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1.
《Aquatic Botany》2005,82(2):121-131
Nutrient-use efficiency (NUE) within forests of the mangroves Rhizophora stylosa and Avicennia marina was estimated in arid Western Australia using litter fall rates and rates of leaf CO2 exchange. Litter fall rates ranged from 9.8 to 34.4 t DW ha−1 y−1 but equated to only 13–41% (mean = 30%) of net canopy primary production. Foliar N:P ratios were in most instances ≥16, suggesting P limitation. NUE for N based on litter fall rates were significantly less (NUEL = 167–322 g DW g−1 N) than those based on photosynthesis measurements (NUEP = 234–448 g DW g−1 N), suggesting that NUE estimates for nitrogen based on litter fall data are underestimates. NUEP estimates for N were significantly greater for R. stylosa than for A. marina. NUE for P were not significantly different, with NUEL ranging from 2905 to 5053 g DW g−1 P and NUEP ranging from 1632 to 4992 g DW g−1 P. Both sets of NUE are at the higher end of the range of estimates calculated for most other forests and equivalent to those for wet tropical mangroves. These arid-zone trees live in low-nutrient habitats, but it appears that selection on components of NUE (i.e. traits that reduce nutrient loss) rather than on NUE itself equates to a lack of clear patterns in NUE between different environments, emphasizing the flexible nature of nutrient allocation in woody plants. NUE in R. stylosa correlated inversely with mature leaf N and P content, implying that NUE in this species is maximized by the synthesis of low-nutrient leaves, i.e. a nutrient retention strategy, whereas such does not appear to be the case for A. marina. This strategy translates into a direct advantage in terms of net primary productivity for R. stylosa. This idea is supported by evidence of longer nutrient residence times for R. stylosa than for A. marina.  相似文献   

2.
Marine eutrophication refers to an ecosystem response to the loading of nutrients, typically nitrogen (N), to coastal waters where several impacts may occur. The increase of planktonic growth due to N-enrichment fuels the organic carbon cycles and may lead to excessive oxygen depletion in benthic waters. Such hypoxic conditions may cause severe effects on exposed ecological communities. The biologic processes that determine production, sink, and aerobic respiration of organic material, as a function of available N, are coupled with the sensitivity of demersal species to hypoxia to derive an indicator of the Ecosystem Response (ER) to N-uptake. The loss of species richness expressed by the ER is further modelled to a marine eutrophication Ecosystem Damage (meED) indicator, as an absolute metric of time integrated number of species disappeared (species yr), by applying a newly-proposed and spatially-explicit factor based on species density (SD). The meED indicator is calculated for 66 Large Marine Ecosystems and ranges from 1.6 × 10−12 species kgN−1 in the Central Arctic Ocean, to 4.8 × 10−8 species kgN−1 in the Northeast U.S. Continental Shelf. The spatially explicit SDs contribute to the environmental relevance of meED scores and to the harmonisation of marine eutrophication impacts with other ecosystem-damage Life Cycle Impact Assessment (LCIA) indicators. The novel features improve current methodologies and support the adoption of the meED indicator in LCIA for the characterization of anthropogenic-N emissions and thus contributing to the sustainability assessment of human activities.  相似文献   

3.
A combination of agro-environmental indicators and energy analysis of a production system, such as vineyards located in Natura 2000 sites, for which little is known, may be a useful tool to decide best farm management practices with low greenhouse gas emissions. In randomly selected vineyards at six sites of Natura 2000 network in Cyprus, we evaluated the energy flow and the greenhouse gas emissions. Hierarchical cluster analysis using production coefficients and a topographic variable (altitude) was used to detect clusters of the studied vineyards. Three groups were revealed. Group 1 (eight vineyards) with the lowest energy inputs, followed by Group 2 (three vineyards) with intermediate inputs and Group 3 (three vineyards) with the highest energy inputs. Altitude, fertilizers, labour, fuel and transportation had the greatest contribution on cluster formation. Non-parametric comparisons concerning 28 indicators showed that ten indicators (total energy inputs, renewable and non-renewable energy inputs, fruit energy outputs, shoot energy outputs, total energy outputs, fruit production, CO2, CH4, and N2O) were significantly higher in high energy input vineyards (Group 3) and three (energy use for renewable inputs, energy productivity and energy fruit efficiency) in low energy input vineyards (Group 1). Five indicators (energy use for fuel, transportation and non-renewable inputs, and energy efficiency for (shoot + fruit) outputs and renewable energy inputs) were significantly lower in Group 3 and two (intensity and non-renewable energy consumption) in Group 1. Similarities and/or dissimilarities among vineyards in Natura 2000 sites were related to altitude, production coefficients and local farming practices. These mixed results stress the importance of taking both local management indicators and vineyard topography into consideration when developing future agri-environment schemes, and suggest that local–regional interactions may affect Natura 2000 sites services and functions. It is important that EU agricultural policies are complemented by national–regional interventions in order to regulate the fragile balance between Natura 2000 sites and agriculture, reducing non-renewable energy inputs as percent of total energy inputs.  相似文献   

4.
Changes in the ratio of volatile N to non-volatile specific minerals or total ash in manure can potentially be used to estimate losses of N from manure. The aim of this study was to evaluate the accuracy of using specific minerals (P, K, Ca, Mg, and Na) or total ash as markers to estimate volatile N losses from incubated manure slurries. Holstein cows were fed diets with the forage as predominantly corn silage (CS) or alfalfa silage (AS) or a diet identical to the CS diet except 5 g/kg urea was added (CSU). Total output of urine and feces were measured and used to prepare two types of slurry mixtures (all slurry mixtures contained 1200 g of manure per tray): (1) as excreted (AsEx) and (2) AsEx + sand (SAND). The SAND slurry was designed to mimic manure from barns that used sand as a bedding material. Feces and urine were mixed in the same proportion as excreted by the cows for both slurry types and 240 g of sand were added to the SAND slurries. Initial and final (3 d incubation period) slurry weights and concentrations of N, ash, and specific minerals were measured to calculate loss of volatile N. Losses of volatile N from the slurries were estimated as: (N intake ? N milk) ? [N/ash × (ash intake ? ash milk)], where N and ash intake = g/d consumed by the cow; N and ash milk = g/d secreted in milk; and N/ash = ratio of N and ash concentrations in slurry samples at 3 d. To evaluate specific minerals as markers, the same equation was used except that Ca, K, Mg, Na or P replaced the ash term. Measured N losses from the AsEx slurries were 0.44, 0.62, and 1.03 g/3 d for the AS, CS, and CSU treatments and estimated N losses (using N/ash) were 0.29, 0.49, and 1.14 g/3 d. Estimated losses were less than measured losses for cows with negative N balance and greater than measured losses for cows in positive N balance. For AsEx slurries, the use of N to specific mineral ratios was generally less accurate than using the N/ash ratio. Estimated N losses from SAND slurries were extremely inaccurate for all markers. The use of the N/ash ratio to estimate N volatilization from manure shows promise but markers that are in appreciable concentrations in bedding material will not be accurate.  相似文献   

5.
It is expected that the CO2 concentration of the Earth’s atmosphere will reach 600–1000 ppm by the end of the 21st century. Therefore, in this study, we evaluated the effects of elevated CO2 concentrations on the development of rain-fed spring wheat in an attempt to identify a practical pathway to increase crop production. To accomplish this, a field experiment was conducted at Guyuan Experimental Station in a semiarid region of China during 2005–2007. During this experiment, the CO2 concentration was increased to 40.0 ppm and supplemental irrigation and nitrogenous fertilizer (N fertilizer) were applied. The experimental results showed that the elevated CO2 concentration significantly improved the thousand-grain weight and the grain number per spike. Furthermore, supplemental irrigation and N fertilizer application during the elongation and booting stage of rain-fed spring wheat in conjunction with an elevated CO2 concentration improved the water use efficiency (WUE), nitrogen use efficiency (NUE), thousand-grain weight, and the yield by 14.6%, 39.6%, 9.3%, and 14.7%, respectively, when compared to groups subjected to the same treatment but not grown under elevated CO2 concentrations. Furthermore, the spring wheat yield was improved by 81.8% in response to an elevated CO2 concentration, 60 mm of supplemental irrigation and applied N fertilizer (37.5 g m?2 NH4NO3). However, the presence of an elevated CO2 concentration without supplemental irrigation and N fertilizer only resulted in an increase in the wheat yield of 7.8%. Consequently, the combination of elevated CO2 concentration, supplemental irrigation and N fertilizer application played an important role in the improvement of WUE, NUE, thousand-grain weight, and grain yield of rain-fed spring wheat in this region.  相似文献   

6.
Dairy production across the world contributes to environmental impacts such as eutrophication, acidification, loss of biodiversity, and use of resources, such as land, fossil energy and water. Benchmarking the environmental performance of farms can help to reduce these environmental impacts and improve resource use efficiency. Indicators to quantify and benchmark environmental performances are generally derived from a nutrient balance (NB) or a life cycle assessment (LCA). An NB is relatively easy to quantify, whereas an LCA provides more detailed insight into the type of losses and associated environmental impacts. In this study, we explored correlations between NB and LCA indicators, in order to identify an effective set of indicators that can be used as a proxy for benchmarking the environmental performance of dairy farms. We selected 55 specialised dairy farms from western European countries and determined their environmental performance based on eight commonly used NB and LCA indicators from cradle-to-farm gate. Indicators included N surplus, P surplus, land use, fossil energy use, global warming potential (GWP), acidification potential (AP), freshwater eutrophication potential (FEP) and marine eutrophication potential (MEP) for 2010. All indicators are expressed per kg of fat-and-protein-corrected milk. Pearson and Spearman Rho’s correlation analyses were performed to determine the correlations between the indicators. Subsequently, multiple regression and canonical correlation analyses were performed to select the set of indicators to be used as a proxy. Results show that the set of selected indicator, including N surplus, P surplus, energy use and land use, is strongly correlated with the eliminated set of indicators, including FEP (r = 0.95), MEP (r = 0.91), GWP (r = 0. 83) and AP (r = 0.79). The canonical correlation between the two sets is high as well (r = 0.97). Therefore, N surplus, P surplus, energy use and land use can be used as a proxy to benchmark the environmental performance of dairy farms, also representing GWP, AP, FEP and MEP. The set of selected indicators can be monitored and collected in a time and cost-effective way, and can be interpreted easily by decision makers. Other important environmental impacts, such as biodiversity and water use, however, should not be overlooked.  相似文献   

7.
Nitrogen (N) losses from agriculture are negatively impacting groundwater, air, and surface water quality. New tools are needed to quickly assess these losses and provide nutrient managers and conservationists with effective tools to assess the effects of current and alternative management practices on N loss pathways. A new N-Index tool was developed in spreadsheet format, allowing prompt assessments of management practices on agricultural N losses. The N-Index tool was compared with experimental field data and shown to estimate the effects of management practices on N loss pathways (probability, P < 0.001). The N-Index correctly assessed the nitrate nitrogen (NO3-N) leaching losses when tested against measured NO3-N leaching data and atmospheric N losses collected over multiple years (annual basis) and locations. The N-Index tool was developed with international cooperation from several countries and there is potential to use this tool at the international level.  相似文献   

8.
Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities.  相似文献   

9.
Regionally mandated budgets often ignore important sub-regional differences. To help identify hot-spots, where environmental pressures and agricultural activities combine and heighten the need to optimise farming strategies, we recommend using detailed spatial target analysis.In this paper, we propose a methodology for identifying different agro-environments, test that method in a case-study territory in the western Po River plain (the largest and most intensive agricultural area in Italy), and then calculate the nutrient budget indicators of these defined agro-environments as a means to assess environmental sustainability.We identified five Macro Land Units (MLUs) representing five different agro-environments from official datasets and territorial surveys, detected and quantified land use, crop productivity, and fertilisation management in these MLUs, and calculated nutrient budgets according to the IRENA European methodology. As expected, the highest nutrient surpluses (103, 39, and 95 kg ha?1 for N, P, and K, respectively) were detected in the most intensely managed area. N surpluses were attributed to excess mineral inputs and P surpluses to excess organic inputs. At the territorial scale, the manure N load was far below the 170 kg ha?1 threshold; at the crop scale, maize showed the least-optimised fertilisation management.This work suggests that GIS-based analysis of environmental pressures of agricultural activities at a sub-regional level is useful for identifying areas and crops for which fertilization must be well managed. The proposed methodology depends on accurate collection and collation of farm data into GIS databases; public authorities should promote investment in planning and managing data collection in agriculture.  相似文献   

10.
Avian influenza (AI) is a respiratory disease complex syndrome recently recorded in vaccinated flocks causing high economic losses. This study aimed to prepare inactivated vaccine from recently isolated field strains [highly pathogenic avian influenza (HPAI) (H5N8) and low pathogenic avian influenza (LPAI) (H9N2)] and compare the efficiency of the two experimental avian influenza vaccines and some commercial avian influenza H5 and H9N2 vaccines in laying hens. The obtained results indicated that the identified experimental vaccines (H5N8 and H9N2) were protected the flocks from AI as compared to commercial H5N1, H5N3, and H9N2 vaccines, which showed a protection level of 80, 70, and 90%, respectively, indicating a high efficacy for the developed vaccines. In addition, it significantly improved the virus shedding, especially when used in booster dose. The experimental vaccines were given high antibody titer higher than commercial vaccine which was reached to 9.3 log2, 9.7log2 for experimental H5N8 vaccine which was significantly higher than and groups 3 and 4 especially at 2nd WPV, while at the 3rd WPV, the significant difference was with group 4 only. The HI titer was 9.3 log2 at 2nd WPV for the experimental H9N2 vaccine that was significantly higher than group 9. In conclusion, the booster dose of the experimental vaccines could elicit strong immunity than single-dose and commercial vaccines.  相似文献   

11.
《Process Biochemistry》2007,42(2):275-278
Gray mold caused by Botrytis cinerea is an important disease of strawberry. Clonostachys rosea is a mycoparasite of B. cinerea that reduces fruit losses when used as a biocontrol agent. Since spore production by C. rosea has not been optimized, we investigated factors affecting sporulation under aseptic conditions on white rice grains. The greatest spore production in glass flasks, 3.4 × 109 spores/g-dry-matter (gDM), occurred with an initial moisture content of 46% (w/w wet basis), inoculated with 1 × 106 spores/gDM and hand shaken every 15 days. However, a lower inoculum density (9 × 103 spores/gDM) and no shaking also gave acceptable sporulation. In plastic bags 1.1 × 108 spores/gDM were produced in 15 days, suggesting that larger scale production may be feasible: with this spore content, 24 m2 of incubator space would produce sufficient spores for the continued treatment of 1 ha of strawberry plants.  相似文献   

12.
Sustainability indicator systems often use administrative entities as a reference, which may cause over- or underestimations of results within topographically different regions. Within the European Alps the highest impacts due to human activities are concentrated below the potential treeline, making these zones comparable to the potentially highly impacted surroundings of the European Alps. An application of the area below the potential treeline as a reference unit for sustainability indicators allows for a more equitable comparison of the European Alps and their surroundings. Therefore, we first developed a method for the identification of the potential treeline in the European Alps. In a second step we tested the zones below the potential treeline as a reference unit for landscape indicators.In order to obtain the position of the potential treeline, initially the highest forest areas within 7 transects throughout the Alps were identified using Corine land cover and a DEM. The correlation among the highest 10% of forest occurring within each transect was then represented by means of a polynomial regression. The resulting 7 polynomial functions were applied to the European Alps within 5 × 5 km raster-cells, thus ascertaining the potential treeline. For testing the zones below the potential treeline as a reference unit for landscape indicators we selected a set of 9 landscape indicators, calculating them for 5936 Alpine municipalities.The potential treeline ascertained is able to represent the real potential treeline at a regional scale. The mean altitudes of the defined potential treeline are 2000 m at the Alpine margin, and 2200–2350 m in the central regions of the European Alps. While in the inner-Alpine regions the actual treeline is on average situated about 350–400 m below the potential treeline, the difference is much smaller in the Alpine fringe. Identifying the difference between the potential and the actual treeline allows for the first time an assessment of the intensity of human impact in formerly forested mountain areas. The statistical analysis of the indicator results revealed strong differences among the results, with the difference increasing from the Alpine margin to inner-Alpine regions. We conclude that indicators referring to municipal areas below the potential treeline allow for a more equitable comparison of topographically different regions. Furthermore, such indicators provide detailed information of those zones within the European Alps that are subject to the highest impact due to human activities, which is of prime importance for local decision-making processes.  相似文献   

13.
Proton (H+ ion) budgets were calculated for 17 forested sites in Europe using open field (bulk) and throughfall deposition and runoff or soil leachate data. Proton budgets integrate information about the complex chemical and biological processes that govern the generation or consumption of acidity in the ecosystem into a single parameter. The sites belong to the multidisciplinary ICP integrated monitoring network, set up to assess the environmental impacts of transboundary air pollution. Mean annual H+ budgets were estimated to quantify the relative importance of different biogeochemical processes, with special emphasis on the N deposition. N deposition exceeded S deposition on an equivalent basis at the studied sites. Model based estimates for quantifying the impact of agreed international emission reduction measures showed that the relative importance of N deposition still is likely to increase in the future. Base cation weathering and ion exchange were the main processes for proton consumption. Sites on base poor soil material showed low base cation fluxes, export of acidity and high external/internal H+ source ratios. At these sites the dissociation of organic acids was commonly a significant internal H+ source. Depending on deposition inputs, the importance of N processes on the H+ budget varied between −4.5 mequiv. m−2 a−1 (small H+ consumption) and 46.2 mequiv. m−2 a−1 (H+ production). A relationship between the deposition inputs and the H+ production from N transformations was also observed, with higher H+ production at higher deposition levels. Net release of sulphate (and associated H+ production) was observed at many sites, being consistent with observations from other recent European budget studies.  相似文献   

14.
Globally human pressure on the biosphere is increasing, in spite of increases in land use efficiency. The pressure consists of land use and potential degradation. Human appropriation of net primary production (HANPP) is emerging as an indicator, which combines the dual aspects of biomass use and land degradation. Recently HANPP has been used to map the increasing dependence of European countries on biomass imports and the conflicting processes of increased yields and increased consumption. However large overview studies could be complemented with indepth analysis into the causes of changes in individual countries and economic sectors. This allows the analysis of the macroeconomic drivers of change and the responses in sectors to these drivers. In this study we decomposed the HANPP of Finland including imports for the years 2000–2010 using IPAT and applied input-output analysis to look at sectoral land use efficiency in that time period. Finland is a country with intensive biomass trade, and with a very high per capita HANPP. During the study period the sum of domestic and embodied in imports HANPP of the Finnish economy decreased from 76 Mt C/a to 62 Mt C/a (−1% annually on average), while the HANPP related to imports increased from 12 Mt C/a to 14 Mt C/a. The overall trend was that of declining exports and increasing domestic consumption. Of the economic sectors wood harvesting and processing dominated HANPP results, followed by residential construction, animal production and energy supply. In terms of HANPP, most of these decreased, but housing and energy production increased considerably from 2002 to 2010. At the macroeconomic level domestic biomass use per unit of value added decreased (−2.2%/a) as did the amount of HANPP per unit of biomass (−1.1%/a) reflecting increased economic efficiency in land use. In contrast, GDP/capita (+1.3%/a), population (+0.4%) and the share of outsourced HANPP (+0.6%) resulted in increased consumption-based HANPP (from 21 Mt C in 2002 to 27 Mt C in 2010). Our results underline the importance of including international trade and consumption in interpreting overall change in regional HANPP.  相似文献   

15.
Riparian zones are central landscape features providing several ecosystem services and are exceptionally rich in biodiversity. Despite their relatively low area coverage, riparian zones consequently represent a major concern for land and water resource managers confirmed within several European directives. These directives involve effective multi-scale monitoring to assess their conditions and their ability to carry out their functions. The objective of this research was to develop automated tools to provide from a single aerial LiDAR dataset new mapping tools and keystone riparian zone attributes assessing the ecological integrity of the riparian zone at a network scale (24 km).Different metrics were extracted from the original LiDAR point cloud, notably the Digital Terrain Model and Canopy Height Model rasters, allowing the extraction of riparian zones attributes such as the wetted channel (0.89 m; mean residual) and floodplain extents (6.02 m; mean residual). Different riparian forest characteristics were directly extracted from these layers (patch extent, overhanging character, longitudinal continuity, relative water level, mean and relative standard deviation of tree height). Within the riparian forest, the coniferous stands were distinguished from deciduous and isolated trees, with high accuracy (87.3%, Kappa index).Going further the mapping of the indicators, our study proposed an original approach to study the riparian zone attributes within different buffer width, from local scale (50 m long channel axis reach) to a network scale (ca. 2 km long reaches), using a disaggregation/re-agraggation process. This novel approach, combined to graphical presentations of the results allow natural resource managers to visualise the variation of upstream–downstream attributes and to identify priority action areas.In the case study, results showed a general decrease of the riparian forests when the river crosses built-up areas. They also highlighted the lower flooding frequency of riparian forest patches in habitats areas.Those results showed that LiDAR data can be used to extract indicators of ecological integrity of riparian zones in temperate climate zone. They will enable the assessment of the ecological integrity of riparian zones to be undertaken at the regional scale (13,000 km, completely covered by an aerial LIDAR survey in 2014).  相似文献   

16.
Several biodiversity features can be linked to landscape heterogeneity, that, in turn, can be informative for management and conservation purposes. Usually, the more the landscape is complex the more the biodiversity increases. Biodiversity indicators can be a useful tool to assess biodiversity status, in function of landscape heterogeneity. In this study, we developed a biodiversity indicator, based on Shannon diversity index and built from distribution maps of protected species. With such an approach, we seek to evaluate the feasibility of using a combination of target species as a surrogate for assessing the status of the whole bird community. Our approach was spread over multiple spatial scales, to determine which was the most informative. We selected four species protected by European regulation and generated a presence-absence map from species distribution modelling. We, therefore, used the FRAGSTATS biodiversity metric to calculate Shannon index for the overlapped presence-absence maps, at two spatial scales (500 m and 1000 m). Then, the relationships with the whole community was assessed through generalised least square models, at the spatial scale of 4 ha, 9 ha and 25 ha. Results showed that the higher rate of variability of community was explained by the biodiversity indicator at 1000 m scale. Indeed, the more informative spatial scale for the whole bird community was 9 ha. In addition, a pattern emerged about the relationships between biodiversity indicator and community richness, that is worth of further research. Our study demonstrates that the usefulness of surrogate species for biodiversity and community assessment can become clear only at a certain spatial scales. Indeed, they can be highly predictive of the whole community, and highly informative for conservation planning. Moreover, their use can optimize biodiversity monitoring and conservation, focusing on a small number of noteworthy species.  相似文献   

17.
《Process Biochemistry》2014,49(12):2199-2202
The oxygenic photosynthetic prokaryotes cyanobacteria have recently attracted worldwide interest in production of biofuels and bioactive natural compounds. Disruption of cells is a prerequisite for extraction of intracellular compounds. However, cyanobacterial cells are difficult to be disrupted because of the multiple-layered cell walls covered with a mucilaginous sheath. Here, we report a new disruption method for cyanobacteria, where an abrasive material, silicon carbide, is ground with cell pellet in situ. A cell disruption efficiency of 93.3 ± 2.3% was achieved in 6 min, an efficiency comparable to that obtained after 30 min of sonication. The new method yielded crude cell extracts with high concentrations of protein and high activity of the target enzyme, d-lactate dehydrogenase. This method has potential to be used for disruption of cells of photosynthetic microorganisms on a larger scale.  相似文献   

18.
Maintaining nitrogen retention efficiency (NRE) is crucial in minimizing N losses when intensifying management of temperate grasslands. Our aim was to evaluate how grassland management practices and sward compositions affect NRE (1  N losses/soil available N), defined as the efficiency with which soil available N is retained in an ecosystem. A three-factorial grassland management experiment was established with two fertilization treatments (without and combined N, phosphorus and potassium fertilization), two mowing frequencies (cut once and thrice per year) and three sward compositions (control, monocot- and dicot-enhanced swards). We measured N losses as leaching and nitrous oxide emissions, and soil available N as gross N mineralization rates. Fertilization increased N losses due to increased nitrification and decreased microbial N immobilization, and consequently decreased NRE. Intensive mowing partly dampened high N losses following fertilization. Sward compositions influenced NRE but not N losses: control swards that developed for decades under extensive management had the highest NRE, whereas monocot-enhanced sward had the lowest NRE. NRE was highly correlated with microbial NH4+ immobilization and microbial biomass and only marginally correlated with plant N uptake, underlining the importance of microbial N retention in the soil-plant system. Microbial N retention is reflected in NRE but not in indices commonly used to reflect plant response. NRE was able to capture the effects of sward composition and fertilization whereas N losses were only sensitive to fertilization; thus, NRE is a better index when evaluating environmental sustainability of sward compositions and management practices of grasslands.  相似文献   

19.
An animal expresses its physiological and well-being status by its behaviour. Changes in behaviour can be associated with health, production or well-being problems and therefore with the profitability of the farm. The objectives of the present study were to analyse lying patterns of healthy cows, collected with a commercial behaviour sensor, in early lactation in relation to environmental conditions, age of the cow and production performance. In future, these results may be used as a ‘baseline’ for detection of alterations in behaviour that indicate health problems. The study involved 210 healthy multiparous Israeli Holstein cows in three commercial dairy farms. Only healthy cows during the first 28 days after calving were included in this study. Data were analysed in relation to calving season, age of cows and correlation between milk production and lying time.The results show that lying time increased significantly with age and is significantly (P < 0.05) higher in winter than in summer (summer lactation 2: 491 ± 17 min/day (mean ± SD), summer lactation 3 and more: 520 ± 25 min/day, winter lactation 2: 531 ± 25 min/day, winter lactation 3 and more: 579 ± 38 min/day).The proportion of positively and negatively milk production and lying time correlated cows is affected by calving season.This study indicates that behaviour variables in early lactation are affected by calving season, lactation number and type of correlation between milk production and lying time.  相似文献   

20.
The aim of this study was to present a new methodology for evaluating the pelvic floor muscle (PFM) passive properties. The properties were assessed in 13 continent women using an intra-vaginal dynamometric speculum and EMG (to ensure the subjects were relaxed) in four different conditions: (1) forces recorded at minimal aperture (initial passive resistance); (2) passive resistance at maximal aperture; (3) forces and passive elastic stiffness (PES) evaluated during five lengthening and shortening cycles; and (4) percentage loss of resistance after 1 min of sustained stretch. The PFMs and surrounding tissues were stretched, at constant speed, by increasing the vaginal antero-posterior diameter; different apertures were considered. Hysteresis was also calculated. The procedure was deemed acceptable by all participants. The median passive forces recorded ranged from 0.54 N (interquartile range 1.52) for minimal aperture to 8.45 N (interquartile range 7.10) for maximal aperture while the corresponding median PES values were 0.17 N/mm (interquartile range 0.28) and 0.67 N/mm (interquartile range 0.60). Median hysteresis was 17.24 N1mm (interquartile range 35.60) and the median percentage of force losses was 11.17% (interquartile range 13.33). This original approach to evaluating the PFM passive properties is very promising for providing better insight into the patho-physiology of stress urinary incontinence and pinpointing conservative treatment mechanisms.  相似文献   

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