Impacts of different climate change regimes and extreme climatic events on an alpine meadow community

Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversityNFR grant (B-AA/BU 08424) to UM

Visitors off the trail: Impacts on the dominant plant, bryophyte and lichen species in alpine heath vegetation in sub-arctic Sweden

Alpine ecosystems are under increasing pressure due to tourism and recreational activities. When leaving designated trails as is frequently observed, visitors can cause unintentional damage to vegetation. This study investigated the effect of human trampling on the dominant species of vascular plants, bryophytes and lichens along an infrequently used hiking trail in an alpine ecosystem in sub-arctic Sweden. The hypothesis tested was that proximity to the trail (as an effect of more people leaving the trail for a short distance compared to a longer distance) causes a decrease in species with low resistance to trampling. With a greater decrease in taller forbs and shrubs than in graminoids and prostrate plants, a greater decrease in lichen than in bryophyte species, and a change in vegetation composition. The results showed that proximity to the trail did not cause a decrease in the majority of dominant species, with none of the eight most dominant vascular plants showing any significant effects of proximity to the trail. One bryophyte species (Dicranum elongatum) among the six most commonly found decreased with proximity to the trail. Three lichen species (Cladonia arbuscula, Cladonia uncinalis, Ochrolechia frigida) among the eight most common species decreased with proximity to the trail. There was no evidence that taller species decreased with proximity to the trail, although the deciduous shrub Betula nana showed a tendency for a decrease. Proximity to the trail caused a greater decrease in lichen species than in bryophyte species. Multivariate analyses showed that distance from trail and transect direction had significant effects on overall vegetation composition. The level of low-intensity trampling recorded indicates that current numbers of hikers at the site can be sustained for longer periods with minimum impact on vascular plant species, but to get a more general understanding of the impact of low-intensity trampling data from additional sites are needed.The project was financially supported by Uppsala University, Carl Tryggers stiftelse för vetenskaplig forskning, and Qatar Petroleum (to JMA)

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

Effects of ambient climate and three warming treatments on fruit production in an alpine, subarctic meadow community

Premise Climate change is having major impacts on alpine and arctic regions, and inter‐annual variations in temperature are likely to increase. How increased climate variability will impact plant reproduction is unclear. Methods In a 4‐year study on fruit production by an alpine plant community in northern Sweden, we applied three warming regimes: (1) a static level of warming with open‐top chambers (OTC), (2) press warming, a yearly stepwise increase in warming, and (3) pulse warming, a single‐year pulse event of higher warming. We analyzed the relationship between fruit production and monthly temperatures during the budding period, fruiting period, and whole fruit production period and the effect of winter and summer precipitation on fruit production. Results Year and treatment had a significant effect on total fruit production by evergreen shrubs, Cassiope tetragona, and Dryas octopetala, with large variations between treatments and years. Year, but not treatment, had a significant effect on deciduous shrubs and graminoids, both of which increased fruit production over the 4 years, while forbs were negatively affected by the press warming, but not by year. Fruit production was influenced by ambient temperature during the previous‐year budding period, current‐year fruiting period, and whole fruit production period. Minimum and average temperatures were more important than maximum temperature. In general, fruit production was negatively correlated with increased precipitation. Conclusions These results indicate that predicted increased climate variability and increased precipitation due to climate change may affect plant reproductive output and long‐term community dynamics in alpine meadow communities.Qatar Petroleu

GrassPlot v. 2.00 – first update on the database of multi-scale plant diversity in Palaearctic grasslands

Abstract: GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phyto- coenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use, information on nestedness, structure and ecology) and preparation of species composition data. Currently, GrassPlot data are intensively used for broad-scale analyses of different aspects of alpha and beta diversity in grassland ecosystems

Can bryophyte groups increase functional resolution in tundra ecosystems?

Funding Information: This study was supported by a grant to SL from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie, Grant No. 797446 and by the Independent Research Fund Denmark, Grant no. 0135-00140B. Funding from the Academy of Finland (grant 322266), National Science Foundation (1504224, 1836839, PLR-1504381 and PLR-1836898), Independent Research Fund Denmark (9040-00314B), Moscow State University, (project No 121032500089-1), Natural Sciences and Engineering Research Council of Canada, ArcticNet, Polar Continental Shelf Program, Northern Science Training Program, Polar Knowledge Canada, Royal Canadian Mounted Police, Tomsk State University competitiveness improvement program and the Russian Science Foundation (grant No 20-67-46018) are gratefully acknowledged. Matthias Ahrens provided valuable insights on the cushion growth form, and we are most thankful. We thank Gaius Shaver and two anonymous reviewers for providing valuable critique and input to earlier versions of this manuscript. Publisher Copyright: © the author(s) or their institution(s).The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.Peer reviewe

Can bryophyte groups increase functional resolution in tundra ecosystems?

The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites

Patterns of species richness and vegetative performance in heath ecosystems at Thingvellir, Southwest Iceland

The Racomitrium lanuginosum (Hedw.) Brid. moss heath is a unique environment and is of great importance for co-occurring established vascular plants. A thick moss carpet can prevent or restrict the growth of vascular plants as they are exposed to more unfavourable growth conditions, but the effect on species richness and abundance is less known. To investigate the negative effects of a well-developed moss carpet on established vascular plants, patterns of species richness, shoot density, and number of leaves (Carex bigelowii Schwein. and Thalictrum alpinum L.) were studied in two different vegetation types, Racomitrium lanuginosum moss heath, and dwarf shrub heath in Þingvellir National Park, Southwest Iceland. Species richness was higher in dwarf shrub heath and increased proportionally with the size of the shrub patches. Total species richness and plant functional dominance did not differ between vegetation types. There were no differences found in shoot density, percentage of flowering and juveniles, number of leaves in Carex bigelowii, or shoot density, flowering percentage or number of leaves in Thalictrum alpinum between the vegetation types. However, leaf length of Carex bigelowii was higher in the dwarf shrubs heath, indicating more favourable growth conditions, shade or shelter effects. It is possible that translocation is taking place between the shoots of the clonal vascular plants in this study so that the plants themselves are counteracting unfavourable effects in the different vegetation types. The effect of global climatic change on moss heaths in Iceland is briefly discussed

LED och ekologiska effekter

LED har olika typer av ekologisk påverkan och kan i vissa fall leda till större effekter än traditionellt använd belysning. Samtidigt har LED potential att kunna utvecklas till en ekologisk neutral belysning. Det finns en rad olika saker man kan tänka på vid inköp av LED-lampor för att minimera ekologisk påverkan, såsom låg effektnivå, använda dimringsteknik, undvika oönskad ljusspridning och att försöka undvika lampor som har höga nivåer av våglängder under 500 nm