Lichen specific thallus mass and secondary compounds change across a retrogressive fire-driven chronosequence

In the long-term absence of major disturbances ecosystems enter a state of retrogression, which involves declining soil fertility and consequently a reduction in decomposition rates. Recent studies have looked at how plant traits such as specific leaf mass and amounts of secondary compounds respond to declining soil fertility during retrogression, but there are no comparable studies for lichen traits despite increasing recognition of the role that lichens can play in ecosystem processes. We studied a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. We used this system to explore how specific thallus mass (STM) and carbon based secondary compounds (CBSCs) change in three common epiphytic lichen species (Hypogymnia phsyodes, Melanohalea olivacea and Parmelia sulcata) as soil fertility declines during this retrogression. We found that STMs of lichens increased sharply during retrogression, and for all species soil N to P ratio (which increased during retrogression) was a strong predictor of STM. When expressed per unit area, medullary CBSCs in all species and cortical CBSCs in P. sulcata increased during retrogression. Meanwhile, when expressed per unit mass, only cortical CBSCs in H. physodes responded to retrogression, and in the opposite direction. Given that lichen functional traits are likely to be important in driving ecological processes that drive nutrient and carbon cycling in the way that plant functional traits are, the changes that they undergo during retrogression could potentially be significant for the functioning of the ecosystem

Contrasting changes in palatability following senescence of the lichenized fungi Lobaria pulmonaria and L. scrobiculata

Epiphytic lichens can contribute significantly to ecosystem nutrient input because they efficiently accumulate atmospheric mineral nutrients and, in the case of cyanolichens, also fix nitrogen. The rate at which carbon and other nutrients gained by lichens enters the ecosystem is determined by lichen litter decomposability and by invertebrate consumption of lichen litter. In turn, these processes are driven by the secondary compounds present in senesced lichens. Therefore, we explored how lichen palatability and concentrations of secondary compounds change with tissue senescence for Lobaria pulmonaria, a green algal lichen with cyanobacterial cephalodia, and L. scrobiculata, a cyanobacterial lichen. During senescence both lichens lost 38-48% of their stictic acid chemosyndrome, while m-scrobiculin and usnic acid in L. scrobiculata remained unchanged. Snails preferred senesced rather than fresh L. pulmonaria, while senesced L. scrobiculata were avoided. This provides evidence that species with labile secondary compounds will have higher turnover rates, through consumption and decomposition, than those producing more stable secondary compounds

Strategic management - An online collaboration between two class groups separated by a "small pond" and six time zones

An undergraduate course in Strategic Management seemingly provides similar basic content to students including the infamous SWOT (strengths, weaknesses, opportunities and threat) analysis along with the identification of functional level, business level, and generic strategies to enhance an organization’s competitiveness. One of the most common resources for this type of course is the article outlining a theoretical framework “How Competitive Forces Shape Strategy” by Michael Porter [Porter, 1979]. This paper discusses the differences and similarities of teaching an undergraduate Strategic Management course for two different institutions located in different countries. Secondly, the paper addresses the logistics of connecting the two separate student groups for a collaboration project using an on-line platform. Additionally, the paper shares the experiences learned when students work in multi-culturally mixed groups to analyze an industry around Michael Porter’s framework [Porter, 1979]

Simulated global warming increases usnic acid but reduces perlatolic acid in the mat-forming terricolous lichen Cladonia stellaris

Lichens as sessile and slow-growing symbiotic associations have evolved various carbon-based secondary compounds (CBSCs) to mitigate the effects of some stressors in the extreme environments in which they often grow. The mat-forming lichen Cladonia stellaris, an important fodder for reindeer, produces usnic acid in the outermost layer and perlatolic acid in the medulla. Here, we studied effects of simulated global warming on these CBSCs in C. stellaris cultivated in climate chambers with: 1) ambient conditions as control or 2) ambient conditions +4°C. The chambers simulated, at an hourly resolution, an averaged 10-year growing season dynamic from a long-term monitored boreal mire in northern Sweden. After two months of acclimation, +4°C warming in one simulated growing season increased the concentration of usnic acid by 31% compared with ambient conditions, whereas the warming decreased the concentration of perlatolic acid by 14%. Since lichen CBSCs play important roles in ecosystem processes such as lichenivory and decomposition, these changes may profoundly affect lichen-dominated ecosystems.acceptedVersio

Microclimatic comparison of lichen heaths and shrubs: Shrubification generates atmospheric heating but subsurface cooling during the growing season

Lichen heaths are declining in abundance in alpine and Arctic areas partly due to an increasing competition with shrubs. This shift in vegetation types might have important consequences for the microclimate and climate on a larger scale. The aim of our study is to measure the difference in microclimatic conditions between lichen heaths and shrub vegetation during the growing season. With a paired plot design, we measured the net radiation, soil heat flux, soil temperature and soil moisture on an alpine mountain area in southern Norway during the summer of 2018 and 2019. We determined that the daily net radiation of lichens was on average 3.15 MJ (26 %) lower than for shrubs during the growing season. This was mainly due to a higher albedo of the lichen heaths but also due to a larger longwave radiation loss. Subsequently, we estimate that a shift from a lichen heath to shrub vegetation leads to an average increase in atmospheric heating of 3.35 MJ d−1 during the growing season. Surprisingly, the soil heat flux and soil temperature were higher below lichens than below shrubs during days with high air temperatures. This implies that the relatively high albedo of lichens does not lead to a cooler soil compared to shrubs during the growing season. We predict that the thicker litter layer, the presence of soil shading and a higher evapotranspiration rate at shrub vegetation are far more important factors in explaining the variation in soil temperature between lichens and shrubs. Our study shows that a shift from lichen heaths to shrub vegetation in alpine and Arctic areas will lead to atmospheric heating, but it has a cooling effect on the subsurface during the growing season, especially when air temperatures are relatively high.publishedVersio

Організаційна структура управління маркетингом на підприємстві

Som en avslutande del i kandidatarbetet inom mekatronik år 2013 gavs uppgiften att konstruera en robot åt pop-artisten Robyn. Arbetet är ett grupparbete där fem teknologer med specialiseringar inom olika områden samarbetar för att konstruera ett mera komplext, sammansatt system. De krav som ställdes var att roboten skulle kunna interagera, antingen med Robyn själv eller hennes publik. De begränsningar som fanns var tidsmässiga så väl som ekonomiska. I en förstudie identifierades viktiga nyckelord baserat på Robyn och hennes musik. Nyckelorden lades som grund för den efterföljande konceptgenereringen. Exempel på nyckelord var självständighet, folkkär, egensinnig och oväntad. Arbetet resulterade i en robot som kan kommunicera via Twitter, dansa i takt till omgivande musik samt skapa olika ljuseffekter. Hela roboten är byggd i ett hölje lånat från en gammal radio från 60-talet. Roboten är inte tänkt att vara en fulländad konstruktion utan illustrerar ett koncept med stor utvecklingspotential.As a final part of the bachelor thesis in mechatronics 2013 the students were given the task to design a robot to pop artist Robyn. The work is a group project in which five students with specializations in different fields collaborate to construct a more complex, composite system. The requirements were that the robot would be able to interact either with Robyn herself or her audience. The project was limited by time as well as economics. In a preliminary study important keywords based on Robyn and her music were established. The key words became the basis for the subsequent concept generation. Examples of keywords are independence, publicly loved, headstrong and unpredictable. The work resulted in a robot that can communicate via Twitter, dancing to the beat of the music, and create different lighting effects. The entire robot is built in a housing from an old radio from the 60's. The robot is by no means a perfect design, but illustrate a concept with great potential

Spatial variation of surface soil carbon in a boreal forest – the role of historical fires, contemporary vegetation, and hydro-topography

Knowledge about the spatial variation of boreal forest soil carbon (C) stocks is limited, but crucial for establishing management practices that prevent losses of soil C. Here, we quantified the surface soil C stocks across small spatial scales, and aim to contribute to an improved understanding of the drivers involved in boreal forest soil C accumulation. Our study is based on C analyses of 192 soil cores, positioned and recorded systematically within a forest area of 11 ha. The study area is a south-central Norwegian boreal forest landscape, where the fire history for the past 650 years has been reconstructed. Soil C stocks ranged from 1.3 to 96.7 kg m−2 and were related to fire frequency, ecosystem productivity, vegetation attributes, and hydro-topography. Soil C stocks increased with soil nitrogen concentration, soil water content, Sphagnum- and litter-dominated forest floor vegetation, and proportion of silt in the mineral soil, and decreased with fire frequency in site 1, feathermoss- and lichen-dominated forest floor vegetation and increasing slope. Our results emphasize that boreal forest surface soil C stocks are highly variable in size across fine spatial scales, shaped by an interplay between historical forest fires, ecosystem productivity, forest floor vegetation, and hydro-topography.Spatial variation of surface soil carbon in a boreal forest – the role of historical fires, contemporary vegetation, and hydro-topographyacceptedVersio

Divergent responses of functional diversity to an elevational gradient for vascular plants, bryophytes and lichens

Question: Cold environments are stressful for vascular plants, and stress-tolerant non-vascular photoautotrophs, e.g. bryophytes and lichens, become relatively more important as competition from vascular plants decreases towards higher elevations. Under increasingly stressful climatic conditions, species assembly of vascular plants is commonly driven more by environmental filtering, and abiotic constraints may lead to increased similarity between species and thus low functional diversity. Because bryophytes and lichens are less constrained by harsh environments, environmental filtering may be less strong. Instead, reduced competition from vascular plants can potentially free up niche space for non-vascular vegetation. Therefore, we hypothesized that functional diversity of vascular plants, bryophytes and lichens are likely to show contrasting responses to elevation. Location: Finse Alpine Research Centre, Southern Norway. Methods: We utilized measurements of species abundance and functional traits of the three groups along a 500-m elevational gradient in alpine southern Norway and calculated multi-trait and single-trait functional dispersion. Results: Functional diversity of vascular plants declined with elevation, indicating increased environmental filtering. By contrast, functional diversity of lichens and bryophytes increased along the same gradient, suggesting they are less exposed to environmental filtering, in line with our hypothesis. Instead, they likely benefit from the lower abundance of vascular plants at higher elevation. Conclusions: Our findings suggest that different photoautotroph groups vary in how they respond to the same environmental gradient, which may contribute to contrasting community assembly processes across groups. These divergent responses likely occur because non-vascular vegetation differs from vascular plants in terms of nutrient acquisition and water economy strategies, meaning that they respond differently to the same factors. This highlights the need to explicitly consider bryophytes and lichens in community-level studies whenever these groups are abundant.acceptedVersio

Legacy effects of experimental environmental change on soil micro-arthropod communities

© 2020 The Authors. Global change experiments such as experimental warming and nutrient addition strongly affect the structure and functioning of high latitude and altitude ecosystems. However, it is often unknown to what extend such effects are permanent or whether changes persist after environmental conditions return to pre-treatment levels. In this study, we assess the legacy effects of temperature manipulation and nutrient addition experiments on alpine soil micro-arthropod (i.e., Collembola and Oribatida) communities nine years after the treatments were discontinued. Treatment effects on the vegetation were still detectable six years after cessation, although grazing increased the recovery rate. Because micro-arthropods are often closely associated with vegetation, we expected to find that treatment effects on Collembola and Oribatida abundance and species composition persisted to date, reflecting plant community dynamics. Also, we expected large-bodied, drought-resistant Collembola species that live on top of the soil to show less strong legacy effects. We did not find legacy effects of environmental treatments on Collembola and Mesostigmata in terms of abundance. However, we found persistent changes in community composition of Collembola and Oribatida, suggesting treatment effects persist to date. The generalist Folsomia quadrioculata was the most responsive Collembola species to initial treatments, most likely due to its variable life-history strategy. Although its abundance recovered, F. quadrioculata remained dominant in Collembola communities after cessation of the treatments. Grazing affected community composition of both Collembola and Oribatida, but we did not find grazing to reduce legacy effects on micro-arthropod as it did for vegetation. We therefore conclude that the environmental treatments had only temporary effects on micro-arthropods in terms of overall abundance, but that effects on individual species and therefore species composition may be long-lasting and less predictable.The study was designed by Johan Asplund, Juha M. Alatalo, and Kari Klanderud. Field work was performed by Ruben Erik Roos, Johan Asplund, Kari Klanderud, and Tone Birkemoe. Peter Ľuptáčik and Natália Raschmanová identified soil micro‐arthropods for 2016. Statistical analyses were performed by Ruben Erik Roos and Siri Lie Olsen. All co‐authors contributed to manuscript revisions and agree with the final version. This study was funded by Carl Tryggers stiftelse för vetenskaplig forskning through a grant to Juha M. Alatalo and a grant from the Research Council of Norway (249902) to Johan Asplund. We thank Sigmund Hågvar for sharing his original data, comments and feedback, Hans Cornelissen and Stef Bokhorst for useful discussions, and Matty Berg for sharing data from his personal Collembola database. Mari Steinert, Ross Wetherbee, Mahdieh Tourani, and Richard Bischof were of great help for discussions on the statistical analyses. We thank the Finse Alpine Research Center and Erika Leslie for hospitality during fieldwork and Kristel van Zuijlen for assistance in the field