排序方式: 共有38条查询结果,搜索用时 31 毫秒
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Förster M Helms Y Herberg A Köppen A Kunzmann K Radtke D Ross L Itzerott S 《Environmental management》2008,41(4):584-598
The use of renewable energy in Europe offers the possibility of reducing greenhouse gas emissions, and contributes to energy
security and independence. With the reform of the Common Agricultural Policy (CAP) and a variety of recently introduced national
directives supporting renewable energy sources in the European Union, the economic attractiveness of bioenergy production
has distinctly increased. This article combines an economic evaluation of biomass production with site-related natural conditions
of the Havelland region, situated in the north-east area of Germany. Two methods for evaluating site-specific potential biomass
yields were compared. For three example biomass crops, evaluations of yield estimations at agricultural lots for site-optimized
suitability (SOS) and conventional suitability (CS) were carried out. Both modelling approaches were compared. The results
of the GIS modelling indicate that the financial support for increasing the use of renewable energy with the German feed-in
system, called Erneuerbare-Energien-Gesetz (EEG), will possibly lead to an increased cultivation of crops with high biomass
output. This monocultural orientation of farming practices and the negative effects on the ecosystem could act in opposition
to other environmental initiatives of the EU. The outputs of the SOS analysis show that high biomass production could be integrated
into environmental policy proposals. Therefore, new EU policy should take modified subsidies into consideration in order to
avoid developing conflicts between small-scale changes in landscape ecosystems caused by large-scale transformations in energy
policy. 相似文献
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Julia Wohlers-Z?llner Antje Biermann Anja Engel Petra D?rge Aleksandra M. Lewandowska Markus von Scheibner Ulf Riebesell 《Marine Biology》2012,159(11):2503-2518
A comparative analysis of data, obtained during four indoor-mesocosm experiments with natural spring plankton communities from the Baltic Sea, was conducted to investigate whether biogeochemical cycling is affected by an increase in water temperature of up to 6?°C above present-day conditions. In all experiments, warming stimulated in particular heterotrophic bacterial processes and had an accelerating effect on the temporal development of phytoplankton blooms. This was also mirrored in the build-up and partitioning of organic matter between particulate and dissolved phases. Thus, warming increased both the magnitude and rate of dissolved organic carbon (DOC) build-up, whereas the accumulation of particulate organic carbon (POC) and phosphorus (POP) decreased with rising temperature. In concert, the observed temperature-mediated changes in biogeochemical components suggest strong shifts in the functioning of marine pelagic food webs and the ocean’s biological carbon pump, hence providing potential feedback mechanisms to Earth’s climate system. 相似文献
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Bénédicte Ritt Catherine Pierre Olivier Gauthier Frank Wenzhöfer Antje Boetius Jozée Sarrazin 《Marine Biology》2011,158(6):1187-1210
The Nile Deep-Sea Fan (NDSF) is located on the passive continental margin off Egypt and is characterized by the occurrence
of active fluid seepage such as brine lakes, pockmarks and mud volcanoes. This study characterizes the structure of faunal
assemblages of such active seepage systems of the NDSF. Benthic communities associated with reduced, sulphidic microhabitats
such as sediments and carbonate crusts were sampled by remotely operated vehicles during two cruises in 2006 (BIONIL) and
2007 (MEDECO). Environmental conditions and biological factors including family-level faunal composition, density and diversity
were measured at local and regional scales. Significant differences were detected at different spatial scales: (1) the fauna
of reduced habitats differed substantially in activity, diversity and biomass from the non-seep environment at similar water
depth, (2) cold seep microhabitats showed differences in community structure and composition related to substratum type as
well as to the intensity and location of fluid emissions. 相似文献
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Dubuc C Muniz L Heistermann M Engelhardt A Widdig A 《Behavioral ecology and sociobiology》2011,65(8):1615-1627
In mammals, when females are clumped in space, male access to receptive females is usually determined by a dominance hierarchy
based on fighting ability. In polygynandrous primates, as opposed to most mammalian species, the strength of the relationship
between male social status and reproductive success varies greatly. It has been proposed that the degree to which paternity
is determined by male rank decreases with increasing female reproductive synchrony. The priority-of-access model (PoA) predicts
male reproductive success based on female synchrony and male dominance rank. To date, most tests of the PoA using paternity
data involved nonseasonally breeding species. Here, we examine whether the PoA explains the relatively low reproductive skew
in relation to dominance rank reported in the rhesus macaque, a strictly seasonal species. We collected behavioral, genetic,
and hormonal data on one group of the free-ranging population on Cayo Santiago (Puerto Rico) for 2 years. The PoA correctly
predicted the steepness of male reproductive skew, but not its relationship to male dominance: the most successful sire, fathering
one third of the infants, was high but not top ranking. In contrast, mating success was not significantly skewed, suggesting
that other mechanisms than social status contributed to male reproductive success. Dominance may be less important for paternity
in rhesus macaques than in other primate species because it is reached through queuing rather than contest, leading to alpha
males not necessarily being the strongest or most attractive male. More work is needed to fully elucidate the mechanisms determining
paternity in rhesus macaques. 相似文献
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Gauri R. Pradhan Antje Engelhardt Carel P. van Schaik Dario Maestripieri 《Behavioral ecology and sociobiology》2006,59(3):333-343
Female copulation calls are mating-associated vocalizations that occur in some species of Old World monkeys and apes. We argue
that copulation calls have two immediate functions: to encourage mating attempts by other males and to increase mate guarding
by the consort male. We hypothesize that female copulation calls have evolved under the selective pressures of risk of infanticide
and sperm competition. When male mate guarding is effective, copulation calls allow females to concentrate paternity in dominant
males and benefit from their protection against the risk of infanticide. When mate guarding is ineffective, copulation calls
may bring genetic benefits to females through facilitation of sperm competition. We present a quantitative model in which
interspecific variation in females' promiscuity predicts their tendency to use copulation calls in conjunction with mating.
The model predicts that in species with little female promiscuity, copulation calls should be rare and exhibited only in association
with mating with dominant males. In species in which females are highly promiscuous, copulation calls should be frequent and
unrelated to male dominance rank. The limited data available to test the model support its main predictions as well as the
predicted relation between copulation calls and male dominance rank.
相似文献
Dario MaestripieriEmail: |