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Hasselquist, Eliza MaherORCID iD iconorcid.org/0000-0003-2152-245x
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Publications (10 of 10) Show all publications
Hasselquist, E. M., Polvi, L. E., Kahlert, M., Nilsson, C., Sandberg, L. & Mckie, B. G. (2018). Contrasting Responses among Aquatic Organism Groups to Changes in Geomorphic Complexity Along a Gradient of Stream Habitat Restoration: Implications for Restoration Planning and Assessment. Water, 10(10), Article ID 1465.
Open this publication in new window or tab >>Contrasting Responses among Aquatic Organism Groups to Changes in Geomorphic Complexity Along a Gradient of Stream Habitat Restoration: Implications for Restoration Planning and Assessment
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2018 (English)In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 10, no 10, article id 1465Article in journal (Refereed) Published
Abstract [en]

Many stream restoration projects aim to increase geomorphic complexity, assuming that this increases habitat heterogeneity and, thus, biodiversity. However, empirical data supporting these linkages remain scant. Previous assessments of stream restoration suffer from incomplete quantification of habitat complexity, or a narrow focus on only one organism group and/or one restoration measure, limiting learning. Based on a comprehensive quantification of geomorphic complexity in 20 stream reaches in northern Sweden, ranging from streams channelized for timber floating to restored and reference reaches, we investigated responses of macroinvertebrates, diatoms, and macrophytes to multiple geomorphic metrics. Sediment size heterogeneity, which was generally improved in restored sites, favored macroinvertebrate and diatom diversity and macroinvertebrate abundance. In contrast, macrophyte diversity responded to increased variation along the longitudinal stream profile (e.g., step-pools), which was not consistently improved by the restoration. Our analyses highlight the value of learning across multiple restoration projects, both in identifying which aspects of restoration have succeeded, and pinpointing other measures that might be targeted during adaptive management or future restoration. Given our results, a combination of restoration measures targeting not only sediment size heterogeneity, but also features such as step-pools and instream wood, is most likely to benefit benthic biota in streams.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
bioassessment, boreal, bryophyte, hydromorphology, riparian, river, substrate heterogeneity, woody bris
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:umu:diva-154362 (URN)10.3390/w10101465 (DOI)000451208400180 ()2-s2.0-85054984343 (Scopus ID)
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Hasselquist, E. M., Hasselquist, N. J., Sparks, J. P. & Nilsson, C. (2017). Recovery of nitrogen cycling in riparian zones after stream restoration using delta N-15 along a 25-year chronosequence in northern Sweden. Plant and Soil, 410(1-2), 423-436
Open this publication in new window or tab >>Recovery of nitrogen cycling in riparian zones after stream restoration using delta N-15 along a 25-year chronosequence in northern Sweden
2017 (English)In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 410, no 1-2, p. 423-436Article in journal (Refereed) Published
Abstract [en]

Swedish boreal streams were modified to transport timber by pushing boulders to stream sides, creating levees that disconnected streams from riparian areas. Many streams have since been restored and our goal was to understand how this affects riparian nitrogen (N) cycling. We compared the natural abundance of delta N-15 isotopes in foliage and roots of Filipendula ulmaria plus soils and litter along streams restored 2-25 years ago. We measured sources of N, potential immobilization of N, namely plant diversity and biomass, and the amount and sources of carbon (C) to determine if these were important for describing riparian N cycling. The delta N-15 of F. ulmaria foliage changed dramatically just after restoration compared to the channelized, disconnected state and then converged over the next 25 years with the steady-state reference. The disturbance and reconnection of the stream with the riparian zone during restoration created a short-term pulse of N availability and gaseous losses of N as a result of enhanced microbial processing of N. With increasing time since restoration, N availability appears to have decreased, and N sources changed to those derived from mycorrhizae, amino acids, or the humus layer, or there was enhanced N-use efficiency by older, more diverse plant communities.

Keywords
Boreal, Mycorrhizae, Phytometer, Space-for-time substitution, Succession, Time gradient
National Category
Ecology Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-131878 (URN)10.1007/s11104-016-3038-3 (DOI)000392392200032 ()
Available from: 2017-02-24 Created: 2017-02-24 Last updated: 2018-06-09Bibliographically approved
Hasselquist, E. M. (2015). Gradients of time and complexity: understanding how riparian and instream ecosystems recover after stream restoration. (Doctoral dissertation). Umeå: Umeå University
Open this publication in new window or tab >>Gradients of time and complexity: understanding how riparian and instream ecosystems recover after stream restoration
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Why evaluations of the ecological outcomes of stream and river restoration have largely reported inconclusive or negative results has been the subject of much debate over the last decade or more. Understanding the reasons behind the lack of positive results is important for bettering future restoration efforts and setting realistic expectations for restoration outcomes. This thesis explores possible explanations for why researchers have failed to find clear and predictable biotic responses to stream restoration: recovery time has been too short, that restoration of habitat complexity is not clearly linked to instream biodiversity, that one monitored organism group is not representative of the entire community, that restoration effort was not intense enough to restore the potential habitat complexity of a system, and that reach-scale restoration done in the presence of catchment-scale degradation obscures restoration results. The overarching goal of this thesis is to study the holistic effect of reach-scale restoration of historic reach-scale simplification, due to timber floating in northern Swedish streams, thus avoiding the added pressure of catchment-scale degradation typically found at most restoration sites (e.g., non-point-source pollution and impervious cover). Using this model system, I was able to show that it took 25 years for riparian plant species richness at restored sites to increase above that of channelized sites. Furthermore, it was clear that restoration of these streams caused a large and rapid change in N-processing in the riparian zone and this alteration persists for at least 25 years. Additionally, multiple metrics of geomorphic complexity were needed to explain some of the more subtle responses of organism groups. Macroinvertebrates, diatoms, and macrophytes did not respond concordantly and cannot serve as surrogates or indicators for each other. I found that older best practice methods of restoration rarely restored the large-scale features needed to bring the sites up to their potential complexity because these elements were destroyed or removed from the system. Advanced restoration techniques used in more recent restorations added big boulders and instream wood and increased complexity to a level that elicited a biological response. By combining surveys of multiple metrics of structure, diversity of multiple organism groups, and process in this thesis I was able to get a holistic view of the effects of restoration of streams after timber floating. We now know that it takes at least 25 years for riparian plants and N-cycling to recover, we understand that multiple metrics of geomorphic complexity should be measured to be able to explain biotic responses, and that restored complexity should better match the potential complexity of the site in order to elicit a biological response. Finally, we know that multiple organism groups need to be assessed when evaluating the response of biodiversity to restoration.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2015. p. 36
Keywords
bioassessment, biodiversity, boreal, bryophyte, chronosequence, complexity, diatom, geomorphology, habitat heterogeneity, hydromorphological, macroinvertebrate, macrophyte, nitrogen cycling, river restoration, riparian buffer, stable isotopes, succession, Sweden
National Category
Ecology
Research subject
biology, Environmental Science
Identifiers
urn:nbn:se:umu:diva-108079 (URN)978-91-7601-302-1 (ISBN)
Public defence
2015-09-25, Älgsalen, Uminova Science Park, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2015-09-04 Created: 2015-09-03 Last updated: 2018-06-07Bibliographically approved
Nilsson, C., Polvi, L. E., Gardeström, J., Maher Hasselquist, E., Lind, L. & Sarneel, J. M. (2015). Riparian and in-stream restoration of boreal streams and rivers: success or failure?. Ecohydrology, 8(5), 753-764
Open this publication in new window or tab >>Riparian and in-stream restoration of boreal streams and rivers: success or failure?
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2015 (English)In: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 8, no 5, p. 753-764Article in journal (Refereed) Published
Abstract [en]

We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration, but in most studies, they recovered after a few years. Riparian plants, macroinvertebrates and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber floating.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
recovery, restoration, streams, timber floating
National Category
Oceanography, Hydrology and Water Resources Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-107307 (URN)10.1002/eco.1480 (DOI)000358538800002 ()
Note

Special Issue:Restoring functional riparian ecosystems: concepts and applications

Available from: 2015-08-24 Created: 2015-08-21 Last updated: 2018-06-07Bibliographically approved
Hasselquist, E. M., Nilsson, C., Hjalten, J., Jørgensen, D., Lind, L. & Polvi, L. E. (2015). Time for recovery of riparian plants in restored northern Swedish streams: a chronosequence study. Ecological Applications, 25(5), 1373-1389
Open this publication in new window or tab >>Time for recovery of riparian plants in restored northern Swedish streams: a chronosequence study
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2015 (English)In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 25, no 5, p. 1373-1389Article in journal (Refereed) Published
Abstract [en]

A lack of ecological responses in stream restoration projects has been prevalent throughout recent literature with many studies reporting insufficient time for recovery. We assessed the relative importance of time, site variables, and landscape setting for understanding how plant species richness and understory productivity recover over time in riparian zones of northern Swedish streams. We used a space-for-time substitution consisting of 13 stream reaches restored 5-25 years ago, as well as five unrestored channelized reference reaches. We inventoried the riparian zone for all vascular plant species along 60-m study reaches and quantified cover and biomass in plots. We found that while species richness increased with time, understory biomass decreased. Forbs made up the majority of the species added, while the biomass of graminoids decreased the most over time, suggesting that the reduced dominance of graminoids favored less productive forbs. Species richness and density patterns could be attributed to dispersal limitation, with anemochorous species being more associated with time after restoration than hydrochorous, zoochorous, or vegetatively reproducing species. Using multiple linear regression, we found that time along with riparian slope and riparian buffer width (e.g., distance to logging activities) explained the most variability in species richness, but that variability in total understory biomass was explained primarily by time. The plant community composition of restored reaches differed from that of channelized references, but the difference did not increase over time. Rather, different time categories had different successional trajectories that seemed to converge on a unique climax community for that time period. Given our results, timelines for achieving species richness objectives should be extended to 25 years or longer if recovery is defined as a saturation of the accumulation of species over time. Other recommendations include making riparian slopes as gentle as possible given the landscape context and expanding riparian buffer width for restoration to have as much impact as possible.

Keywords
boreal forest, buffer strip, chronosequence, riparian buffer, riparian slope, river restoration, seed dispersal, space-for-time substitution, time gradient, vegetation
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-106561 (URN)10.1890/14-1102.1 (DOI)000356898400017 ()
Available from: 2015-07-20 Created: 2015-07-20 Last updated: 2018-06-07Bibliographically approved
Jørgensen, D., Nilsson, C., Hof, A. R., Hasselquist, E. M., Baker, S., Chapin, F. S., . . . Meyerson, L. A. (2014). Policy Language in Restoration Ecology. Restoration Ecology, 22(1), 1-4
Open this publication in new window or tab >>Policy Language in Restoration Ecology
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2014 (English)In: Restoration Ecology, ISSN 1061-2971, E-ISSN 1526-100X, Vol. 22, no 1, p. 1-4Article in journal (Refereed) Published
Abstract [en]

Relating restoration ecology to policy is one of the aims of the Society for Ecological Restoration and its journal Restoration Ecology. As an interdisciplinary team of researchers in both ecological science and political science, we have struggled with how policy-relevant language is and could be deployed in restoration ecology. Using language in scientific publications that resonates with overarching policy questions may facilitate linkages between researcher investigations and decision-makers' concerns on all levels. Climate change is the most important environmental problem of our time and to provide policymakers with new relevant knowledge on this problem is of outmost importance. To determine whether or not policy-specific language was being included in restoration ecology science, we surveyed the field of restoration ecology from 2008 to 2010, identifying 1,029 articles, which we further examined for the inclusion of climate change as a key element of the research. We found that of the 58 articles with climate change or global warming in the abstract, only 3 identified specific policies relevant to the research results. We believe that restoration ecologists are failing to include themselves in policy formation and implementation of issues such as climate change within journals focused on restoration ecology. We suggest that more explicit reference to policies and terminology recognizable to policymakers might enhance the impact of restoration ecology on decision-making processes.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2014
Keywords
climate change, policymaking, research implications, scientific communication
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-85791 (URN)10.1111/rec.12069 (DOI)000329369400001 ()
Funder
Swedish Research Council Formas
Available from: 2014-02-12 Created: 2014-02-10 Last updated: 2018-06-08Bibliographically approved
Polvi, L. E., Nilsson, C. & Hasselquist, E. M. (2014). Potential and actual geomorphic complexity of restored headwater streams in northern Sweden. Geomorphology, 210, 98-118
Open this publication in new window or tab >>Potential and actual geomorphic complexity of restored headwater streams in northern Sweden
2014 (English)In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 210, p. 98-118Article in journal (Refereed) Published
Abstract [en]

Stream restoration usually relies on ecological theories presuming that increased habitat heterogeneity leads to higher biodiversity. However, to test this hypothesis a quantitative metric of overall geomorphic complexity is needed. We quantified geomorphic complexity using 29 metrics over five dimensions (sediment distribution, longitudinal profile, cross section, planform, and instream wood) of headwater streams in northern Sweden. We examined reaches with four different restoration statuses after a century of timber floating (channelized, restored, demonstration restored, and unimpacted) to determine (1) whether restoration increases complexity in all dimensions, (2) whether a complexity gradient can be quantified and which metrics can serve as proxies for the gradient, and (3) levels of potential complexity based on large-scale controls (drainage area, glacial legacy sediment, valley slope, valley confinement old-growth forest/buffer zone, and beaver activity). We found a significantly higher complexity in unimpacted and demonstration restoration sites than in channelized sites in all five dimensions except the cross section (based on the two metrics quantifying variability in the cross section). Multivariate analyses were able to elucidate an apparent complexity gradient driven by three complexity metrics: longitudinal roughness, sediment sorting, and cross section chain and tape ratio. The large-scale factors of valley and channel gradient as well as median grain size, along with restoration status, drive differences in complexity composition. Restoring a reach to its potential complexity is beneficial in regions without reference systems or sufficient data to model flow and sediment processes. Unimpacted and demonstration restoration reaches displayed not only more intrareach variability than channelized reaches but also greater interreach heterogeneity in complexity composition, which supports a focus on reach-scale controls on potential complexity and a landscape-scale view on restoration. (C) 2014 Elsevier B.V. All rights reserved.

Keywords
Geomorphic complexity, Stream restoration, Sweden, Boreal, Headwater streams, Channelization
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-88319 (URN)10.1016/j.geomorph.2013.12.025 (DOI)000332820800009 ()
Available from: 2014-06-17 Created: 2014-04-30 Last updated: 2018-06-07Bibliographically approved
Hasselquist, E. M., Hasselquist, N. J. & Rogers, D. L. (2013). Management of non-native annual plants to support recovery of an endangered perennial forb, Ambrosia pumila. Restoration Ecology, 21(2), 224-231
Open this publication in new window or tab >>Management of non-native annual plants to support recovery of an endangered perennial forb, Ambrosia pumila
2013 (English)In: Restoration Ecology, ISSN 1061-2971, E-ISSN 1526-100X, Vol. 21, no 2, p. 224-231Article in journal, Editorial material (Refereed) Published
Abstract [en]

Invasive non-native plants pose a ubiquitous threat to native plant communities and have been blamed for the decline of many endangered species. Endangered species legislation provides legal instruments for protection, but identifying a general method for protecting endangered species by managing non-natives is confounded by multiple factors. We compared non-native management methods aimed at increasing populations of an endangered forb, Ambrosia pumila, and associated native plants. We compared the effects of a grass-specific herbicide (Fusilade II), hand-pulling, and mowing in two degraded coastal sage scrub sites in southern California, U.S.A. At both sites, hand-pulling had the greatest effect on non-native cover, and correspondingly resulted in the greatest increase in A. pumila stems. Fusilade II application also led to an increase in A. pumila, but was not as effective in controlling non-native plants as hand-pulling and its effect varied with the dominant non-native species. Mowing was not effective at promoting A. pumila, and its effect on non-native cover seemed to be related to rainfall patterns. Although some methods increased A. pumila, none of our treatments simultaneously increased cover of other native plants. Hand-pulling, the most effective treatment, is labor intensive and thus only feasible at small spatial scales. At larger scales, managers should take an experimental approach to identifying the most appropriate method because this can vary depending on the specific management objective (endangered species or whole native community), the dominant non-natives, yearly variation in weather, and the timing of treatment application.

Keywords
California, coastal sage scrub, Erodium, exotic plant, Fusilade, Mediterranean
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-81416 (URN)10.1111/j.1526-100X.2012.00883.x (DOI)000316075000015 ()
Available from: 2013-10-10 Created: 2013-10-10 Last updated: 2018-06-08Bibliographically approved
Hasselquist, E. M. & Germino, M. J. (2006). Microsite differentiation among conifer species during seedling establishment at alpine treeline. Ecoscience, 13(3), 334-341
Open this publication in new window or tab >>Microsite differentiation among conifer species during seedling establishment at alpine treeline
2006 (English)In: Ecoscience, ISSN 1195-6860, Vol. 13, no 3, p. 334-341Article in journal (Refereed) Published
Abstract [en]

Tree establishment is a potentially important factor affecting tree populations in alpine-treeline ecotones. Patterns of seedling establishment of Abies lasiocarpaPinus albicaulis, and Picea engelmannii were evaluated relative to neighbouring trees and herbs over two years and three treelines of the Rocky Mountains, USA. The greatest mortality rates were observed in seedlings that had just emerged from seed and were in their first year of growth and in seedlings that had the least amount of cover provided by trees or other landscape features that block exposure to the sky. Although herb cover promoted survivorship in microsites that were not near trees, no seedlings were detected at or above the upper limit of the treeline ecotone. Microsite tree cover was greatest for A. lasiocarpa and least for P. albicaulis seedlings, which matches predictions based on their relative photosynthetic tolerances to the bright sunlight and frequent frost that occur in exposed microsites. Interspecific differences in seedling requirements for neighbouring plant cover likely contribute to the apparent coexistence and possible interdependency of these conifers along a continuum of colonization and succession within treelines.

Abstract [fr]

L'établissement est un facteur potentiellement important affectant les populations d'arbres dans les écotones de la limite alpine des arbres. Les patrons d'établissement de Abies lasiocarpaPinus albicaulis et Picea engelmannii ont été étudié en relation avec la couverture d'arbres et d'herbes voisins, sur une période de deux ans dans trois secteurs à la limite des arbres dans les montagnes Rocheuses des États-Unis. Les taux les plus élevés de mortalité ont été observés pour les semis qui venaient tout juste d'émerger de graines et qui étaient dans leur première année de croissance et pour ceux qui avaient la moins grande couverture d'arbres ou d'autres éléments du paysage leur masquant le ciel. Même si la couverture herbacée favorisait la survie dans les microsites éloignés d'arbres, aucun semis n'a été détecté à la limite supérieure de l'écotone forestier ou au-dessus de celle-ci. La couverture d'arbres des microsites était la plus élevée pour A. lasiocarpa et la moins élevée pour P. albicaulis, ce qui concorde avec les prédictions basées sur leur tolérance photosynthétique relative au rayonnement intense et au fréquents gels qui affectent les microsites exposés. Des différences interspécifiques dans les exigences des semis au niveau de la couverture de plantes voisines contribuent probablement à la coexistence et la possible interdépendance des conifères le long d'un continuum de colonisation et de succession à la limite des arbres.

Place, publisher, year, edition, pages
Presses de L`Université Laval, 2006
Keywords
Abies lasiocarpa, alpine treeline, Picea engelmannii, Pinus albicaulis, seedling establishment, Abies lasiocarpa, établissement de semis, limite alpine des arbres, Picea engelmannii, Pinus albicaulis
National Category
Natural Sciences
Identifiers
urn:nbn:se:umu:diva-82374 (URN)10.2980/i1195-6860-13-3-334.1 (DOI)000240960500006 ()
Available from: 2013-10-31 Created: 2013-10-31 Last updated: 2018-06-08Bibliographically approved
Maher, E. L., Germino, M. J. & Hasselquist, N. J. (2005). Interactive effects of tree and herb cover on survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone. Canadian Journal of Forest Research, 35(3), 567-574
Open this publication in new window or tab >>Interactive effects of tree and herb cover on survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone
2005 (English)In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 35, no 3, p. 567-574Article in journal (Refereed) Published
Abstract [en]

Factors affecting the establishment of trees in subalpine meadows are important to population dynamics of trees in the alpine tree- line ecotone ( ATE). Interactive effects of tree and herb cover on conifer seedlings were investigated in the ATE of the Snowy Range, Wyoming, USA. Microclimate, physiology, and survivorship of first-year conifer seedlings of Pinus albicaulis Engelm., Picea engelmannii Parry, and Abies lasiocarpa Hook. were measured in response to manipulations of surrounding herb and tree cover, as well as water availability. Tree and herb cover had nearly additive effects on survivorship and photosynthesis of conifer seedlings, except under alleviated water stress. In P. albicaulis, photosynthesis was greater near compared with away from trees and herbs, and photosynthetic efficiency ( F-v/ F-m) increased under herb cover. Tree cover led to greater nighttime temperatures, soil water contents, and, like herb cover, shade from solar radiation for seedlings. We did not detect any negative responses of conifer seedlings to surrounding vegetation. Furthermore, the effect of surrounding vegetation on conifer establishment appeared dependent on the type of surrounding vegetation, the species of conifer, and microsite stress level. These factors may lead to variation in the way conifer seedlings interact with surrounding vegetation and could explain changes in the relative abundances of tree species during forest succession in ATEs.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-81417 (URN)10.1139/X04-201 (DOI)000228454300008 ()
Available from: 2013-10-10 Created: 2013-10-10 Last updated: 2018-06-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2152-245x

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