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Hasselquist, Eliza Maher
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Publications (7 of 7) Show all publications
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, 753-764 p.Article 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 More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration.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
Keyword
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: 2018-01-11Bibliographically 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, 1373-1389 p.Article 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.

Keyword
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: 2017-12-04Bibliographically 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, 1-4 p.Article 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
Keyword
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: 2017-12-06Bibliographically 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, 98-118 p.Article 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.

Keyword
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: 2017-12-05Bibliographically 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, 224-231 p.Article 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.

Keyword
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: 2017-12-06Bibliographically 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, 334-341 p.Article 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
Keyword
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: 2017-12-06Bibliographically 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, 567-574 p.Article 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: 2017-12-06Bibliographically approved
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