Wang W., Min Q., Sardans J., Wang C., Asensio D., Bartrons M., Peñuelas J. (2016) Organic cultivation of jasmine and tea increases carbon sequestration by changing plant and soil stoichiometry. Agronomy Journal. 108: 1636-1648.EnllaçDoi: 10.2134/agronj2015.0559
Organic cultivation methods would be a good alternative to conventional cultivation, avoiding the use of industrial fertilizer and reducing the risk of eutrophication, but its impacts on soil elemental composition and stoichiometry warrants to be clearly stated. This study was conducted to determine the effects of long-term organic cultivation on soil elemental composition, stoichiometry, and C storing capacity and CO2 emissions in the plant-soil systems of jasmine (Jasminum spp.) and tea [Camellia sinensis (L.) Ktze.] plantations in Fujian and other regions in China. We examined the impact of organic cultivation on the concentrations, contents and stoichiometric relationships among C, N, P, and K. Organic cultivation was associated with lower plant N and P concentrations, and P mineralomasses and with higher total plant C/N, C/P, C/K, and N/P ratios and higher soil N and P concentrations and contents at some depths. Organic cultivation was thus associated with a shift of P from plants to soil and with a higher nutrient-use efficiency in biomass production, mainly of P. Soil CO2 emissions were higher under organic cultivation, but the soil was able to accumulate more C with no changes in C storage in plant biomass, suggesting that organic cultivation could increase the overall C sequestration, thereby mitigating climate change and enhancing soil nutrient content. Our results thus showed that the organic cultivation of jasmine and tea in Fujian can improve soil fertility and C accumulation, reduce the use of industrial fertilizers and phytosanitary products, and improve product quality without loss of economical profits. © 2016 by the American Society of Agronomy.
Wang W., Sardans J., Tong C., Wang C., Ouyang L., Bartrons M., Peñuelas J. (2016) Typhoon enhancement of N and P release from litter and changes in the litter N:P ratio in a subtropical tidal wetland. Environmental Research Letters. 11: 0-0.EnllaçDoi: 10.1088/1748-9326/11/1/014003
Litter production and decomposition are key processes controlling the capacity of wetland to store and cycle carbon (C) and nutrients. Typhoons deposit large amounts of green and semi-green (between green and withered) plant tissues and withered litter (normal litter) on wetland soils, generating a pulse of litter production. Climatic models project an increase in typhoon intensity and frequency. Elucidating the impacts of typhoons on C, N and P cycles and storage capacities in subtropical and tropical wetland areas is thus important. We analyzed the patterns and changes of litter decomposition after a typhoon in the Minjiang River estuary in southeastern China. Green litter decomposed the fastest, and the loss of mass did not differ significantly between semi-green litter, withered litter and mixed litter (all soil litter after a typhoon). During the decomposition process the remaining green litter had the highest, and withered litter the lowest N and P concentrations. The biomass loss rate of litter during the studied period was related to the initial litter N and P concentrations. Remaining litter generally increased its N:P ratio during decomposition. The ratio of the released N and P was consequently lower than the initial N:P ratio in all litter types. The typhoon enhanced the release of C, N and P from the litter (884, 12.3 and 6 kg ha-1, respectively) by 264 days after the typhoon. The soil was accordingly enriched with organic matter and nutrients for several months, which should favor microbial growth rates (higher C, N and P availability and lower C:nutrient and N:P ratios) and increase the rates of C and nutrient cycling. If the frequency and/or intensity of typhoons increase, a constant increase in the release of N and P to the soil with lower N:P ratios could change the N and P cycles in wetlands and provide better conditions for the spread of fast-growing species. © 2016 IOP Publishing Ltd.
Wang W., Zeng C., Sardans J., Wang C., Zeng D., Peñuelas J. (2016) Amendment with industrial and agricultural wastes reduces surface-water nutrient loss and storage of dissolved greenhouse gases in a subtropical paddy field. Agriculture, Ecosystems and Environment. 231: 296-303.EnllaçDoi: 10.1016/j.agee.2016.07.012
Paddy fields are important ecosystems for supporting human life. They are frequently fertilized more than necessary for providing high yields of rice (Oryza sativa), so nutrients are lost by leaching into aquatic ecosystems, which become eutrophic. Rice production is also an important source of greenhouse gases (GHGs). Mitigation of the nutrient losses and GHG emissions from paddy fields is crucial both for the sustainability of rice production and the reduction of adverse environmental effects. We examined the effects of the application of biochar, steel slag, shell slag, gypsum slag and silicate and calcium slag (produced from steel slag) on water nutrient concentrations and dissolved GHGs in a paddy field in subtropical southeastern China, one of the most important areas of rice production in the world. The concentrations of total dissolved nitrogen (TN) and total dissolved phosphorus (TP) in the surface water were lower in plots amended with shell slag than the control plots. Mean porewater TN and TP concentrations, however, were higher, and the mean porewater dissolved CO2 concentration was 68% lower in the plots amended with silicate and calcium slag than the control plots. Mean dissolved CH4 concentrations were 92 and 70% lower in the plots amended with gypsum slag and silicate and calcium slag, respectively. Mean dissolved N2O concentrations did not differ significantly among all plots. The concentrations of dissolved CO2 and CH4 were correlated with their production and emission. The concentration of dissolved CO2 was negatively correlated with porewater concentrations of NH4 +, NO2 −, NO3 −, TN, TP and Cl−. The concentration of dissolved CH4 was negatively correlated with porewater concentrations of NH4 +, TN, TP, dissolved organic carbon (DOC), SO4 2− and Cl−. The concentration of dissolved N2O was correlated positively with the concentrations of NO2 −, NO3 −, DOC and SO4 2− and negatively with the porewater concentration of NH4 +. These results support the use of these fertilizers alone or in combination for the mitigation of water nutrient losses and GHG production in rice agriculture and will provide a scientific basis for continuing the search for an easy, economical and optimum management of fertilization. © 2016 Elsevier B.V.
Yan Z., Han W., Peñuelas J., Sardans J., Elser J.J., Du E., Reich P.B., Fang J. (2016) Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts. Ecology Letters. : 0-0.EnllaçDoi: 10.1111/ele.12658
Combined effects of cumulative nutrient inputs and biogeochemical processes that occur in freshwater under anthropogenic eutrophication could lead to myriad shifts in nitrogen (N):phosphorus (P) stoichiometry in global freshwater ecosystems, but this is not yet well-assessed. Here we evaluated the characteristics of N and P stoichiometries in bodies of freshwater and their herbaceous macrophytes across human-impact levels, regions and periods. Freshwater and its macrophytes had higher N and P concentrations and lower N: P ratios in heavily than lightly human-impacted environments, further evidenced by spatiotemporal comparisons across eutrophication gradients. N and P concentrations in freshwater ecosystems were positively correlated and N: P was negatively correlated with population density in China. These results indicate a faster accumulation of P than N in human-impacted freshwater ecosystems, which could have large effects on the trophic webs and biogeochemical cycles of estuaries and coastal areas by freshwater loadings, and reinforce the importance of rehabilitating these ecosystems. © 2016 John Wiley & Sons Ltd.
(2015) The application of ecological stoichiometry to plant-microbial-soil organic matter transformations. . : -.EnllaçDoi: 10.1890/14-0777.1
Blanch J.S., Peñuelas J., Llusià J., Sardans J., Owen S.M. (2015) Differences in photosynthesis and terpene content in leaves and roots of wild-type and transgenic Arabidopsis thaliana plants. Russian Journal of Plant Physiology. 62: 823-829.EnllaçDoi: 10.1134/S1021443715060035
We investigated the hypotheses that two different varieties of Arabidopsis thaliana show differences in physiology and terpene production. The two varieties of A. thaliana used in this study were wild-type (WT) and transgenic line (CoxIV-FaNES I) genetically modified to emit nerolidol with linalool/nerolidol synthase (COX). Photosynthetic rate, electron transport rate, fluorescence, leaf volatile terpene contents and root volatile terpene contents were analyzed. For both types, we found co-eluting α-pinene+β-ocimene, limonene, and humulene in leaves; and in the roots we found co-eluting α-pinene+β-ocimene, sabinene+β-pinene, β-myrcene, limonene, and humulene. At the end of the growing cycle, COX plants tended to have lower pools of terpene compounds in their leaves, with 78.6% lower photosynthesis rates and 30.8% lower electron transport rates, compared with WT plants at that time. The maximal photochemical efficiency Fv/Fm was also significantly lower (25.5%) in COX plants, indicating that these varieties were more stressed than WT plants. However, COX plants had higher (239%) root terpene contents compared to WT plants. COX plants appear to favor root production of volatile terpenes rather than leaf production. Thus we conclude that there were significant differences between COX and WT plants in terms of terpenoid pools, stress status and physiology. © 2015, Pleiades Publishing, Ltd.
Fernández-Martínez M., Vicca S., Janssens I.A., Sardans J., Luyssaert S., Campioli M., Chapin F.S., Ciais P., Malhi Y., Obersteiner M., Papale D., Piao S.L., Reichstein M., Rodà F., Peñuelas J. (2015) Reply to 'Uncertain effects of nutrient availability on global forest carbon balance' and 'Data quality and the role of nutrients in forest carbon-use efficiency'. Nature Climate Change. 5: 960-961.EnllaçDoi: 10.1038/nclimate2794
[No abstract available]
Gargallo-Garriga A., Sardans J., Perez-Trujillo M., Oravec M., Urban O., Jentsch A., Kreyling J., Beierkuhnlein C., Parella T., Penuelas J. (2015) Warming differentially influences the effects of drought on stoichiometry and metabolomics in shoots and roots. New Phytologist. : 0-0.EnllaçDoi: 10.1111/nph.13377
Plants in natural environments are increasingly being subjected to a combination of abiotic stresses, such as drought and warming, in many regions. The effects of each stress and the combination of stresses on the functioning of shoots and roots have been studied extensively, but little is known about the simultaneous metabolome responses of the different organs of the plant to different stresses acting at once. We studied the shift in metabolism and elemental composition of shoots and roots of two perennial grasses, Holcus lanatus and Alopecurus pratensis, in response to simultaneous drought and warming. These species responded differently to individual and simultaneous stresses. These responses were even opposite in roots and shoots. In plants exposed to simultaneous drought and warming, terpenes, catechin and indole acetic acid accumulated in shoots, whereas amino acids, quinic acid, nitrogenous bases, the osmoprotectants choline and glycine betaine, and elements involved in growth (nitrogen, phosphorus and potassium) accumulated in roots. Under drought, warming further increased the allocation of primary metabolic activity to roots and changed the composition of secondary metabolites in shoots. These results highlight the plasticity of plant metabolomes and stoichiometry, and the different complementary responses of shoots and roots to complex environmental conditions. © 2015 New Phytologist Trust.
Huang Z., Liu B., Davis M., Sardans J., Peñuelas J., Billings S. (2015) Long-term nitrogen deposition linked to reduced water use efficiency in forests with low phosphorus availability. New Phytologist. : 0-0.EnllaçDoi: 10.1111/nph.13785
The impact of long-term nitrogen (N) deposition is under-studied in phosphorus (P)-limited subtropical forests. We exploited historically collected herbarium specimens to investigate potential physiological responses of trees in three subtropical forests representing an urban-to-rural gradient, across which N deposition has probably varied over the past six decades. We measured foliar [N] and [P] and stable carbon (δ13C), oxygen (δ18O) and nitrogen (δ15N) isotopic compositions in tissue from herbarium specimens of plant species collected from 1947 to 2014. Foliar [N] and N: P increased, and δ15N and [P] decreased in the two forests close to urban centers. Consistent with recent studies demonstrating that N deposition in the region is 15N-depleted, these data suggest that the increased foliar [N] and N: P, and decreased [P], may be attributable to atmospheric deposition and associated enhancement of P limitation. Estimates of intrinsic water use efficiency calculated from foliar δ13C decreased by c. 30% from the 1950s to 2014, contrasting with multiple studies investigating similar parameters in N-limited forests. This effect may reflect decreased photosynthesis, as suggested by a conceptual model of foliar δ13C and δ18O. Long-term N deposition may exacerbate P limitation and mitigate projected increases in carbon stocks driven by elevated CO2 in forests on P-limited soils. © 2015 New Phytologist Trust.
Rajsnerova P., Klem K., Holub P., Novotna K., Vecerova K., Kozacikova M., Rivas-Ubach A., Sardans J., Marek M.V., Penuelas J., Urban O. (2015) Morphological, biochemical and physiological traits of upper and lower canopy leaves of European beech tend to converge with increasing altitude. Tree Physiology. 35: 47-60.EnllaçDoi: 10.1093/treephys/tpu104
The present work has explored for the first time acclimation of upper versus lower canopy leaves along an altitudinal gradient. We tested the hypothesis that restrictive climatic conditions associated with high altitudes reduce within-canopy variations of leaf traits. The investigated beech (Fagus sylvatica L.) forest is located on the southern slope of the Hrubý Jeseník Mountains (Czech Republic). All measurements were taken on leaves from upper and lower parts of the canopy of mature trees (>85 years old) growing at low (400 m above sea level, a.s.l.), middle (720 m a.s.l.) and high (1100 m a.s.l.) altitudes. Compared with trees at higher altitudes, those growing at low altitudes had lower stomatal conductance, slightly lower CO2 assimilation rate (A max) and leaf mass per area (LMA), and higher photochemical reflectance index, water-use efficiency and Rubisco content. Given similar stand densities at all altitudes, the different growth conditions result in a more open canopy and higher penetration of light into lower canopy with increasing altitude. Even though strong vertical gradients in light intensity occurred across the canopy at all altitudes, lower canopy leaves at high altitudes tended to acquire the same morphological, biochemical and physiological traits as did upper leaves. While elevation had no significant effect on nitrogen (N) and carbon (C) contents per unit leaf area, LMA, or total content of chlorophylls and epidermal flavonoids in upper leaves, these increased significantly in lower leaves at higher altitudes. The increases in N content of lower leaves were coupled with similar changes in A max. Moreover, a high N content coincided with high Rubisco concentrations in lower but not in upper canopy leaves. Our results show that the limiting role of light in lower parts of the canopy is reduced at high altitudes. A great capacity of trees to adjust the entire canopy is thus demonstrated. © © The Author 2015. Published by Oxford University Press. All rights reserved.
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