| 1. |
- Barrio, Isabel C., et al.
(författare)
-
Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome
- 2017
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 40:11, s. 2265-2278
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6-7% over the current levels with a 1 degrees C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.
|
|
| 2. |
- Barrio, Isabel C., et al.
(författare)
-
Publisher Correction to : Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome (vol 40, pg 2265, 2017)
- 2018
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 41:8, s. 1653-1654
-
Tidskriftsartikel (refereegranskat)abstract
- The above mentioned article was originally scheduled for publication in the special issue on Ecology of Tundra Arthropods with guest editors Toke T. Hoye . Lauren E. Culler. Erroneously, the article was published in Polar Biology, Volume 40, Issue 11, November, 2017. The publisher sincerely apologizes to the guest editors and the authors for the inconvenience caused.
|
|
| 3. |
- Björkman, Anne, 1981, et al.
(författare)
-
Tundra Trait Team: A database of plant traits spanning the tundra biome
- 2018
-
Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 27:12, s. 1402-1411
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd Motivation: The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (>1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.
|
|
| 4. |
- Björkman, Anne, 1981, et al.
(författare)
-
Plant functional trait change across a warming tundra biome
- 2018
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 562:7725, s. 57-62
-
Tidskriftsartikel (refereegranskat)abstract
- The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.
|
|
| 5. |
- Hallinger, Martin, et al.
(författare)
-
Factors driving tree mortality in retained forest fragments
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 368, s. 163-172
-
Tidskriftsartikel (refereegranskat)abstract
- Green tree retention is often applied in forests otherwise harvested by clearcutting. Its aim is to support biodiversity by contributing to a continuity of living trees and large-diameter dead wood in the new generation of a forest. However, high levels of mortality can undermine the aims of tree retention and pose a concern for forest managers. Therefore, knowledge about the mortality of retention trees over the long term is needed. We calculated cumulative tree mortality for the seven most common tree species up to 20 years after clearcutting based on a chronosequence of dead and living trees in 583 tree groups on 206 clearcuts distributed over a wide area in boreal central Sweden. For all tree taxa combined and for the three most common tree taxa (Scots pine, Norway spruce and two birch species) we modeled tree mortality based on structural and environmental variables measured for each tree group and characteristics of the clearcut using generalized linear mixed effects models. The cumulative mortality averaged over all clearcut ages was 12% for Scots pine, 25% for Norway spruce and 16% for birch. Only 10% of all retention tree groups had a mortality >50%. Key factors reducing mortality for all tree taxa combined were tree density, tree volume of a retention group and the position at a former stand edge abutting open habitat, while a high wind exposure increased tree mortality. For the three most common species (pine, spruce, birch), the same factors as for all taxa combined were of importance, except tree density that resulted in species specific responses. For pine and spruce, the presence of seed trees on the clearcut reduced mortality. Increased mortality was additionally observed on wet soils. Mortality increased with tree height in birch and with diameter and slenderness ratio in spruce. Generally, a focus on retaining trees in groups with large tree volumes and tree density in less wind exposed positions and on forest edges will decrease the mortality after clearcutting and thus also reduce dead wood input. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 6. |
- Lindén, Elin, et al.
(författare)
-
Circum-Arctic distribution of chemical anti-herbivore compounds suggests biome-wide trade-off in defence strategies in Arctic shrubs
- 2022
-
Ingår i: Ecography. - : John Wiley & Sons. - 0906-7590 .- 1600-0587. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial variation in plant chemical defence towards herbivores can help us understand variation in herbivore top–down control of shrubs in the Arctic and possibly also shrub responses to global warming. Less defended, non-resinous shrubs could be more influenced by herbivores than more defended, resinous shrubs. However, sparse field measurements limit our current understanding of how much of the circum-Arctic variation in defence compounds is explained by taxa or defence functional groups (resinous/non-resinous). We measured circum-Arctic chemical defence and leaf digestibility in resinous (Betula glandulosa, B. nana ssp. exilis) and non-resinous (B. nana ssp. nana, B. pumila) shrub birches to see how they vary among and within taxa and functional groups. Using liquid chromatography–mass spectrometry (LC–MS) metabolomic analyses and in vitro leaf digestibility via incubation in cattle rumen fluid, we analysed defence composition and leaf digestibility in 128 samples from 44 tundra locations.We found biogeographical patterns in anti-herbivore defence where mean leaf triterpene concentrations and twig resin gland density were greater in resinous taxa and mean concentrations of condensing tannins were greater in non-resinous taxa. This indicates a biome-wide trade-off between triterpene- or tannin-dominated defences. However, we also found variations in chemical defence composition and resin gland density both within and among functional groups (resinous/non-resinous) and taxa, suggesting these categorisations only partly predict chemical herbivore defence. Complex tannins were the only defence compounds negatively related to in vitro digestibility, identifying this previously neglected tannin group as having a potential key role in birch anti-herbivore defence.We conclude that circum-Arctic variation in birch anti-herbivore defence can be partly derived from biogeographical distributions of birch taxa, although our detailed mapping of plant defence provides more information on this variation and can be used for better predictions of herbivore effects on Arctic vegetation.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Hallinger, Martin
(författare)
-
Divergence of Arctic shrub growth associated with sea ice decline
- 2020
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117, s. 33334-33344
-
Tidskriftsartikel (refereegranskat)abstract
- Arctic sea ice extent (SIE) is declining at an accelerating rate with a wide range of ecological consequences. However, determining sea ice effects on tundra vegetation remains a challenge. In this study, we examined the universality or lack thereof in tundra shrub growth responses to changes in SIE and summer climate across the Pan-Arctic, taking advantage of 23 tundra shrub-ring chronologies from 19 widely distributed sites (56 degrees N to 83 degrees N). We show a clear divergence in shrub growth responses to SIE that began in the mid-1990s, with 39% of the chronologies showing declines and 57% showing increases in radial growth (decreasers and increasers, respectively). Structural equation models revealed that declining SIE was associated with rising air temperature and precipitation for increasers and with increasingly dry conditions for decreasers. Decreasers tended to be from areas of the Arctic with lower summer precipitation and their growth decline was related to decreases in the standardized precipitation evapotranspiration index. Our findings suggest that moisture limitation, associated with declining SIE, might inhibit the positive effects of warming on shrub growth over a considerable part of the terrestrial Arctic, thereby complicating predictions of vegetation change and future tundra productivity.
|
|
| 11. |
- Hallinger, Martin, et al.
(författare)
-
Does it pay to concentrate conservation efforts for dead-wood dependent insects close to existing reserves : a test on conservation planning in Sweden
- 2018
-
Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-458X .- 1752-4598. ; 11:4, s. 317-329
-
Tidskriftsartikel (refereegranskat)abstract
- Forestry has significantly changed many boreal forest landscapes with negative effects on biodiversity. Main reasons are habitat loss and deterioration, due to a simplified forest composition, including a reduction in old trees and dead wood. In Sweden, measures to counter the loss of biodiversity are taken at forest harvesting, and include forest harvest retention.Areas of high conservation values (AHCV) have been identified in Sweden to prioritise conservation efforts, but so far these areas have not been used when making decisions about forest harvest retention.In this study, we tested if dead wood from forest harvest retention is used by more dead wood‐dependent insect species (24 beetles and four other insects, redlisted or indicating high biodiversity) on clearcuts within than outside of AHCVs and whether the composition of the surrounding landscape influences species occurrence.There were not more dead wood‐dependent insect species per clearcut within AHCVs than outside. The surrounding landscape had an influence on the species richness on clearcuts, but in several cases the pattern was the opposite of our hypotheses. Increased standing volume of relevant tree species, however, tended to increase the occurrence or number of associated species.The designation of ACHVs in Sweden is not related with occurrence of dead wood or dead wood‐dependent organisms. We also found that landscape context can have effects on species richness. The result urges for better planning so that ACHV areas are designated in landscapes where their potential for conservation of dead wood‐dependent organisms is highest.
|
|
| 12. |
- Hallinger, Martin
(författare)
-
Does sex matter? Gender-specificity and its influence on site-chronologies in the common dioecious shrub Juniperus communis
- 2018
-
Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 49, s. 118-126
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years an increasing number of studies have shown shrubs to be reliable proxies of environmental conditions in regions where Trees - due to harsh climate conditions - are absent. Although many shrubs are monoecious, some are dioecious, which poses certain questions related to gender-specific growth as observed for trees in previous studies. Here, we address the questions whether dioecious shrubs, similar to trees, show growth differences between male and female plants, and - if so - whether this difference needs to be considered in terms of sample selection. We chose Juniperus communis. L., the most widely distributed woody plant, and a common and well-studied dioecious shrub species in the northern hemisphere, especially in the Boreal, Subarctic tundra and Alpine regions. Our samples were collected from four sites - three from the Ural Mountains and one site from Kirkenes in Norway. To see if there were differences in radial growth between sexes we performed four different analyses. First, we used multivariate explorative statistics to see if there were gender biased sub-populations and generally found no differences. Secondly, to compare growth over the lifetime of shrubs we computed cumulative annual increments of basal area which revealed no gender-specific growth patterns. Thirdly, to test if differences in radial growth between male and female shrubs affect the resulting site-chronology, we compared individual shrub chronologies with the site-chronology and found a significant differentiation between normalized correlations of gender-specific chronologies to the site-chronology. This significant difference was restricted to an overall comparison, but not evident at individual site-level. Lastly, we compared correlations of gender-specific chronologies and a mean site-chronology with monthly climate records to find only very few meaningful differences in their responses. In summary, we could not detect any clear gender-specific growth pattern in Juniperus communis but observed a trend towards more non-climatic signals in female junipers which may affect the resulting site-chronology.
|
|
| 13. |
- Hallinger, Martin
(författare)
-
Growth response to climatic change over 120 years for Alnus viridis and Salix glauca in West Greenland
- 2015
-
Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 26, s. 155-165
-
Tidskriftsartikel (refereegranskat)abstract
- ConclusionOverall, estimated growth did not increase over the past 120yr, but considerable variations in growth are conspicuous and match known historical patterns of the Atlantic Multidecadal Oscillation. Perspectives regarding the observed shrub expansion in W Greenland are discussed, and based on the estimated growth patterns, we consider it unlikely that the recent 10-15-yr period of favourable climate is the main responsible cause.
|
|
| 14. |
- Hallinger, Martin
(författare)
-
Methods for measuring arctic and alpine shrub growth: A review
- 2015
-
Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 140, s. 1-13
-
Forskningsöversikt (refereegranskat)abstract
- Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure radial and axial growth, estimate age, and assess growth dynamics in relation to environmental variables. Recent advances in sampling methods, analysis and applications have improved our ability to investigate growth and recruitment dynamics of shrubs. However, to extrapolate findings to the biome scale, future dendroecological work will require improved approaches that better address variation in growth within parts of the plant, among individuals within populations and between species. (C) 2014 Elsevier B.V. All rights reserved.
|
|
| 15. |
- Hallinger, Martin
(författare)
-
Shrubs tracing sea surface temperature-Calluna vulgaris on the Faroe Islands
- 2015
-
Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 0020-7128 .- 1432-1254. ; 59, s. 1567-1575
-
Tidskriftsartikel (refereegranskat)abstract
- The climate of Central and Northern Europe is highly influenced by the North Atlantic Ocean due to heat transfer from lower latitudes. Detailed knowledge about spatio-temporal variability of sea surface temperature (SST) in that region is thus of high interest for climate and environmental research. Because of the close relations between ocean and coastal climate and the climate sensitivity of plant growth, annual rings of woody plants in coastal regions might be used as a proxy for SST. We show here for the first time the proxy potential of the common and widespread evergreen dwarf shrub Calluna vulgaris (heather), using the Faroe Islands as our case study. Despite its small and irregular ring structure, the species seems suitable for dendroecological investigations. Ring width showed high and significant correlations with summer and winter air temperatures and SST. The C. vulgaris chronology from the Faroe Islands, placed directly within the North Atlantic Current, clearly reflects variations in summer SSTs over an area between Iceland and Scotland. Utilising shrubs like C. vulgaris as easy accessible and annually resolved proxies offers an interesting possibility for reconstruction of the coupled climate-ocean system at high latitudes.
|
|
| 16. |
- Thomas, H. J. D., et al.
(författare)
-
Global plant trait relationships extend to the climatic extremes of the tundra biome
- 2020
-
Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world.
|
|
| 17. |
- Thomas, H. J.D., et al.
(författare)
-
Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome
- 2019
-
Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 28:2, s. 78-95
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd Aim: Plant functional groups are widely used in community ecology and earth system modelling to describe trait variation within and across plant communities. However, this approach rests on the assumption that functional groups explain a large proportion of trait variation among species. We test whether four commonly used plant functional groups represent variation in six ecologically important plant traits. Location: Tundra biome. Time period: Data collected between 1964 and 2016. Major taxa studied: 295 tundra vascular plant species. Methods: We compiled a database of six plant traits (plant height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, seed mass) for tundra species. We examined the variation in species-level trait expression explained by four traditional functional groups (evergreen shrubs, deciduous shrubs, graminoids, forbs), and whether variation explained was dependent upon the traits included in analysis. We further compared the explanatory power and species composition of functional groups to alternative classifications generated using post hoc clustering of species-level traits. Results: Traditional functional groups explained significant differences in trait expression, particularly amongst traits associated with resource economics, which were consistent across sites and at the biome scale. However, functional groups explained 19% of overall trait variation and poorly represented differences in traits associated with plant size. Post hoc classification of species did not correspond well with traditional functional groups, and explained twice as much variation in species-level trait expression. Main conclusions: Traditional functional groups only coarsely represent variation in well-measured traits within tundra plant communities, and better explain resource economic traits than size-related traits. We recommend caution when using functional group approaches to predict tundra ecosystem change, or ecosystem functions relating to plant size, such as albedo or carbon storage. We argue that alternative classifications or direct use of specific plant traits could provide new insight into ecological prediction and modelling.
|
|
