Gargallo-Garriga A., Ayala-Roque M., Sardans J., Bartrons M., Granda V., Sigurdsson B.D., Leblans N.I.W., Oravec M., Urban O., Janssens I.A., Peñuelas J. (2017) Impact of soil warming on the plant metabolome of Icelandic grasslands. Metabolites. 7: 0-0.LinkDoi: 10.3390/metabo7030044
Climate change is stronger at high than at temperate and tropical latitudes. The natural geothermal conditions in southern Iceland provide an opportunity to study the impact of warming on plants, because of the geothermal bedrock channels that induce stable gradients of soil temperature. We studied two valleys, one where such gradients have been present for centuries (long-term treatment), and another where new gradients were created in 2008 after a shallow crustal earthquake (short-term treatment). We studied the impact of soil warming (0 to +15° C) on the foliar metabolomes of two common plant species of high northern latitudes: Agrostis capillaris, a monocotyledon grass; and Ranunculus acris, a dicotyledonous herb, and evaluated the dependence of shifts in their metabolomes on the length of the warming treatment. The two species responded differently to warming, depending on the length of exposure. The grass metabolome clearly shifted at the site of long-term warming, but the herb metabolome did not. The main up-regulated compounds at the highest temperatures at the long-term site were saccharides and amino acids, both involved in heat-shock metabolic pathways. Moreover, some secondary metabolites, such as phenolic acids and terpenes, associated with a wide array of stresses, were also up-regulated. Most current climatic models predict an increase in annual average temperature between 2–8° C over land masses in the Arctic towards the end of this century. The metabolomes of A. capillaris and R. acris shifted abruptly and nonlinearly to soil warming >5° C above the control temperature for the coming decades. These results thus suggest that a slight warming increase may not imply substantial changes in plant function, but if the temperature rises more than 5° C, warming may end up triggering metabolic pathways associated with heat stress in some plant species currently dominant in this region. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.
Benavides R., Escudero A., Coll L., Ferrandis P., Gouriveau F., Hodar J.A., Ogaya R., Rabasa S.G., Granda E., Santamaria B.P., Martinez-Vilalta J., Zamora R., Espelta J.M., Penuelas J., Valladares F. (2015) Survival vs. growth trade-off in early recruitment challenges global warming impacts on Mediterranean mountain trees. Perspectives in Plant Ecology, Evolution and Systematics. : 0-0.LinkDoi: 10.1016/j.ppees.2015.06.004
Climate change is expected to alter the geographic distribution of many plant species worldwide. However, there is still no clear evidence showing a generalised direction and magnitude of these distribution shifts. Here, we have surveyed, in nine mountainous regions in Spain, an array of tree species along entire elevational ranges, as surrogates of their global climatic ranges, to test for elevational shifts towards cooler locations. We analysed the distribution recruitment patterns of five dominant tree species, recording the abundance and measuring the primary growth of juveniles in 306 plots. Three of the species have a temperate-boreal distribution with populations at their southern edge in the Mediterranean mountain ranges: Pinus sylvestris, Pinus uncinata and Fagus sylvatica; and the other two species have a Mediterranean distribution: Quercus ilex and Pinus nigra. Despite the contrasting phylogenies and biogeographies, we identified a similar pattern in recruitment abundance across species, with an asymmetric distribution of juveniles (more recruits in the middle-upper elevation of their range), but higher annual growths at lower elevations. This survival-growth trade-off at the early recruitment stage may potentially counterbalance at population level the negative effect of global warming on recruit survival at the lower edge of species ranges. These findings suggest a demographic stabilisation process at the early recruitment stage of these tree species, and highlight the importance of considering the different demographic stages across the whole climatic range to understand the effects that climate change may exert on species distributions and population dynamics. © 2015 Geobotanisches Institut ETH, Stiftung Ruebel.
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