Liv Guri Velle

Research Scientist

(+47) 997 71 177
liv.guri.velle@nibio.no

Place
Trondheim

Visiting address
Klæbuveien 153, bygg C 1.etasje, 7031 Trondheim

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Abstract

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Abstract

Questions During the winter of 2014, an intense drought combined with sub-zero temperatures resulted in a massive Calluna dieback in Norwegian heathlands. We studied the initial vegetation recovery under two management approaches: natural recovery and prescribed burning. We hypothesized that natural recovery will be slower in more drought-affected sites, whereas burning will facilitate post-fire recovery in all sites by effectively removing dead and damaged heath. Both natural recovery and post-fire succession will be slower in the north. Location Calluna heath in seven sites spanning an approx. 600-km latitudinal gradient along the coast of Norway (60.22–65.69° N). Methods After a natural drought, 10 permanent plots per site were either burnt or left for natural recovery. Vegetation data were recorded annually in 2016 (pre-fire) and 2017–2019 (post-fire) reflecting a factorial repeated-measures design (n = 280). The data were analyzed using mixed-effects models. Results Two years after the drought, we observed high but variable Calluna damage and mortality. Over the four years of study, damaged Calluna recovered, whereas dead Calluna showed little recovery. Both the extent of the damage and mortality, as well as the rate of natural recovery, are only weakly related to site climate or environmental factors. Fire efficiently removed dead and damaged Calluna and facilitated post-fire successional dynamics and recovery in a majority of sites. Conclusions Extreme winter drought resulted in substantial and often persistent damage and dieback on Calluna along the latitudinal gradient. In sites with high mortality, prescribed burning removed the dead biomass and, in some cases, facilitated vegetation recovery. Traditional heathland management, which uses burning to facilitate all-year grazing by Old Norse sheep in Atlantic coastal heathlands, can be an efficient tool to mitigate dieback events and more generally to increase resistance to and resilience after extreme drought events in the future.

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In the last decade, several major dwarf-shrub dieback events have occurred in northern European coastal heathlands. These dieback events occur after extended periods with sub-zero temperatures under snow-free conditions and clear skies, suggesting that coastal heathlands have low resistance to winter drought. As climate projections forecast increased drought frequency, intensity, and duration, coastal heathlands are likely to experience more such diebacks in the future. There are, however, few empirical studies of drought impacts and responses on plant communities in humid oceanic ecosystems. We established a drought experiment with two distinct levels of intensified drought to identify responses and thresholds of drought resistance in coastal heathland vegetation. We repeated the experiment in two regions, separated by five degrees latitude, to represent different bioclimatic conditions within the coastal heathlands' wide latitudinal range in Europe. As coastal heathlands are semi-natural habitats managed by prescribed fire, and we repeated the experiment across three post-fire successional phases within each region. Plant community structure, annual primary production, and primary and secondary growth of the dominant dwarf-shrub Calluna vulgaris varied between climate regions. To our surprise, these wide-ranging vegetation- and plant-level response variables were largely unaffected by the drought treatments. Consequently, our results suggest that northern, coastal heathland vegetation is relatively resistant to substantial intensification in drought. This experiment represents the world's wettest (2200 mm year−1) and northernmost (65°8'N) drought experiment to date, thus filling important knowledge gaps on ecological drought responses in high-precipitation and high-latitude ecosystems across multiple phases of plant community succession.

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Sustainable nature management and ecosystem conservation depends critically on scientifically sound and stakeholder-relevant analytical frameworks for monitoring and assessing ecological condition. Several general frameworks are currently being developed internationally, including the Essential Biodiversity Variables (EBV), and the UN’s SEEA EEA Ecosystem Condition Typology (ECT). However, there has so far been few attempts to develop empirical implementations of these general frameworks, or to assess their applicability for environmental decision-making at national or regional scales. In this paper, we aim to fill this implementation gap by demonstrating a practical application of an empirically-based ecological condition assessment framework, the Index-Based Ecological Condition Assessment (IBECA). IBECA defines seven major classes of indicators of ecological condition, representing distinct ecosystem characteristics, and empirically synthesizes indicators for each of these characteristics from various monitoring data. We exemplify and explore the utility and robustness of IBECA using a case study from forest and alpine ecosystems in central Norway, and we investigate how IBECA aligns with the two international frameworks EBV and ECT. In particular, we analyze how the different approaches to categorize indicators into classes affect the assessment of ecological condition, both conceptually and using the case study indicators. We used eleven indicators for each of the two ecosystems and assessed the ecological condition according to IBECA for i) each individual indicator, ii) the seven ecosystem characteristics (indicator classes), and iii) a synthetic ecological condition value for the whole ecosystem. IBECA challenges key concepts of the international frameworks and illustrates practical challenges for national or regional level implementation. We identify three main strengths with the IBECA approach: i) it provides a transparent and management-relevant quantitative approach allowing assessment of spatio-temporal variation in ecological condition across indicators, characteristics and ecosystems, ii) the high degree of flexibility and transparency facilitates updating the ecological condition assessments, also back in time, as improved data and knowledge of indicators emerge, and iii) the quantitative and flexible procedure makes it a cost-effective approach suitable for fast management implementations. More generally, we stress the need for carefully choosing appropriate classification and aggregation approaches in ecological condition assessments, and for transparent and data-driven analytical approaches that can be adjusted as knowledge improves.

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The combined impact of climate and land-use change poses increasing threats to nature and nature's benefit to people. The LandPress project makes use of the severe Norwegian winter-drought in 2014 as a case study; and combines geographical, ecological and social science approaches to explore the drivers of ecosystem resilience to drought die-back, the ecological processes and implications of drought responses, and management options for mitigating damage and costs. First, by means of remote sensing, we assess the role of climate, environment and land-use in regulating resilience of Calluna heaths to drought die-back locally and along a biogeographic gradient. We find that drought-damage in heather varies across landscapes, and can be quantified by aerial photos, allowing us to establish that both environment (slope) and land-use (prescribed fire) influence ecosystem resistance to drought. Second, we conduct a drought experiment to understand and assess the impacts of severe drought events on coastal heathland ecosystem dynamics and functioning. After the three first years we find only weak effects on plant communities, but distinct responses in plant functional traits suggesting that ecosystem resistance to drought decreases with time since the last prescribed fire. Third, we experimentally assess whether prescribed burning can be used to promote Calluna's resilience after severe drought, and find that prescribed burning efficiently removes damaged heather, stimulating post-fire vegetation development and restore ecosystem functioning after drought. Finally, we conduct a cost-benefit analysis to understand the contribution of land management to the provision of ecosystem services, with focus on securing low fire-risk landscapes. We find that management has more benefits than food production; land-use can reduce the extent of extreme drought, reduce fire risk and help us keep the ecosystem functioning. Our project demonstrates the importance of understanding how interactions between climate-change and land-use and is crucial in developing new management strategies.

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Effective evidence-based nature conservation and habitat management relies on developing and refining our methodological toolbox for detecting critical ecological changes at an early stage. This requires not only optimizing the use and integration of evidence from available data, but also optimizing methods for dealing with imperfect knowledge and data deficiencies. For policy and management relevance, ecological data are often synthesized into indicators, which are assessed against reference levels and limit values. Here we explore challenges and opportunities in defining ecological condition in relation to a reference condition reflecting intact ecosystems, as well as setting limit values for good ecological condition, linked to critical ecological thresholds in dose–response relationships between pressures and condition variables. These two concepts have been widely studied and implemented in aquatic sciences, but rarely in terrestrial systems. In this paper, we address practical considerations, theoretical challenges and possible solutions using different approaches to determine reference and limit values for good ecological condition in terrestrial ecosystems, based on empirical experiences from a case study in central Norway. We present five approaches for setting indicator reference values for intact ecosystems: absolute biophysical boundaries, reference areas, reference communities, ecosystem dynamics based models, and habitat availability based models. We further present four approaches for identifying indicator limit values for good ecological condition: empirically estimated values, statistical distributions, assumed linear relationships, and expert judgement-based limits. This exercise highlights the versatile and robust nature of ecological condition assessments based on reference and limit values for different management purposes, for situations where knowledge of the underlying relationships is lacking, and for situations limited by data availability. Ecological condition Index Management Reference condition Terrestrial

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Changes in land-use and climate represent major threats to Atlantic heathlands, and extreme climatic events, such as droughts, are likely to increase in frequency and intensity in the future. This is of particular relevance for nature management, and conservation, as extreme events are expected to have system-wide impacts on species and ecosystems. During the winter of 2014 an intense drought combined with low temperatures resulted in a massive dieback of Calluna vulgaris in the Norwegian heathlands, and two severe heathland wildfires occurred. With this as a background, a new Norwegian research project: Land use management to ensure ecosystem service delivery under new societal and environmental pressures in heathlands (LandPress) were initiated. LandPress combines observational data on ecosystem responses and resilience after the 2014 event with targeted experiments, one of them the International Drought Experiment, integrating our project into an international context. Drought impacts in mature Calluna-stands is investigated along a 650-km latitudinal gradient in Norway. Our first results indicate more drought damage in northern heathlands than in southern. Healthy Calluna was only observed in scattered patches with more suitable micro-climate, and, interestingly, in some areas regenerating after recent prescribed management burning. Moreover, drying experiments to learn how quickly Calluna plants dry up at 20°C and 50% relative humidity from rain-wet conditions showed that old Calluna stands represents a severe fire risk within two days. Young and more vigorous plants in the building phase (6–15 years old), as well as freeze drought damaged (typically some dead small branches), old but still live plants, showed different drying characteristics and dried more slowly. LandPress interlaces five work packages, exploring the impact of land-use change in combination with extreme climatic events in terms of vegetation change, ecosystem resilience, ecosystem services provisioning, sustainability, and evidence-based management and fire risk prevention.

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The 2015-2018 PROMAC (Energy efficient Processing of Macroalgae in blue-green value chains) is financed by the Norwegian Research Council. The PROMAC consortium is led by Møreforsking AS and consists of both Norwegian (SINTEF, NIBIO, NTNU, NMBU) and European (CEVA, MATIS, SLU)research institutes, as well as industrial partners (TafjordKraftvarme, FelleskjøpetFôrutvikling, Firmenich, LegaseaBiomarine Cluster, The Northern Company, Orkla Foods, Hortimare, Marinox).An advisory panel with public authority and interest groups from the marine, energy and agricultural sectors, also oversee the 4,5Mill EUR project’s relevance in a societal context.The current approaches to meeting the demands for meat and other protein-rich food sources are often associated with damage to natural resources and negative effects on climate, air quality, soils and fresh water availability. Therefore, the PROMAC project (http://promac.no/) investigates an alternative approach for providing food and sources of proteins and energy in animal feed, and health benefits in human food through cultivation of macroalgae. The project focuses on the three macroalgaespecies Alariaesculenta, Saccharinalatissima andPalmariapalmata.The research project (i) assesses variation of raw material composition and quality from both harvested and cultured macroalgae, (ii) develops primary processing methods enhancing desired raw material properties, (iii) establishes fractionation and extraction methods best suited to enrich beneficial proteins or remove undesirable anti-nutrients and (iv) evaluates nutritional and health values of processed macroalgal ingredients for various animal groups and in relation to their distinct digestive systems.PROMAC assesses the costs and benefits of macroalgal products from a value chain perspective (from raw material to primary market) through process-based Life Cycle Assessment (LCA), Material and Energy Flow Analysis (MEFA) and business models. To reduce the substantial energy required for primary processing of macroalgae - organisms characterized by ahigh-water content - PROMAC includes a case study utilizing excess heat from a waste incinerator for primary drying and processing of macroalgae biomass. This case study is integrated into both environmental and economic models.Initialresults identifyingmacroalgae food and feed products (ingredients)and associatedprocessing methods most relevant for commercial applications, will be presented integrated across work packages and subject fields.

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Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly inv asive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestr ial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distr i- bution modelling to test for a region effect on each species’ climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with str ictly disjunct populations and 58 species (16%) of the 358 species with distant popula- tions showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species’ climatic niche is constant in space and time – at least on time scales 10 4 years or less – seems to be largely valid for arctic–alpine plants.

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Recent studies from mountainous areas of small spatial extent (<2,500 km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2,500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT), and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1,000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically- and geographically-derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 46-72% of variation in LmT and 92-96% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 60-65°N and increased with terrain roughness, averaging 1.97°C (SD = 0.84°C) and 2.68°C (SD = 1.26°C) within the flattest and roughest units, respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32°C km-1) than spatial turnover in growing-season GiT (0.18°C km-1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.

Abstract

Kystlyngheiane nordvest i Europa er eit gammalt kulturlandskap som har blitt kontinuerleg skjøtta gjennom sviing og beiting i minst 5000 år. Vegetasjonen er i stor grad karakterisert av lyngplanter, men med variasjonar i plantesamansettinga både mellom geografiske regionar, og i forhold til bruk. Opphøyr av tradisjonell drift har ført til at kystlyngheiane i dag er klassifisert som trua i heile Europa, og har kome på raudlista over naturtypar i Noreg. Auka fokus på ivaretaking av kystlyngheiane har gjort det nødvendig å betre kunnskapsstatusen kring skjøtsel av dette kulturlandskapet. Velle undersøkjer korleis sviing i kombinasjon med beiting må tilpassast den biogeografiske nord-sør gradienten langs kysten. Stadig fleire av dei norske kystlyngheiane er i dårleg hevd, og Velle kvantifiserer korleis høg røsslyngalder påverkar gjenveksten av vegetasjon etter sviing. Vidare vert det undersøkt om bruken i kystlyngheiane fører til ein auke av artar med stor geografisk utbreiing etter sviing (biotisk homogenisering), og om røykindusert spiring i røsslyngfrø kan vere ein kulturbetinga eigenskap i dette økosystemet. Arbeidet til Velle syner at lyngsviing saman med beiting framleis har ei viktig rolle i skjøtselen av kystlynghei, både for å hindre gjengroing, for å få meir variasjon i plantesamansetnaden og for å fornye røsslyngen. Geografi, veksestad (habitat) og alder på røsslyngplanta påverkar vegetasjonssamansettinga og vekstraten til vegetasjonen etter sviing, noko ein må ein ta omsyn til i utarbeiding og oppfølging av skjøtselsplanar. Arbeidet peikar på at ulikskapar i regenereringsevne hos røsslyng gjer at brannrotasjonar bør bestemmast ut i frå røsslyngen sin vekst og ikkje alder. Velle syner at gammal kystlynghei har eit restaureringspotensiale, og at artane som kjem inn etter sviing er naturlege artar som høyrer til i dette økosystemet. Dette er det første arbeidet som antydar at røykindusert spiring hos røsslyngfrø langs kysten her til lands skuldast ei evolusjonær tilpassing til skjøtsel, og syner viktigheita lyngsviinga har hatt over tid.