ResearchPad - nonvascular-plants https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Flavonoids and antioxidant activity of rare and endangered fern: <i>Isoetes sinensis</i>]]> https://www.researchpad.co/article/elastic_article_7844 Isoetes sinensis Palmer is a critically endangered, first-class protected plant in China. Until now, researchers have primarily focused on the ultrastructure, phylogeny, and transcriptomes of the plant. However, flavonoid profiles and bioactivity of I. sinensis have not been extensively investigated. To develop the endangered I. sinensis for edible and medicinal purposes, flavonoid content, chemical constitution, and antioxidant activities were investigated in this study. Results revealed the following. 1) The total flavonoid content was determined as 10.74 ± 0.25 mg/g., 2) Antioxidant activities were stronger than most ferns, especially ABTS free radical scavenging activities. 3) Four flavones, containing apigenin, apigenin-7-glucuronide, acacetin-7-O-glcopyranoside, and homoplantageninisoetin; four flavonols, namely, isoetin, kaempferol-3-O-glucoside, quercetin-3-O-[6”-O-(3-hydroxy-3-methylglutaryl)-β-D-glucopyranoside], and limocitrin-Neo; one prodelphinidin (procyanidins;) and one nothofagin (dihydrochalcone) were tentatively identified in the mass spectrometry-DAD (254nm) chromatograms. This study was the first to report on flavonoid content and antioxidant activities of I. sinensis. Stronger antioxidant activity and flavonoid content suggests that the endangered I. sinensis is an important and potentially edible and medicinal plant.

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<![CDATA[The long journey of Orthotrichum shevockii (Orthotrichaceae, Bryopsida): From California to Macaronesia]]> https://www.researchpad.co/article/5c6dca01d5eed0c48452a691

Biogeography, systematics and taxonomy are complementary scientific disciplines. To understand a species’ origin, migration routes, distribution and evolutionary history, it is first necessary to establish its taxonomic boundaries. Here, we use an integrative approach that takes advantage of complementary disciplines to resolve an intriguing scientific question. Populations of an unknown moss found in the Canary Islands (Tenerife Island) resembled two different Californian endemic species: Orthotrichum shevockii and O. kellmanii. To determine whether this moss belongs to either of these species and, if so, to explain its presence on this distant oceanic island, we combined the evaluation of morphological qualitative characters, statistical morphometric analyses of quantitative traits, and molecular phylogenetic inferences. Our results suggest that the two Californian mosses are conspecific, and that the Canarian populations belong to this putative species, with only one taxon thus involved. Orthotrichum shevockii (the priority name) is therefore recognized as a morphologically variable species that exhibits a transcontinental disjunction between western North America and the Canary Islands. Within its distribution range, the area of occupancy is limited, a notable feature among bryophytes at the intraspecific level. To explain this disjunction, divergence time and ancestral area estimation analyses are carried out and further support the hypothesis of a long-distance dispersal event from California to Tenerife Island.

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<![CDATA[Does Spore Ultrastructure Mirror Different Dispersal Strategies in Mosses? A Study of Seven Iberian Orthotrichum Species]]> https://www.researchpad.co/article/5989dadbab0ee8fa60bb9f8f

Most mosses have xerochastic dispersal (i.e., they open their capsules when conditions are dry), which is thought to favor long-distance dispersal. However, there are several species that use a hygrochastic strategy: spores are dispersed when conditions are wet. The significance of this strategy in the Mediterranean region is unknown. In this study, we explored whether ultrastructural features related to differences in spore resistance may explain these different strategies of spore dispersal. To this end, we examined the ultrastructural features of the spores of seven closely related species in the moss genus Orthotrichum. These species all grow as epiphytes in sub-Mediterranean forests, and the group includes both xerochastic and hygrochastic members. First, we found that the spore wall layers exhibit several features previously undescribed in mosses. Second, we discovered that there are only subtle differences in spore ultrastructure with regards to spore wall thickness, the degree of plastid development, or the storage substances used. We suggest that the hygrochastic dispersal in mosses from Mediterranean environments might be related to a safe-site strategy, rather than to drought avoidance, and we underscore the necessity of conducting spore ultrastructural studies on a greater number of bryophyte species.

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<![CDATA[Classification and identification of Rhodobryum roseum Limpr. and its adulterants based on fourier-transform infrared spectroscopy (FTIR) and chemometrics]]> https://www.researchpad.co/article/5989db51ab0ee8fa60bdc4d0

Fourier-transform infrared spectroscopy (FTIR) with the attenuated total reflectance technique was used to identify Rhodobryum roseum from its four adulterants. The FTIR spectra of six samples in the range from 4000 cm−1 to 600 cm−1 were obtained. The second-derivative transformation test was used to identify the small and nearby absorption peaks. A cluster analysis was performed to classify the spectra in a dendrogram based on the spectral similarity. Principal component analysis (PCA) was used to classify the species of six moss samples. A cluster analysis with PCA was used to identify different genera. However, some species of the same genus exhibited highly similar chemical components and FTIR spectra. Fourier self-deconvolution and discrete wavelet transform (DWT) were used to enhance the differences among the species with similar chemical components and FTIR spectra. Three scales were selected as the feature-extracting space in the DWT domain. The results show that FTIR spectroscopy with chemometrics is suitable for identifying Rhodobryum roseum and its adulterants.

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<![CDATA[Performance of Forest Bryophytes with Different Geographical Distributions Transplanted across a Topographically Heterogeneous Landscape]]> https://www.researchpad.co/article/5989da40ab0ee8fa60b89aa9

Most species distribution models assume a close link between climatic conditions and species distributions. Yet, we know little about the link between species' geographical distributions and the sensitivity of performance to local environmental factors. We studied the performance of three bryophyte species transplanted at south- and north-facing slopes in a boreal forest landscape in Sweden. At the same sites, we measured both air and ground temperature. We hypothesized that the two southerly distributed species Eurhynchium angustirete and Herzogiella seligeri perform better on south-facing slopes and in warm conditions, and that the northerly distributed species Barbilophozia lycopodioides perform better on north-facing slopes and in relatively cool conditions. The northern, but not the two southern species, showed the predicted relationship with slope aspect. However, the performance of one of the two southern species was still enhanced by warm temperatures. An important reason for the inconsistent results can be that microclimatic gradients across landscapes are complex and influenced by many climate-forcing factors. Therefore, comparing only north- and south-facing slopes might not capture the complexity of microclimatic gradients. Population growth rates and potential distributions are the integrated results of all vital rates. Still, the study of selected vital rates constitutes an important first step to understand the relationship between population growth rates and geographical distributions and is essential to better predict how climate change influences species distributions.

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<![CDATA[Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests]]> https://www.researchpad.co/article/5989db10ab0ee8fa60bcbca3

Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights into the important ecological associations between understory plant community composition and heterogeneity in ecosystem properties and processes within forests dominated by a single canopy species.

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<![CDATA[Non-Destructive Lichen Biomass Estimation in Northwestern Alaska: A Comparison of Methods]]> https://www.researchpad.co/article/5989daa0ab0ee8fa60ba5a8e

Terrestrial lichen biomass is an important indicator of forage availability for caribou in northern regions, and can indicate vegetation shifts due to climate change, air pollution or changes in vascular plant community structure. Techniques for estimating lichen biomass have traditionally required destructive harvesting that is painstaking and impractical, so we developed models to estimate biomass from relatively simple cover and height measurements. We measured cover and height of forage lichens (including single-taxon and multi-taxa “community” samples, n = 144) at 73 sites on the Seward Peninsula of northwestern Alaska, and harvested lichen biomass from the same plots. We assessed biomass-to-volume relationships using zero-intercept regressions, and compared differences among two non-destructive cover estimation methods (ocular vs. point count), among four landcover types in two ecoregions, and among single-taxon vs. multi-taxa samples. Additionally, we explored the feasibility of using lichen height (instead of volume) as a predictor of stand-level biomass. Although lichen taxa exhibited unique biomass and bulk density responses that varied significantly by growth form, we found that single-taxon sampling consistently under-estimated true biomass and was constrained by the need for taxonomic experts. We also found that the point count method provided little to no improvement over ocular methods, despite increased effort. Estimated biomass of lichen-dominated communities (mean lichen cover: 84.9±1.4%) using multi-taxa, ocular methods differed only nominally among landcover types within ecoregions (range: 822 to 1418 g m−2). Height alone was a poor predictor of lichen biomass and should always be weighted by cover abundance. We conclude that the multi-taxa (whole-community) approach, when paired with ocular estimates, is the most reasonable and practical method for estimating lichen biomass at landscape scales in northwest Alaska.

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<![CDATA[PnLRR-RLK27, a novel leucine-rich repeats receptor-like protein kinase from the Antarctic moss Pohlia nutans, positively regulates salinity and oxidation-stress tolerance]]> https://www.researchpad.co/article/5989db4fab0ee8fa60bdbbed

Leucine-rich repeats receptor-like kinases (LRR-RLKs) play important roles in plant growth and development as well as stress responses. Here, 56 LRR-RLK genes were identified in the Antarctic moss Pohlia nutans transcriptome, which were further classified into 11 subgroups based on their extracellular domain. Of them, PnLRR-RLK27 belongs to the LRR II subgroup and its expression was significantly induced by abiotic stresses. Subcellular localization analysis showed that PnLRR-RLK27 was a plasma membrane protein. The overexpression of PnLRR-RLK27 in Physcomitrella significantly enhanced the salinity and ABA tolerance in their gametophyte growth. Similarly, PnLRR-RLK27 heterologous expression in Arabidopsis increased the salinity and ABA tolerance in their seed germination and early root growth as well as the tolerance to oxidative stress. PnLRR-RLK27 overproduction in these transgenic plants increased the expression of salt stress/ABA-related genes. Furthermore, PnLRR-RLK27 increased the activities of reactive oxygen species (ROS) scavengers and reduced the levels of malondialdehyde (MDA) and ROS. Taken together, these results suggested that PnLRR-RLK27 as a signaling regulator confer abiotic stress response associated with the regulation of the stress- and ABA-mediated signaling network.

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<![CDATA[Moss Mediates the Influence of Shrub Species on Soil Properties and Processes in Alpine Tundra]]> https://www.researchpad.co/article/5989d9e6ab0ee8fa60b6b30e

In tundra ecosystems, bryophytes influence soil processes directly and indirectly through interactions with overstory shrub species. We experimentally manipulated moss cover and measured seasonal soil properties and processes under two species of deciduous shrubs with contrasting canopy structures, Salix planifolia pulchra and Betula glandulosa-nana complex. Soil properties (seasonal temperature, moisture and C:N ratios) and processes (seasonal litter decomposition and soil respiration) were measured over twelve months. Shrub species identity had the largest influence on summer soil temperatures and soil respiration rates, which were higher under Salix canopies. Mosses were associated with lower soil moisture irrespective of shrub identity, but modulated the effects of shrubs on winter soil temperatures and soil C:N ratios so that moss cover reduced differences in soil winter temperatures between shrub species and reduced C:N ratios under Betula but not under Salix canopies. Our results suggest a central role of mosses in mediating soil properties and processes, with their influence depending on shrub species identity. Such species-dependent effects need to be accounted for when forecasting vegetation dynamics under ongoing environmental changes.

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<![CDATA[Sequencing of small RNAs of the fern Pleopeltis minima (Polypodiaceae) offers insight into the evolution of the microrna repertoire in land plants]]> https://www.researchpad.co/article/5989db5aab0ee8fa60bdf77f

MicroRNAs (miRNAs) are short, single stranded RNA molecules that regulate the stability and translation of messenger RNAs in diverse eukaryotic groups. Several miRNA genes are of ancient origin and have been maintained in the genomes of animal and plant taxa for hundreds of millions of years, playing key roles in development and physiology. In the last decade, genome and small RNA (sRNA) sequencing of several plant species have helped unveil the evolutionary history of land plants. Among these, the fern group (monilophytes) occupies a key phylogenetic position, as it represents the closest extant cousin taxon of seed plants, i.e. gymno- and angiosperms. However, in spite of their evolutionary, economic and ecological importance, no fern genome has been sequenced yet and few genomic resources are available for this group. Here, we sequenced the small RNA fraction of an epiphytic South American fern, Pleopeltis minima (Polypodiaceae), and compared it to plant miRNA databases, allowing for the identification of miRNA families that are shared by all land plants, shared by all vascular plants (tracheophytes) or shared by euphyllophytes (ferns and seed plants) only. Using the recently described transcriptome of another fern, Lygodium japonicum, we also estimated the degree of conservation of fern miRNA targets in relation to other plant groups. Our results pinpoint the origin of several miRNA families in the land plant evolutionary tree with more precision and are a resource for future genomic and functional studies of fern miRNAs.

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<![CDATA[Total flavonoid concentrations of bryophytes from Tianmu Mountain, Zhejiang Province (China): Phylogeny and ecological factors]]> https://www.researchpad.co/article/5989db50ab0ee8fa60bdbd9e

The flavonoids in bryophytes may have great significance in phylogeny and metabolism research. However, to date there has been little research on bryophyte metabolites, especially flavonoids. To redress this somewhat, we determined flavonoid concentrations of bryophytes from Tianmu Mountain through a colorimetric assay and considered the factors influencing the results. This is the first time that the flavonoid contents of bryophytes have been examined in detail. The results revealed a range of total flavonoid concentrations in 90 samples collected from Tianmu Mountain from 1.8 to 22.3 mg/g (w/w). The total flavonoid contents of liverworts were generally higher than those of mosses; acrocarpous mosses had generally higher values than that of pleurocarpous mosses. The total flavonoid contents of bryophytes growing at lower light levels were general higher than those growing in full-sun. The total flavonoid contents of epiphytic bryophytes were highest, while those of aquatic bryophytes were the lowest. Total flavonoid contents of species growing at low-latitudes were much higher than those at high-latitude individuals. In conclusion, total flavonoid contents of bryophytes have some connection with plant phylogeny; more flavonoids might be contained in relatively primitive bryophytes. Meanwhile, the effects of ecological factors on total flavonoid contents of bryophytes exist; light and habitat (especially tree habitat and river habitat) might be representative factor.

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<![CDATA[Abiotic Determinants of the Historical Buildings Biodeterioration in the Former Auschwitz II – Birkenau Concentration and Extermination Camp]]> https://www.researchpad.co/article/5989d9f1ab0ee8fa60b6ea85

The paper presents the results of a study conducted at the Auschwitz-Birkenau State Museum in Oświęcim on the occurrence of biodeterioration. Visual assessment of the buildings revealed signs of deterioration of the buildings in the form of dampness, bulging and crumbling plaster, and wood fiber splitting. The external surfaces, and especially the concrete strips and ground immediately adjoining the buildings, were colonized by bryophytes, lichens, and algae. These organisms developed most intensively close to the ground on the northern sides of the buildings. Inside the buildings, molds and bacteria were not found to develop actively, while algae and wood-decaying fungi occurred locally. The factors conducive to biological corrosion in the studied buildings were excessive dampness of structural partitions close to the ground and a relative air humidity of above 70%, which was connected to ineffective moisture insulation. The influence of temperature was smaller, as it mostly affected the quantitative composition of the microorganisms and the qualitative composition of the algae. Also the impact of light was not very strong, but it was conducive to algae growth.

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<![CDATA[Plastidial α-glucan phosphorylase 1 complexes with disproportionating enzyme 1 in Ipomoea batatas storage roots for elevating malto-oligosaccharide metabolism]]> https://www.researchpad.co/article/5989db5aab0ee8fa60bdf569

It has been proposed that malto-oligosaccharides (MOSs) are possibly recycled back into amylopectin biosynthesis via the sequential reactions catalyzed by plastidial α-glucan phosphorylase 1 (Pho1) and disproportionating enzyme 1 (Dpe1). In the present study, the reciprocal co-immunoprecipitation experiments using specific antibodies against Pho1 and Dpe1 demonstrated that these two enzymes can form a complex (the PD complex) in Ipomoea batatas storage roots. The immunohistochemistry analyses also revealed the co-localization of Pho1 and Dpe1 in the amyloplasts, and the protein levels of Pho1 and Dpe1 increased gradually throughout sweet potato storage root development. A high molecular weight PD complex was co-purified from sweet potato storage root lysates by size exclusion chromatography. Enzyme kinetic analyses showed that the PD complex can catalyze maltotriose and maltotetraose to generate glucose-1-phosphate in the presence of inorganic phosphate, and it also performs greater Dpe1 activity toward MOSs than does free form Dpe1. These data suggest that Pho1 and Dpe1 may form a metabolon complex, which provides elevated metabolic fluxes for MOS metabolism via a direct transfer of sugar intermediates, resulting in recycling of glucosyl units back into amylopectin biosynthesis more efficiently.

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<![CDATA[Impacts of fire on non-native plant recruitment in black spruce forests of interior Alaska]]> https://www.researchpad.co/article/5989db4fab0ee8fa60bdbac6

Climate change is expected to increase the extent and severity of wildfires throughout the boreal forest. Historically, black spruce (Picea mariana (Mill.) B.S.P.) forests in interior Alaska have been relatively free of non-native species, but the compounding effects of climate change and an altered fire regime could facilitate the expansion of non-native plants. We tested the effects of wildfire on non-native plant colonization by conducting a seeding experiment of non-native plants on different substrate types in a burned black spruce forest, and surveying for non-native plants in recently burned and mature black spruce forests. We found few non-native plants in burned or mature forests, despite their high roadside presence, although invasion of some burned sites by dandelion (Taraxacum officinale) indicated the potential for non-native plants to move into burned forest. Experimental germination rates were significantly higher on mineral soil compared to organic soil, indicating that severe fires that combust much of the organic layer could increase the potential for non-native plant colonization. We conclude that fire disturbances that remove the organic layer could facilitate the invasion of non-native plants providing there is a viable seed source and dispersal vector.

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<![CDATA[Chronic Nitrogen Deposition Has a Minor Effect on the Quantity and Quality of Aboveground Litter in a Boreal Forest]]> https://www.researchpad.co/article/5989dad2ab0ee8fa60bb6821

There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal soils. However, key underlying mechanisms explaining this increase have not been resolved. Two potentially important mechanisms are that aboveground litter production increases, or that litter quality changes in response to N enrichment. As such, our aim was to quantify whether simulated chronic N deposition caused changes in aboveground litter production or quality in a boreal forest. We conducted a long-term (17 years) stand-scale (0.1 ha) forest experiment, consisting of three N addition levels (0, 12.5, and 50 kg N ha-1 yr-1) in northern Sweden, where background N deposition rates are very low. We measured the annual quantity of litter produced for 8 different litter categories, as well as their concentrations of C, N, phosphorus (P), lignin, cellulose and hemi-cellulose. Our results indicate that mosses were the only major litter component showing significant quantitative and qualitative alterations in response to the N additions, indicative of their ability to intercept a substantial portion of the N added. These effects were, however, offset by the other litter fractions where we found no changes in the total litter fluxes, or individual chemical constituents when all litter categories were summed. This study indicates that the current annual litter fluxes cannot explain the increase in soil C that has occurred in our study system in response to simulated chronic N application. These results suggest that other mechanisms are likely to explain the increased soil C accumulation rate we have observed, such as changes in soil microbial activity, or potentially transient changes in aboveground litter inputs that were no longer present at the time of our study.

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<![CDATA[Predictors of Current and Longer-Term Patterns of Abundance of American Pikas (Ochotona princeps) across a Leading-Edge Protected Area]]> https://www.researchpad.co/article/5989da9dab0ee8fa60ba4652

American pikas (Ochotona princeps) have been heralded as indicators of montane-mammal response to contemporary climate change. Pikas no longer occupy the driest and lowest-elevation sites in numerous parts of their geographic range. Conversely, pikas have exhibited higher rates of occupancy and persistence in Rocky Mountain and Sierra Nevada montane ‘mainlands’. Research and monitoring efforts on pikas across the western USA have collectively shown the nuance and complexity with which climate will often act on species in diverse topographic and climatic contexts. However, to date no studies have investigated habitat, distribution, and abundance of pikas across hundreds of sites within a remote wilderness area. Additionally, relatively little is known about whether climate acts most strongly on pikas through direct or indirect (e.g., vegetation-mediated) mechanisms. During 2007–2009, we collectively hiked >16,000 km throughout the 410,077-ha Glacier National Park, Montana, USA, in an effort to identify topographic, microrefugial, and vegetative characteristics predictive of pika abundance. We identified 411 apparently pika-suitable habitat patches with binoculars (in situ), and surveyed 314 of them for pika signs. Ranking of alternative logistic-regression models based on AICc scores revealed that short-term pika abundances were positively associated with intermediate elevations, greater cover of mosses, and taller forbs, and decreased each year, for a total decline of 68% during the three-year study; whereas longer-term abundances were associated only with static variables (longitude, elevation, gradient) and were lower on north-facing slopes. Earlier Julian date and time of day of the survey (i.e., midday vs. not) were associated with lower observed pika abundance. We recommend that wildlife monitoring account for this seasonal and diel variation when surveying pikas. Broad-scale information on status and abundance determinants of montane mammals, especially for remote protected areas, is crucial for land and wildlife-resource managers trying to anticipate mammalian responses to climate change.

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<![CDATA[Impact of Land-Use Intensity and Productivity on Bryophyte Diversity in Agricultural Grasslands]]> https://www.researchpad.co/article/5989db03ab0ee8fa60bc78bf

While bryophytes greatly contribute to plant diversity of semi-natural grasslands, little is known about the relationships between land-use intensity, productivity, and bryophyte diversity in these habitats. We recorded vascular plant and bryophyte vegetation in 85 agricultural used grasslands in two regions in northern and central Germany and gathered information on land-use intensity. To assess grassland productivity, we harvested aboveground vascular plant biomass and analyzed nutrient concentrations of N, P, K, Ca and Mg. Further we calculated mean Ellenberg indicator values of vascular plant vegetation. We tested for effects of land-use intensity and productivity on total bryophyte species richness and on the species richness of acrocarpous (small & erect) and pleurocarpous (creeping, including liverworts) growth forms separately. Bryophyte species were found in almost all studied grasslands, but species richness differed considerably between study regions in northern Germany (2.8 species per 16 m2) and central Germany (6.4 species per 16 m2) due environmental differences as well as land-use history. Increased fertilizer application, coinciding with high mowing frequency, reduced bryophyte species richness significantly. Accordingly, productivity estimates such as plant biomass and nitrogen concentration were strongly negatively related to bryophyte species richness, although productivity decreased only pleurocarpous species. Ellenberg indicator values for nutrients proved to be useful indicators of species richness and productivity. In conclusion, bryophyte composition was strongly dependent on productivity, with smaller bryophytes that were likely negatively affected by greater competition for light. Intensive land-use, however, can also indirectly decrease bryophyte species richness by promoting grassland productivity. Thus, increasing productivity is likely to cause a loss of bryophyte species and a decrease in species diversity.

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<![CDATA[Forests Regenerating after Clear-Cutting Function as Habitat for Bryophyte and Lichen Species of Conservation Concern]]> https://www.researchpad.co/article/5989dae1ab0ee8fa60bbbf1b

The majority of managed forests in Fennoscandia are younger than 70 years old but yet little is known about their potential to host rare and threatened species. In this study, we examined red-listed bryophytes and lichens in 19 young stands originating from clear-cutting (30–70 years old) in the boreal region, finding 19 red-listed species (six bryophytes and 13 lichens). We used adjoining old stands, which most likely never had been clear-cut, as reference. The old stands contained significantly more species, but when taking the amount of biological legacies (i.e., remaining deciduous trees and dead wood) from the previous forest generation into account, bryophyte species number did not differ between old and young stands, and lichen number was even higher in young stands. No dispersal effect could be detected from the old to the young stands. The amount of wetlands in the surroundings was important for bryophytes, as was the area of old forest for both lichens and bryophytes. A cardinal position of young stands to the north of old stands was beneficial to red-listed bryophytes as well as lichens. We conclude that young forest plantations may function as habitat for red-listed species, but that this depends on presence of structures from the previous forest generation, and also on qualities in the surrounding landscape. Nevertheless, at repeated clear-cuttings, a successive decrease in species populations in young production stands is likely, due to increased fragmentation and reduced substrate amounts. Retention of dead wood and deciduous trees might be efficient conservation measures. Although priority needs to be given to preservation of remnant old-growth forests, we argue that young forests rich in biological legacies and located in landscapes with high amounts of old forests may have a conservation value.

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<![CDATA[Experimentally Induced Repeated Anhydrobiosis in the Eutardigrade Richtersius coronifer]]> https://www.researchpad.co/article/5989daafab0ee8fa60baada6

Tardigrades represent one of the main animal groups with anhydrobiotic capacity at any stage of their life cycle. The ability of tardigrades to survive repeated cycles of anhydrobiosis has rarely been studied but is of interest to understand the factors constraining anhydrobiotic survival. The main objective of this study was to investigate the patterns of survival of the eutardigrade Richtersius coronifer under repeated cycles of desiccation, and the potential effect of repeated desiccation on size, shape and number of storage cells. We also analyzed potential change in body size, gut content and frequency of mitotic storage cells. Specimens were kept under non-cultured conditions and desiccated under controlled relative humidity. After each desiccation cycle 10 specimens were selected for analysis of morphometric characteristics and mitosis. The study demonstrates that tardigrades may survive up to 6 repeated desiccations, with declining survival rates with increased number of desiccations. We found a significantly higher proportion of animals that were unable to contract properly into a tun stage during the desiccation process at the 5th and 6th desiccations. Also total number of storage cells declined at the 5th and 6th desiccations, while no effect on storage cell size was observed. The frequency of mitotic storage cells tended to decline with higher number of desiccation cycles. Our study shows that the number of consecutive cycles of anhydrobiosis that R. coronifer may undergo is limited, with increased inability for tun formation and energetic constraints as possible causal factors.

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<![CDATA[Ice-cover is the principal driver of ecological change in High Arctic lakes and ponds]]> https://www.researchpad.co/article/5989db52ab0ee8fa60bdc757

Recent climate change has been especially pronounced in the High Arctic, however, the responses of aquatic biota, such as diatoms, can be modified by site-specific environmental characteristics. To assess if climate-mediated ice cover changes affect the diatom response to climate, we used paleolimnological techniques to examine shifts in diatom assemblages from ten High Arctic lakes and ponds from Ellesmere Island and nearby Pim Island (Nunavut, Canada). The sites were divided a priori into four groups (“warm”, “cool”, “cold”, and “oasis”) based on local elevation and microclimatic differences that result in differing lengths of the ice-free season, as well as about three decades of personal observations. We characterized the species changes as a shift from Condition 1 (i.e. a generally low diversity, predominantly epipelic and epilithic diatom assemblage) to Condition 2 (i.e. a typically more diverse and ecologically complex assemblage with an increasing proportion of epiphytic species). This shift from Condition 1 to Condition 2 was a consistent pattern recorded across the sites that experienced a change in ice cover with warming. The “warm” sites are amongst the first to lose their ice covers in summer and recorded the earliest and highest magnitude changes. The “cool” sites also exhibited a shift from Condition 1 to Condition 2, but, as predicted, the timing of the response lagged the “warm” sites. Meanwhile some of the “cold” sites, which until recently still retained an ice raft in summer, only exhibited this shift in the upper-most sediments. The warmer “oasis” ponds likely supported aquatic vegetation throughout their records. Consequently, the diatoms of the “oasis” sites were characterized as high-diversity, Condition 2 assemblages throughout the record. Our results support the hypothesis that the length of the ice-free season is the principal driver of diatom assemblage responses to climate in the High Arctic, largely driven by the establishment of new aquatic habitats, resulting in increased diversity and the emergence of novel growth forms and epiphytic species.

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