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261.
Sven Kullander 《Ambio》2010,39(3):249-256
Humankind is currently faced with the huge challenge of securing a sustainable energy supply and biofuels constitute one of
the major options. However, the commercially traded edible crops are barely sufficient to meet food demand of the present
world population. Certain regions, for example EU-27, do not even have a sufficient indigenous crop production. Of this follows
that motor biofuels based on edible crops should be avoided. To replace more than some percent of the fossil motor fuels,
non-edible biomass—rest products and wastes—should instead be considered for conversion to biofuels. In this way, about 10%
of the current fossil fuels can be replaced. Feeding a world population expected to grow by some 50% during the next 50 years
will be a major challenge. For environmental reasons it seems that agricultural land cannot be expanded very much, maybe not
at all. The solution to the increasing food demand seems therefore to be using the present crop production more efficiently
and increasing output from present agricultural land, maintaining biodiversity and climate stability within reasonable limits.
In the future, agriculture will need more energy and more water irrigation. Food production is, however, already very energy
demanding, requiring several times more externally provided energy than the energy content of the food itself. A sufficient
energy supply will be a key issue for the future farming! 相似文献
262.
Ove C. Mφrck Jens O. Hansen 《生态毒理学报》2001,23(3):16-17
MEDUCA(教育性建筑模式)项目包括7个国家的8个示范项目.这些项目分布在挪威的格龙(65°);瑞典的哥德堡(58°N);瑞典的Falkenberg(57°N);丹麦的巴勒鲁普(56°N);德国的新明斯特(54°N);西班牙的阿尔梅里亚(36°50'N);意大利的Bagheria(38°N);和希腊的Legraina(38°N). 相似文献
263.
At the inter-specific level, per offspring investment (POI), degree of abbreviated development, and lecithotrophic potential all increase with increasing latitude and freshwater penetration among crustaceans. These traits are considered adaptations to conditions of decreasing growth potential. We hypothesise that this relationship between POI and abbreviated development also occurs at the intra-specific level. We studied the caridean shrimp, Palaemonetes varians, to investigate the hypothesis that under food-limited conditions, higher POI enables development through fewer larval instars. Under starvation stress, larvae from broods of greater POI (measured as hatchling brood average dry weight, DW) generally developed through fewer larval instars. With increasing starvation period, larval development time increased, whilst larval growth rate, juvenile DW, juvenile carbon mass, and juvenile carbon:nitrogen (C:N) ratio all decreased. Larval development time generally decreased with increasing brood average dry weight. In contrast, larval growth rate, juvenile DW, juvenile carbon mass, and juvenile C:N ratio all increased with increasing larval brood average DW. The relationship between POI and larval instar number (abbreviation of development) reported here is consistent with that at the inter-specific level and supports the concept that macro-ecological trends in development modes at the inter-specific level may be driven by selection occurring on POI at the intra-specific level. 相似文献
264.
Sven R. Laming Sébastien Duperron Marina R. Cunha Sylvie M. Gaudron 《Marine Biology》2014,161(6):1319-1333
The Bathymodiolinae are pervasive in reducing environments in the deep sea, yet data on post-larval and juvenile development and on the process of symbiont acquisition remain elusive. To understand how these opportunistic metazoans survive in ephemeral reducing habitats, individuals of the small bathymodiolin, Idas modiolaeformis, were examined histologically to trace their reproductive development, and with fluorescence and transmission electron microscopy to identify patterns of infection by their environmentally acquired bacterial symbionts. A size series of these mussels was retrieved from larval colonisation devices containing vegetative substrates, deployed for 51 weeks (November 2006–2007) in the central ‘Pockmarks’ region (site 2A) of the Nile deep-sea fan in the eastern Mediterranean (NDSF), a zone where methane seepage can occur (N 32° 31.97, E 30° 21.18, 1,693 m deep). Developmental patterns of germ cell migration, size at first maturity, and symbiont acquisition and localisation are presented for the post-larva to adult transition. The smallest mature adult was a male with shell length (SL) 2.35 mm. All larger individuals in the series were male (maximum SL 6.54 mm). Based on the absence of bacterial signals, plantigrades were asymbiotic, indicating strict heterotrophy in larvae and early post-larvae. During the early stages of dissoconch deposition, extracellular symbiont infection was non-specific. This was followed by increasing specificity on non-ciliated gill epithelia in adults. These observations on early development in I. modiolaeformis represent evolutionary adaptations to their ephemeral, reducing habitats. 相似文献
265.
The importance of preserving both protected areas and their surrounding landscapes as one of the major conservation strategies
for tigers has received attention over recent decades. However, the mechanism of how land-use surrounding protected areas
affects the dynamics of tiger populations is poorly understood. We developed Panthera Population Persistence (PPP)—an individual-based
model—to investigate the potential mechanism of the Sumatran tiger population dynamics in a protected area and under different
land-use scenarios surrounding the reserve. We tested three main landscape compositions (single, combined and real land-uses
of Tesso-Nilo National Park and its surrounding area) on the probability of and time to extinction of the Sumatran tiger over
20 years in Central Sumatra. The model successfully explains the mechanisms behind the population response of tigers under
different habitat landscape compositions. Feeding and mating behaviours of tigers are key factors, which determined population
persistence in a heterogeneous landscape. All single land-use scenarios resulted in tiger extinction but had a different probability
of extinction within 20 years. If tropical forest was combined with other land-use types, the probability of extinction was
smaller. The presence of agroforesty and logging concessions adjacent to protected areas encouraged the survival of tiger
populations. However, with the real land-use scenario of Tesso-Nilo National Park, tigers could not survive for more than
10 years. Promoting the practice of agroforestry systems surrounding the park is probably the most reasonable way to steer
land-use surrounding the Tesso-Nilo National Park to support tiger conservation. 相似文献
266.
The oxyfuel process is one of the most promising options to capture CO2 from coal fired power plants. The combustion takes place in an atmosphere of almost pure oxygen, delivered from an air separation unit (ASU), and recirculated flue gas. This provides a flue gas containing 80–90 vol% CO2 on a dry basis. Impurities are caused by the purity of the oxygen from the ASU, the combustion process and air ingress. Via liquefaction a CO2 stream with purity in the range from 85 to 99.5 vol% can be separated and stored geologically. Impurities like O2, NOX, SOX, and CO may negatively influence the transport infrastructure or the geological storage site by causing geochemical reactions. Therefore the maximum acceptable concentrations of the impurities in the separated CO2 stream must be defined regarding the requirements from transportation and storage. The main objective of the research project COORAL therefore is to define the required CO2 purity for capture and storage. 相似文献
267.
268.
269.
Management strategies to control invasive species need information about dispersal distances to predict establishment potential. Fraxinus pennsylvanica is a North American anemochorous tree species that is invasive in many Central European floodplain forests. To predict seed-dispersal potential, the stochastic model WaldStat was used, which enables different options for directionality (isotropic and anisotropic) to be simulated. In this article, we (1) show empirical results of fructification and seed dispersal for this tree species. The model predicts approximately 250,000 seeds for one F. pennsylvanica tree. These results were used to (2) calculate species-specific dispersal distances and effects of wind direction. To consider the influence of wind on dispersal potential of the tree species, long-distance dispersal (LDD [95th percentile dispersal distance]) was calculated. Mean dispersal distances varied between 47 and 66 m. LDD values modelled along the main wind direction ranged from 60 to 150 m. Seed production, dispersal distance, and direction data were (3) incorporated into theoretical management scenarios for forest ecosystems. Finally (4), we discuss management options and the practical relevance of model scenarios in relation to the accuracy of spatial dispersal predictions. Further analyses should be focused on possible, well-adapted management concepts at stand level that could restrict the potential spread of invasive species. 相似文献
270.
Within beetles, those species that are adapted to life on plants have developed widened tarsi with specialised hairy attachment
structures. The capability to adhere to smooth surfaces is based on a liquid film on the surface of these structures, the
composition of which is similar to the cuticular lipids. By means of a cluster analysis based on chemical similarities between
samples obtained from tarsi or elytra of 35 species using solid phase microextraction, the present study strongly suggests
that this chemical congruence is a principle in beetles. This supports the idea of tarsal liquids being part of the cuticular
lipid layer and contributes to the understanding of liquid-mediated attachment systems. 相似文献