| 1. |
- Thomas, H. J. D., et al.
(author)
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Global plant trait relationships extend to the climatic extremes of the tundra biome
- 2020
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 11:1
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Journal article (peer-reviewed)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.
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| 2. |
- Walker, M. D., et al.
(author)
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Plant community responses to experimental warming across the tundra biome
- 2006
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:5, s. 1342-1346
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Journal article (peer-reviewed)abstract
- Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3 degrees C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.
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| 3. |
- Björkman, Anne, 1981, et al.
(author)
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Plant functional trait change across a warming tundra biome
- 2018
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 562:7725, s. 57-62
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Journal article (peer-reviewed)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.
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| 4. |
- Hollister, R. D., et al.
(author)
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A review of open top chamber (OTC) performance across the ITEX Network
- 2023
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In: Arctic Science. - : Canadian Science Publishing. - 2368-7460. ; 9:2, s. 331-344
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Journal article (peer-reviewed)abstract
- Open top chambers (OTCs) were adopted as the recommended warming mechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hundreds of papers have reported the im-pacts of OTCs on the abiotic environment and the biota. Here, we review the impacts of the OTC on the physical environment, with comments on the appropriateness of using OTCs to characterize the response of biota to warming. The purpose of this review is to guide readers to previously published work and to provide recommendations for continued use of OTCs to under -stand the implications of warming on low stature ecosystems. In short, the OTC is a useful tool to experimentally manipulate temperature; however, the characteristics and magnitude of warming varies greatly in different environments; therefore, it is important to document chamber performance to maximize the interpretation of biotic response. When coupled with long-term monitoring, warming experiments are a valuable means to understand the impacts of climate change on natural ecosystems.
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| 5. |
- Barrio, Isabel C., et al.
(author)
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Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome
- 2017
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In: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 40:11, s. 2265-2278
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Journal article (peer-reviewed)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.
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| 6. |
- Barrio, Isabel C., et al.
(author)
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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
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In: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 41:8, s. 1653-1654
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Journal article (peer-reviewed)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.
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| 7. |
- Post, Eric, et al.
(author)
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Ecological Dynamics Across the Arctic Associated with Recent Climate Change
- 2009
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In: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 325:5946, s. 1355-1358
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Research review (peer-reviewed)abstract
- At the close of the Fourth International Polar Year, we take stock of the ecological consequences of recent climate change in the Arctic, focusing on effects at population, community, and ecosystem scales. Despite the buffering effect of landscape heterogeneity, Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity. We highlight areas of ecological research that deserve priority as the Arctic continues to warm.
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| 8. |
- Arft, M, et al.
(author)
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Responses of tundra plants to experimental warming : Meta-analysis of the international tundra experiment
- 1999
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In: Ecological Monographs. - 0012-9615 .- 1557-7015. ; 69:4, s. 491-511
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Journal article (peer-reviewed)abstract
- The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX was designed specifically to examine variability in arctic and alpine species response to increased temperature. We compiled from one to four years of experimental data from 13 different ITEX sites and used meta-analysis to analyze responses of plant phenology, growth, and reproduction to experimental warming. Results indicate that key phenological events such as leaf bud burst and flowering occurred earlier in warmed plots throughout the study period; however, there was little impact on growth cessation at the end of the season. Quantitative measures of vegetative growth were greatest in warmed plots in the early years of the experiment, whereas reproductive effort and success increased in later years. A shift away from vegetative growth and toward reproductive effort and success in the fourth treatment year suggests a shift from the initial response to a secondary response. The change in vegetative response may be due to depletion of stored plant reserves, whereas the lag in reproductive response may be due to the formation of flower buds one to several seasons prior to flowering. Both vegetative and reproductive responses varied among life-forms; herbaceous forms had stronger and more consistent vegetative growth responses than did woody forms. The greater responsiveness of the herbaceous forms may be attributed to their more flexible morphology and to their relatively greater proportion of stored plant reserves. Finally, warmer, low arctic sites produced the strongest growth responses, but colder sites produced a greater reproductive response. Greater resource investment in vegetative growth may be a conservative strategy in the Low Arctic, where there is more competition for light, nutrients, or water, and there may be little opportunity for successful germination or seedling development. In contrast, in the High Arctic, heavy investment in producing seed under a higher temperature scenario may provide an opportunity for species to colonize patches of unvegetated ground. The observed differential response to warming suggests that the primary forces driving the response vary across climatic zones, functional groups, and through time.
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| 9. |
- Barrio, I. C., et al.
(author)
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Biotic interactions mediate patterns of herbivore diversity in the Arctic
- 2016
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In: Global Ecology and Biogeography. - : Wiley-Blackwell. - 1466-822X .- 1466-8238. ; 25:9, s. 1108-1118
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Journal article (peer-reviewed)abstract
- Aim: Understanding the forces shaping biodiversity patterns, particularly for groups of organisms with key functional roles, will help predict the responses of ecosystems to environmental changes. Our aim was to evaluate the relative role of different drivers in shaping the diversity patterns of vertebrate herbivores, a group of organisms exerting a strong trophic influence in terrestrial Arctic ecosystems. This biome, traditionally perceived as homogeneous and low in biodiversity, includes wide variation in biotic and physical conditions and is currently undergoing major environmental change. Location: The Arctic (including the High Arctic, Low Arctic and Subarctic) MethodsWe compiled available data on vertebrate (birds and mammals) herbivore distribution at a pan-Arctic scale, and used eight variables that represent the most relevant hypotheses for explaining patterns of species richness. We used range maps rasterized on a 100kmx100km equal-area grid to analyse richness patterns of all vertebrate herbivore species combined, and birds and mammalian herbivores separately. Results: Overall, patterns of herbivore species richness in the Arctic were positively related to plant productivity (measured using the normalized difference vegetation index) and to the species richness of predators. Greater species richness of herbivores was also linked to areas with a higher mean annual temperature. Species richness of avian and mammalian herbivores were related to the distance from the coast, with the highest avian richness in coastal areas and mammalian richness peaking further inland. Main conclusions: Herbivore richness in the Arctic is most strongly linked to primary productivity and the species richness of predators. Our results suggest that biotic interactions, with either higher or lower trophic levels or both, can drive patterns of species richness at a biome-wide scale. Rapid ongoing environmental changes in the Arctic are likely to affect herbivore diversity through impacts on both primary productivity and changes in predator communities via range expansion of predators from lower latitudes.
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| 10. |
- Björk, Robert G., 1974, et al.
(author)
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Effect of reduced below-ground C sequestration on greenhouse gas fluxes within dry tundra ecosystems along an altitudinal gradient
- 2008
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In: The 15th ITEX workshop, Reykjavik, Iceland, 9–12 October 2008..
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Conference paper (other academic/artistic)abstract
- It has been suggested that global climate change will have a great impact on arctic and alpine areas, affecting the carbon and nitrogen dynamics in these ecosystems. Temperature is widely thought to be the main limiting factor for plants and microorganisms in these tundra ecosystems, and warming the soil in high latitude tundra has been shown to change trace gas (CO2, CH4, and N2O) exchange rates and increase N availability. However, little attention has been paid, to date, to variations in trace gas fluxes with altitude, although altitude is a key determinant of temperature and should therefore be strongly correlated with these fluxes if temperature is a major variable affecting these processes. The objectives of this study were, therefore, to measure growing season variation in carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes from heath plant communities along an altitudinal gradient ranging from mid alpine (~950 m a.s.l) to high alpine (~1,365 m a.s.l) zones within an alpine tundra landscape in the subarctic region of Sweden. Furthermore, by reducing the C supply to the root system and mycorrhizal fungi (achieved by clipping the above-ground plant parts) we wanted to decrease the rhizosphere priming effect and thereby change the C sequestration pattern within the ecosystem to be able to separate heterotrophic and autotrophic respiration. The study was conducted on the slopes of Mt. Latnjatjårro (1,447 m a.s.l.; 68°21’N, 18°31’E), near Latnjajaure Field Station, 16 km west of Abisko in Northern Sweden. Flux measurements of CO2 were analysed using a portable infra red gas analyser (IRGA) based on the SBA-4 OEM CO2 Analyzer (PP System). Fluxes of CH4 and N2O were sampled using a closed chamber system, where chambers were placed on collars, which were gently pressed into the ground. Air from the chamber was circulated into a headspace bottle and analysed by gas chromatograph. A two-step incubation technique was also used to determine Nitrification Enzyme Activity (NEA) for analysing nitrification in acid soils with low activities, and for Denitrification Enzyme Activity (DEA) an anaerobic incubation technique, based on acetylene inhibition of the N2O-reductase, was used. Our results show a decrease in average growing season CO2 efflux with altitude, but not consistently, and although soil temperature in general decreased with altitude there was only a loose association between soil temperature and average growing season CO2 efflux. Furthermore, the clipping of the above-ground plant parts reduced the CO2 efflux at all altitudes, except at 1,225 m a.s.l., and in August the reduction in CO2 efflux was largest at 950 m a.s.l. (231 mg CO2 m-2 h-1) and decreased with altitude (to 33 mg CO2 m-2 h-1 at 1,365 m a.s.l.). However, the proportion of the reduced CO2 efflux, corresponding to autotrophic respiration, was relatively constant with altitude (28-43% of total respiration), except at 1,365 m a.s.l. where the autotrophic respiration only contributed 12%. The fluxes of CH4 and N2O were very low, and resolution was constrained by the large number of samples with apparent fluxes below the limit of detection for the gas chromatograph, thus no particular pattern could be identified. However, to try to improve the resolution along the altitudinal gradient, the NEA and DEA were used, and give a potential measure of the nitrification and denitrification rates, which goes back to the actual populations of nitrifiers and denitrifiers in the soil. The results show that there were a substantial increases with altitude in the activities of nitrifying and denitrifying microbes; this is contrary to expectations and the average growing season CO2 efflux if the decline in mean annual temperature with altitude is the main driver for nitrification and denitrification. Thus, our results are indicative of the complex interaction that may occur along altitudinal gradients. But, clearly, there is a need for further studies to assess the effects of altitude and temperature on carbon and nitrogen dynamics in high alpine and arctic ecosystems across wide altitudinal ranges.
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