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991.
Globalisation accelerates the dynamics of the network society and economy, in which distant relationships become functionally
more significant than local landscape relationships. This presents challenges and opportunities for landscape analysis. Using
social scientific concepts of global and local space, and ecological concepts of hierarchy, two qualitative case studies are
undertaken of urban fringe landscapes in Copenhagen, Denmark, and Christchurch, New Zealand. They reveal a convergence of
landscape pattern over time, but this disguises significant differences in underlying socio-economic process and institutional
response. There are several implications for landscape analysis and policy. First, there is a need for studies grounded in
particular landscapes that acknowledge both local spatial landscape relationships and non spatial ‘global’ processes. Second, the transformation of landscapes through urbanisation provides a useful focus for
the connection of landscape ecological understanding of landscape systems with social scientific understanding of human agency
and social structure. Third, there is a significant challenge in how to develop local and regional institutions and policies
that have the capacity to utilise and apply these diverse analytical perspectives. 相似文献
992.
993.
Isaac Ishaaya Anna Elsner K. R. Simon Ascher John E. Casida 《Pest management science》1983,14(4):367-372
The potency of six dietary pyrethroids, as toxicants and inhibitors of weight gain in first- and fourth-instar Tribolium castaneum (Herbst) larvae, decreased in the order of cis-cypermethrin and deltamethrin > trans-cypermethrin and cis-permethrin > fenvalerate and trans-permethrin. Dosages that reduced larval weight also delayed pupation and emergence, probably due to their antifeeding activity. Three oxidase inhibitors (piperonyl butoxide, O, O-diethyl O-phenyl phosphorothioate, and O-isobutyl O-prop-2-ynyl phenylphosphonate), at a dietary concentration of 100 mg kg?1, had little or no effect on the toxicity of trans-permethrin, but strongly synergised the toxicity of cis-cypermethrin by about 3-, 3- and 10-fold, respectively. Piperonyl butoxide also synergised the toxicity of cis-permethrin, trans-cypermethrin and deltamethrin, but not that of fenvalerate. On the other hand, an esterase inhibitor, profenofos, did not enhance the potency of any of the α-cyano-3-phenoxybenzyl pyrethroids. Oxidases appear to be more important than esterases in pyrethroid detoxification by T. castaneum larvae. 相似文献
994.
Four pigs (59-65 kg live weight) were labelled over a period of 10 days with 15N in the feeding of a fishmeal diet (1), a fishmeal diet + partly hydrolysed straw meal (2), a horse bean diet (3) and a horse bean diet + partly hydrolysed straw meal (4). After a 24-hour fasting the animals were provided with simple cannulae in the upper part of the small intestines. After a fasting period of 24 h all four pigs received a 14C-leucine injection and the cannula secretion was collected in the subsequent 24 h. After the feeding of the diets without straw meal supplement (1 and 3) there were distinct differences in the secretion in comparison with the feeding with straw meal supplements (2 and 4) despite the long fasting period (48-72 h). 14C-activity could already be detected in the TCA-precipitable fraction of the secretion after 3-6 min of the injection in 1 and 3 but only 20 to 25 min after the 14C-leucine injection in 2 and 4. The specific 14C-leucine activity of the TCA-soluble fraction of the secretion was, after the straw meal supplementation to the fish meal diet, 15 times higher 25 min after the 14C-leu-injection, 25 times higher after 70 min, 36 times after 2 h and 1.8 times after 4 h than without straw meal supplementation. For all four diets a specific correlation (r = 0.96) could be ascertained between the increase of 14C-activity/mg N in the TCA-soluble fraction and the increasing crude fibre content in the diet between 25 and 180 min after the injection. Furthermore, a distinctly decreased N-secretion/h could be ascertained (correlation coefficient r = 0.84) with the increasing crude fibre content in the diet. The influence of the crude fibre on the parameters mentioned is seen in the changed osmotic conditions in the secretion, which may be caused by the changed regulation by hormones of the gastro-intestinal tract. The atom-% 15N' in both TCA-fractions of the secretion underwent big rhythmic variations, which is explained by different ratios of the components pancreatic juice, bile, and intestinal juice. 相似文献
995.
996.
Jensen J Simon D Murua Escobar H Escobar HM Soller JT Bullerdiek J Beelitz P Pfister K Nolte I 《Zoonoses and public health》2007,54(2):94-101
A total number of 111 dogs were included in the present prospective study investigating the prevalence of Anaplasma phagocytophilum in dogs in Germany. Dogs were divided into two groups. Dogs of group 1 (n = 49) showed clinical and/or haematological signs seen in infections with A. phagocytophilum, whereas those of group 2 (n = 62) did not have any evidence of anaplasmosis. For each dog, an A. phagocytophilum 16S rRNA-nested polymerase chain reaction (PCR) of ethylenediaminetetraacetic acid (EDTA)-anticoagulated whole blood analysis, a microscopic evaluation of a buffy coat and a serum indirect fluorescent antibody test (IFAT) were performed. Forty-eight seroreactive dogs were identified altogether, which amounts to an overall point prevalence of 43.2%. There was no significant difference between the seroreactivity to A. phagocytophilum antigens among group 1 (44.9%) and 2 (41.9%) (P > 0.5). Seven dogs (6.3%) had positive PCR results. All of them were seroreactive. Six belonged to group 1. Morulae in neutrophilic granulocytes were found in two dogs of group 1 but in none of group 2. Both dogs were seroreactive. Very high antibody titres (> or =1:1024) were detected significantly more frequently in dogs with clinical signs attributable to infection with A. phagocytophilum (group 1) than in those without (group 2) (P < 0.001). There was no significant correlation of overall positives or antibody titres to age, breed, sex, or whether the dogs were family or working dogs. Dogs with high tick infestation were significantly more often seroreactive to A. phagocytophilum than those with no or low tick infestation (P = 0.007). In conclusion, there seems to be a high risk of infection with A. phagocytophilum in Germany. Results of this study suggest that severe illness solely caused by A. phagocytophilum may be possible although definitive evidence does not exist. Very high antibody titres (>1:1024) may be associated with clinical anaplasmosis. 相似文献
997.
The objective of this study was to assess the regeneration response oftrembling aspen (Populus tremuloides Michx.) to differentmechanical site preparation (MSP) techniques commonly used in operationalforestry (disc trenching, drag scarifying and blading) and the specificmicrosites created by each treatment. This study was designed to measureregeneration after at least the first two growing seasons, however a largewildfire burned 80% of the study sites at the beginning of the second growingseason. Consequently, only limited second year data were presented, butregeneration from the first growing season following the fire was alsoassessed.Results indicated that microsites where the forest floor was disturbed and theparent root system was only lightly injured were more conducive to suckeringthan undisturbed microsites or where the root system was severely injured.Also,the fire disturbance after the first growing season resulted in increasedsuckering relative to the untreated controls in the first year. These resultssuggest that aspen sites with thick organic layers or vigorous competition fromother species can benefit from MSP when applied before the first growingseason.In addition, if first year suckering is inadequate, subsequent disturbancessuchas prescribed fire have the potential to improve suckering provided the parentroot system remains intact. 相似文献
998.
In Alberta, Canada, pairs of grafted lodgepole pine trees were selected to study the longevity and location of live roots of snags that were grafted to living trees, to determine the impact of these live residual roots on the diameter growth of the living tree. In a second study, dense groups of grafted trees were manually thinned and one leave tree was left to grow for two growing seasons. For both studies, roots were excavated. Results indicate that more live roots were maintained on snags connected to living trees with a large graft and that roots located within 90° of the root grafted to the live tree persisted longer. Also, tree ring index in the living trees significantly increased following manual thinning, but was unaffected when the grafted partner died naturally. Grafts with large phloem connections maintained a higher number of live roots on snags, than grafts with small connections. 相似文献
999.
Ur?a?VilharEmail author Michael?Starr Mihej?Urban?i? Igor?Smolej Primo??Simon?i? 《European Journal of Forest Research》2005,124(3):165-175
The monthly water balance in gaps in a managed Dinaric silver fir–beech forest and a virgin forest remnant located in SE Slovenia
was modelled using a capacity water balance model for two growing seasons. Two gaps of different size (ca. 0.07 and 0.15 ha)
were selected in each forest and plots for soil moisture monitoring were established in each gap (2–4) and in the surrounding
forest (2–3). We report on the modelled actual evapotranspiration (AET) and potential evapotranspiration (PET) and drainage
fluxes (DF) from the rooting zone at the plots. Precipitation over the 2001 growing season (May–October) was considerably
drier than average and that for 2002 growing season was wetter than average. Modelled AET for the 2001 growing season varied
between 88% and 96% of PET for the managed forest plots and between 90% and 100% for the virgin forest plots. The values for
the gap plots varied between 87% and 100% at the managed forest site and between 92% and 96% for the gaps in the virgin forest
site. Monthly AET values declined to 57–59% of PET at plots in the centre of the gaps in the managed forest site and to 63–74%
in the gaps in the virgin forest site (July), indicating that the highest drought stress occurs in gap centres. For 2002 growing
season, AET for all plots was 100% of PET. Modelled DF values in 2001 were 13–35% of rainfall for plots in the gap centres
and 12–16% for plots in the forest at the managed forest site. On an average, gap DF values were 20% (154 mm) higher than
the forest plot values. DF values in 2002 were similar for all plots at the managed forest site, 31–33% of rainfall. At the
virgin forest site, 2001 growing season, DF values varied between 12% and 30% of rainfall at the forest plots and between
12% and 32% at the gap plots. In 2002, DF values for all plots in the virgin forest site varied between 24% and 38% of growing
season rainfall. The varying development of vegetation and forest in the gaps of the virgin forest remnant resulted in more
variable evapotranspiration and DF during the drought year 2001, with values not as clearly related to distance from the gap
centre as in the managed forest site. 相似文献
1000.
Marsh reed grass (Calamagrostis canadensis (Michx.) Beauv.)is a common, highly competitive grass native to the boreal mixedwoodforest. This grass increases in abundance after clear-cut loggingbut little is known about its effects on trembling aspen (Populustremuloides Michx.) sucker regeneration. The effects of Calamagrostissod and its litter on aspen regeneration were studied in twoseparate greenhouse studies. Calamagrostis sod did not affectthe initiation of suckers, but resulted in 30 per cent fewersuckers emerging above the soil that were smaller and had 40per cent less leaf area. Calamagrostis litter had little effecton the initiation and number of emerged suckers; however, itdelayed emergence by 10 days. The physical barrier by rootsand litter of Calamagrostis reduced or delayed the expansionof suckers and therefore prolonged their dependence on rootreserves. By the time the suckers reached the surface, theyhad to compete for light with Calamagrostis shoots that hademerged a week earlier. This, coupled with low soil temperaturesassociated with Calamagrostis in other experiments, will significantlyreduce the number and growth of suckers. Any reduction and delayin sucker emergence will decrease aspen regeneration and productivitysince the growing season in the boreal forest region is short. 相似文献