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131.
Anne B. Willems Cara A. AugustenborgSimone Hepp Gary LaniganTamara Hochstrasser Claudia Kammann Christoph Müller 《Agriculture, ecosystems & environment》2011,144(1):347-351
Grassland re-seeding or land-use change requires ploughing, which may enhance carbon dioxide (CO2) emissions from soil. This study observed the short to intermediate-term (37 days) effects of ploughing on CO2 emissions from poorly drained grassland using automated soil respiration chambers. Immediately after ploughing, a brief peak in CO2 emissions from soil occurred with a maximum observed flux of 6.91 g CO2 m−2 h−1. Contradictory to other reported results, ecosystem respiration after ploughing was lower on the ploughed than on the grass site. After including estimates of photosynthesis in the analysis, ploughing led to significantly higher net CO2 emissions than from grassland. The main mechanism of C loss during ploughing was most likely due to a reduction in gross primary production rather than enhanced soil respiration. 相似文献
132.
Recent studies showed that nectar odors brought back by honeybee foragers can be learned associatively inside the hive. In
the present study, we focused on the learning abilities of bees, which directly interact via trophallaxis with the incoming
nectar foragers: the workers that perform nectar-receiving tasks inside the hive. Workers that have received food directly
from foragers coming back from a feeder offering either unscented or scented sugar solution [phenylacetaldehyde (PHE) or nonanal
diluted] were captured from two observational hives, and their olfactory memories were tested using the proboscis extension
response paradigm. Bees that have received scented solution from incoming foragers showed significantly increased response
frequencies for the corresponding solution odor in comparison with those that have received unscented solution. No differences
in the response frequencies were found between food odors and colonies. The results indicate that first-order receivers learn
via trophallaxis the association between the scent and the sugar solution transferred by incoming foragers. The implications
of these results should be considered at three levels: the operational cohesion of bees involved in foraging-related tasks,
the information propagation inside the hive related to the floral type exploited, and the putative effect of these memories
on future preferences for resources. 相似文献
133.
Seasonal and Regional Patterns in Performance for a Baltic Sea Drainage Basin Hydrologic Model 下载免费PDF全文
Steve W. Lyon Roya Meidani Ype van der Velde Helen E. Dahlke Dennis P. Swaney Carl‐Magnus Mörth Christoph Humborg 《Journal of the American Water Resources Association》2015,51(2):550-566
This study evaluates the ability of the Catchment SIMulation (CSIM) hydrologic model to describe seasonal and regional variations in river discharge over the entire Baltic Sea drainage basin (BSDB) based on 31 years of monthly simulation from 1970 through 2000. To date, the model has been successfully applied to simulate annual fluxes of water from the catchments draining into the Baltic Sea. Here, we consider spatiotemporal bias in the distribution of monthly modeling errors across the BSDB since it could potentially reduce the fidelity of predictions and negatively affect the design and implementation of land‐management strategies. Within the period considered, the CSIM model accurately reproduced the annual flows across the BSDB; however, it tended to underpredict the proportion of discharge during high‐flow periods (i.e., spring months) and overpredict during the summer low flow periods. While the general overpredictions during summer periods are spread across all the subbasins of the BSDB, the underprediction during spring periods is seen largely in the northern regions. By implementing a genetic algorithm calibration procedure and/or seasonal parameterization of subsurface water flows for a subset of the catchments modeled, we demonstrate that it is possible to improve the model performance albeit at the cost of increased parameterization and potential loss of parsimony. 相似文献
134.
The role of species and functional group diversity of primary producers for decomposers and decomposition processes is little understood. We made use of the "Jena Biodiversity Experiment" and tested the hypothesis that increasing plant species (1, 4, and 16 species) and functional group diversity (1, 2, 3, and 4 groups) beneficially affects decomposer density and activity and therefore the decomposition of plant litter material. Furthermore, by manipulating the densities of decomposers (earthworms and springtails) within the plant diversity gradient we investigated how the interactions between plant diversity and decomposer densities affect the decomposition of litter belonging to different plant functional groups (grasses, herbs, and legumes). Positive effects of increasing plant species or functional group diversity on earthworms (biomass and density) and microbial biomass were mainly due to the increased incidence of legumes with increasing diversity. Neither plant species diversity nor functional group diversity affected litter decomposition, However, litter decomposition varied with decomposer and plant functional group identity (of both living plants and plant litter). While springtail removal generally had little effect on decomposition, increased earthworm density accelerated the decomposition of nitrogen-rich legume litter, and this was more pronounced at higher plant diversity. The results suggest that earthworms (Lumbricus terrestris L.) and legumes function as keystone organisms for grassland decomposition processes and presumably contribute to the recorded increase in primary productivity with increasing plant diversity. 相似文献
135.
Carin Jantzen Christian Wild Mohammed El-Zibdah Hilly Ann Roa-Quiaoit Christoph Haacke Claudio Richter 《Marine Biology》2008,155(2):211-221
Two species of giant clams, Tridacna maxima and T. squamosa, coexist in the Red Sea, but exhibit distinctly different depth distributions: T. maxima mostly occurs in shallow waters (reef flat and edge), while T. squamosa may occur down to the lower fore-reef slope. Giant clams have been described as mixotrophic, capable of both filter-feeding
and photosynthesis due to algal symbionts (zooxanthellae), therefore, observed depth preferences were investigated in relation
to possible differences in autotrophy vs. heterotrophy. This study was conducted from April to June 2004, at the reef near
the Marine Science Station, Aqaba, Gulf of Aqaba, Red Sea, and in May 2007, at a reef near Dahab, Sinai Peninsula, Egypt.
In situ measurements using a submersible pulse amplitude modulated fluorometer (Diving PAM), revealed no significant differences
in effective PSII quantum yield (ΔF/Fm′) and relative electron transport rates (ETR) between the two species; but rapid light curves (ETR vs. light, photosynthetically
active irradiance, PAR) showed significant differences in maximum photosynthetic rates (ETRmax), with 20% higher values in T. maxima. Chamber incubations displayed higher net and gross oxygen production by T. maxima (88.0 and 120.3 μmol O2 cm−2 mantle area day−1) than T. squamosa (56.7 and 84.8 μmol O2 cm−2 mantle area day−1); even under shading conditions (simulated depth of 20 m) T. maxima still achieved 93% of the surface gross O2 production, whereas T. squamosa reached only 44%. A correlation was found between ETR and net photosynthesis measured as oxygen production (T. maxima: R
2 = 0.53; T. squamosa: R
2 = 0.61). Calculated compensation depth (CD) (gross photosynthesis equals respiration) in T. maxima (16 m) matches the maximum depth of occurrence in this study (17 m). By contrast, the CD of T. squamosa (9 m) was much shallower than the maximum vertical range (42 m). Findings suggest T. maxima is a strict functional photoautotroph limited by light, whereas T. squamosa is a mixotroph whose photoautotrophic range is extended by heterotrophy.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
136.
Verona Borges Ferreira Leonardo Fontes Estrella Marcelo Guzzon Rodrigues Alves Christoph Gallistl Walter Vetter Thadia Turon Costa Silva 《Journal of environmental science and health. Part. B》2020,55(1):30-41
AbstractOrganochlorine (OCP) pesticides were determined in samples of sardine (Sardinella brasiliensis), whitemouth croaker (Micropogonias furnieri), and mullet (Mugil liza) from Guanabara Bay (state of Rio de Janeiro, Brazil). OCP concentrations and fish consumption were linked with acceptable daily intake values in order to assess the human health risk for the Brazilian population. The total concentrations of OCPs (Σ OCP) was 6.6?ng/g f.w., 7.5?ng/g f.w., and 2.8?ng/g f.w. for sardines, corvina, and mullet, respectively. There was a significant difference (P?<?0.05) among the species related to o,p’-DDD and o,p’-DDT concentrations. Both DDT-related compounds were 5 and 76 times more abundant in sardines than in whitemouth croaker and mullet. Newly discovered DDT metabolite, o-Cl-DDMU, was frequently detected in the fish. None of the samples exceeded the maximum limits for acceptable levels of OCP residues. According to the data of average intake of Brazilian population, none of three species exceeded toxicological parameter. The investigated fishes are considered as safe for human consumption in regard to exposure of the studied OCPs. However, fish may be a intake source of OCP metabolites such as o-Cl-DDMU whose toxicity is still unknown. 相似文献
137.
Archetypical patterns and trajectories of land systems in Europe 总被引:1,自引:0,他引:1
Levers Christian Müller Daniel Erb Karlheinz Haberl Helmut Jepsen Martin Rudbeck Metzger Marc J. Meyfroidt Patrick Plieninger Tobias Plutzar Christoph Stürck Julia Verburg Peter H. Verkerk Pieter J. Kuemmerle Tobias 《Regional Environmental Change》2018,18(3):715-732
Regional Environmental Change - Assessments of land-system change have dominantly focused on conversions among broad land-use categories, whereas intensity changes within these categories have... 相似文献
138.
Christoph Kämpfer Thomas-Benjamin Seiler Anna-Lena Beger Georg Jacobs Manuel Löwer Franziska Moser Julia Reimer Martin Trautz Björn Usadel Alexandra Wormit Henner Hollert 《Environmental Sciences Europe》2017,29(1):27
Technical product harvesting (TEPHA) is a newly developing interdisciplinary approach in which bio-based production is investigated from a technical and ecological perspective. Society‘s demand for ecologically produced and sustainably operable goods is a key driver for the substitution of conventional materials like metals or plastics through bio-based alternatives. Technical product harvesting of near net shape grown components describes the use of suitable biomass for the production of technical products through influencing the natural shape of plants during their growth period. The use of natural materials may show positive effects on the amount of non-renewable resource consumption. This also increases the product recyclability at the end of its life cycle. Furthermore, through the near net shape growth of biomass, production steps can be reduced. As a consequence such approaches may save energy and the needed resources like crude oil, coal or gas. The derived near net shape grown components are not only considered beneficial from an environmental point of view. They can also have mechanical advantages through an intrinsic topology optimization in contrast to common natural materials, which are influenced in their shape after harvesting. In order to prove these benefits a comprehensive, interdisciplinary scientific strategy is needed. Here, both mechanical investigations and life cycle assessment as a method of environmental evaluation are used. 相似文献
139.
140.
Spatial variability of soil gas concentration and methane oxidation capacity in landfill covers 总被引:2,自引:0,他引:2
In order to devise design criteria for biocovers intended to enhance the microbial oxidation of landfill methane it is critical to understand the factors influencing gas migration and methane oxidation in landfill cover soils. On an old municipal solid waste landfill in north-western Germany soil gas concentrations (10, 40, 90 cm depth), topsoil methane oxidation capacity and soil properties were surveyed at 40 locations along a 16 m grid. As soil properties determine gas flow patterns it was hypothesized that the variability in soil gas composition and the subsequent methanotrophic activity would correspond to the variability of soil properties. Methanotrophic activity was found to be subject to high spatial variability, with values ranging between 0.17 and 9.80 g CH4 m−2 h−1. Considering the current gas production rate of 0.03 g CH4 m−2 h−1, the oxidation capacity at all sampled locations clearly exceeded the flux to the cover, and can be regarded as an effective instrument for mitigating methane fluxes. The methane concentration in the cover showed a high spatial heterogeneity with values between 0.01 and 0.32 vol.% (10 cm depth), 22.52 vol.% (40 cm), and 36.85 vol.% (90 cm). The exposure to methane raised the oxidation capacity, suggested by a statistical correlation to an increase in methane concentration at 90 cm depth. Methane oxidation capacity was further affected by the methanotroph bacteria pH optimum and nutrient availability, and increased with decreasing pH towards neutrality, and increased with soluble ion concentration). Soil methane and carbon dioxide concentration increased with lower flow resistance of the cover, as represented by the soil properties of a reduced bulk density, increase in air capacity and in relative ground level. 相似文献