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2022-08-06Zeitschriftenartikel
Modelling cropland expansion and its drivers in Trans Nzoia County, Kenya
(Lebenswissenschaftliche Fakultät) Kipkulei, Harison Kiplagat; Bellingrath-Kimura, Sonoko Dorothea; Lana, Marcos; Ghazaryan, Gohar; Boitt, Mark; Sieber, Stefan
Population growth and increasing demand for agricultural production continue to drive global cropland expansions. These expansions lead to the overexploitation of fragile ecosystems, propagating land degradation, and the loss of natural diversity. This study aimed to identify the factors driving land use/land cover changes (LULCCs) and subsequent cropland expansion in Trans Nzoia County in Kenya. Landsat images were used to characterize the temporal LULCCs in 30 years and to derive cropland expansions using change detection. Logistic regression (LR), boosted regression trees (BRTs), and evidence belief functions (EBFs) were used to model the potential drivers of cropland expansion. The candidate variables included proximity and biophysical, climatic, and socioeconomic factors. The results showed that croplands replaced other natural land covers, expanding by 38% between 1990 and 2020. The expansion in croplands has been at the expense of forestland, wetland, and grassland losses, which declined in coverage by 33%, 71%, and 50%, respectively. All the models predicted elevation, proximity to rivers, and soil pH as the critical drivers of cropland expansion. Cropland expansions dominated areas bordering the Mt. Elgon forest and Cherangany hills ecosystems. The results further revealed that the logistic regression model achieved the highest accuracy, with an area under the curve (AUC) of 0.96. In contrast, EBF and the BRT models depicted AUC values of 0.86 and 0.77, respectively. The findings exemplify the relationships between different potential drivers of cropland expansion and contribute to developing appropriate strategies that balance food production and environmental conservation.
2022-10-21Zeitschriftenartikel
Assessment of Maize Yield Response to Agricultural Management Strategies Using the DSSAT–CERES-Maize Model in Trans Nzoia County in Kenya
(Lebenswissenschaftliche Fakultät) Kipkulei, Harison Kiplagat; Bellingrath-Kimura, Sonoko Dorothea; Lana, Marcos; Ghazaryan, Gohar; Baatz, Roland; Boitt, Mark; Chisanga, Charles B.; Rotich, Brian; Sieber, Stefan
Maize production in low-yielding regions is influenced by climate variability, poor soil fertility, suboptimal agronomic practices, and biotic influences, among other limitations. Therefore, the assessment of yields to various management practices is, among others, critical for advancing site-specific measures for production enhancement. In this study, we conducted a multiseason calibration and evaluation of the DSSAT–CERES-Maize model to assess the maize yield response of two common cultivars grown in Trans Nzoia County in Kenya under various agricultural strategies, such as sowing dates, nitrogen fertilization, and water management. We then applied the Mann–Kendall (MK), and Sen’s Slope Estimator (SSE) tests to establish the yield trends and magnitudes of the different strategies. The evaluated model simulated long-term yields (1984–2021) and characterized production under various weather regimes. The model performed well in simulating the growth and development of the two cultivars, as indicated by the model evaluation results. The RMSE for yield was 333 and 239 kg ha −1 for H614 and KH600-23A, respectively, representing a relative error (RRMSE) of 8.1 and 5.1%. The management strategies assessment demonstrated significant feedback on sowing dates, nitrogen fertilization, and cultivars on maize yield. The sowing date conducted in mid-February under fertilization of 100 kg of nitrogen per hectare proved to be the best strategy for enhancing grain yields in the region. Under the optimum sowing dates and fertilization rate, the average yield for cultivar KH600-23A was 7.1% higher than that for H614. The MK and SSE tests revealed a significant (p < 0.05) modest downwards trend in the yield of the H614 cultivar compared to the KH600-23A. The eastern part of Trans Nzoia County demonstrated a consistent downwards trend for the vital yield enhancement strategies. Medium to high nitrogen levels revealed positive yield trends for more extensive coverage of the study area. Based on the results, we recommend the adoption of the KH600-23A cultivar which showed stability in yields under optimum nitrogen levels. Furthermore, we recommend measures that improve soil quality and structure in the western and northern parts, given the negative model response on maize yield in these areas. Knowledge of yield enhancement strategies and their spatial responses is of utmost importance for precision agricultural initiatives and optimization of maize production in Trans Nzoia County.
2023-02-27Zeitschriftenartikel
Seasonal and diurnal patterns of littoral microhabitat use by fish in gravel pit lakes, with special reference to supplemented deadwood brush piles
(Lebenswissenschaftliche Fakultät) Maday, Andreas; Matern, Sven; Monk, Christopher T.; Klefoth, Thomas; Wolter, Christian; Arlinghaus, Robert
The habitat quality of the littoral zone is of key importance for almost all lentic fish species. In anthropogenically created gravel pit lakes, the littoral zone is often structurally homogenized with limited fish habitats. We supplemented deadwood brush piles in the littoral zone of eight gravel pit lakes and investigated the diurnal and seasonal use of this and other typical microhabitats by six dominant fish species. Shoreline habitats were sampled using point abundance electrofishing during day and night in all four seasons, and patterns of fish abundance were compared amongst unstructured littoral habitats, emerged macrophytes and brush piles. We caught a total of 14,458 specimens from 15 species in the gravel pit lakes. Complex shoreline structures were used by all fish species that we examined, especially during daytime, whilst the use of unstructured habitats was highest during night. The newly added brush piles constituted suitable microhabitats for selected fish species, perch ( Perca fluviatilis ), roach ( Rutilus rutilus ) and pike ( Esox lucius ), particularly during winter. Supplemented deadwood provides suitable fish habitat in gravel pit lakes and may to some degree compensate for the loss of submerged macrophytes in winter by offering refuge and foraging habitat for selected fish species.
2022-03-23Zeitschriftenartikel
Who Opts Out? The Customisation of Marriage in the German Matrimonial Property Regime
(Kultur-, Sozial- und Bildungswissenschaftliche Fakultät) Nutz, Theresa; Nelles, Anika; Lersch, Philipp M.
This study examines the prevalence of marital contracts across marriage cohorts (1990–2019) in Germany. We further investigate the characteristics of spouses who signed a marital contract. Using cross-sectional data from the German Family Panel (pairfam, 2018/19), we employ complementary log–log and multinomial logistic regression models to predict the prevalence and the type of marital contracts. The results show that 5% of all married couples opt out of the default matrimonial property regime by signing a contract in Germany. Differentiating between contract types, most couples either specify a separation of property (40%) or modify the default community of accrued gains (31%). We find an increase in the prevalence of marital contracts across marriage cohorts. The decision to opt out of the default is strongly positively associated with self-employment that often requires the customisation of asset ownership structures within marriage. Married individuals with prior divorce experiences are more likely to opt for the separation of property, indicating that the awareness of the economic consequences of divorce promotes the individualisation of marriage. Our results are in line with the cross-national trend towards customised marriages, although the trend in Germany is less pronounced than in other countries.
2022-08-12Zeitschriftenartikel
The Nexus between Methods and Power in Sociological Research
(Kultur-, Sozial- und Bildungswissenschaftliche Fakultät) Schmitz, Andreas; Hamann, Julian
This article develops an integrative perspective on the nexus between power and sociological research methods. By reflecting upon two of the most widely used methodological approaches in sociology – standardized survey research and qualitative interview research – we develop a comprehensive heuristic framework for examining the ways in which the use of sociological methods affects and intersects any social scientific practice: (1) the power effects that societies and institutional settings exert on methods and the use of methods, (2) power in the use and implementation of methods, and (3) the power effects that methods and the use of methods exert on societies and institutional settings.
2022-10-01Zeitschriftenartikel
Size-selective mortality fosters ontogenetic changes in collective risk-taking behaviour in zebrafish, Danio rerio
Roy, Tamal; Arlinghaus, Robert
Size-selective mortality is common in fish populations and can operate either in a positive size-selective fashion by harvesting larger-than-average fish or be negatively size-selective by harvesting smaller-than-average fish. Through various mechanisms (like genetic correlations among behaviour and life-history traits or direct selection on behaviour co-varying with growth rate or size-at-maturation), size-selection can result in evolutionary changes in behavioural traits. Theory suggests that both positive and negative size-selection without additional selection on behaviour favours boldness, while evolution of shyness is possible if the largest fish are harvested. Here we examined the impact of size-selective mortality on collective boldness across ontogeny using three experimental lines of zebrafish (Danio rerio) generated through positive (large-harvested), negative (small-harvested) and random (control line) size-selective mortality for five generations and then relaxed selection for 10 generations to examine evolutionarily fixed outcomes. We measured collective risk-taking during feeding (boldness) under simulated aerial predation threat, and across four contexts in presence/absence of a cichlid. Boldness decreased across ontogeny under aerial predation threat, and the small-harvested line was consistently bolder than controls. The large and small-harvested lines showed higher behavioural plasticity as larvae and developed personality earlier compared to the controls. The large-harvested line showed increased variability and plasticity in boldness throughout ontogeny. In the presence of a live predator, fish did not differ in boldness in three contexts compared to the controls, but the large-harvested line showed reduced behavioural plasticity across contexts than controls. Our results confirmed theory by demonstrating that size-selective harvesting evolutionarily alters collective boldness and its variability and plasticity.
2022-01-15Zeitschriftenartikel
Resource frontiers and agglomeration economies: The varied logics of transnational land-based investing in Southern and Eastern Africa
Abeygunawardane, Dilini; Kronenburg García, Angela; Sun, Zhanli; Müller, Daniel; Sitoe, Almeida; Meyfroidt, Patrick
Actor-level data on large-scale commercial agriculture in Sub-Saharan Africa are scarce. The peculiar choice of transnational investing in African land has, therefore, been subject to conjecture. Addressing this gap, we reconstructed the underlying logics of investment location choices in a Bayesian network, using firm- and actor-level interview and spatial data from 37 transnational agriculture and forestry investments across 121 sites in Mozambique, Zambia, Tanzania, and Ethiopia. We distinguish four investment locations across gradients of resource frontiers and agglomeration economies to derive the preferred locations of different investors with varied skillsets and market reach (i.e., track record). In contrast to newcomers, investors with extensive track records are more likely to expand the land use frontier, but they are also likely to survive the high transaction costs of the pre-commercial frontier. We highlight key comparative advantages of Southern and Eastern African frontiers and map the most probable categories of investment locations.
2023-10-30Zeitschriftenartikel
Charting the course of plant virology: innovations in diagnostics and beyond—reports from the DPG meeting
Krenz, Björn; Niehl, Annette; Büttner, Carmen
Plant viruses pose a significant threat to global agriculture, resulting in economic losses and threatening food security. High-throughput sequencing and molecular techniques are advancing our understanding of these viruses, allowing for their detection, characterization, and control. The 55th meeting of the DPG Working Group “Viruskrankheiten der Pflanzen” showcased these advancements, encouraging international collaboration and idea exchange to tackle plant virus challenges. The perspectives paper we present summarizes this conference’s findings, highlighting the potential of these technologies in revolutionizing plant virus research.
2024-09-11Zeitschriftenartikel
Nanohoops in membranes: confined supramolecular spaces within phospholipid bilayer membranes
(Mathematisch-Naturwissenschaftliche Fakultät) Chinner, Kylie; Grabicki, Niklas; Hamaguchi, Rei; Ikeguchi, Mitsunori; Kinbara, Kazushi; Toyoda, Sayaka; Sato, Kohei; Dumele, Oliver
Nanohoops, an exciting class of fluorophores with supramolecular binding abilities, have the potential to become innovative tools within biological imaging and sensing. Given the biological importance of cell membranes, incorporation of macrocyclic materials with the dual capability of fluorescence emission and supramolecular complexation would be particularly interesting. A series of different-sized nanohoops—ethylene glycol-decorated [ n ]cyclo- para -pyrenylenes (CPYs) ( n = 4–8)—were synthesised via an alternate synthetic route which implements a stannylation-based precursor, producing purer material than the previous borylation approach, enabling the growth of single-crystals of the Pt-macrocycle. Reductive elimination of these single-crystals achieved significantly higher selectivity and yields towards smaller ring-sized nanohoops ( n = 4–6). The supramolecular binding capabilities of these CPYs were then explored through host–guest studies with a series of polycyclic (aromatic)hydrocarbons, revealing the importance of molecular size, shape, and CH–π contacts for efficient binding. CPYs were incorporated within the hydrophobic layer of lipid bilayer membranes, as confirmed by microscopic imaging and emission spectroscopy, which also demonstrated the size-preferential incorporation of the five-fold nanohoop. Molecular dynamics simulations revealed the position and orientation within the membrane, as well as the unique non-covalent threading interaction between nanohoop and phospholipid.
2023-10-02Zeitschriftenartikel
Root Development and Subsoil 15N-labelled N Uptake in Soybean (Glycine max (L.) Merr.)
Porte, Anne; Bellingrath-Kimura, Sonoko D.; Schmidtke, Knut
Abstract The aim of this study was to investigate fertiliser-derived N uptake of soybean from different depths of the soil under field conditions. In addition, soybean root growth in sandy and loess soil was evaluated to understand the impact of site and soybean variety characteristics on soybean N uptake under continental conditions in Central Europe. Root analysis to determine rooting depth and root length density (RLD) was carried out using the profile wall method at three growth stages and two soybean cultivars ( Glycine max (L.) Merr. cvs. Merlin and Sultana) in three consecutive years at two locations in eastern Germany. Fertiliser-derived N uptake of soybean from the soil surface and the subsoil was determined at 0.3 and 0.6 m depths using 15 N-labelled nitrate N. Root studies showed that soybean roots grew up to 1.4 m on sandy and loess soil sites. Root length densities of up to 2.4 cm cm −3 were documented in the topsoil. By means of 15 N application, soybean was shown to take up 15% of the surface-applied nitrogen in the dry growing season and 67 % in high rainfall years, between 19 and 77 % of the nitrogen placed at 0.3 m soil depth, and between 2 and 64 % of the nitrogen placed at 0.6 m soil depth by flowering. The field trials showed that soybeans can absorb a high proportion of the nitrogen placed in the subsoil by flowering time. Due to a well-developed root system reaching deep into the soil, soybeans are able to cover their N demand from soil-borne sources and secure yield formation during dry periods by water uptake from the subsoil.
2022-08-02Zeitschriftenartikel
Dealing with the COVID-19 pandemic: an opportunity to reflect on sustainability research
(Integrative Forschungsinstitute) Nölting, Benjamin; König, Bettina; Zimmermann, Anne B.; Di Giulio, Antonietta; Schäfer, Martina; Schneider, Flurina
The COVID-19 pandemic has jolted societies out of normality, possibly creating new conditions for sustainability transformations. What does this mean for sustainability research? Because of the scope of the crisis, researchers have been heavily involved: not only have they had to speed up the pace of scientific production to provide urgently needed COVID-19 knowledge, but they have also been affected citizens. For sustainability science, this calls for an experience-based reflection on the positionality and orientation of research aiming to support sustainability transformations. Twenty sustainability researchers discussed their sustainability research on COVID-19 in three workshops based on the following questions: How does the pandemic—and the measures taken to deal with it—affect sustainable development? What can we learn from the pandemic from the perspective of societal transformation? The present discussion paper emerged from this multidisciplinary exchange among sustainability researchers, considering five topics: impacts of the COVID-19 crisis on sustainability transformations; learning for sustainability transformations; the role of solidarity; governance and political steering; and the role of science in society. Our discussions led to a meta-level reflection on what sustainability research can learn from research on COVID-19 regarding topics and disciplinary angles, time dimensions, the role of researchers, and how adequate preparation for both crises and long-term transformations requires interdisciplinary interaction.
2022-11-30Zeitschriftenartikel
Graphene-on-gold surface plasmon resonance sensors resilient to high-temperature annealing
(Mathematisch-Naturwissenschaftliche Fakultät) Jungnickel, Robert; Mirabella, Francesca; Stockmann, Jörg Manfred; Radnik, Joerg; Balasubramanian, Kannan
Gold films coated with a graphene sheet are being widely used as sensors for the detection of label-free binding interactions using surface plasmon resonance (SPR). During the preparation of such sensors, it is often essential to subject the sensor chips to a high-temperature treatment in order to ensure a clean graphene surface. However, sensor chips used currently, which often use chromium as an adhesion promoter, cannot be subjected to temperatures above 250 °C, because under such conditions, chromium is found to reorganize and diffuse to the surface, where it is easily oxidized, impairing the quality of SPR spectra. Here we present an optimized preparation strategy involving a three-cycle tempering coupled with chromium (oxide) etching, which allows the graphene-coated SPR chips to be annealed up to 500 °C with little deterioration of the surface morphology. In addition, the treatment delivers a surface that shows a clear enhancement in spectral response together with a good refractive index sensitivity. We demonstrate the applicability of our sensors by studying the kinetics of avidin–biotin binding at different pH repeatedly on the same chip. The possibility to anneal can be exploited to recover the original surface after sensing trials, which allowed us to reuse the sensor for at least six cycles of biomolecule adsorption.
2022-09-02Zeitschriftenartikel
Discussion on: “Programmable money: next generation blockchain-based conditional payments” by Ingo Weber and Mark Staples
(Wirtschaftswissenschaftliche Fakultät) Burda, Michael
My comment on Weber and Staples (Digit Financ, https://doi.org/10.1007/s42521-022-00064-8 [Titel anhand dieser DOI in Citavi-Projekt übernehmen] , 2022) elaborates an economic perspective of their “programmable money” proposal. While claims issued and tendered for goods and services resemble money, a number of issues must be resolved before this innovation is feasible as money in analog trade or digital finance. These include secondary tradability, permissioned access, standardization and transparency. Programmable money is an important step towards the implementation of contingent commodities in the sense of Arrow and Debreu (Econometrica, 22(3):265–290, 1954) and Debreu (1959).
2024Buch
El pensamiento literario
(Sprach- und literaturwissenschaftliche Fakultät) Kamecke, Gernot
2024Buch
Human Enhancements und Patentrecht
(Juristische Fakultät) Vetter, Sven
Ist das Patentrecht wirklich »wertneutral« oder gar »ethisch blind«? Die Praxis des Patentrechts wird von einem ungebrochenen Fortschrittsoptimismus getragen. Das hohe Maß an Technik- und Innovationsgläubigkeit lässt traditionell wenig Raum für eine tiefergehende Reflexion außerrechtlicher Wirkdimensionen des Patentsystems. Es stellt sich jedoch die Frage, ob Innovationsförderung ohne ein Mindestmaß an gesellschaftlicher Innovationsverantwortung überhaupt ein sinnvolles Ziel sein kann. Ein so facettenreiches Forschungsthema wie »Human Enhancements« eignet sich hervorragend dazu, um die Funktionen und Wirkungen des Patentschutzes zu veranschaulichen. An die Stelle eines allgemeinen Verweises auf »ethisch umstrittene Forschungsfelder« treten konkrete Beispiele. Die gewonnenen Erkenntnisse können wiederum in den interdisziplinären Gesamtdiskurs einfließen, der die biotechnische Selbstgestaltung des Menschen als Teil und Folge der modernen Gesellschaft und ihrer Charakteristika betrachtet. Die Arbeit wurde mit dem Innovationspreis 2023 der Humboldt-Universität zu Berlin und als beste Dissertation im Zivilrecht mit dem Promotionspreis 2023 der Juristischen Fakultät der Humboldt-Universität zu Berlin ausgezeichnet.
2017-10-04Zeitschriftenartikel
High resolution remote sensing for reducing uncertainties in urban forest carbon offset life cycle assessments
(Mathematisch-Naturwissenschaftliche Fakultät) Tigges, Jan; Lakes, Tobia
Background Urban forests reduce greenhouse gas emissions by storing and sequestering considerable amounts of carbon. However, few studies have considered the local scale of urban forests to effectively evaluate their potential long-term carbon offset. The lack of precise, consistent and up-to-date forest details is challenging for long-term prognoses. Therefore, this review aims to identify uncertainties in urban forest carbon offset assessment and discuss the extent to which such uncertainties can be reduced by recent progress in high resolution remote sensing. We do this by performing an extensive literature review and a case study combining remote sensing and life cycle assessment of urban forest carbon offset in Berlin, Germany. Main text Recent progress in high resolution remote sensing and methods is adequate for delivering more precise details on the urban tree canopy, individual tree metrics, species, and age structures compared to conventional land use/cover class approaches. These area-wide consistent details can update life cycle inventories for more precise future prognoses. Additional improvements in classification accuracy can be achieved by a higher number of features derived from remote sensing data of increasing resolution, but first studies on this subject indicated that a smart selection of features already provides sufficient data that avoids redundancies and enables more efficient data processing. Our case study from Berlin could use remotely sensed individual tree species as consistent inventory of a life cycle assessment. However, a lack of growth, mortality and planting data forced us to make assumptions, therefore creating uncertainty in the long-term prognoses. Regarding temporal changes and reliable long-term estimates, more attention is required to detect changes of gradual growth, pruning and abrupt changes in tree planting and mortality. As such, precise long-term urban ecological monitoring using high resolution remote sensing should be intensified, especially due to increasing climate change effects. This is important for calibrating and validating recent prognoses of urban forest carbon offset, which have so far scarcely addressed longer timeframes. Additionally, higher resolution remote sensing of urban forest carbon estimates can improve upscaling approaches, which should be extended to reach a more precise global estimate for the first time. Conclusions Urban forest carbon offset can be made more relevant by making more standardized assessments available for science and professional practitioners, and the increasing availability of high resolution remote sensing data and the progress in data processing allows for precisely that.
2015-06-01Zeitschriftenartikel
Effects of ankle–foot braces on medial gastrocnemius morphometrics and gait in children with cerebral palsy
(Kultur-, Sozial- und Bildungswissenschaftliche Fakultät) Hösl, Matthias; Böhm, Harald; Arampatzis, Adamantios; Döderlein, Leonhard
Purpose In children with cerebral palsy (CP), braces are used to counteract progressive joint and muscle contracture and improve function. We examined the effects of positional ankle–foot braces on contracture of the medial gastrocnemius (MG) and gait in children with CP while referencing to typically developing children. Methods Seventeen independently ambulant children with CP and calf muscle contracture (age 10.4 ± 3.0y) and 17 untreated typically developing peers (age 9.5 ± 2.6y) participated. Children with CP were analysed before and 16 ± 4 weeks after ankle–foot bracing. MG muscle belly length and thickness, tendon and fascicle length, as well as their extensibility were captured by 2D ultrasound and 3D motion capturing during passive, manually applied stretches. In addition, 3D gait analysis was conducted. Results Prior to bracing, the MG muscle–tendon unit in children with CP was 22 % less extensible. At matched amounts of muscle–tendon unit stretch, the muscle belly and fascicles in CP were 7 % and 14 % shorter while the tendon was 11 % longer. Spastic fascicles displayed 32 % less extensibility than controls. Brace wear increased passive dorsiflexion primarily with the knees flexed. During gait, children walked faster and foot lift in swing improved. MG muscle belly and tendon length showed little change, but fascicles further shortened (−11 %) and muscle thickness (−8 %) decreased. Conclusions Use of ankle–foot braces improves function but may lead to a loss of sarcomeres in series, which could explain the shortened fascicles. To potentially induce gastrocnemius muscle growth, braces may also need to extend the knee or complementary training may be necessary to offset the immobilizing effects of braces.
2016-04-29Zeitschriftenartikel
Small-scale variability of particulate matter and perception of air quality in an inner-city recreational area in Aachen, Germany
(Mathematisch-Naturwissenschaftliche Fakultät) Paas, Bastian; Schmidt, Teresa; Markova, Stanimira; Maras, Isabell; Ziefle, Martina; Schneider, Christoph
Spatial micro-scale variability of particle mass concentrations is an important criterion for urban air quality assessment. In this study we present results from detailed spatio-temporal measurements in the urban roughness layer along with a survey to determine perceptions of citizens regarding air quality in an inner city park in Aachen, Germany. Particles were sampled with two different approaches in February, May, July and September 2014 using an optical particle counter at six fixed measurement locations, representing different degrees of outdoor particle exposure that can be experienced by a pedestrian walking in an intra-urban recreational area. A simulation of aerosol emissions induced by road traffic was conducted using the German reference dispersion model Austal2000. The mobile measurements revealed unexpected details in the distribution of urban particles with highest mean concentrations of PM(1;10) inside the green area 100 m away from bus routes (arithmetic mean: 22.5 μg m−3 and 18.9 μg m−3; geometric mean: 9.3 μg m−3 and 6.5 μg m−3), whereas measurement sites in close proximity to traffic lines showed far lower mean values (arithmetic mean: 7.5 μg m−3 and 8.7 μg m−3; geometric mean: 5.8 μg m−3 and 6.5 μg m−3). Concerning simulation results, motor traffic is still proved to be an important aerosol source in the area, although the corresponding concentrations declined rapidly as the distances to the line sources increased. Further analysis leads to the assumption that particularly coarse particles were emitted through diffuse sources e.g. on the ability of surfaces to release particles by resuspension which were dominantly apparent in measured PM(1;10) and PM(0.25;10) data. The contribution of diffuse particle sources and urban background transport to local PM(0.25;10) concentrations inside the green area were quantified to be up to 17.9 μg m−3. The analysis of perception related experiments demonstrate that particle concentrations in form of PM(0.25;10) were inconsistent with park user opinions regarding perception of air quality. At least in investigated concentration magnitudes there proved to be no connection between user assessment and physical values at all.
2017-09-19Zeitschriftenartikel
Uncertainties in demonstrating environmental benefits of payments for ecosystem services
(Mathematisch-Naturwissenschaftliche Fakultät) Lima, Letícia Santos de; Krueger, Tobias; García-Marquez, Jaime
Payments for Ecosystem Services (PES) have become the flagship of conservation organizations in recent years. However, PES schemes are as much criticized as they are acclaimed in the literature. Researchers have pointed that many PES schemes, particularly water-related ones, are based on unreliable assumptions and lack strong causal links between land use and ecosystem services. Evidence of outcomes is hardly demonstrated. This uncertainty in PES schemes arises not only from practical difficulties, but from the complexity of the human-environment systems (HES), and the limits of current knowledge about HES. Many scientists and practitioners have proposed that more research is needed to improve the scientific basis of PES. Here we argue that this research should be complemented with a deeper understanding of the uncertainties involved in PES, an explicit treatment of these in the whole process of PES negotiation, design and monitoring, and clear uncertainty communication among the actors involved. Neglecting uncertainties could lead to unfounded expectations and poor assessments of PES outcomes. If recognizing and accounting for uncertainties are to threaten the success of PES, then uncertainty can be seen as an opportunity to open up the dialogue to alternative ways of achieving the desired conservation goals.
2017-09-28Zeitschriftenartikel
Decoupled systems on trial: Eliminating bottlenecks to improve aquaponic processes
(Lebenswissenschaftliche Fakultät) Monsees, Hendrik; Kloas, Werner; Wuertz, Sven
In classical aquaponics (coupled aquaponic systems, 1-loop systems) the production of fish in recirculating aquaculture systems (RAS) and plants in hydroponics are combined in a single loop, entailing systemic compromises on the optimal production parameters (e.g. pH). Recently presented decoupled aquaponics (2-loop systems) have been awarded for eliminating major bottlenecks. In a pilot study, production in an innovative decoupled aquaponic system was compared with a coupled system and, as a control, a conventional RAS, assessing growth parameters of fish (FCR, SGR) and plants over an experimental period of 5 months. Soluble nutrients (NO3--N, NO2--N, NH4+-N, PO43-, K+, Ca2+, Mg2+, SO42-, Cl2- and Fe2+), elemental composition of plants, fish and sludge (N, P, K, Ca, Mg, Na, C), abiotic factors (temperature, pH, oxygen, and conductivity), fertilizer and water consumption were determined. Fruit yield was 36% higher in decoupled aquaponics and pH and fertilizer management was more effective, whereas fish production was comparable in both systems. The results of this pilot study clearly illustrate the main advantages of decoupled, two-loop aquaponics and demonstrate how bottlenecks commonly encountered in coupled aquaponics can be managed to promote application in aquaculture.

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