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  • 1.
    Alatalo, Juha
    Göteborgs Universitet.
    Gender lability in trioecious Silene acaulis (Caryophyllaceae)1997In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 17, no 2, p. 181-183Article in journal (Refereed)
    Abstract [en]

    Gender expression of individual cushions of Silene acaulis was shown to vary between years. Fifteen of thirty-nine (= 38%) cushions monitored changed gender expression between 1993 and 1995. Cushions dominated by female flowers were shown to be more stable in gender expression than cushions dominated by male or hermaphrodite flowers.

  • 2.
    Alatalo, Juha M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Jaegerbrand, Annika K.
    Molau, Ulf
    Climate change and climatic events: community-, functional- and species-level responses of bryophytes and lichens to constant, stepwise, and pulse experimental warming in an alpine tundra2014In: Alpine Botany, ISSN 1664-2201, E-ISSN 1664-221X, Vol. 124, no 2, p. 81-91Article in journal (Refereed)
    Abstract [en]

    We experimentally imposed three different kinds of warming scenarios over 3 years on an alpine meadow community to identify the differential effects of climate warming and extreme climatic events on the abundance and biomass of bryophytes and lichens. Treatments consisted of (a) a constant level of warming with open top chambers (an average temperature increase of 1.87 A degrees C), (b) a yearly stepwise increase of warming (average temperature increases of 1.0; 1.87 and 3.54 A degrees C, consecutively), and (c) a pulse warming, i.e., a single first year pulse event of warming (average temperature increase of 3.54 A degrees C only during the first year). To our knowledge, this is the first climate change study that attempts to distinguish between the effects of constant, stepwise and pulse warming on bryophyte and lichen communities. We hypothesised that pulse warming would have a significant short-term effect compared to the other warming treatments, and that stepwise warming would have a significant mid-term effect compared to the other warming treatments. Acrocarpous bryophytes as a group increased in abundance and biomass to the short-term effect of pulse warming. We found no significant effects of mid-term (third-year) stepwise warming. However, one pleurocarpous bryophyte species, Tomentypnum nitens, generally increased in abundance during the warm year 1997 but decreased in control plots and in response to the stepwise warming treatment. Three years of experimental warming (all treatments as a group) did have a significant impact at the community level, yet changes in abundance did not translate into significant changes in the dominance hierarchies at the functional level (for acrocarpous bryophytes, pleurocarpous bryophytes, Sphagnum or lichens), or in significant changes in other bryophyte or lichen species. The results suggest that bryophytes and lichens, both at the functional group and species level, to a large extent are resistant to the different climate change warming simulations that were applied.

  • 3.
    Alatalo, Juha M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Little, Chelsea J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Simulated global change: contrasting short and medium term growth and reproductive responses of a common alpine/Arctic cushion plant to experimental warming and nutrient enhancement2014In: SpringerPlus, E-ISSN 2193-1801, Vol. 3, article id 157Article in journal (Refereed)
    Abstract [en]

    Cushion plants are important components of alpine and Arctic plant communities around the world. They fulfill important roles as facilitators, nurse plants and foundation species across trophic levels for vascular plants, arthropods and soil microorganisms, the importance of these functions increasing with the relative severity of the environment. Here we report results from one of the few experimental studies simulating global change impacts on cushion plants; a factorial experiment with warming and nutrient enhancement that was applied to an alpine population of the common nurse plant, Silene acaulis, in sub-arctic Sweden. Experimental perturbations had significant short-term impacts on both stem elongation and leaf length. S. acaulis responded quickly by increasing stem elongation and (to a lesser extent) leaf length in the warming, nutrient, and the combined warming and nutrient enhancements. Cover and biomass also initially increased in response to the perturbations. However, after the initial positive short-term responses, S. acaulis cover declined in the manipulations, with the nutrient and combined warming and nutrient treatments having largest negative impact. No clear patterns were found for fruit production. Our results show that S. acaulis living in harsh environments has potential to react quickly when experiencing years with favorable conditions, and is more responsive to nutrient enhancement than to warming in terms of vegetative growth. While these conditions have an initial positive impact, populations experiencing longer-term increased nutrient levels will likely be negatively affected.

  • 4.
    Alatalo, Juha M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Little, Chelsea J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Jagerbrand, Annika K.
    Molau, Ulf
    Dominance hierarchies, diversity and species richness of vascular plants in an alpine meadow: contrasting short and medium term responses to simulated global change2014In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 2, p. e406-Article in journal (Refereed)
    Abstract [en]

    We studied the impact of simulated global change on a high alpine meadow plant community. Specifically, we examined whether short-term (5 years) responses are good predictors for medium-term (7 years) changes in the system by applying a factorial warming and nutrient manipulation to 20 plots in Latnjajaure, subarctic Sweden. Seven years of experimental warming and nutrient enhancement caused dramatic shifts in dominance hierarchies in response to the nutrient and the combined warming and nutrient enhancement treatments. Dominance hierarchies in the meadow moved from a community being dominated by cushion plants, deciduous, and evergreen shrubs to a community being dominated by grasses, sedges, and forbs. Short-termresponses were shown to be inconsistent in their ability to predict medium-term responses for most functional groups, however, grasses showed a consistent and very substantial increase in response to nutrient addition over the seven years. The non-linear responses over time point out the importance of longer-term studies with repeated measurements to be able to better predict future changes. Forecasted changes to temperature and nutrient availability have implications for trophic interactions, and may ultimately influence the access to and palatability of the forage for grazers. Depending on what anthropogenic change will be most pronounced in the future (increase in nutrient deposits, warming, or a combination of them both), different shifts in community dominance hierarchies may occur. Generally, this study supports the productivity-diversity relationship found across arctic habitats, with community diversity peaking in mid-productivity systems and degrading as nutrient availability increases further. This is likely due the increasing competition in plant-plant interactions and the shifting dominance structure with grasses taking over the experimental plots, suggesting that global change could have high costs to biodiversity in the Arctic.

  • 5.
    Alatalo, Juha M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Little, Chelsea J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Jagerbrand, Annika K.
    Molau, Ulf
    Vascular plant abundance and diversity in an alpine heath under observed and simulated global change2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 10197Article in journal (Refereed)
    Abstract [en]

    Global change is predicted to cause shifts in species distributions and biodiversity in arctic tundra. We applied factorial warming and nutrient manipulation to a nutrient and species poor alpine/arctic heath community for seven years. Vascular plant abundance in control plots increased by 31%. There were also notable changes in cover in the nutrient and combined nutrient and warming treatments, with deciduous and evergreen shrubs declining, grasses overgrowing these plots. Sedge abundance initially increased significantly with nutrient amendment and then declined, going below initial values in the combined nutrient and warming treatment. Nutrient addition resulted in a change in dominance hierarchy from deciduous shrubs to grasses. We found significant declines in vascular plant diversity and evenness in the warming treatment and a decline in diversity in the combined warming and nutrient addition treatment, while nutrient addition caused a decline in species richness. The results give some experimental support that species poor plant communities with low diversity may be more vulnerable to loss of species diversity than communities with higher initial diversity. The projected increase in nutrient deposition and warming may therefore have negative impacts on ecosystem processes, functioning and services due to loss of species diversity in an already impoverished environment.

  • 6.
    Alatalo, Juha M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Ostapenko, Oksana V.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    The Swedish system: The image cracking when taking a closer look2014In: Geoforum, ISSN 0016-7185, E-ISSN 1872-9398, Vol. 53, p. 82-83Article, review/survey (Refereed)
    Abstract [en]

    Sweden has a high international profile regarding social issues and projects an image as one of the best countries in the world in terms of social indicators. Here we argue for a revised view as the reality is that Swedish system is very segregated, particularly in terms of (1) relative lack of women in positions of high influence, (2) it is the worst country in the EU28 regarding long-term unemployment for people born outside the country, and (3) it has a education system that after a number of reforms is involved in a "race towards the bottom" to profit from students. At the same time Sweden undervalues foreign academic qualifications and getting work largely depends on "who you know", not "what you know".

  • 7.
    Alatalo, Juha
    et al.
    Göteborgs Universitet.
    Molau, U
    Effect of Altitude on the Sex-Ratio in Populations of Silene Acaulis (Caryophyllaceae): Effect of Altitude on the Sex-Ratio in Populations of Silene Acaulis (Caryophyllaceae)1995In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 15, no 3, p. 251-256Article in journal (Refereed)
    Abstract [en]

    Predicted increase of female frequencies in gynodioecious Silene acaulis was tested along an altitude gradient in northern Sweden. Average female frequencies for the four sites increased with altitude from 42% to 59% within a short geographical distance. This follows the outcrossing hypothesis, that female frequencies should be positively correlated with selfing rates of hermaphrodites in populations. More adverse environmental conditions should favour gynodioecy in areas where reproduction to a greater part relies on vegetative reproduction or selfing. Further, a significant difference in corolla width was found between females and the larger hermaphrodites, but not between sites. Cushion size and the number of flowers per cushion decreased with altitude.

  • 8.
    Alatalo, Juha
    et al.
    Göteborgs Universitet.
    Molau, U
    Pollen viability and limitation of seed production in a population of the circumpolar cushion plant, Silene acaulis (Caryophyllaceae)2001In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 21, no 4, p. 365-372Article in journal (Refereed)
    Abstract [en]

    Pollen viability among genders and limitation of female seed production in a natural trioecious population of the circumpolar cushion plant Silene acaulis was examined. Pollen viability was estimated by an in vitro pollen germination experiment. Both male and hermaphrodite flowers displayed large variation in pollen viability (0-53% in hermaphrodite and 0-54% in male flowers). There was a significant difference between genders in pollen viability: male plants had on average higher pollen viability than hermaphrodite plants. Resource and pollen limitation of seed production was studied by an experiment consisting of three treatments; (I) hand-pollination and removal of all other flowers on the cushion, (II) harid-pollination without removal of other flowers, and (III) open pollination without removal of flowers, Hand-pollination increased seed production, whereas removal of flowers had no effect on seed production. Abortion of pollinated ovules during seed development and seed mass did not differ among treatments. To control for effect of fruit number on seed production, data from naturally pollinated individuals was used. There was a positive correlation between both total number of seeds and fruit number, mean seed number per fruit and fruit number, respectively. These results indicate that seed production of S. acaulis is mainly limited by pollen availability whereas resource competition between fruits is not important as a limiting factor. The possible role of male quality differences between genders and pollen limitation of seed production for maintenance of trioecious reproductive systems is discussed.

  • 9.
    Alatalo, Juha
    et al.
    Göteborgs Universitet.
    Totland, O
    Response to simulated climatic change in an alpine and subarctic pollen-risk strategist, Silene acaulis1997In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 3, p. 74-79Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to test if early no overing species respond with increased seed production to climate warming as is predicted for late-flowering seed-risk strategists. Experimental climate warming of about 3 degrees C was applied to two populations of the cushion-forming plant Silene acaulis (L.) Jacq. The experiment was run at one subarctic site and one alpine site for 2 years and 1 year, respectively, using open-top chambers (OTC). The 2-year temperature enhancement at the subarctic site had a marked effect on the flowering phenology. Cushions inside the OTC started flowering substantially earlier than control cushions. Both the male and female phases developed faster in the OTCs, and maturation of capsules occurred earlier. The cushions also responded positively in reproductive terms and produced more mature seeds and had a higher seed/ovule ratio. After 1 year temperature enhancement at the alpine site there was a weak trend for earlier flowering, but there was no significant difference in seed production or seed/ovule ratio.

  • 10.
    Arft, M
    et al.
    Univ Colorado.
    Walker, D
    Gurevitch, J
    Alatalo, Juha
    Göteborgs Universitet.
    Bret-Harte, S
    Dale, M
    Diemer, M
    Gugerli, F
    Henry, R
    Jones, H
    Hollister, D
    Jonsdottir, S
    Laine, K
    Levesque, E
    Marion, M
    Molau, U
    Molgaard, P
    Nordenhall, U
    Raszhivin, V
    Robinson, H
    Starr, G
    Stenstrom, A
    Stenstrom, M
    Totland, O
    Turner, L
    Walker, J
    Webber, J
    Welker, M
    Wookey, A
    Responses of tundra plants to experimental warming: Meta-analysis of the international tundra experiment1999In: Ecological Monographs, ISSN 0012-9615, E-ISSN 1557-7015, Vol. 69, no 4, p. 491-511Article in journal (Refereed)
    Abstract [en]

    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.

  • 11.
    Bai, Yang
    et al.
    Shanghai Acad Environm Sci, Inst Appl Ecol, Shanghai 200233, Peoples R China..
    Jiang, Bo
    Changjiang Water Resources Protect Inst, Wuhan 430051, Peoples R China..
    Wang, Min
    Shanghai Acad Environm Sci, Inst Appl Ecol, Shanghai 200233, Peoples R China..
    Li, Hui
    Yunnan Univ, Sch Urban Construct & Management, Kunming 650091, Peoples R China..
    Alatalo, Juha M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Qatar Univ, Coll Arts & Sci, Dept Biol & Environm Sci, POB 2713, Doha, Qatar..
    Huang, Shenfa
    Shanghai Acad Environm Sci, Inst Appl Ecol, Shanghai 200233, Peoples R China..
    New ecological redline policy (ERP) to secure ecosystem services in China2016In: Land use policy, ISSN 0264-8377, E-ISSN 1873-5754, Vol. 55, p. 348-351Article in journal (Refereed)
    Abstract [en]

    China is facing huge environmental problems, with its current rapid rate of urbanization and industrialization causing biodiversity loss, ecosystem degradation, and land resources degradation on a major scale. To overcome management conflicts and secure ecosystem services, China has proposed a new 'ecological redline policy' (ERP) using ecosystem services as a way to meet its targets. By giving environmental policy redline status, China is demonstrating strong commitment in its efforts to tackle environmental degradation and secure ecosystem services for the future. This is already having impact, as the Chinese Ministry of Environmental Protection and the National Development and Reform Commission are prepared to work together to implement the new environmental policy.

  • 12.
    Cornelissen, C
    et al.
    Vrije Univ Amsterdam.
    Callaghan, V
    Alatalo, Juha
    Göteborgs Universitet.
    Michelsen, A
    Graglia, E
    Hartley, E
    Hik, S
    Hobbie, E
    Press, C
    Robinson, H
    Henry, R
    Shaver, R
    Phoenix, K
    Jones, G
    Jonasson, S
    Chapin, S
    Molau, U
    Neill, C
    Lee, A
    Melillo, M
    Sveinbjornsson, B
    Aerts, R
    Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass?2001In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 89, no 6, p. 984-994Article in journal (Refereed)
    Abstract [en]

    1 Macrolichens are important for the functioning and biodiversity of cold northern ecosystems and their reindeer-based cultures and economics. 2 We hypothesized that, in climatically milder parts of the Arctic, where ecosystems have relatively dense plant canopies, climate warming and/or increased nutrient availability leads to decline in macrolichen abundance as a function of increased abundance of vascular plants. In more open high-arctic or arctic-alpine plant communities such a relationship should be absent. To test this, we synthesized cross-continental arctic vegetation data from ecosystem manipulation experiments simulating mostly warming and increased nutrient availability, and compared these with similar data from natural environmental gradients. 3 Regressions between abundance or biomass of macrolichens and vascular plants were consistently negative across the subarctic and mid-arctic experimental studies. Such a pattern did not emerge in the coldest high-arctic or arctic-alpine sites. The slopes of the negative regressions increased across 10 sites as the climate became milder (as indicated by a simple climatic index) or the vegetation denser (greater site above-ground biomass). 4 Seven natural vegetation gradients in the lower-altitude sub- and mid-arctic zone confirmed the patterns seen in the experimental studies, showing consistent negative relationships between abundance of macrolichens and vascular plants. 5 We conclude that the data supported the hypothesis. Macrolichens in climatically milder arctic ecosystems may decline if and where global changes cause vascular plants to increase in abundance. 6 However, a refining of our findings is needed, for instance by integrating other abiotic and biotic effects such as reindeer grazing feedback on the balance between vascular plants and lichens.

  • 13.
    Cornelissen, C
    et al.
    Vrije Univ Amsterdam.
    van Bodegom, M
    Aerts, Rien
    Callaghan, V
    van Logtestijn, P
    Alatalo, Juha
    Swedish Govt Agency Innovat Syst, VINNOVA.
    Chapin, Stuart
    Gerdol, Renato
    Gudmundsson, Jon
    Gwynn-Jones, Dylan
    Hartley, E
    Hik, S
    Hofgaard, Annika
    Jonsdottir, S
    Karlsson, Staffan
    Klein, A
    Laundre, Jim
    Magnusson, Borgthor
    Michelsen, Anders
    Molau, Ulf
    Onipchenko, G
    Quested, M
    Sandvik, M
    Schmidt, K
    Shaver, R
    Solheim, Bjorn
    Soudzilovskaia, A
    Stenstrom, Anna
    Tolvanen, Anne
    Totland, Orjan
    Wada, Naoya
    Welker, M
    Zhao, Xinquan
    Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes2007In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 10, no 7, p. 619-627Article in journal (Refereed)
    Abstract [en]

    Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide. Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.

  • 14. Elmendorf, Sarah C.
    et al.
    Henry, Gregory H. R.
    Hollister, Robert D.
    Alatalo, Juha
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Bjork, Robert G.
    Bjorkman, Anne D.
    Callaghan, Terry V.
    Collier, Laura Siegwart
    Cooper, Elisabeth J.
    Cornelissen, Johannes H. C.
    Day, Thomas A.
    Fosaa, Anna Maria
    Gould, William A.
    Gretarsdottir, Jarngerdur
    Harte, John
    Hermanutz, Luise
    Hik, David S.
    Hofgaard, Annika
    Jarrad, Frith
    Jonsdottir, Ingibjorg Svala
    Keuper, Frida
    Klanderud, Kari
    Klein, Julia A.
    Koh, Saewan
    Kudo, Gaku
    Lang, Simone I.
    Loewen, Val
    May, Jeremy L.
    Mercado, Joel
    Michelsen, Anders
    Molau, Ulf
    Myers-Smith, Isla H.
    Oberbauer, Steven F.
    Pieper, Sara
    Post, Eric
    Rixen, Christian
    Robinson, Clare H.
    Schmidt, Niels Martin
    Shaver, Gaius R.
    Stenstrom, Anna
    Tolvanen, Anne
    Totland, Orjan
    Troxler, Tiffany
    Wahren, Carl-Henrik
    Walker, Marilyn D.
    Webber, Patrick J.
    Welker, Jeffery M.
    Wookey, Philip A.
    Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time2012In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 15, no 2, p. 164-175Article, review/survey (Refereed)
    Abstract [en]

    Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation and associated ecosystem consequences have the potential to be much greater than we have observed to date.

  • 15. Jagerbrand, Annika K.
    et al.
    Alatalo, Juha M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Effects of human trampling on abundance and diversity of vascular plants, bryophytes and lichens in alpine heath vegetation, Northern Sweden2015In: SpringerPlus, E-ISSN 2193-1801, Vol. 4, article id 95Article in journal (Refereed)
    Abstract [en]

    This study investigated the effects of human trampling on cover, diversity and species richness in an alpine heath ecosystem in northern Sweden. We tested the hypothesis that proximity to trails decreases plant cover, diversity and species richness of the canopy and the understory. We found a significant decrease in plant cover with proximity to the trail for the understory, but not for the canopy level, and significant decreases in the abundance of deciduous shrubs in the canopy layer and lichens in the understory. Proximity also had a significant negative impact on species richness of lichens. However, there were no significant changes in species richness, diversity or evenness of distribution in the canopy or understory with proximity to the trail. While not significant, liverworts, acrocarpous and pleurocarpous bryophytes tended to have contrasting abundance patterns with differing proximity to the trail, indicating that trampling may cause shifts in dominance hierarchies of different groups of bryophytes. Due to the decrease in understory cover, the abundance of litter, rock and soil increased with proximity to the trail. These results demonstrate that low-frequency human trampling in alpine heaths over long periods can have major negative impacts on lichen abundance and species richness. To our knowledge, this is the first study to demonstrate that trampling can decrease species richness of lichens. It emphasises the importance of including species-level data on non-vascular plants when conducting studies in alpine or tundra ecosystems, since they often make up the majority of species and play a significant role in ecosystem functioning and response in many of these extreme environments.

  • 16. Jagerbrand, Annika K.
    et al.
    Alatalo, Juha M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Kudo, Gaku
    Variation in responses to temperature treatments ex situ of the moss Pleurozium schreberi (Willd. ex Brid.) Mitt. originating from eight altitude sites in Hokkaido, Japan2014In: Journal of Bryology, ISSN 0373-6687, E-ISSN 1743-2820, Vol. 36, no 3, p. 209-216Article in journal (Refereed)
    Abstract [en]

    Thermal acclimatisations are important for the survival and growth of individuals and populations but seldom studied for different populations of bryophytes. The aims of this study were to (I) investigate if responses to temperature treatments were independent of the site sampled or if the intra- and inter-population variation in responses were larger than the responses to the temperature treatments (control, press, and pulse), and to (II) examine if experimental responses varied, depending on the sampled sites. We collected samples of the circumpolar bryophyte species, Pleurozium schreberi (Willd. ex Brid.) Mitt., originating from eight altitude sites on Mt. Oakan in Hokkaido, Japan, and exposed them to three different temperature treatments ex situ for four weeks. Thermal acclimatisation was estimated by measuring responses in growth length increase, biomass increase, number of branches, and the maximum quantum yield of PS II (Fv/Fm). We found that responses to temperature treatments were dependent on the site sampled, and that differences were most pronounced in the length increase. Results also shows that the responses to experimental treatments may differ between sites. Our results therefore raise important concerns regarding the general validity of both ex situ and in situ experiments when performed on a single or a limited number of sites.

  • 17.
    Jagerbrand, K
    et al.
    Göteborgs Universitet.
    Alatalo, Juha
    Högskolan i Jönköping.
    Chrimes, Dillon
    Molau, Ulf
    Plant community responses to 5 years of simulated climate change in meadow and heath ecosystems at a subarctic-alpine site2009In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 161, no 3, p. 601-610Article in journal (Refereed)
    Abstract [en]

    Climate change was simulated by increasing temperature and nutrient availability in an alpine landscape. We conducted a field experiment of BACI-design (before/after control/impact) running for five seasons in two alpine communities (heath and meadow) with the factors temperature (increase of ca. 1.5-3.0A degrees C) and nutrients (5 g N, 5 g P per m(2)) in a fully factorial design in northern Swedish Lapland. The response variables were abundances of plant species and functional types. Plant community responses to the experimental perturbations were investigated, and the responses of plant functional types were examined in comparison to responses at the species level. Nutrient addition, exclusively and in combination with enhanced temperature increase, exerted the most pronounced responses at the species-specific and community levels. The main responses to nutrient addition were increases in graminoids and forbs, whereas deciduous shrubs, evergreen shrubs, bryophytes, and lichens decreased. The two plant communities of heath or meadow showed different vegetation responses to the environmental treatments despite the fact that both communities were located on the same subarctic-alpine site. Furthermore, we showed that the abundance of forbs increased in response to the combined treatment of temperature and nutrient addition in the meadow plant community. Within a single-plant functional type, most species responded similarly to the enhanced treatments although there were exceptions, particularly in the moss and lichen functional types. Plant community structure showed BACI responses in that vegetation dominance relationships in the existing plant functional types changed to varying degrees in all plots, including control plots. Betula nana and lichens increased in the temperature-increased enhancements and in control plots in the heath plant community during the treatment period. The increases in control plots were probably a response to the observed warming during the treatment period in the region.

  • 18.
    Jagerbrand, K
    et al.
    Göteborgs Universitet.
    Lindblad, M
    Bjork, G
    Alatalo, Juha
    Swedish EU, R&D Council.
    Molau, Ulf
    Bryophyte and lichen diversity under simulated environmental change compared with observed variation in unmanipulated alpine tundra2006In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 15, no 14, p. 4453-4475Article in journal (Refereed)
    Abstract [en]

    Effects of simulated environmental change on bryophyte and lichen species richness and diversity in alpine tundra were investigated in a 5-year experiment at Latnjajaure, northern Sweden. The experiment had a factorial design including fertilisation and temperature enhancement in one meadow and one heath plant community. Responses in species richness, biodiversity, and species composition of bryophytes and lichens to experimental treatments were compared to the observed variation in six naturally occurring plant communities. The combination of fertilisation and enhanced temperature resulted in a species impoverishment, for bryophytes in the bryophyte-dominated community, and for lichens in the lichen-dominated communities, but the species composition stayed within the observed natural variation. During the course of the study, no species new to the investigated mid-alpine landscape were recorded, but that scenario is realistic within a decade when comparing with the processes seen in vascular plants.

  • 19.
    Jägerbrand, Annika K.
    et al.
    Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
    Kudo, Gaku
    Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
    Alatalo, Juha M
    Gotland University, School of Culture, Energy and Environment.
    Molau, Ulf
    Department of Plant and Environmental Sciences, Göteborg University, Göteborg, Sweden.
    Effects of neighboring vascular plants on the abundance of bryophytes in different vegetation types2012In: Polar Science, ISSN 1873-9652, E-ISSN 1876-4428, Vol. 6, no 2, p. 200-208Article in journal (Refereed)
    Abstract [en]

    Due to the climate change, vegetation of tundra ecosystems is predicted to shift toward shrub and tree dominance, and this change may influence bryophytes. To estimate how changes in growing environment and the dominance of vascular plants influence bryophyte abundance, we compared the relationship of occurrence of bryophytes among other plant types in a five-year experiment of warming (T), fertilization (F) and T + F in two vegetation types, heath and meadow, in a subarctic–alpine ecosystem. We compared individual leaf area among shrub species to confirm that deciduous shrubs might cause severe shading effect. Effects of neighboring functional types on the performance of Hylocomium splendens was also analyzed.

    Results show that F and T + F treatments significantly influenced bryophyte abundance negatively. Under natural conditions, bryophytes in the heath site were negatively related to the abundance of shrubs and lichens and the relationship between lichens and bryophytes strengthened after the experimental period. After five years of experimental treatments in the meadow, a positive abundance relationship emerged between bryophytes and deciduous shrubs, evergreen shrubs and forbs. This relationship was not found in the heath site. Our study therefore shows that the abundance relationships between bryophytes and plants in two vegetation types within the same area can be different. Deciduous shrubs had larger leaf area than evergreen shrubs but did not show any shading effect on H. splendens.

  • 20.
    Little, Chelsea J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Eawag, CH-8600 Dubendorf, Switzerland..
    Jagerbrand, Annika K.
    Swedish Natl Rd & Transport Res Inst, VTI, S-10215 Stockholm, Sweden..
    Molau, Ulf
    Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    Alatalo, Juha M.
    Uppsala Univ, Dept Ecol & Genet, S-62167 Visby, Sweden..
    Community and species-specific responses to simulated global change in two subarctic-alpine plant communities2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 11, article id 227Article in journal (Refereed)
    Abstract [en]

    Long-term observational studies have detected greening and shrub encroachment in the subarctic attributed to current climate change, while global change simulations have showed that community composition and productivity may shift drastically in arctic, subarctic, and alpine tundra plant communities in the future. However, responses to global change can be highly species-and context-dependent. We examined community-level and species-specific responses to a six-year factorial temperature and nutrient (nitrogen and phosphorus) amendment experiment in two alpine plant communities in northern Sweden: a species-poor dwarf shrub heath, and a more species-rich meadow. We hypothesized that abundance responses to global change would be variable within commonly defined vascular plant functional groups (e.g., forbs, evergreen shrubs, deciduous shrubs) and that new species would appear in experimental plots over time due to the ameliorated growing conditions. We found that within most functional groups, species were highly individualistic with respect to the global change simulation, particularly within the forbs, whereas within the shrubs, responses were neutral to negative and widely variable in magnitude. In the heath community the response of the graminoid functional group was driven almost entirely by the grass Calamagrostis lapponica, which increased in abundance by an order of magnitude in the combined temperature and nutrient treatment. Furthermore, community context was important for species' responses to the simulations. Abundance of the pan-arctic species Carex bigelowii and Vaccinium vitis-idaea responded primarily to the temperature treatment in the meadow community whereas the nutrient treatment had stronger effects in the heath community. Over six growing seasons, more new species appeared in the experimental plots than in control plots in the meadow community, whereas in the heath community only one new species appeared. Our results from two closely situated but different plant communities show that functional groups do not predict individual species responses to simulated global change, and that these responses depend to a large extent on pre-existing physical conditions as well as biotic interactions such as competition and facilitation. It may be difficult to apply general trends of global change responses to specific local communities.

  • 21.
    Molau, U
    et al.
    Göteborgs Universitet.
    Alatalo, Juha
    Göteborgs Universitet.
    Responses of subarctic-alpine plant communities to simulated environmental change: Biodiversity of bryophytes, lichens, and vascular plants1998In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 27, no 4, p. 322-329Article in journal (Refereed)
    Abstract [en]

    The predicted changes in climate over the next 50 years are expected to be most pronounced in arctic and subarctic regions. In the present study, we examine the responses of a subarctic-alpine rich meadow and poor heath community to factorial manipulations of temperature and nutrient treatments. Specifically, we address response to the treatments in terms of biodiversity and relative cover of the bryophyte, lichen and vascular plant communities. We point out that the responses differ among mosses, lichens, vascular plants, and communities, and this will probably cause shifts in the dominance of both bottom layer and canopy layer species. It is important to note that the decrease in cover and species number of the bottom layer mainly occurred due to a decline in mosses; in contrast, lichen cover increased in all treatments in both communities. Climate change may thus cause a shift in the bottom layer from being dominated by mosses, to become dominated by lichens.

  • 22.
    Molau, U
    et al.
    Göteborgs Universitet.
    Alatalo, Juha
    Göteborgs Universitet.
    Jägerbrandt, AK
    Göteborgs Universitet.
    Responses of bryophytes to simulated environmental change at Latnjajaure, northern Sweden2003In: Journal of Bryology, ISSN 0373-6687, E-ISSN 1743-2820, Vol. 25, p. 163-168Article in journal (Refereed)
    Abstract [en]

    We simulated a predicted environmental change in a subarctic-alpine plant community to study short-term growth in Hylocomium splendens, and three-year effects in abundance changes of the five most common bryophytes at Latnjajaure, northern Sweden. The experiment had a factorial design with increased temperature and nutrients, alone and in combination. Moss growth was measured during the 1995 growing season, and we measured species abundance before and after three years of environmental perturbation. The combined treatments of fertilizer and temperature enhancement caused a decreased growth in length and dry weight in H. splendens. There was a significant decrease in abundance of Rhytidium rugosum in the combined temperature and fertilizer treatment. The other four common bryophyte species (Aulacomnium turgidum, Dicranum groenlandicum, Hylocomium splendens, and Ptilidium ciliare) showed weaker, but not significant trends in the same direction. As the bryophytes are an important component of arctic and subarctic vegetation, we expect that they will play a key role in the impact of anticipated Global Change on the ecosystems.

  • 23. Molau, Ulf
    et al.
    Alatalo, Juha
    Nordenhäll, Urban
    Stenström, Mikael
    Population structure of Arctic flowering plants1995In: Swedish-Russian Tundra Ecology-expedition-94. Tundra Ecology-94. A Cruise Report, Stockholm: Swedish Polar Research Secretariat , 1995Chapter in book (Other academic)
  • 24.
    Tolvanen, A
    et al.
    Univ Oulu.
    Alatalo, Juha
    Swedish EU, R&D Council.
    Henry, R
    Resource allocation patterns in a forb and a sedge in two arctic environments - short-term response to herbivory2004In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 22, no 6, p. 741-747Article in journal (Refereed)
    Abstract [en]

    The present work investigates C and N allocation patterns in two forage plants: a forb, Oxyria digyna, and a sedge, Eriophorum angustifolium, in subarctic Sweden and high arctic Canada. Short-term changes in concentrations after simulated or natural herbivory (caused by Gynaephora groenlandica on Oxyria in the high arctic habitat) were also investigated. There were no clear differences in concentrations of C and N between the high arctic and subarctic sites in either species. In Oxyria of the subarctic habitat, the minimum N concentrations occurred at earlier phenological stages compared with plants in the high arctic habitat. Simulated herbivory increased the concentration of C in belowground tissues relative to those in control plants in Oxyria at the subarctic site, which may indicate increased allocation of non-C compounds to the growing shoots or daughter ramets. Herbivory by Gynaephora groenlandica caterpillars increased the N concentrations of Oxyria both in aboveground and belowground tissues, possible indicating increased uptake of N in the high arctic habitat. Eriophorum did not show clear trends in concentrations relating to habitat, phenology or simulated herbivory. The difference between Oxyria and Eriophorum in their response to herbivory apparently resulted from contrasting growth habits between the species. Tiller death after reproduction and long leaf life span may be the main reasons for the lack of clear patterns in concentrations in Eriophorum. Compensation after herbivory may be attained by the early production of daughter tillers in Eriophorum instead of the regrowth of the damaged ramets, as in Oxyria. Monitoring the responses for only one season is apparently a too short time period in these long-lived plants.

  • 25.
    Totland, O
    et al.
    Agr Univ Norway.
    Alatalo, Juha
    Göteborgs Universitet.
    Effects of temperature and date of snowmelt on growth, reproduction, and flowering phenology in the arctic/alpine herb, Ranunculus glacialis2002In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 133, no 2, p. 168-175Article in journal (Refereed)
    Abstract [en]

    Changes in growing season temperature and duration may have profound effects on the population dynamics of arctic and alpine plant species in snow-bed and fell-field habitats. We examined how a typical herbaceous pioneer species, Ranunculus glacialis, responded to experimental climate change in open-top chambers for three seasons at an alpine site in southern Norway. Warming had no significant effect on any reproductive, growth or phenological variables, except for seed weight, which increased significantly during the first 2 ears. Despite large differences in average date of snow-melt among years, average reproductive output and ramet size differed little among years. Within-year variation in date of snowmelt had no impact on seed number or weight in either control or warmed plots. Leaf width and ramet leaf number decreased significantly with later snowmelt within a year. Experimental warming reduced the negative effect on ramet size of late snowmelt within a year to some extent. In general, R. glacialis reacts contrary to most other arctic/alpine species to experimental warming. Species with such low responsiveness to environmental conditions may be particularly vulnerable to climatic change, especially if their habitat is invaded by other species with higher phenotypic plasticity and a better competitive ability.

  • 26.
    Walker, D
    et al.
    Univ Alaska Fairbanks.
    Wahren, H
    Hollister, D
    Henry, R
    Ahlquist, E
    Alatalo, Juha
    Göteborgs Universitet.
    Bret-Harte, S
    Calef, P
    Callaghan, V
    Carroll, B
    Epstein, E
    Jonsdottir, S
    Klein, A
    Magnusson, B
    Molau, U
    Oberbauer, F
    Rewa, P
    Robinson, H
    Shaver, R
    Suding, N
    Thompson, C
    Tolvanen, A
    Totland, O
    Turner, L
    Tweedie, E
    Webber, J
    Wookey, A
    Plant community responses to experimental warming across the tundra biome2006In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 103, no 5, p. 1342-1346Article in journal (Refereed)
    Abstract [en]

    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.

1 - 26 of 26
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