Factors at multiple scales influence the composition of terricolous lichen communities in temperate semi-arid sandy grasslands

Inland dune ecosystems are rich in terricolous lichen species. However, these communities are sensitive to human activities, both locally and globally. Since terricolous lichens have a dominant role in semi-arid sandy grasslands, it is important to explore the composition of their communities and the environmental factors affecting them. We studied the structure of the terricolous lichen assemblages of calcareous grassland in an inland duneland ecosystem by comparing the lichen communities of arid and humid dune sides on two sites with different disturbance histories. Microcoenological data were collected according to the Braun-Blanquet method. Environmental variables include the cover of bare soil, moss, litter, herb cover and height of herbs. We investigated the relationship of these variables and the presence and absence data of terricolous lichen species to sites and dune side. We found that the site had a significant effect on species richness that might reflect the different types and severity of previous disturbance events at the studied sites. On a smaller, ‘dune’ scale, in general lower herb cover and height and a higher moss cover were characteristic of arid dune sides. Most of the frequent species were negatively affected by higher moss cover. Some lichen species were more abundant (e.g. Cladonia furcata) or found only (e.g. Xanthoparmelia subdiffluens, Gyalolechia fulgens) on arid dune sides, while others preferred (e.g. C. pyxidata) or occurred only on (e.g. Peltigera species, C. rei) humid sides. It was observed that the impact of the dune side on several variables differed between sites. The diverse microhabitat types, microclimate and landscape structure, results in species-rich and valuable terricolous lichen communities forming in inland dune ecosystems.

Mosses are Important for Soil Carbon Sequestration in Forested Peatlands

Nutrient-rich peat soils have previously been demonstrated to lose carbon despite higher photosynthesis and litter production compared to nutrient-poor soils, where instead carbon accumulates. To understand this phenomenon, we used a process-oriented model (CoupModel) calibrated on data from two closely located drained peat soil sites in boreal forests in Finland, Kalevansuo and Lettosuo, with different soil C/N ratios. Uncertainty-based calibrations were made using eddy-covariance data (hourly values of net ecosystem exchange) and tree growth data. The model design used two forest scenarios on drained peat soil, one nutrient-poor with dense moss cover and another with lower soil C/N ratio with sparse moss cover. Three vegetation layers were assumed: conifer trees, other vascular plants, and a bottom layer with mosses. Adding a moss layer was a new approach, because moss has a modified physiology compared to vascular plants. The soil was described by three separate soil organic carbon (SOC) pools consisting of vascular plants and moss litter origin and decomposed organic matter. Over 10 years, the model demonstrated a similar photosynthesis rate for the two scenarios, 903 and 1,034 g C m−2 yr−1, for the poor and rich site respectively, despite the different vegetation distribution. For the nutrient-rich scenario more of the photosynthesis produce accumulated as plant biomass due to more trees, while the poor site had abundant moss biomass which did not increase living aboveground biomass to the same degree. Instead, the poor site showed higher litter inputs, which compared with litter from vascular plants had low turnover rates. The model calibration showed that decomposition rate coefficients for the three SOC pools were similar for the two scenarios, but the high quantity of moss litter input with low decomposability for the nutrient poor scenario explained the major difference in the soil carbon balance. Vascular plant litter declined with time, while SOC pools originating from mosses accumulated with time. Large differences between the scenarios were obtained during dry spells where soil heterotrophic respiration doubled for the nutrient-rich scenario, where vascular plants dominated, owing to a larger water depletion by roots. Where moss vegetation dominated, the heterotrophic respiration increased by only 50% during this dry period. We suggest moss vegetation is key for carbon accumulation in the poor soil, adding large litter quantities with a resistant quality and less water depletion than vascular plants during dry conditions.

On the effect of different moss species on soil erosion, percolation and carbon relocation

<p>For decades, soil erosion has been a major environmental problem as it degrades the most productive soil layers, which threatens, among other things, food production worldwide. Although these effects have been known for a long time, there are still a variety of challenges to mitigating soil erosion in different ecosystems. As climate change progresses, the risk of soil loss increases, making the preparation of effective solutions very urgent. A current research focus is on the restoration of a protective soil cover following disturbances in the vegetation layer, e.g., through the reestablishment of biological soil crust communities. These are often dominated by bryophytes in humid climates. So far, several studies examined the general protective influence of bryophytes against soil erosion, however only few of them addressed how individual species affect specific erosion processes in detail.</p><p>To fill this research gap we investigated the impact of six moss species on soil erosion, percolation and carbon relocation by means of rainfall simulations. Therefore, we used topsoil substrate from four sites in the Schönbuch Nature Park in South Germany which covers different kinds of bedrock and varying soil texture and pH. Subsequently, they were sieved by 6.3 mm and filled into metal infiltration boxes (40 x 30 cm) up to a height of 6.5 cm. The moss species differ in origin (either collected in the field or cultivated in the lab) as well as growth form (pleurocarpous or acrocarpous). Rainfall simulations were performed for bare soil substrates, as well as for moss-covered soil substrates six months later and both in dry and wet conditions. Additionally, we conducted rainfall simulations with leaf and coniferous litter on bare soil substrates. During the simulations we monitored soil moisture in two position - 3 cm depth plus soil surface - with biocrust wetness probes (BWP) and quantified surface runoff, percolation and sediment discharge. Afterwards we determined carbon contents of the sediment and dissolved organic carbon in the liquid phase of runoff and percolated water.</p><p>While surface runoff was increased by 5% due to the litter cover compared to the bare soil substrate, sediment discharge decreased to 97%. Runoff rates could also be mitigated by 90 % as a result of the moss cover. Furthermore, due to the dense moss cover sediment rates were almost reduced to zero. Preliminary results show that there are differences between the moss species in terms of sediment discharge, but not in context with runoff. The analyses of carbon contents in surface runoff and the percolated water are still in progress, as is the evaluation of the BWP measurements. These outcomes will be presented at vEGU21.</p>

Current State of Forest Moss Communities after Reduction of Emissions from the Middle-Ural Copper Smelter

The moss cover of forests in an 50×36 km area around the Middle-Ural Copper Smelter was analyzed after almost complete reduction of its emissions. It has been shown that the moss communities in the low and high pollution zones differ significantly in composition, number and frequency of species, but are characterized by a similar cover of ground mosses. The frequency of most species in the high pollution zones, compared to the low pollution zones, was decreased. A significant increase of the frequency in the pollution gradient was found for Pohlia nutans only. Species loss was expressed more strongly on the mesoscale (species richness within a community) than on the macroscale (the total number of species in a pollution zone). The elimination of species under increasing pollution was revealed for species with a low (up to 40%) initial frequency. Despite of the almost complete cessation of emissions from the smelter, the moss cover in the high pollution zones remains severely damaged and is formed by a single species (Pohlia nutans) over a significant area. However, localities with high species richness and high similarity of composition with the background communities occur even under high pollution conditions. The presence of such localities, in combination with a considerable time lag before the extinction of species from the study area as a whole, may have major significance for recolonization of degraded areas after emission reduction.

The status of Listera cordata cenopopulation in the nurgush state nature reserve

The census of Listera was conducted on routes with a total length of 11.05 km on 2020. The width of the recording transect was 10 m. In suitable habitats, plants were located in relatively dense groups, separated from each other by considerable distances. We have revealed 31 subpopulations of Listera with a total of 283 generative shoots and 1949 vegetative ones. The density of Listera in the surveyed habitats was 3.50 ind./ha, density in the subpopulations was from 5 to 13 ind./sq.m, on the average 6.81 ind./sq.m. All the Subpopulations were confined to areas of moss cover dominated by sphagnum mosses, but with the obligatory presence of Polytrichum commune and hypnum mosses. The setting and ripening of Listera fruits in 2020 were high: fruits were developed from 84% of flowers. The Tulashor site of the Nurgush State Nature Reserve plays an important role for the conservation of Listera cordata in the Kirov region.

Pigment Composition of Sphagnum fuscum of Wetlands under Anthropogenic Impact

Oligotrophic bogs prevail among wetlands in the mainland of the North of Russia. The study of the moss cover response to the increase in anthropogenic load makes it possible to reveal a shift in the ecological balance of bog ecosystems. The goаl of the research is to reveal changes in the pigment apparatus of the moss cover under drainage, road construction and mining operation as in the case of the Arkhangelsk region. Sphagnum fuscum (Schimp.) H. Klinggr. was used as the main object for studying the pigment composition of the photosynthetic apparatus. A change in the pigment composition during the drainage of bogs was found when comparing the pigments of S. fuscum moss on the undisturbed Ilas bog massif and the drained bog massif “Ovechye”; the content of carotenoids decreases and the content of chlorophyll a increases. The influence of the traffic load was studied in an open wetland of the Mezen district, where there is no tree-shrub layer. Succession of dominant species is observed in the moss-lichen layer of the bog in the immediate vicinity of the road (34 m); the projective cover of sphagnum mosses decreases to less than 10 %, and brie mosses emerge as dominants. The content of all analyzed pigments in moss samples increases with the distance from unpaved roads, especially the content of chlorophylls (>5 times at a distance of 100 m and more). As an example of the anthropogenic impact of a mining enter prise, we used terricones of the Lomonosov Mining and Processing Plant, PJSC Severalmaz, from which aeolian transport of dust particles of rocks containing saponite occurs. Near the pollution source, the content of total moss pigments is noticeably lower than in the area protected by a forest belt. A decrease in the proportion of chlorophylls a and b with a slight increase in the content of carotenoids was found in the pigment complex. The changes are due to the transfer of saponite; a clay mineral that actively absorbs water. The increased moisture provides favorable conditions for the moss vegetation, which mitigates the negative effect of pollutants on the pigment apparatus of plants. Overall, pigments content change represents plants adaptation to the adverse impacts and anthropogenic pressing.

Role of the bryophytes in substrate revitalization on a post-technogenic salinized territory

This work aims to investigate the role of the bryophyte cover in substrate revitalization on a post-technogenic salinized territory. The influence of the moss cover on the organic carbon content, actual acidity, redox potential, and the content of the main ecological and trophic groups of microorganisms in the substrate of the tailings storage of the Stebnyk Mining and Chemical Enterprise "Polymineral" was investigated. Bryophytes significantly affect the tailings storage saline substrates. They colonize areas with a very strong and strong degree of salinity, which are unsuitable for other plants. It was indicated that pioneer moss species promote the accumulation of organic matter in saline substrates of the tailings storage. Under moss turfs, the amount of organic carbon increased 2.2–5.0 times, compared with its content in the uncovered substrate. The high variability of the organic matter content is determined by the species characteristics of mosses, primarily their life form. The dense-turf species Didymodon rigidulus and Pthychostomum pseudotriquetrum var. bimum accumulated the most organic matter. The thickness of the litter under the moss turf of these species was much greater than in Barbula unguiculata and Funaria hygrometrica, which form loose turf. We assessed the specificity of the accumulation of organic carbon in the turfs of the studied mosses. It founded that most organic matter accumulated in the dead parts of the moss turf. In the green parts of the shoots of these moss species the amount of organic carbon was 3–4 times less, which indicates a relationship between litter capacity and content of carbon in the substrate under moss turfs. We investigated the influence of mosses on the actual acidity of the tailings storage substrate. Moss turfs promote the increase of acidity of the aqueous solution of the tailings substrate by 0.2–0.5 units. The tailings storage substrates are characterized by a reduction regime. The redox potential of the substrate under moss cover significantly depended on the species characteristics of mosses. Under the moss cover, the redox potential increased by 1.2–1.4 times, compared with the index for the substrate without moss cover. We studied the influence of moss cover on microbial biomass and the quantity of some ecological-trophic groups of microorganisms in the substrates of the tailings storage. The amount of microbial biomass under moss turfs increased depending on the degree of the substrate salinization and the species characteristics of the mosses. In areas with a very high degree of salinization under the moss turfs of Didymodon rigidulus and Funaria hygrometrica, the microbial biomass index increased almost two times, compared with the uncovered substrate. We found a significant increase in the quantity of the main ecological and trophic groups of microorganisms (saprophytes, cellulose-destroying bacteria, oligonitrophils and nitrogen fixers) in the substrate under the moss cover. Thus, pioneer moss species have a complex effect on the saline substrate of tailings storage. They accumulate organic matter, increase the acidity of the upper layer, improve the redox regime of the substrate and promote the development of soil microbiota.

Post-wildfire moss colonisation and soil functional enhancement in forests of the southwestern USA

Fire mosses, including Ceratodon purpureus, Funaria hygrometrica and Bryum argenteum, can achieve high cover within months to years after high-severity fire, but do so heterogeneously across space and time. We conducted a survey of moss cover and erosion-related functions after 10 wildfires in Pinus ponderosa and mixed-conifer forests of the southwestern USA. We sampled 65 plots in high-severity patches, stratifying by elevation and insolation over each fire. Using three landscape-scale predictor variables and one temporal predictor, we explained 37% of the variance in fire moss cover using a random forest model. The predictors in order of importance were: equinox insolation (sunlight/day), pre-fire vegetation type, pre-fire soil organic carbon and time since fire. Within each plot we examined differences between bare and moss-covered soil surface microsites and found moss-covered microsites had a mean increase of 55% water infiltration, 106% shear strength, 162% compressive strength and 195% aggregate stability. We tested a suite of nutrients, finding 35% less manganese in the moss-covered soil. This research demonstrated that post-fire colonisation by moss is predictable and that colonisation improves soil surface erosion resistance and hydrological function, with implications for managing severely burned landscapes.