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Biological and biogeochemical methods for estimating bioirrigation : A case study in the Oosterschelde estuary
No full textBioirrigation, the exchange of solutes between overlying water and sediment by benthic organisms, plays an important role in sediment biogeochemistry. Bioirrigation either is quantified based on tracer data or a community (bio)irrigation potential (IPc) can be derived based on biological traits. Both these techniques were applied in a seasonal study of bioirrigation in subtidal and intertidal habitats in a temperate estuary. The combination of a tracer time series with a high temporal resolution and a mechanistic model allowed for us to simultaneously estimate the pumping rate and the sediment attenuation, a parameter that determines irrigation depth. We show that, although the total pumping rate is similar in both intertidal and subtidal areas, there is deeper bioirrigation in intertidal areas. This is explained by higher densities of bioirrigators such as Corophium sp., Heteromastus filiformis and Arenicola marina in the intertidal, as opposed to the subtidal, areas. The IPc correlated more strongly with the attenuation coefficient than the pumping rate, which highlights that the IPc index reflects more the bioirrigation depth than the rate.</p
Accelerated grain-filling rate increases seed size and grain yield of recent naked oat cultivars under well-watered and water-deficit conditions
No full textIncreased seed size has greater contribution in yield improvement in recent naked oat (Avena sativa L. subsp. nudisativa) cultivars than cultivars derived from landraces. However, the underlying grain-filling mechanisms associated with seed size and grain yield in naked oat have received limited study. Two field experiments and a pot experiment compared grain-filling mechanisms, seed size and grain yield of ten naked oat cultivars, including old (landraces, released before 1950s) and new (released since 2008) cultivars. In both well-watered and water-deficit conditions, the new cultivars had higher grain yields, higher thousand kernel weights (TKW) and higher grain numbers per spike, but fewer fertile spikes per unit area or per plant, and no significant differences in grain number per unit area or per plant, than old cultivars. The findings in both the field and pot experiments demonstrated that increased grain-filling rate, rather than duration, enhanced seed size (TKW) and grain yield in the new cultivars. The increased grain-filling rate in a new cultivar was associated with higher rates of endosperm cell division and higher number of endosperm cells, compared to that in an old cultivar, but there were no significant differences in starch synthesis enzyme activity and ABA concentration between the old and new cultivars. As a result of current breeding and selection, the increased the grain yield of new cultivars of naked oat is primarily due to increased seed size (increased sink size) arising from a greater number of endosperm cells per grain, and not because of increased enzyme or phytohormonal activity. The larger seed size is important in the production of oats for food rather than for forage.</p
Corporate social responsibility and dynamic productivity change in the US food and beverage manufacturing industry
No full textThis study examines the relationship between corporate social responsibility (CSR) and dynamic productivity change of each input employed and investment undertaken in the US food and beverage manufacturing industry. We compute input‐ and investment‐specific dynamic Luenberger indicators and decompose them into the contributions of input‐ and investment‐specific dynamic technical inefficiency changes and dynamic technological changes. We then relate these indicators to an overall CSR measure and aspect‐specific CSR measures (governance, environment, and social). Our results confirm that the association between CSR and productivity change has different signs and effects on specific inputs or investments. We also find that only certain aspects of CSR participate in the association between CSR and dynamic productivity change and its components. [EconLit citations: C61, D24, L66, M14]
Soil organic matter dynamics in Dutch production grasslands : Measurement and management
No full textBodemmaatregelen op dalgrond in de Veenkoloniën: effecten op bodemkwaliteit, opbrengst en financiële meerwaarde : Analyse van de resultaten van de systeemproef Bodemkwaliteit Veenkoloniën 2014-2017
No full textIn een langjarig experiment op proefbedrijf Valthermond wordt op dalgrond met gemiddeld 11% organische stof een vijftal maatregelen in een vierjarige akkerbouwvruchtwisseling vergeleken met de standaard werkwijze, in vier herhalingen. De maatregelen Tagetes, Compost, sturen Ca/Mg-verhouding, Steenmeel zijn elk op hun eigen wijze gericht op verbetering van de bodemkwaliteit. Ook een combinatie van alle maatregelen is onderzocht. Over de maatregelen heen liggen varianten van grondbewerking (NKG en Spitten) in duplo. Na vier jaar blijkt de maatregel Tagetes (de teelt van zomergerst vervangen door een hoofdteelt Tagetes) zowel meer opbrengst op te leveren in de aardappelteelt als economisch rendabel te zijn, ondanks de opbrengstderving door het wegvallen van de verkoop van gerst. De andere strategieën hebben weinig of geen effect op de opbrengst en de kosten zijn hoger dan de eventuele extra inkomsten door opbrengstverhoging. NKG lijkt een positief effect te hebben op de opbrengst maar dat is nog niet statistisch significant. Wel leidt NKG tot kostenbesparing ten opzichte van Spitten door lagere machinekosten en lager brandstofverbruik. Veranderingen in bodemkwaliteit zijn nog nauwelijks waargenomen. Dat komt naar verwachting mede doordat die effecten meer tijd nodig hebben om zich te tonen. De nitraatnorm voor grondwater wordt meestal overschreden, onafhankelijk van de maatregel. Waar de norm wel gehaald wordt ligt het aan bodem en grondwater, niet aan de bemestingsstrategie. Het onderzoek wordt voortgezet
Aiming for Sustainability and Scalability: Community Engagement in Forest Payment Schemes
No full textCommunity-based forest monitoring is seen as a way both to improve community engagement and participation in national environmental payment schemes and climate mitigation priorities and to implement reducing emissions from deforestation and forest degradation and foster conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries (REDD+). There is a strong assumption among community-based monitoring advocates that community monitoring is a desirable approach. However, it is unclear why community members would want to participate in their own surveillance or be involved in a program likely to limit livelihood uses of forest areas and possibly even sanction them based on the data provided. This paper explores these issues by examining three communities involved in Peru’s Conditional Direct Transfer Program, in which indigenous communities are compensated for protecting communal forests through various mechanisms, including forest monitoring. The case studies focus specifically on communities that received smartphones and were trained in their use for monitoring. The results affirm the importance that benefits outweigh the costs of local participation to sustain motivation. They also point to key factors supporting the legitimacy of the program, specifically to overcome historical tensions between the state and indigenous communities. These include the nature of engagement by program implementers and the importance of building trust over time
Effects of land use and land cover change on the water cycle in the Amazon basin under a changing climate
No full textThe Amazon rainforest, the world’s largest tropical rainforest, plays an important role on climate regulation by carbon fixation and cooling temperature throughout its high evapotranspiration rates. Nonetheless, the biome is pressured by deforestation on large part of its territory. The abandonment of deforested area due to low productivity and natural resources exhaustion, have resulted in a landscape characterized by a mosaic of several land covers, mainly the natural forest, pastures and secondary growth. This thesis aims to evaluate the seasonal and spatial variability of the fluxes of evapotranspiration over diverse Amazon land covers, with the purpose of investigating whether natural recovery counterbalances the effects caused by anthropogenic actions on the water cycle components. Besides that, the impact of future scenarios of land use and land cover change in combination with global climate change on river discharges and hydropower was also evaluated in an Amazon tributary by explicitly modeling the role of each land cover on evapotranspiration. Water and carbon fluxes were measured by eddy covariance and scintilometry besides other micrometeorological data, in three different land covers in Central and Southwestern Amazonia, in order to compare the effects of deforestation and natural regrowth on the water cycle components. The conversion of forest to pasture reduces the evapotranspiration. Two pasture sites analyzed present much lower evapotranspiration than in forests during the dry season, and with only one of them reaching the same rates of evaporation of primary vegetation during the wet season. Nonetheless, when pastures are abandoned due to low productivity, the secondary growth that replaces those areas reaches evapotranspiration 20% higher than that in primary forest at both dry and wet seasons. The gross primary productivity of the secondary vegetation is also higher than the primary in the wet season, but in a lower percentage (5% higher), and the same during the dry season. Besides the field data collection, this work is one of the first to consider the impacts of secondary forest in the hydrological modeling driven by different climate change scenarios (CC) and two future socioeconomic-based potential land-cover land-use change scenarios (LCLUC) on regional scale. The model projected a decrease on discharge under CC scenarios, and when deforestation scenarios without secondary growth are considered, the effects of CC are weakened. However, when secondary growth is also considered, the effects of CC are slightly enhanced. Results suggest that different aspects of environmental change, such as secondary growth, may affect water production and the sectors depending on it. For example, the potential energy production for Tucuruí power plant, is projected to decrease of up to 58% under all land use change scenarios in 2041 to 2070 time slice. Secondary forest growth plays an important role in minimizing the impacts of land cover and land use changes from primary forest to pasture on the water balance in Amazonia, since the secondary forest contributes with higher transpiration than pastures, and even higher than in the primary forest. This indicates that secondary forests can contribute to the maintenance of moisture production of the Amazon region. In addition, secondary forest takes more carbon from the atmosphere than pasture sites, playing an important role on carbon uptake from the atmosphere together with primary forest, minimizing emission from deforestation
Microbial Community Drivers in Anaerobic Granulation at High Salinity
No full textIn the recent years anaerobic sludge granulation at elevated salinities in upflow anaerobic sludge blanket (UASB) reactors has been investigated in few engineering based studies, never addressing the microbial community structural role in driving aggregation and keeping granules stability. In this study, the combination of different techniques was applied in order to follow the microbial community members and their structural dynamics in granules formed at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Experiments were carried out in four UASB reactors fed with synthetic wastewater, using two experimental set-ups. By applying 16S rRNA gene analysis, the comparison of granules grown at low and high salinity showed that acetotrophic Methanosaeta harundinacea was the dominant methanogen at both salinities, while the dominant bacteria changed. At 5 g/L Na+, cocci chains of Streptoccoccus were developing, while at 20 g/L Na+ members of the family Defluviitaleaceae formed long filaments. By means of Fluorescence in Situ Hybridization (FISH) and Scanning Electron Microscopy (SEM), it was shown that aggregation of Methanosaeta in compact clusters and the formation of filaments of Streptoccoccus and Defluviitaleaceae during the digestion time were the main drivers for the granulation at low and high salinity. Interestingly, when the complex protein substrate (tryptone) in the synthetic wastewater was substituted with single amino acids (proline, leucine and glutamic acid), granules at high salinity (20 g/L Na+) were not formed. This corresponded to a decrease of Methanosaeta relative abundance and a lack of compact clustering, together with disappearance of Defluviitaleaceae and consequent absence of bacterial filaments within the dispersed biomass. In these conditions, a biofilm was growing on the glass wall of the reactor instead, highlighting that a complex protein substrate such as tryptone can contribute to granules formation at elevated salinity.</p