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Effects of land ownership and landscape-level factors on rare-species richness in natural areas of southern Ontario,Canada 总被引:5,自引:0,他引:5
Lovett-Doust J. Biernacki M. Page R. Chan M. Natgunarajah R. Timis G. 《Landscape Ecology》2003,18(6):621-633
Surprisingly few studies have considered the extent to which the nature of the ownership of land is associated with differences
in biodiversity. We analysed ownership and other landscape-level effects on rare-species richness for both globally- and regionally-rare
biota (including birds, herpetofauna, butterflies, mammals, and plants) in 289 designated natural areas (NAs) in southern
Ontario, Canada. Information about each NA −including area, number of plant communities, ownership status and details of species
diversity were collected from published sources. Length of perimeter of NA, relative isolation, and an estimate of fragmentation
were measured using image analysis and GIS techniques. NAs were in general relatively small, with mean area of 158 ha (median
85 ha, range from 0.9 to 1278 ha) for private NAs; public NAs had mean area of 132 ha (median 16 ha, range from 0.1 to 1481
ha). Mean number of plant communities was 4.6 (median 4, range 1- 13) at private NAs and 3.8 (median 3, range 1-16) at public
NAs. Our results show that, of several landscape-level factors, area had the greatest effects on rare-species richness and
other biotic indices. Effects of area were followed by effects of plant community diversity, however this was itself significantly
affected by area and the extent of perimeter of the NA. Both these factors were followed by effects of ownership of the NA
and by effects of isolation of the NA (represented by minimum distance to nearest NA and by number of NAs in 10 km radius).
Other landscape- level factors did not appear to have overall significant effects. Variation in area accounted for 0.1% to
29% of variation in number of rare species, with lower values for globally-rare, than for regionally-rare taxa. For all biotic
groups, public ownership of NAs was associated with significantly greater rare-species richness compared to private ownership,
even after other factors such as area were controlled. For all globally-rare biota except butterflies, area of NA had greater
effects on rare-species richness than did ownership. Richness of regionally- rare birds was more affected by plant community
diversity than by area of NA. Number of recorded plant communities accounted from 2.1% of variation in number of globally-rare
plant species to as high as 31% of variation in regionally-rare butterflies. The diversity of plant communities was itself
influenced by total site area (accounting for 45% of variation), extent of elongation of the NA, and both external- and interior-
edge perimeters. Public NAs had greatest numbers of rare biota and so should be a significant focus for conservation programs.
Smaller, privately-owned patches of natural area dominate (by number and area) in this densely populated region and their
significance should not be overlooked.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Classification study for using acoustic-ultrasonics to detect internal decay in glulam beams 总被引:2,自引:0,他引:2
Bayes, k-nearest neighbor (KNN), and neural network classifiers were used to study the decay detection efficiency of acousto-ultrasonics
(AU). Brown-rotted Douglas-fir glulam beams removed from service were measured by using through-transmission AU. Single and
multiple sets of AU signal features included velocity, attenuation, shape, and frequency content. Although all of the AU signal
features were sensitive to decay, they were also affected by natural characteristics of wood. However, it was possible to
improve the detection efficiency by using multiple signal feature sets in classification analysis. A 79% efficiency was achieved
with the neural network classifier for detecting small levels of decay (10% of the cross section) and a 68% overall correct
classification for different degrees of decay when using three or four signal features as inputs. The results of the Bayes
and KNN classifiers were quite similar, with 79% KNN and 75% Bayes detection efficiency for small levels of decay, and 67%
overall.
Received 22 January 1999 相似文献
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Two nondestructive evaluation methods, impact-induced stress wave techniques and ultrasonics, were investigated to detect
lathe checks and knots in veneer, which were identified as key veneer quality properties for some engineered applications.
Measurements included wave velocity and attenuation in the directions parallel and perpendicular to the grain. The results
showed that both techniques were sensitive to lathe checks when using wave propagation perpendicular to grain. For wave transmission
parallel to grain, signals showed some sensitivity to knots. There was no significant difference in wave velocity measurements
between stress wave and ultrasonic techniques. Regression models based on stress wave velocities in these two orthogonal directions
were developed to estimate the veneer quality index giving a coefficient of determination ranging between 0.39 and 0.50.
Received: 20 December 1998 相似文献
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Residues of dimetridazole in eggs after treatment of laying hens 总被引:1,自引:0,他引:1
A. Posyniak S. Semeniuk J. Žmudzki J. Niedzielska B. Biernacki 《Veterinary research communications》1996,20(2):167-174
Laying hens were dosed orally with dimetridazole (DMZ) (50 and 250 mg/kg) for 3 days or intramuscularly (50 mg/kg), also for 3 days, and the residues were determined by liquid chromatography in albumen and yolk. The sensitivity of the whole procedure was 2 ng/g. The drug was excreted preferentially into the yolk (about 57% of the total) and the elimination period lasted for 4–6 days after treatment.Abbreviations AUC
area under the plasma concentration-time curve
- depletion time
the time needed for the DMZ concentration to fall below 0.01 g/g
-
elimination rate constant
- Cl
clearance
- DMZ
demetridazole 相似文献
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