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Barrena I.,University of the Basque Country | Menendez S.,Institute of Agro biotechnology IdAB | Dunabeitia M.,University of the Basque Country | Merino P.,Tecnalia | And 4 more authors.
Forest Ecology and Management

Forest systems are considered quintessential terrestrial systems for atmospheric CO2 sequestration to mitigate the effect of global warming. Temperate forest soils also present the highest rates of methane uptake among all the natural systems, while may represent a significant source of N2O. Despite of the large area occupied by forest in the Basque Country, no data is yet available regarding greenhouse gas fluxes under these edaphoclimatic conditions. In this manuscript we present a 2-year study which determined the magnitude of CO2, N2O, and CH4 soil gas fluxes in radiata pine, beech and Douglas fir forests using a closed chamber technique. The magnitude of these gas fluxes was additionally compared between different growth stages of radiata pine and beech forest, and the edaphoclimatic parameters that control these gas fluxes in the different forest systems and growth stages were studied. Measured greenhouse gas fluxes were in a low range as already published elsewhere for temperate forest ecosystems. A nitrogen deficit appears to be responsible for these relatively low gas fluxes. Apparently, the different forest species play a key role as controllers responsible for the differences of soil gas-exchange fluxes between the three different forest type systems. The mature pine plantation soil was emitting the most CO2 (1.5 and 2.5 times more than the mature beech and the Douglas fir, respectively), while the Douglas fir forest soil was emitting the most N2O (3 and 17 times more than the mature pine and the mature beech, respectively) and the mature beech forest was the soil type showing the highest CH4 consumption rates (2 and 5.5 times more than the mature pine and the Douglas fir, respectively). The stage of growth and its usual management appear to be important concerning the soil gas-exchange behavior within one forest type. The young beech forest soil emitted 9 times more N2O than the mature, and the new pine and the mature pine plantation soils emitted 2.5 and 2 times more CO2 than the young, respectively. The ground vegetation cover percentage, the organic matter accumulation and the soil porosity seem to be factors which merit a closer look in future studies, as possibly responsible for the differences in gas fluxes among forest types and growth stages. © 2013 Elsevier B.V. Source

Penuelas J.,CREAF | Penuelas J.,Global Ecology Unit CREAF CEAB CSIC UAB | Guenther A.,U.S. National Center for Atmospheric Research | Rapparini F.,CNR Institute of Neuroscience | And 31 more authors.
Atmospheric Environment

MONTES ("Woodlands") was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest-warmest sites and optimal conditions in the wettest-coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC-MS, PTR-MS, meteorological sensors, O3 monitors,. .) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2mgm-2h-1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6mgm-2h-1 for isoprene and ca. 4.5mgm-2h-1 for monoterpenes, depending on the site vegetation and footprint area considered. There were clear daily and seasonal patterns with higher emission rates and mixing ratios at midday and summer relative to early morning and early spring. There was a significant trend in CO2 fixation (from 1 to 10mgCm-2d-1), transpiration (from1-5kgCm-2d-1), and sensible and latent heat from the warmest-driest to the coolest-wettest site. The results showed the strong land-cover-specific influence on emissions of BVOCs, gas, energy and water exchange, and therefore demonstrate the potential for feed-back to atmospheric chemistry and climate. •We present a multidisciplinary biosphere-atmosphere field campaign.•We measured a gradient from semi-desertic shrublands to wet temperate forests.•A wide range of instruments and vertical platforms were used.•Land cover strongly influenced emissions of BVOCs and gas, energy and water exchange.•Vegetation has strong potential for feed-back to atmospheric chemistry and climate. © 2013 Elsevier Ltd. Source

Menendez S.,Institute of Agro biotechnology IdAB | Barrena I.,University of the Basque Country | Setien I.,University of the Basque Country | Gonzalez-Murua C.,University of the Basque Country | Estavillo J.M.,University of the Basque Country
Soil Biology and Biochemistry

Agricultural intensification has led to the use of very high inputs of nitrogen fertilizers into cultivated land. As a consequence of this, nitrous oxide (N 2O) emissions have increased significantly. Nowadays, the challenge is to mitigate these emissions in order to reduce global warming. Addition of nitrification inhibitors (NI) to fertilizers can reduce the losses of N 2O to the atmosphere, but field studies have shown that their efficiency varies depending greatly on the environmental conditions. Soil water content and temperature are key factors controlling N 2O emissions from soils and they seem to be also key parameters responsible for the variation in nitrification inhibitors efficiency. We present a laboratory study aimed at evaluating the effectiveness of the nitrification inhibitor 3,4-dimethylpyrazol phosphate (DMPP) at three different temperatures (10, 15 and 20 °C) and three soil water contents (40%, 60% and 80% of WFPS) on N 2O emissions following the application of 1.2 mg N kg -1 dry soil (equivalent to 140 kg N ha -1). Also the CO 2 and CH 4 emissions were followed to see the possible side effects of DMPP on the overall microbial activities. Nitrogen was applied either as ammonium sulfate nitrate (ASN) or as ENTEC 26 (ASN + DMPP). The application of ENTEC 26 was effective reducing N 2O losses up to the levels of an unfertilized control treatment in all conditions. Nevertheless, the percentage of reduction induced by DMPP in the ENTEC treatment with respect to the ASN varied from 3% to 45% depending on temperature and soil water content conditions. At 40% of WFPS, when nitrification is expected to be the main process producing N 2O, the increase of N 2O emissions in ASN together with temperature provoked an increase in DMPP efficiency reducing these emissions from 17% up to 42%. Contrarily, at 80% of WFPS, when denitrification is expected to be the main source of N 2O, emissions after ASN application decreased with temperature, which induced a decrease from 45% to 23% in the efficiency of DMPP reducing N 2O losses. Overall, the results obtained in this study suggest that DMPP performance regarding N 2O emissions reduction would be the best in cold and wet conditions. Neither CO 2 emissions nor CH 4 emissions were affected by the use of DMPP at the different soil water contents and temperatures. © 2012 Elsevier Ltd. Source

Stange C.F.,Bundesanstalt fur Geowissenschaften und Rohstoffe | Spott O.,Helmholtz Center for Environmental Research | Arriaga H.,Tecnalia | Menendez S.,Institute of Agro biotechnology IdAB | And 2 more authors.
Soil Biology and Biochemistry

Forest soils exhibit a variety of complex biochemical nitrogen (N) reactions in which nitric oxide (NO) and nitrous oxide (N2O) can be produced by coexisting processes that respond differently to the same environmental conditions. In general, two biochemical processes, (i) the oxidation of ammonia (nitrification) and (ii) the reduction of nitrate (denitrification), are known as the major sources of nitrogen oxides. Few reports indicated that a direct oxidation of soil organic N compounds (Norg) to NO and N2O may also be significant in soils.A triplet 15N tracer experiment (TTE) combined with an inverse abundance approach (IAA) was applied to quantify NO and N2O formation in soil related to different but simultaneously utilized soil N sources (ammonium, nitrate, and Norg). In addition, the impact of oxic and hypoxic conditions (21 and 2% v/v O2, respectively) on total soil NO/N2O release and source composition was studied. Experiments were conducted with soil samples from 5 different Basque forest stands (mature beech, young beech, mature pine, young pine, and new pine plantation).The release rates of NO and N2O were higher in the soil samples from beech stands than in the samples from pine stands. The change from oxic to hypoxic conditions increased the NO release rate 2- to 14-fold and the N2O release rate 3.6- to 25-fold. The study suggests that, under oxic conditions, N2O formation based on Norg appears to be the dominant pathway of soil N2O production (48-76% to total N2O release). Under hypoxic conditions, the relative contribution of Norg significantly decreased, whereas its absolute contribution increased concomitantly. Denitrification was the dominant process of soil N2O release under hypoxic conditions and served as the major pathway of soil NO release under both oxic and hypoxic conditions (40 and 60% of total soil NO release, respectively).We conclude that the individual contribution of different soil N pools to the total soil N gas release and the impact of environmental parameters (e.g., O2 availability) are site-specific. Nonetheless, further research is required to elucidate the impact of forest stands on soil NO and N2O production, particularly N2O formation directly based on Norg transformation. © 2012 Elsevier Ltd. Source

Lasa B.,Institute of Agro biotechnology IdAB | Menendez S.,Institute of Agro biotechnology IdAB | Sagastizabal K.,Inurrieta Winery | Cervantes M.E.C.,Institute of Agro biotechnology IdAB | And 4 more authors.
Plant Growth Regulation

A careful control of the N nutritional status of grapevines can have a determining effect on wine characteristics; therefore a suitable management of N fertilization might allow some wine parameters to be modified, thereby improving product quality. The aim of this study was to determine the effect of foliar application of urea at different doses and different times of the growing season on the parameters of Sauvignon Blanc and Merlot grape juice. The research described herein involved Sauvignon Blanc and Merlot grapevines (V. vinifera L.) at a commercial vineyard and was conducted over 2 years. In the first year, N treatment involved a foliar application at a dose of 10 kg N ha -1 during veraison, whereas in the second year it involved a foliar urea application at two doses (10 and 50 kg N ha -1) and at three different times-3 weeks before veraison, during veraison and 3 weeks after veraison. In this second year, the urea applied at a dose of 10 kg N ha -1 was isotopically labelled with 1% 15N. Chemical parameters, yeast assimilable N, amino acid content, amino acid profile and N isotopic composition were determined for all treatments. Grape and grape-juice parameters for Merlot were found to be more affected by N fertilization than for Sauvignon Blanc and were also more affected during the second year than during the first year, thus indicating that the climatic characteristics of each campaign could affect these parameters. The yeast assimilable N in grape juice was found to be higher for late applications of foliar urea, with application of the higher dose of urea during veraison increasing the amino acid and proline contents in both varieties. The isotopic analysis data showed that the urea applied to leaves was transferred to the berries, with the maximum translocation in Sauvignon Blanc occurring for the post-veraison treatment and in Merlot for the veraison treatment. We can therefore conclude that foliar application of urea could modify grape juice quality and could therefore be used as a tool for obtaining quality wines. © 2012 Springer Science+Business Media B.V. Source

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