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Effect of elevated [CO2 ] on stem wood properties of mature Norway spruce grown at different soil nutrient availability 总被引:1,自引:0,他引:1
Katri Kostiainen Seija Kaakinen Pekka Saranpää† Bjarni D. Sigurdsson‡ Sune Linder§ Elina Vapaavuori 《Global Change Biology》2004,10(9):1526-1538
The objective of the present study was to investigate the interactive effects of elevated [CO2] and soil nutrient availability on secondary xylem structure and chemical composition of 41‐year‐old Norway spruce (Picea abies (L.) Karst.) trees. The nonfertilized and irrigated‐fertilized trees were, for 3 years, continuously exposed to elevated [CO2] in whole‐tree chambers. Elevated [CO2] decreased concentrations of soluble sugars, acid‐soluble lignin and nitrogen in stem wood, but the effects were not consistent between sampling height and/or fertilization. The effect of 2*ambient [CO2] on wood structure depended on the exposure year and/or fertilization. Radial lumen diameter decreased and annual ring width increased in the second year of exposure (1999) in elevated [CO2]. In the latter, the CO2 effect was significant only in the nonfertilized trees. Stem wood chemistry and structure were significantly affected by fertilization. Fertilization increased the concentrations of nitrogen and gravimetric lignin, annual ring width, and radial lumen diameter. Fertilization decreased C/N ratio, mean ring density, earlywood density, latewood density, cell wall thickness, cell wall index, and latewood percentage. We conclude that elevated [CO2] had only minor effects on wood properties while fertilization had more marked effects and thus may affect ecosystem processes and suitability of wood for different end‐use purposes. 相似文献
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Hydrobiologia - The invertebrate fauna from 22 lava spring sources throughout Iceland’s volcanically active zone was studied to investigate the role of spring type and environmental variables... 相似文献
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Bjarni Már Magnússon 《Ocean Development & International Law》2017,48(1):1-16
Although most provisions of the United Nations Convention on the Law of the Sea are regarded customary international law and the United States views most of its provisions as such, the outsider status of the United States causes problems in some areas, especially concerning the continental shelf beyond 200 nautical miles. This article asks whether it is possible for the United States to establish the outer limits of its continental shelf beyond 200 nautical miles in line with international law without becoming a state party to the convention, and if that is possible, how could the United States proceed? 相似文献
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Plant invasion is associated with higher plant–soil nutrient concentrations in nutrient‐poor environments 下载免费PDF全文
Jordi Sardans Mireia Bartrons Olga Margalef Albert Gargallo‐Garriga Ivan A. Janssens Phillipe Ciais Michael Obersteiner Bjarni D. Sigurdsson Han Y. H. Chen Josep Peñuelas 《Global Change Biology》2017,23(3):1282-1291
Plant invasion is an emerging driver of global change worldwide. We aimed to disentangle its impacts on plant–soil nutrient concentrations. We conducted a meta‐analysis of 215 peer‐reviewed articles and 1233 observations. Invasive plant species had globally higher N and P concentrations in photosynthetic tissues but not in foliar litter, in comparison with their native competitors. Invasive plants were also associated with higher soil C and N stocks and N, P, and K availabilities. The differences in N and P concentrations in photosynthetic tissues and in soil total C and N, soil N, P, and K availabilities between invasive and native species decreased when the environment was richer in nutrient resources. The results thus suggested higher nutrient resorption efficiencies in invasive than in native species in nutrient‐poor environments. There were differences in soil total N concentrations but not in total P concentrations, indicating that the differences associated to invasive plants were related with biological processes, not with geochemical processes. The results suggest that invasiveness is not only a driver of changes in ecosystem species composition but that it is also associated with significant changes in plant–soil elemental composition and stoichiometry. 相似文献
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Eoin J. O'Gorman Jonathan P. Benstead Wyatt F. Cross Nikolai Friberg James M. Hood Philip W. Johnson Bjarni D. Sigurdsson Guy Woodward 《Global Change Biology》2014,20(11):3291-3299
Understanding and predicting how global warming affects the structure and functioning of natural ecosystems is a key challenge of the 21st century. Isolated laboratory and field experiments testing global change hypotheses have been criticized for being too small‐scale and overly simplistic, whereas surveys are inferential and often confound temperature with other drivers. Research that utilizes natural thermal gradients offers a more promising approach and geothermal ecosystems in particular, which span a range of temperatures within a single biogeographic area, allow us to take the laboratory into nature rather than vice versa. By isolating temperature from other drivers, its ecological effects can be quantified without any loss of realism, and transient and equilibrial responses can be measured in the same system across scales that are not feasible using other empirical methods. Embedding manipulative experiments within geothermal gradients is an especially powerful approach, informing us to what extent small‐scale experiments can predict the future behaviour of real ecosystems. Geothermal areas also act as sentinel systems by tracking responses of ecological networks to warming and helping to maintain ecosystem functioning in a changing landscape by providing sources of organisms that are preadapted to different climatic conditions. Here, we highlight the emerging use of geothermal systems in climate change research, identify novel research avenues, and assess their roles for catalysing our understanding of ecological and evolutionary responses to global warming. 相似文献
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Guðbjörg Ásta Ólafsdóttir Alexandreou Andreou Kit Magellan Bjarni K. Kristjánsson 《Biological journal of the Linnean Society. Linnean Society of London》2014,113(1):194-203
Foraging in social groups has a number of benefits but can also increase the risk of exploitation. High tendency to shoal may be correlated with groups foraging, although facultatively social fish adjust both shoaling decisions and food resource defence based on intrinsic and extrinsic factors. The main aim of this study was to examine the relationships between shoaling, solitary foraging and aggression, forager tolerance of conspecifics joining at a discovered food patch and forager exploitation of resources discovered by others. We used two intra‐lacustrine three‐spined stickleback morph pairs, lava and mud, and monomorphic morphs from each of lava and mud habitats. The lava morph formed less cohesive shoals, was bolder during solitary foraging, approached and entered an occupied food patch less frequently than the mud morph, suggesting a link between shoaling and the propensity for social foraging. However, shoaling tendency and joiner tolerance were not correlated at a population level. Intralacustrine lava and mud morphs differed more markedly in joiner tolerance than morphs from single habitat lakes, whereas the opposite was true for shoaling tendency. We conclude that, in addition to differentiation in shoaling tendency, the lava and mud morphs differ in social foraging and these variations may act to promote population divergence. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 194–203. 相似文献
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Hans J. De Boeck Juliette M. G. Bloor Rien Aerts Michael Bahn Claus Beier Bridget A. Emmett Marc Estiarte Jos M. Grünzweig Aud H. Halbritter Petr Holub Anke Jentsch Karel Klem Juergen Kreyling Gyrgy Krel‐Dulay Klaus Steenberg Larsen Alexandru Milcu Jacques Roy Bjarni D. Sigurdsson Melinda D. Smith Marcelo Sternberg Vigdis Vandvik Thomas Wohlgemuth Ivan Nijs Alan K. Knapp 《Global Change Biology》2020,26(2):e6-e7
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Variation in the magnitude of morphological and dietary differences between individuals among populations of small benthic Arctic charr in relation to ecological factors 下载免费PDF全文
The early stages of intraspecific diversity are important for the evolution of diversification and speciation. Early stages of diversification can be seen in individual specialization, where individuals consume only a portion of the diet of the population as a whole, and how such specialization is related to phenotypic diversity within populations. Here, we study the strength of the relationship between morphological and dietary distances among individuals in eighteen populations of Icelandic small benthic charr. We furthermore studied if the strength of the relationship could be related to variation in local ecological factors these populations inhabit. In all the populations studied, there was a clear relationship between morphological and dietary distances, indicating that fish that had similar morphology were at the same time‐consuming similar food items. Our findings show a systematic variation in the relationship between morphology and diet at early stages of diversification in a highly specialized small benthic charr morph. The results show the importance of fine scale comparisons within populations and furthermore the value that systematic comparisons among populations under parallel evolution can contribute toward our increased understanding of evolutionary and ecological processes. 相似文献