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Helena Kahiluoto Elise Ketoja Mauritz Vestberg 《Agriculture, ecosystems & environment》2009,134(1-2):36-45
The aim of this study was to determine how the potential to rely on arbuscular mycorrhiza (AM) for plant nutrition differs between a conventional and a low-input cropping system in the long term. The roles of fertilisation rate, composting of recycled plant residues and stage of the rotations in the overall impact of the cropping systems on soil quality and AM were also identified. The conventional cropping system with a non-leguminous crop rotation (barley–barley–rye–oat–potato–oat) was fertilised at either full or half the recommended rate. In the low-input cropping system, one year with barley was replaced by clover, and oat was cultivated mixed with pea. Straw and clover were returned to the soil either with or without composting. In the low-input system, biotite and rock phosphate were used to compensate for K and P in the harvested yield, while animal manure was applied at the start only. After 15 years, crop growth and nutrition, AMF colonisation and soil quality were assessed in the field, while the AM contribution to growth and nutrient uptake were determined in a bioassay in a growth chamber. AM functioning made a higher contribution to soil quality in terms of crop performance and environmental benefits in the low-input cropping system than at either fertilisation rate in the conventional system. Halving fertilisation in the conventional system prevented some costs and enhanced some of the benefits of AM in comparison with full fertilisation. However, only the low-input system with composting conclusively favoured AM in comparison with the conventional system. It resulted in the highest percentage colonisation and, in a bioassay with flax and clover, gave a relative average contribution to growth of 27% and to P uptake of 68% in comparison with 4 and 36%, respectively, for the conventional cropping system with full fertilisation. Rye yield was in the low-input system without composting similar to that in the conventional system with full fertilisation, and with composting 87% of the latter one. Incorporation of clover green manure without composting inhibited AM functioning, leading to a temporary loss of AM contribution to crop performance. This effect draws attention to the impact of the form of recycled organic matter on supporting ecosystem services such as nutrient cycling. 相似文献
254.
The concept of animal welfare refersto the animal's quality of life. The choice ofdefinition always reflects some basicvaluation. This makes a particular conceptionof welfare value-dependent. Also, the animalhusbandry system reflects certain values oraims. The values reflected in the chosenconception of animal welfare ought tocorrespond to values aimed for in the husbandrysystem. The IFOAM Basic Standards and otherwritings dealing with organic animal husbandryshould be taken as a departure point for adiscussion of how to interpret the conceptionof welfare in organic farming systems. Theconception of welfare is related to two corevalues in the organic agriculture movement.These core values should be considered in termsof (1) aim for holistic view and (2) aim forsustainability. A third, implicit core value,based on bio- and ecocentric views: (3) respectfor nature is needed as a supplement to thesetwo core values. There are importantimplications of these core values for an``organic' conception of animal welfare and forconfronting two dilemmas due to conflictinginterests. Comparisons among the three commonlyused welfare definitions will show thesuperiority of the third approach, which canprovide an outline for a conception of animalwelfare more suitable for organic farmingsystems. This outline combines a holisticecocentric approach with respect for theindividual animal, and it can be used as thebasis for a complex definition with emphasis onnatural behavior. Such a systemic approachconsiders welfare in relation to differentsystemic levels. The systemic view also offerspossibilities for resolving the dilemmas in newways. 相似文献
255.
The Wadden Sea is an important habitat for harbour seals and grey seals. They regularly haul-out on sandbanks and islands
along the coast. Comparably little is known about the time seals spend at sea and how they use the remainder of the North
Sea. Yet, human activity in offshore waters is increasing and information on seal distribution in the North Sea is crucial
for conservation and management. Aerial line transect surveys were conducted in the German bight from 2002 to 2007 to investigate
the distribution and abundance of marine mammals. Distance sampling methodology was combined with density surface modelling
for a spatially explicit analysis of seal distribution in the German North Sea. Depth and distance to coast were found to
be relevant predictor variables for seal density. Density surface modelling allowed for a depiction of seal distribution in
the study area as well as an abundance estimate. This is the first study to use aerial survey data to develop a density surface
model (DSM) for a spatially explicit distribution estimate of seals at sea.
相似文献
Helena HerrEmail: |
256.
A new heterogeneous photocatalyst was prepared by oxidative polymerization of the thiophene with ferric chloride in the ZSM-5 zeolite type. The synthesized polythiophene absorbs radiation in the visible range of the electromagnetic spectrum and by illumination with visible light generates reactive oxygen species (ROS) in water medium. During illumination reactive hydroxyl radical was detected by the spin trapping EPR method. Efficiency of the photocatalyst was tested on the killing of Gram-positive bacteria Staphylococcus aureus and Gram negative bacteria Escherichia coli. 相似文献
257.
João Porteiro Helena Calado Margarida Pereira Adriano Quintela Tomáz Dentinho 《国际发展与全球生态学杂志》2013,20(2):192-200
The Sete Cidades Lake (437 ha) is located in a volcanic crater of São Miguel Island (Azores). The watershed is 1923 ha, and 25% of it is covered with water. Extreme logging and the use of fertilizers in the cattle grazing areas have caused sedimentation and eutrophication of the main water body (Carlson Trophic State Index TSI = 40–50 mesoeutrophy). To deal with the issue, a linear programming model was created to generate efficient land-use scenarios for different amounts of phosphorus release. The model was calibrated for the present situation and then simulated to obtain 29 scenarios. It allowed us to derive parameters for each scenario. Then a multiobjective program was used to derive an acceptable weight for each indicator. The dominant solutions were discovered and discussed with different stakeholders. 相似文献
258.
Geospatial analysis of vulnerable beach-foredune systems from decadal time series of lidar data 总被引:1,自引:0,他引:1
Helena Mitasova Eric Hardin Margery F. Overton Mustafa Onur Kurum 《Journal of Coastal Conservation》2010,14(3):161-172
Time series of lidar data, acquired over the past decade along the North American East Coast, provide opportunities to gain
new insights into 3D evolution of barrier islands and their beach and dune systems. GIS-based per grid cell statistics and
map algebra was applied to time series of Digital Surface Models representing two sections of North Carolina barrier islands
to quantify elevation change trends, map dynamic and stable locations, identify new and lost buildings, measure relative volume
evolution in the beach and foredune systems and analyze shoreline dynamics. Results show a relatively small stable core in
both study areas, with beaches and the ocean side of the dunes exhibiting systematic high rates of elevation loss while areas
landward from the dunes increase slightly in elevation. Significant number of new homes have been built at locations with
very small core surface elevation, and homes built within the shoreline dynamics band have already been lost. The raster-based
methodology used in this study can be applied to perform similar analyses in other coastal areas where time series of lidar
data are available. 相似文献
259.
PROBLEM: Suicide is a dominating, although hidden, safety problem on Swedish railroads. The aim of this paper is to describe the epidemiology of fatal train-person collisions as a basis for systems-oriented prevention. METHOD: Data on collision circumstances were collected from narrative reports at the Swedish National Rail Administration. RESULTS: The events were evenly distributed by months and weekdays, however, most suicides occur during the day while unintentional events usually occur at night. Most train-person collisions happened in densely populated areas, and 75% of the suicide victims were waiting on the track before the collision. Significance test between types of injury event (suicide, accident, or unknown intent) showed small or no differences. CONCLUSION: Traditional approaches to accident prevention by systems modification seem largely applicable to combat railroad suicide as well. IMPACT ON INDUSTRY: Our findings show promising preventive potentials. 相似文献
260.