was a gradual replacement of tree age ranges for 58 lichens and 37 bryophytes along the chronosequence of beech. Red-listed lichens favoured damaged beech trees (,180 years), whereas red-listed bryophytes were found on old and young stems in dense stands. Conclusions: Tree age exerts a profound influence on epiphytic lichens and bryophytes growing on beech. Many of the habitat specialists were found mainly on old beech because they inhabit specific substrates that occur on older trees. The association to high tree age commonly excludes red-listed lichens from conventionally managed beech forests with a 100- to 140-year rotation period. [source] | |||||||||||||