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91.
Pekka Rossi 《New Forests》1991,5(3):211-218
The influence of length of cuttings on establishment of a short rotation plantation was investigated over a period of two years using direct field planting of unrooted Populus Rasumowskiana cuttings. The longer the cuttings, the higher were the survival and dry mass production. Survival at the end of the second growing season varied from 75% to 97%. In two years, the two longest cutting lengths (40 cm and 50 cm) produced about 100 g dry mass per living cutting; but owing to the higher survival rate of the longest cuttings, there was a difference per area unit: 360 g/m2 for 40 cm and 400 g/m2 for 50 cm-long cuttings. The shortest (10 cm) cuttings produced only 115 g/m2. 相似文献
92.
Needle fluctuating asymmetry (FA) in Scots pine (Pinus sylvestris) was studied south of the Severonikel nickel-copper smelter in the Kola Peninsula, Russia. We measured the difference in length of two needles of the same pair, and calculated FA as the ratio between this difference and the average length of the two needles of this pair. Needle FA did not depend on tree age, distance from the nearest neighbour or branch position within the crown, but increased with an increase in branching order. Needles originating in different years (1993-1997) demonstrated among-year variation in FA, which, however, was not related to annual fluctuations in SO2 emission by the smelter. FA increased with decreasing distance from the smelter, and in the sites proximate to the smelter FA was double that found at the most distant (background) sites. The increase in FA was primarily due to an increased difference in the length of the two needles, and this difference may serve as a practicable indicator of pollution-induced stress in Scots pine. 相似文献
93.
Varhimo E Varmanen P Fallarero A Skogman M Pyörälä S Iivanainen A Sukura A Vuorela P Savijoki K 《Veterinary microbiology》2011,149(3-4):381-389
Streptococcus uberis is an environmental udder pathogen that infects cattle and can cause persistent intramammary infection (IMI), despite the fact that isolates are mainly susceptible to antibiotics. As biofilm growth can cause persistent infection, the ability of ten S. uberis isolates from clinical and subclinical IMIs to form biofilms on the polystyrene surface of a conventional 96-microplates model was examined. Biofilm formation was judged by different staining methods (crystal violet and resazurin) and by atomic force and fluorescence microscopy. These analyses revealed that two out of ten S. uberis strains tested were able to form biofilms. Upon treatment with Proteinase K, biofilms of S. uberis were completely disintegrated, which indicates that biofilm formation is protein-mediated in these strains. Addition of trace amounts of milk, the natural growth medium of S. uberis, significantly increased biofilm formation by most of the strains initially classified as non-biofilm producers. Alpha-casein and β-casein were the primary inducers of biofilm growth, and casein degradation by serine protease activity was required to achieve maximal biofilm production. These results suggest that the extracellular proteolytic activity of S. uberis contributes to an increased biofilm formation. Such a mode of growth induced by host proteins might help to explain the persistence of IMIs caused by this pathogen. 相似文献
94.
Salin O Törmäkangas L Leinonen M Saario E Hagström M Ketola RA Saikku P Vuorela H Vuorela PM 《Journal of agricultural and food chemistry》2011,59(24):12836-12842
Corn mint ( Mentha arvensis ) provides a good source of natural phenols such as flavone glycosides and caffeic acid derivatives, which may have prophylactic properties against inflammations. This study investigated whether corn mint extract would be beneficial against a universal respiratory tract pathogen, Chlamydia pneumoniae , infection. The extract inhibited the growth of C. pneumoniae CWL-029 in vitro in a dose-dependent manner. The inhibition was confirmed against a clinical isolate K7. The phenolic composition of the extract was analyzed by UPLC-ESI/Q-TOF/MS, the main components being linarin and rosmarinic acid. These compounds were active in vitro against C. pneumoniae. Linarin completely inhibited the growth at 100 μM. Inbred C57BL/6J mice were inoculated with C. pneumoniae K7. M. arvensis extract was given intraperitoneally once daily for 3 days prior to inoculation and continued for 10 days postinfection. The extract was able to diminish the inflammatory parameters related to C. pneumoniae infection and significantly (p = 0.019) lowered the number of C. pneumoniae genome equivalents detected by PCR at biologically relevant amounts. 相似文献
95.
A. Lappalainen O. Mähönen J. Erkinaro M. Rask E. Niemelä 《Water, air, and soil pollution》1995,85(2):439-444
Sulphur emissions from Russian Kola Peninsula smelters are known to cause surface water acidification in the border areas between Norway and Russia. The sulphur deposition is also high in the eastern part of Finnish Lapland. In 1990, a monitoring programme was started to survey the effects of acid deposition on sensitive fish populations in north-eastern Finnish Lapland. Altogether 103 sites in three areas were electrofished and autumn water samples were taken. Besides the brown trout (Salmo trutta), special attention was paid to the occurrence of minnow (Phoxinus phoxinus) since it is a common species in small waters and is highly sensitive to acidification. During the first three years of monitoring no signs of acidification were recorded. The alkalinity values of brooks generally exceeded 0.1 mmol/1. Brown trout, minnow and burbot (Lota lota) were caught frequently in the study sites. Later the study was focused on the uninhabited Vätsäri area which is receiving the highest sulphur deposition in Finnish Lapland. The alkalinity values of the sampled brooks were in most cases below 0.05 mmol/1, indicating a decreased buffer capacity. However, the electrofishing of the brooks showed no acid-induced damage. The lowest alkalinity values were detected from a group of small upland ponds. In four such ponds the alkalinity was zero or negative. No minnows were caught from these four ponds apart from one, where the minnows were exceptionally large. The results show that the waters near the eastern border of northern Finnish Lapland are threatened by acidification. No damage to fish populations subject to fishing was observed. The absence of minnows in some small waters is possibly the first sign of acid-induced fish population damage. 相似文献
96.
There is a trend to continuously update forest data in forest management planning systems. Thus, changes in forest stands
caused by, e.g. operations and storm damages should be detected in order to ensure the accuracy of forest data and beneficial
decisions related to the treatments of the stands. This justifies the application of aerial photographs in change detection
as being reasonable because they are already used in forest management planning. This study presents a semi-automatic method
based on bi-temporal aerial photographs and registration at the stand and segment levels for the detection of changes in boreal
forests. Linear stepwise discriminant analysis and the non-linear k-nearest neighbour (k-NN) method were tested and statistically compared in classification. The classification results at the stand level were found
to be better than at the segment level. Compared to previous studies, the results of this study demonstrate remarkable improvement
in the classification accuracy of moderate changes. The results showed that change detection substantially improved when the
registration at the stand level was used, especially in the detection of thinned stands. To some extent, the method can be
already applied operationally. 相似文献
97.
98.
99.
Carabid beetle assemblages (Coleoptera,Carabidae) across urban-rural gradients: an international comparison 总被引:14,自引:0,他引:14
Niemelä Jari Kotze D. Johan Venn Stephen Penev Lyubomir Stoyanov Ivailo Spence John Hartley Dustin de Oca Enrique Montes 《Landscape Ecology》2002,17(5):387-401
We studied communities of carabid beetles in residual forest patchesalong urban-suburban-rural gradients in three cities (Helsinki, Finland; Sofia,Bulgaria and Edmonton, Canada) to examine their responses to urbanisation. OnlyFinnish carabids showed a marked division of community structure along thegradient. In Bulgaria and Canada, carabids did not separate into distincturban,suburban and rural communities. Our results provide some support for thepredictions that species richness will decrease, that opportunistic specieswillgain dominance, and that small-sized species will become more numerous underdisturbance such as that provided by urbanisation. The rather weak and variedresponse of carabids to this disturbance suggests that local factors and theirinteraction are of primary importance for community composition. Occurrence ofreasonably similar carabid communities across the gradient at each of the threelevels of urbanisation suggests that habitat changes commonly associated withurbanisation have not affected the ecological integrity of carabid assemblagesin residual urban forest patches.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
100.
The opinions of animal owners and practising veterinarians concerning a new restraint-reversal medication (medetomidine-atipamezole) for dogs were obtained by two questionnaires in connection with a clinical study. Four alternative answers to each statement question scored as "completely agree", "somewhat agree", "somewhat disagree" and "completely disagree". The questionnaires were completed by 21 veterinarians and 245 dog owners. The overall response to the treatment was clearly positive. Both groups had a favourable attitude towards drug use with mean combined scores (from 1 to 4; 4 = most favourable) of 48.1 (max 56) for the dog owners and 39.2 (max 52) for the veterinarians. Only a little information was gained about the background of negative sentiments. Some pet owners (19%) opposed to medication on a priori grounds, some (26%) reacted strongly to the dizziness of their animals and some owners (21%) complained because of general anxiety before, during and after their pets were treated. 相似文献