DEP08 - Artículos de revista

N2-fixing Shrubs as Nature-based Solutions to Store Soil Nutrients in Grazed Post-mining Pastures of Northern Spain

Thu, 01 Jan 2026 00:00:00 GMT

Grazing can adversely affect soil physicochemical properties and, despite its potential benefits on restored areas, may ultimately lead to the ecosystem degradation. Given that shrubs can partially buffer these effects, we investigate their potential as a Nature-based Solution to enhance soil nutrient storage in grazed, post-mining pastures. We assessed the combined influence of legume shrubs (plots with vs. without shrubs) and grazing (plots with vs. without a fence to prevent browsing and trampling) on soil C: N:P stoichiometry, as well as on C-N-P and exchangeable cations’ stocks in a rehabilitated coal mine. The natural colonization of legume shrubs in post-mining Mediterranean pastures maintained C: N:P stoichiometry and nutrient stocks at levels comparable to those in ungrazed areas. Specifically, the presence of shrubs increased total soil organic carbon, nitrogen, and phosphorus stocks by approximately 15%, 18%, and 12%, respectively, compared to grazed areas without shrubs. In addition, exchangeable potassium (K+) and magnesium (Mg+ 2) stocks increased by approximately 20% and 16%, respectively, under shrub canopies. In contrast, exchangeable calcium (Ca+ 2) and sodium (Na+) stocks exhibited divergent trends. In Mediterranean post-mining grasslands with low grazing pressure, native leguminous shrubs can effectively replicate the benefits of grazing exclusion by significantly enhancing soil nutrient storage. Variations in soil organic matter and structural properties accounted for 75% and 76% of the variability in nutrient stocks, respectively, underscoring their key mediating roles. These findings highlight the importance of integrating shrub management with grazing practices to support nutrient cycling and soil restoration in degraded grassland ecosystems.

Irrigation in Mediterranean urban areas: a good strategy to face the ongoing climate change impacts on urban cedar trees?

Mon, 01 Jan 2024 00:00:00 GMT

Irrigated trees are known to develop large aboveground structures that can be detrimental during dry spells, and therefore irrigated trees are expected to perform worse than non-irrigated ones under climate change. In this study, we evaluated the climate-growth relationship of irrigated and non-irrigated trees of the species Cedrus atlantica (Endl.) Manetti ex Carrière (Atlas cedar) in an urban environment in central Spain. We first studied climate-growth relationships with and without irrigation to test the hypothesis that irrigated trees should be less sensitive to interannual climatic variability than non-irrigated ones. Secondly, we identified the four most intense droughts over the 21st century (2005, 2012, 2017, 2019) to test the hypothesis that growth resilience should be lower in irrigated than non-irrigated trees due to traits such as total height. Our results support the idea that irrigated trees are less responsive to climatic interannual variability and notably less resilient to drought stress, with these differences becoming more pronounced with age. These results suggest that irrigation may increase the risk in a scenario of more frequent and intense droughts in Mediterranean urban areas. Thus, widening urban green areas to meet the European Green Deal 2030 in Mediterranean cities should consider better-adapted tree species and ad hoc adaptation to water shortage rather than watering and strategies based on resource supplements.

Considerations on image resolution, measurement accuracy, and crossdating in the digital era

Wed, 01 Jan 2025 00:00:00 GMT

The field of dendrochronology is currently undergoing a transition, with an increasing reliance on digital analysis. Recent advances in hardware and software have enabled the rapid acquisition of information from wood in ways that were previously unattainable. However, the variety of digitization tools and the high resolutions achievable present a challenge in maintaining replicability and comparabil- ity of results. In addition, the high speed at which data are collected can lead to overlooking important aspects of dendrochronological techniques. For example, awareness of resolution of images for tree-ring measurements or even crossdating may play a minor role when setting tree-ring boundaries or may be biased towards the first samples measured. This commentary addresses potential sources of error in the novel advances of digital techniques and highlights the suitability of combining digital advances with traditional data-control procedures that maintain the robustness and replicability of dendrochronological methods.

Water shortages means greening southern European cities won’t be easy

Mon, 01 Jan 2024 00:00:00 GMT

The European Union’s biodiversity strategy for 2030 aims to bring nature back to cities, supporting and preserving tree ecosystems that promote biodiversity, mitigate pollution and alleviate high temperatures. This is commendable, but urban greening faces huge challenges in Mediterranean Europe. Management of urban ecosystems in Mediterranean cities must reconcile conflicting demands. Increasing tree canopy cover to better combat heat, for example, strains water resources that are already under pressure from climate change. When drought strikes, the trees are at risk of dangerous loss of sap and insufficient water transport. Species more suited to a warmer future might not offer the same ecosystem services as established species. The situation is exacerbated by a conspicuous lack of understanding of tree species outside their natural environments. Research aims to fill this gap, focusing on areas such as resilience to increasing temperatures and drought stress, the role of microorganisms and soil–plant feedback in adaptation to water shortages and the complexities of urban microhabitats. The European greening strategy must be adapted to the reality of water availability, with a specific plan developed for the Mediterranean Basin. Urban design must consider the biological needs of trees, rather than requiring trees to adjust to urban conditions.

Resin ducts as resistance traits in conifers: linking dendrochronology and resin-based defences

Wed, 01 Jan 2020 00:00:00 GMT

Conifers have evolved different chemical and anatomical defences against a wide range of antagonists. Resin ducts produce, store and translocate oleoresin, a complex terpenoid mixture that acts as both a physical and a chemical defence. Although resin duct characteristics (e.g., number, density, area) have been positively related to biotic resistance in several conifer species, the literature reporting this association remains inconclusive. Axial resin ducts recorded in annual growth rings are an archive of annual defensive investment in trees. This whole-life record of defence investment can be analysed using standard dendrochronological procedures, which allows us to assess interannual variability and the effect of understudied drivers of phenotypic variation on resin-based defences. Understanding the sources of phenotypic variation in defences, such as genetic differentiation and environmental plasticity, is essential for assessing the adaptive potential of forest tree populations to resist pests under climate change. Here, we reviewed the evidence supporting the importance of resin ducts in conifer resistance, and summarized current knowledge about the sources of variation in resin duct production. We propose a standardized methodology to measure resin duct production by means of dendrochronological procedures. This approach will illuminate the roles of resin ducts in tree defence across species, while helping to fill pivotal knowledge gaps in plant defence theory, and leading to a robust understanding of the patterns of variation in resin-based defences throughout the tree’s lifespan.

Climate response and drought resilience of Nothofagus obliqua secondary forests across a latitudinal gradient in south-central Chile

Fri, 01 Jan 2021 00:00:00 GMT

The climate response and resilience of tree growth to drought events have been widely reported for forests from the Northern Hemisphere. However, studies are much scarcer in the extra-tropical forests of southern South America. Mediterranean and Temperate forests of Chile are suffering from a moderate warming and a sustained precipitation decrease, occurring on top of an unprecedented megadrought since 2010. This study evaluated tree-growth patterns, the climate response and drought resilience of nine secondary Nothofagus obliqua forests across a latitudinal gradient from Mediterranean to Temperate climate in the Andes of Chile (35.7° to 40.3° S). Moreover, to improve the understanding of the spatial variation in productivity patterns, this research assessed trends in the maximum Normalized Difference Vegetation Index (peak in the NDVI) across the gradient for 2001–2018. Tree-growth patterns were highly influenced by stand dynamics, with steep decreasing trends in most of the stands related to a gradual canopy closure. Productivity trends had a flat pattern north of 38oS, but positive trends south of this latitude, which were mostly attributed to stand development. Tree growth was positively related to precipitation in all the sites, with annual and summer rainfall being more important in the north (Mediterranean climate) and south (Temperate climate), respectively. Conversely, maximum temperature had a negative effect on growth in most of the studied forests. This implies that projected warmer and drier conditions may have a detrimental effect on N. obliqua growth during coming decades. The two northern stands, located at the species dry range edge, were among the most resilient to drought and have not been strongly affected by the current megadrought in the area. Overall climate conditions, however, do not define the tolerance of stands to droughts, likely because local environmental and forests conditions play a key role. Although droughts have not strongly impacted the growth of N. obliqua across its distribution so far, future studies should assess the effects of the current long-term megadrought on growth resilience, and physiological studies should address the impacts of droughts and heat waves on forest function beyond what growth can unveil.

Mitigating ammonia emissions for a sustainable livestock farming by advances in membrane technology and modelling tools

Thu, 01 Jan 2026 00:00:00 GMT

With the agricultural sector contributing to 93 % of total ammonia emissions, the development of mitigation technologies is imperative for livestock farming. This study compared the nitrogen recovery performance of two novel gas-permeable membrane configurations: System 1 (S1), with external gas flow, and System 2 (S2), with internal gas flow. The influence of initial N concentration and exposure time on N recovery rates was investigated. The results established the markedly superior performance of S2, which achieved a N recovery rate of 237 g m⁻² d⁻¹, outperforming the 154 g m⁻² d⁻¹ rate of S1. This peak rate represents a 7-fold increase when compared to previous results. Mathematical models derived from regression analysis were developed for S1 and S2 and indicating that the theoretical maximum performance of S2 was 1.8-fold higher than that of S1 (Maximum N recovery rates of 155.65 and 281.2 g N m⁻² d⁻¹ for S1 and S2, respectively). The enhanced efficiency of S2 is ascribed to its internal flow configuration, which promotes a superior nitrogen mass transfer rate across the membrane. This design demonstrated greater robustness in managing high nitrogen loads, positioning it as a highly promising technology for practical implementation in livestock operations.

Developing a New System Based on Membranes for Ammonia Recovery from the Atmosphere: Effect of Operation Time and Manure Temperature

Wed, 01 Jan 2025 00:00:00 GMT

Ammonia (NH3) is a significant air pollutant with major environmental and health impacts, largely attributed to agriculture. Pig production is a major contributor, accounting for 25% of livestock NH3 emissions. This study developed a new system based on gas-permeable membranes (GPM) technology for NH3 recovery from the atmosphere obtaining a solution of ammonium sulfate as the resulting fertilizer product. Various experimental configurations were evaluated in the novel system using a synthetic NH3-emitting solution. The optimal arrangement was a GPM system with recirculation of the generated NH3 and without recirculation of the acidic trapping solution, yielding a nitrogen (N) recovery rate of up to 237 g m−2 d−1. Subsequent tests using pig manure (PM) at varying durations achieved rates of up to 73 g m−2 d−1, representing a four-fold increase in N capture efficiency compared to previous research. The influence of manure temperature on NH3 emission and capture were analyzed, simulating the possible differences between seasons (summer and winter), and revealing higher N recovery rates at elevated temperatures. At 21.5 °C, the recovery rate was 7.7 g m−2 d−1, while increased temperatures of 38.8 °C and 49.3 °C yielded rates of 15.9 and 27.2 g m−2 d−1, respectively.

Combining Novel Membrane Technologies for Sustainable Nutrient Recovery from Digestate: Effect of Solid Content

Wed, 01 Jan 2025 00:00:00 GMT

Nutrient recovery from anaerobic digestate has gained increasing importance in recent years due to its potential to reduce resource dependency and to close nutrient cycles. The aim of this work is to evaluate the influence of a previous solid–liquid separation phase on nutrient recovery efficiency using two innovative membrane technologies, namely, gas-permeable membranes (GPM) and electrodialytic (ED) processes, applied individually or in combination. The obtained results were compared with those obtained through the centrifugation of the raw digestate and direct chemical precipitation followed by centrifugation in terms of the efficiency in the recovery of N (nitrogen) and P (phosphorous). A total of nine scenarios of digestate processing were compared. GPM technology allowed for the recovery of 65% of the N content in the raw digestate (41.5 g total solids (TS) kg−1) and 67% of N in the liquid fraction (28.0 g TS kg−1), without any significant difference between the two scenarios. However, the results revealed significant differences in the P recovery with ED from the raw digestate (15%) and the liquid fraction (34%), suggesting that phosphorous extraction can be improved by the application of a prior solid–liquid phase. The recovery of N with the GPM technology also enhanced the further recovery of total P with the ED processes. Furthermore, the combination of these technologies allowed for the recovery of N- and P-rich solutions, which were used to precipitate secondary struvite with an efficiency of up to 85%. This research provides a practical framework for sustainable nutrient management, advancing solutions for resource efficiency and environmental stewardship.

A Novel Food Wastewater Treatment Approach: Developing a Sustainable Fungicide for Agricultural Use

Wed, 01 Jan 2025 00:00:00 GMT

Three wastewater sources, namely slaughterhouse wastewater, cheese whey, and wine lees, were used for volatile fatty acid (VFA) production with the aim of reducing polluted wastewater discharge to the water bodies and creating a useful product. Cheese whey and wine lees were proved to be good substrates to produce VFAs, obtaining maximum bioconversion percentages in g COD-VFA/g TCOD initial of 90% and 72% for cheese whey and wine lees, respectively. The composition of the VFAs produced from each wastewater stream varied, with acetic, propionic, isobutyric, and isovaleric acids being the most dominant. These VFAs were used as an environmentally friendly fungicide against Fusarium culmorum, resulting in a reduction of the radial mycelial growth of Fusarium culmorum for all the effluents tested. A thermal pretreatment of the VFAs resulted in an improved antifungal efficiency if compared to the untreated VFAs or a UV pretreatment.

Production of Volatile Fatty Acids from Cheese Whey and Their Recovery Using Gas-Permeable Membranes

Mon, 01 Jan 2024 00:00:00 GMT

The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery using a novel approach based on gas-permeable membranes. VFA bioconversion and composition were studied with initial and sequential control of pH, both in acidic and alkaline conditions. Bioconversion efficiencies for assays with initial pH control were 36% and 45% for acidic and alkaline conditions, respectively. Sequential control of pH resulted in an increase in bioconversion to 54% under acidic conditions. Under acidic conditions, a variety of VFA was produced (mainly butyric, acetic, and propionic acids), while under alkaline conditions the majority was acetic acid. VFA recovery using a novel system of tubular gas-permeable membranes accounted for 15% and 100% of the total VFA from effluent 1 (butyric, acetic, and propionic acids) and effluent 2 (mainly acetic acid), respectively.

Energy and Nutrients from Apple Waste Using Anaerobic Digestion and Membrane Technology

Sat, 01 Jan 2022 00:00:00 GMT

The worldwide increment of food waste requires innovative management solutions, aligned with sustainability, energy, and food security. Anaerobic digestion (AD), followed by nutrient recovery, may be considered an interesting approach. This study proposed a co-digestion of apple pomace (AP) with swine manure (SM) to study the effect of different proportions of AP (0, 7.5, 15, and 30%, on a volatile solids (VS) basis) on the methane production and the stability of the process. Subsequently, the gas-permeable membrane (GPM) technology was applied to recover nitrogen (N) as ammonium sulfate (bio-based fertilizer) from the digestates produced after the AD of 7.5% of AP and SM, and SM alone. The results showed that the co-digestion of 7.5% and 15% of AP with SM presented a methane production similar to the AD of SM alone (with 412.3 ± 62.6, 381.8 ± 134.1, and 421.7 ± 153.6 mL g VS−1 day−1, respectively). The later application of the GPM technology on the resulting digestates, with SM alone and with 7.5% of AP with SM, showed total ammoniacal N recovery rates of 33 and 25.8 g N m−2 d−1, respectively. Therefore, the AP valorization through the AD process, followed by N recovery from the digestate, could be a good management strategy.

Effect of Operational Conditions on Ammonia Recovery from Simulated Livestock Wastewater Using Gas-Permeable Membrane Technology

Sat, 01 Jan 2022 00:00:00 GMT

Gas-permeable membrane (GPM) technology is a novel alternative to reduce N content in wastewater while recovering N in the form of an ammonium salt solution that can be used as fertilizer. This work aims to elucidate the effects of three operational conditions on the performance of GPM technology for ammonia recovery in batch conditions using synthetic wastewater that simulates livestock wastewater. Firstly, the effect of the ratio of the initial mass of total ammonia nitrogen (TAN) per membrane surface from 197 to 936 g N per m2 of membrane was investigated. The highest ratio presented the highest TAN recovery rate (90 g N m−2 d−1). Secondly, the influence of the ratio of the volume of wastewater per volume of acidic trapping solution in the range from 7.8 to 33.3 L L−1 was studied. In this case, the higher the ratio, the higher the N concentration in the trapping solution, achieving a N concentration of 43,773 mg N L−1 with a ratio of 33.3 L L−1. Finally, two different TAN concentrations (<0.1 and 30 g N L−1) in the acidic trapping solution were evaluated. The use of a trapping solution with a TAN concentration of 30 g N L−1 led to a reduction in the TAN recovery rate, which meant that the diffusion of ammonia through the membrane was more difficult as the trapping solution became saturated with TAN. Overall, the tested conditions highly influence the performance of GPM technology, and therefore, these conditions should be set to optimize the ammonia recovery and reduce nitrogen losses.

Ammonia Recovery from Digestate Using Gas-Permeable Membranes: A Pilot-Scale Study

Fri, 01 Jan 2021 00:00:00 GMT

The reduction and recovery of nitrogen (N) from anaerobically digested manure (digestate) is desirable to mitigate N-related emissions, mainly ammonia and nitrate, derived from digestate land application in nutrient-saturated zones. This work reports the results of a gas-permeable membrane (GPM) pilot-scale plant to recover ammonia from digestate in the framework of the EU project Ammonia Trapping. The total ammonia nitrogen (TAN) concentration in digestate was reduced by 34.2% on average (range 9.4–57.4%). The recovery of TAN in the trapping solution in the form of a (NH4)2SO4 solution averaged 55.3% of the removed TAN, with a TAN recovery rate of 16.2 g N m−2 d−1 (range between 14.5 and 21.0 g Nm−2 d−1). The TAN concentration in the trapping solution achieved a value of up to 35,000 mg N L−1. The frequent change of the trapping solution has been proven as an efficient strategy to improve the overall performance of the GPM technology.

Rendimientos productivos y digestibilidad aparente de raciones de corderos suplementadas con distintos aceites vegetales

Sat, 01 Jan 2011 00:00:00 GMT

Se utilizaron 15 corderos de raza Merina con un peso medio de 16,3 kg (SEM 1,48), divididos en 3 tratamientos, para estudiar el efecto que la incorporación de distintos aceites en la ración de corderos en cebo (4% de aceite hidrogenado de palma o 4% de aceite de girasol) tenía sobre la ingestión, la ganancia media diaria de peso y la digestibilidad aparente de la ración. Los animales recibieron el pienso experimental (Control sin grasa añadida, Palma o Girasol) y paja de cebada ad libitum hasta que alcanzaron el peso al sacrificio (25 kg). La incorporación de un 4% de aceite de palma o aceite de girasol en el pienso concentrado de corderos dio lugar a mayores coeficientes de digestibilidad aparente de la grasa bruta, sin afectar a la digestibilidad de la fibra, la ingestión, el crecimiento y el índice de conversión de los animales.; Fifteen Merino lambs 16,3 (sem 1,48) kg live weight were used to study the effects of the addition of 4% hydrogenated palm oil or 4% sunflower oil to the concentrate on intake, average daily gain, feed conversion ratio and digestibility of diets. Animals were divided into three experimental treatments (Control, Palm and Sunflower) and received the concentrate and barley straw ad libitum until 25 kg live weight. Lambs receiving oils showed greater ether extract digestibility coefficients without affecting fiber digestibility, intake, average daily gain and feed conversion ratio.

Evaluation of grape pomace from red wine by-product as feed for sheep

Sun, 01 Jan 2017 00:00:00 GMT

BACKGROUND This work aimed to study the chemical composition and in vitro digestibility of seeds and pulp from grape pomace. In sacco degradability, ruminal fermentation of grape pomace fractions and plasma lipid peroxidation were also studied in sheep fed with or without grape pomace. RESULTS Seed and pulp fractions of grape pomace had different values for cell walls (523 vs 243 g kg−1 dry matter (DM)), crude protein (CP, 104 vs 138 g kg−1 DM), ether extract (EE, 99.0 vs 31.7 g kg−1 DM), polyunsaturated fatty acids (PUFA, 69.6 vs 53.3%) and extractable polyphenols (55.0 vs 32.1 g kg−1 DM). The in vitro true digestibility, DM in sacco degradability and CP degradability of seeds and pulp were also different (0.51 vs 0.82, 0.30 vs 0.45 and 0.66 vs 0.39 respectively). The ammonia-N concentration and total volatile fatty acids (VFA) in ruminal liquid were significantly lower and plasma lipid peroxidation was also numerically lower in sheep that consumed grape pomace. CONCLUSION The nutritive value of grape pomace varies depending on the proportion of seeds and pulp. The interest of this by-product in sheep feeding could be related to its polyphenol and PUFA content, which could improve meat and milk quality.