(2016) SAPFLUXNET: towards a global database of sap flow measurements. . : -.LinkDoi: https://doi.org/10.1093/treephys/tpw110
Achotegui-Castells A., Della Rocca G., Llusià J., Danti R., Barberini S., Bouneb M., Simoni S., Michelozzi M., Peñuelas J. (2016) Terpene arms race in the Seiridium cardinale - Cupressus sempervirens pathosystem. Scientific Reports. 6: 0-0.LinkDoi: 10.1038/srep18954
The canker-causing fungus Seiridium cardinale is the major threat to Cupressus sempervirens worldwide. We investigated the production of terpenes by canker-resistant and susceptible cypresses inoculated with S. cardinale, the effect of these terpenes on fungal growth, and the defensive biotransformation of the terpenes conducted by the fungus. All infected trees produced de novo terpenes and strongly induced terpenic responses, but the responses were stronger in the canker-resistant than the susceptible trees. In vitro tests for the inhibition of fungal growth indicated that the terpene concentrations of resistant trees were more inhibitory than those of susceptible trees. The highly induced and de novo terpenes exhibited substantial inhibition (more than a fungicide reference) and had a high concentration-dependent inhibition, whereas the most abundant terpenes had a low concentration-dependent inhibition. S. cardinale biotransformed three terpenes and was capable of detoxifying them even outside the fungal mycelium, in its immediate surrounding environment. Our results thus indicated that terpenes were key defences efficiently used by C. sempervirens, but also that S. cardinale is ready for the battle.
Aguillaume L., Rodrigo A., Avila A. (2016) Long-term effects of changing atmospheric pollution on throughfall, bulk deposition and streamwaters in a Mediterranean forest. Science of the Total Environment. 544: 919-928.LinkDoi: 10.1016/j.scitotenv.2015.12.017
The abatement programs implanted in Europe to reduce SO2, NO2 and NH3 emissions are here evaluated by analyzing the relationships between emissions in Spain and neighboring countries and atmospheric deposition in a Mediterranean forest in the Montseny mountains (NE Spain) for the last 3decades. A canopy budget model was applied to throughfall data measured during a period of high emissions (1995-1996) and a period of lower emissions (2011-2013) to estimate the changes in dry deposition over this time span.Emissions of SO2 in Spain strongly decreased (77%) and that was reflected in reductions for nssSO4 2- in precipitation (65% for concentrations and 62% for SO4 2-S deposition). A lower decline was found for dry deposition (29%).Spanish NO2 emissions increased from 1980 to 1991, remained constant until 2005, and decreased thereafter, a pattern that was paralleled by NO3 - concentrations in bulk precipitation at Montseny. This pattern seems to be related to a higher share of renewable energies in electricity generation in Spain in recent years. However, dry deposition increased markedly between 1995 and 2012, from 1.3 to 6.7kgha-1year- 1. Differences in meteorology between periods may have had a role, since the recent period was drier thus probably favoring dry deposition.Spanish NH3 emissions increased by 13% between 1980 and 2012 in Spain but NH4 + concentrations in precipitation and NH4 +-N deposition showed a decreasing trend (15% reduction) at Montseny, probably linked to the reduction ammonium sulfate and nitrate aerosols to be scavenged by rainfall. NH4 +-N dry deposition was similar between the compared periods.The N load at Montseny (15-17kgha-1year-1) was within the critical load range proposed for Mediterranean sclerophyllous forests (15-17.5kgha-1year-1). The onset of N saturation is suggested by the observed increasing N export in streamwaters. © 2015 Elsevier B.V.
Aguillaume, L. (2016) La deposición de nitrógeno en encinares Mediterráneos: Cargas e indicadores. Ecosistemas. 25: 110-113.LinkDoi: 10.7818/ECOS.2016.25-2.15
Ameztegui A., Coll L., Brotons L., Ninot J.M. (2016) Land-use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees. Global Ecology and Biogeography. 25: 263-273.LinkDoi: 10.1111/geb.12407
Aim: To assess the effects of climate change, past land uses and physiography on the current position of the tree line in the Catalan Pyrenees and its dynamics between 1956 and 2006. Location: More than 1000 linear kilometres of sub-alpine tree line in the Catalan Pyrenees (north-east Spain) Methods: Using aerial photographs and supervised classification, we reclassified the images into a binary raster with 'tree' and 'non-tree' values, and determined canopy cover in 1956 and 2006. We then determined the change in position of the tree line between 1956 and 2006 based on changes in forest cover. We used the distance from the position of the tree line in 1956 to the theoretical potential tree line - determined from interpretation of aerial photographs, identifying the highest old remnants of forest for homogeneous areas of the landscape in terms of bioclimatic conditions, bedrock, landform and exposure - as a surrogate of intensity of past land uses. Results: Our analyses showed that the Pyrenean tree line has moved upwards on average almost 40m (mean advance±SE: 35.3±0.5m, P
Ameztegui, A., Paquette, A., Shipley, B., Heym, M., Messier, C., Gravel, D. (2016) Shade tolerance and the functional trait: Demography relationship in temperate and boreal forests. Functional Ecology. : 0-0.LinkDoi: 10.1111/1365-2435.12804
Anderegg, W.R.L., Martinez-Vilalta, J., Cailleret, M., Camarero, J.J., Ewers, B.E., Galbraith, D., Gessler, A., Grote, R., Huang, C.-Y., Levick, S.R., Powell, T.L., Rowland, L., Sánchez-Salguero, R., Trotsiuk, V. (2016) When a Tree Dies in the Forest: Scaling Climate-Driven Tree Mortality to Ecosystem Water and Carbon Fluxes. Ecosystems. 19: 1133-1147.LinkDoi: 10.1007/s10021-016-9982-1
Andresen, L.C., Müller, C., de Dato, G., Dukes, J.S., Emmett, B.A., Estiarte, M., Jentsch, A., Kröel-Dulay, G., Lüscher, A., Niu, S., Peñuelas, J., Reich, P.B., Reinsch, S., Ogaya, R., Schmidt, I.K., Schneider, M.K., Sternberg, M., Tietema, A., Zhu, K., Bilton, M.C. (2016) Shifting Impacts of Climate Change: Long-Term Patterns of Plant Response to Elevated CO2, Drought, and Warming Across Ecosystems. Advances in Ecological Research. : 0-0.LinkDoi: 10.1016/bs.aecr.2016.07.001
Andrés P., Moore J.C., Simpson R.T., Selby G., Cotrufo F., Denef K., Haddix M.L., Shaw E.A., de Tomasel C.M., Molowny-Horas R., Wall D.H. (2016) Soil food web stability in response to grazing in a semi-arid prairie: The importance of soil textural heterogeneity. Soil Biology and Biochemistry. 97: 131-143.LinkDoi: 10.1016/j.soilbio.2016.02.014
Grazing of grasslands by large herbivores is a form of land use intensification that affects not only plant communities but also soil biota and the ecosystem services that it provides. While grassland ecosystem responses to grazing have been extensively studied, few studies have focused on the effects of aboveground herbivores on belowground diversity and functions. In this work, we quantified effects of grazing on the structure, function and dynamic stability of soil food webs. We sampled a long-term grazing manipulation in a semi-arid shortgrass steppe (USA Great Plains) at sites showing contrasting soil textures. Treatments included native steppe plots that have been moderately grazed since 1939 paired with plots totally protected from grazing since 1996. We sampled our plots for soil C and N, and for soil biota, separated microbes and micro- and mesofauna in trophic functional groups and defined trophic relationships. We used models to estimate carbon and nitrogen mineralization, energy flow throughout the food web, interaction strengths between trophic groups at steady-state and, eventually, asymptotic (near-equilibrium or local) stability (Moore and de Ruiter, 2012). Soil food web response to grazing depended on soil texture and organic matter content. In our food webs, most energy flowed through the fungal and bacterial detritus-based channels (sensu Moore and Hunt, 1988). There was a clear asymmetry between the amount of energy flowing through each of the two channels and, the higher this asymmetry, the higher was food web stability. Stability was affected by both grazing and soil properties (increased under grazing in high clay soils with high organic matter content but decreased in less organic loam sandy soils), and positively associated with soil organic matter content. Overall, we found that the carbon flow through the soil food web of the shortgrass steppe is responsive to grazing in ways that altered stability and that structural, functional, and dynamic attributes are sensitive parameters for evaluating soil response to land use under changing scenarios. © 2016 Elsevier Ltd.
Arnan X., Cerdá X., Retana J. (2016) Relationships among taxonomic, functional, and phylogenetic ant diversity across the biogeographic regions of Europe. Ecography. : 0-0.LinkDoi: 10.1111/ecog.01938
Understanding how different biodiversity components are related across different environmental conditions is a major goal in macroecology and conservation biogeography. We investigated correlations among alpha and beta taxonomic (TD), phylogenetic (PD), and functional diversity (FD) in ant communities in the five biogeographic regions most representative of western Europe; we also examined the degree of niche conservatism. We combined data from 349 ant communities composed of 154 total species, which were characterized by 10 functional traits and by phylogenetic relatedness. We computed TD, PD, and FD using the Rao quadratic entropy index, which allows each biodiversity component to be partitioned into α and β diversity within the same mathematical framework. We ran generalized least squares and multiple matrix regressions with randomization to investigate relationships among the diversity components. We used Pagel's λ test to explore niche conservatism in each biogeographic region. At the alpha scale, TD was consistently, positively related to PD and FD, although the strength and scatter of this relationship changed among the biogeographic regions. Meanwhile, PD and FD consistently matched up across regions. Accordingly, we found similar degrees of niche conservatism across regions. Nonetheless, these alpha-scale relationships had low coefficients of determination. At the beta scale, the three diversity components were highly correlated across all regions (especially TD and FD, as well as PD and FD). Our results imply that the different diversity components, and especially PD and FD, are consistently related across biogeographic regions and analytical scale. However, the alpha-scale relationships were quite weak, suggesting environmental factors might influence the degree of association among diversity components at the alpha level. In conclusion, conservation programs should seek to preserve functional and phylogenetic diversity in addition to species richness, and this approach should be applied universally, regardless of the biogeographic locations of the sites to be protected. © 2016 Nordic Society Oikos.
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