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61.
Green infrastructure (GI) is a strategic planning instrument to achieve sustainable development. The main functions of GI are to protect biodiversity and safeguard and enhance the provision of ecosystem services (ES). In this paper we present the development of a semi-quantitative place-based method, aiming at assessing GI based on the provision potential of all main ES. Our method combines a wide spectrum of GIS data with expert assessments. Here we focus especially on how interaction with experts and local and regional actors impacted the method development. Our results showed that involving experts in dataset selection is very useful in compiling the most relevant data for the assessment of ES. Expert knowledge is also valuable in evaluating the actual coverage and quality of datasets. By involving both experts and local and regional actors in assessing ES provision potential we can add local knowledge to the general scientific understanding. Qualitative assessments can be complemented with quantitative data in our method. The resulting maps support land use planning, as they assist in identifying the multifunctional key areas of GI and in examining the provision potential of various ES. The group discussions involved in our method provided an additional benefit, as the experts and local and regional actors felt that this discussion platform enhanced their understanding of both GI and ES.  相似文献   
62.
In this study, 221 two‐year‐old hatchery‐reared salmon, Salmo salar, smolts were tagged with radio transmitters over a period of three consecutive years and released in the river in groups of 20–21 fish in various dates between late April and early June. Tagged smolts were tracked during their downstream migration in the lower 36‐km stretch of the regulated River Oulujoki, with the focus on the effects of release date, water temperature and river flow on migration behaviour and survival. The results indicate that release timing and river temperature have profound effects on the initiation of migration, swimming speed and survival of released S. salar smolts. Smolts released early in the spring in cold waters ceased migration after brief downstream movement and were vulnerable to predation, whereas the migration speed and survival rates increased markedly for smolts released later in the spring.  相似文献   
63.
Abstract – After release to the wild, captive reared salmon have shown lower foraging rates on natural prey and impaired ability to avoid natural predators and thus lower survival compared with wild‐born conspecifics. Here, we examine whether captive breeding influences learning of foraging on natural prey and how enriched rearing methods may improve foraging on natural prey by Atlantic salmon (Salmo salar) parr. We reared offspring of hatchery or wild salmon of the same population in either a standard or enriched environment at production‐scale densities. The enriched environment featured submerged overhead shelter, varying water current, depth and direction and consequently alterations in food dispersion. Parr reared in the enriched environment expressed higher feeding rates, and parr of wild origin started to forage earlier on natural prey. The enriched method promoted foraging of hatchery reared parr on natural prey and is easily applicable to commercial production of salmonids for reintroduction or stock enhancement purposes.  相似文献   
64.
Johne’s disease (JD) is a chronic enteric infection of cattle caused by Mycobacterium avium subsp. paratuberculosis (MAP). The high economic cost and potential zoonotic threat of JD have driven efforts to develop tools and approaches to effectively manage this disease within livestock herds. Efforts to control JD through traditional animal management practices are complicated by MAP’s ability to cause long-term environmental contamination as well as difficulties associated with diagnosis of JD in the pre-clinical stages. As such, there is particular emphasis on the development of an effective vaccine. This is a daunting challenge, in large part due to MAP’s ability to subvert protective host immune responses. Accordingly, there is a priority to understand MAP’s interaction with the bovine host: this may inform rational targets and approaches for therapeutic intervention. Here we review the early host defenses encountered by MAP and the strategies employed by the pathogen to avert or subvert these responses, during the critical period between ingestion and the establishment of persistent infection in macrophages.  相似文献   
65.
Rossi  Pekka 《New Forests》1999,18(2):161-177
The effect of length of cuttings, 10 to 50 cm long, on establishment and productivity of short-rotation plantations was investigated in five trials, for periods of 2 to 9 years. The trials were established on abandoned agricultural fields planted with unrooted Salix Aquatica cuttings. The effect of cutting length was very similar in all five trials: the longer the cuttings (up to 30–50 cm), the better the survival and growth. In most trials the greatest difference in survival was between cutting lengths of 10 and 20 cm, especially in unfavorable growing conditions. In an annually harvested trial during the 9-year test period, a cutting length up to 30 cm affected biomass production per stool positively. In two trials grown with 5-year rotation, the longest cuttings produced 7 times the above-ground biomass of the shortest ones. Results of these trials also emphasize the importance of establishment for the future success of willow plantations.  相似文献   
66.
Changes in the carbon stock of soil in response to climate change would significantly affect the atmospheric carbon dioxide concentration and consequently climate. The isotopes of carbon provide a means to study the temperature sensitivities of different soil carbon fractions. Where C3 vegetation has changed for C4, soil organic matter (SOM) from the different origins have different 13C/12C ratios. Relying on this feature, we took soil samples from a control field and a field where ordinary grain (C3) vegetation was replaced by maize (C4), 5 years ago. We measured the respiration rate and the 13C/12C ratio of the CO2 produced by the samples at different temperatures. Based on these measurements, we quantified that Q10 was 3.4-3.6 for the total CO2 production while it was 2.4-2.9 at 20 °C for the maize-derived young carbon and 3.6 for the older C3-derived carbon. Our results suggest that climatic warming will accelerate especially the decomposition of the large pool of old soil carbon in these fields.  相似文献   
67.
Below-ground transfer of nitrogen (N) fixed by legume trees to associated non-N2-fixing crops has received little attention in agroforestry, although the importance of below-ground interactions is shown in other ecosystems. We used 15N natural abundance to estimate N transfer from the legume tree Gliricidia sepium (Jacq.) Kunth ex Walp. to C4 grass Dichanthium aristatum (Poir.) C.E. Hubb. in a silvopastoral system, where N was recycled exclusively by below-ground processes and N2 fixation by G. sepium was the sole N input to the system. Finding a suitable reference plant, a grass without contact with tree roots or litter, was problematic because tree roots invaded adjacent grass monocrop plots and soil isotopic signature in soil below distant grass monocrops differed significantly from the agroforestry plots. Thus, we used grass cultivated under greenhouse conditions in pots filled with agroforestry soil as the reference. A model of soil 15N fractionation during N mineralization was developed for testing the reliability of that estimate. Experimental and theoretical results indicated that 9 months after greenhouse transplanting, the percentage of fixed N in the grass decreased from 35% to <1%, due to N export in cut grass and dilution of fixed N with N taken up from the soil. The effect of soil 15N fractionation on the estimate of the reference value was negligible. This indicates that potted grass is a suitable reference N transfer studies using 15N natural abundance. About one third of N in field-grown grass was of atmospheric origin in agroforestry plots and in adjacent D. aristatum grassland invaded by G. sepium roots. The concentration of fixed N was correlated with fine root density of G. sepium but not with soil isotopic signature. This suggests a direct N transfer from trees to grass, e.g. via root exudates or common mycorrhizal networks.  相似文献   
68.
The effect of the herbicide dinoseb (2-sec-butyl-4,6-dinitrophenol) on the symbiotic nitrogen fixation of red clover (Trifolium pratense cv. Venla) was studied in field, greenhouse and laboratory experiments. In the field, the herbicide reduced the levels of nitrogenase (C2H2) activity of the plants up to 18 days after treatment, but increased the yields compared to hand-weeded and unweeded controls. Rhizobium strains isolated from root nodules of plants treated with dinoseb showed resistance to the herbicide when grown on laboratory media containing dinoseb. However, in a pot experiment, inoculation with a strain which grew in the presence of 200 μg dinoseb ml?1 did not improve the performance of red clover treated with dinoseb. In the pot experiment dinoseb inhibited nitrogenase activity when sprayed on the leaves, but not when added to the growth medium. Application of starter nitrogen did not influence the effect of dinoseb. The results suggest that dinoseb did not act directly on the nodules, but affected nitrogen fixation by damaging the photosynthetic parts of the plant.  相似文献   
69.
Improving broad specificity hapten recognition with protein engineering   总被引:1,自引:0,他引:1  
Sulfa antibiotics (sulfonamides) are derivatives of p-aminobenzenesulfonamide that are widely used in veterinary medicine. Foods derived from treated animals may be contaminated with these drugs. However, current immunobased sulfonamide detection methods are unfit for screening of products because they are either too insensitive or specific for a few compounds only. An immunoassay capable of detecting all sulfas in a single reaction would be ideal for screening. For development of a binder capable of binding all sulfas, a protein engineering approach was chosen and the properties of monoclonal antibody 27G3 were improved with mutagenesis followed by selection with phage display. Several different mutant antibodies were isolated. The cross-reaction profile of the best mutant antibody was significantly improved over that of the wild-type antibody: it was capable of binding 9 of the tested 13 sulfonamides within a narrow concentration range and also bound the rest of the sulfas, albeit within a wider concentration range.  相似文献   
70.
Many freshwater ecosystems face severe threats from anthropogenic disturbances, yet little is known about the degree to which their biotic communities have been degraded by human activities. We analysed temporal changes and persistence of bryophyte communities in 40 springs in eastern Finland by comparing field surveys conducted in 1986 and 2000. During that period, some springs had remained in a near-pristine state, while others had undergone varying degrees of disturbance from forest management, drainage, and water abstraction. Several spring bryophytes (e.g., Philonotis fontana) declined between the study years, whereas Sphagnum mosses (e.g., Sphagnum warnstorfii) increased in abundance. Species richness of spring bryophytes declined significantly from 1986 to 2000, irrespective of bryophyte group (spring vs. other bryophytes) and spring condition (severely disturbed vs. unaltered springs). Bryophyte cover also decreased dramatically from 1986 to 2000, but this effect was related to both spring condition and bryophyte type. Spring bryophytes lost much of their cover in severely altered springs, while in unaltered springs they remained relatively stable through time. No such trend was observed for other, habitat generalist bryophytes. Persistence and stability of bryophyte communities showed significant, albeit rather weak, relationships with spring condition, with communities in unaltered springs being more persistent than those in altered springs. Given the importance of springs to boreal forest and aquatic biodiversity, restoration of degraded springs is a major challenge to maintaining and conserving biodiversity of boreal landscapes.  相似文献   
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