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Michael G. Michie 《Mathematical Geology》1982,14(6):661-667
Transformation of data effectively limits the distortion by outlying values on the Bray-Curtis similarity measure. It represents an effective method of using cluster analysis in distinguishing biotopes of benthic foraminifera. 相似文献
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Wahizatul Afzan A Che Salmah M R 《湿地科学》2005,3(3):167-175
1INTRODUCTION Manyfactorshavebeenlinkedwithobserved patternsofodonatediversity.Eachhabitatisdifferent andpresentsitsownopportunitiesforexploitationby welladaptedspecies(Krebs,1989).Theyaresensi tiveresponderstonewlycreatedphysicalandtogether withphysiogra… 相似文献
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Abstract. In the Cyclades plateau (Aegean Sea), a qualitative and quantitative analysis of macro-benthic fauna was carried out in 1986. Standard multivariate analysis techniques were applied to both ecological (living benthic fauna) and paleoecological data sets in order to distinguish distribution patterns.
Results showed that caution must prevail in drawing conclusions from a limited data set. The clearest classification was obtained using total living fauna, while the dead molluscan fauna gave a similar pattern; this indicates similar response to the environmental conditions of the area. In the analysis of the living molluscan fauna, the groups failed to show any clusters, probably as an effect of some impoverished sites.
In the two groups delineated, depth seems to be the major factor in the distribution of species.
The fact that two distinct data sets (subfossil assemblages and living communities), when treated separately, produce similar grouping indicates that the subfossil assemblages could be reliably used as a first approach for determination of the living communities' distribution patterns. 相似文献
Results showed that caution must prevail in drawing conclusions from a limited data set. The clearest classification was obtained using total living fauna, while the dead molluscan fauna gave a similar pattern; this indicates similar response to the environmental conditions of the area. In the analysis of the living molluscan fauna, the groups failed to show any clusters, probably as an effect of some impoverished sites.
In the two groups delineated, depth seems to be the major factor in the distribution of species.
The fact that two distinct data sets (subfossil assemblages and living communities), when treated separately, produce similar grouping indicates that the subfossil assemblages could be reliably used as a first approach for determination of the living communities' distribution patterns. 相似文献
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Although wetlands play a key role in controlling flooding and nonpoint source pollution, sequestering carbon and providing an abundance of ecological services, the inventory and characterization of wetland habitats are most often limited to small areas. This explains why the understanding of their ecological functioning is still insufficient for a reliable functional assessment on areas larger than a few hectares. While LiDAR data and multispectral Earth Observation (EO) images are often used separately to map wetland habitats, their combined use is currently being assessed for different habitat types. The aim of this study is to evaluate the combination of multispectral and multiseasonal imagery and LiDAR data to precisely map the distribution of wetland habitats. The image classification was performed combining an object-based approach and decision-tree modeling. Four multispectral images with high (SPOT-5) and very high spatial resolution (Quickbird, KOMPSAT-2, aerial photographs) were classified separately. Another classification was then applied integrating summer and winter multispectral image data and three layers derived from LiDAR data: vegetation height, microtopography and intensity return. The comparison of classification results shows that some habitats are better identified on the winter image and others on the summer image (overall accuracies = 58.5 and 57.6%). They also point out that classification accuracy is highly improved (overall accuracy = 86.5%) when combining LiDAR data and multispectral images. Moreover, this study highlights the advantage of integrating vegetation height, microtopography and intensity parameters in the classification process. This article demonstrates that information provided by the synergetic use of multispectral images and LiDAR data can help in wetland functional assessment 相似文献
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Acoustic seabed classification is a useful tool for monitoring marine benthic habitats over broad-scales (>1 km2) and meso-scales (10 m2–1 km2). Its utility in this context was evaluated using two approaches: by describing natural changes in the temporal distribution of marine biotopes across the broad-scale (4 km2), and by attempting to detect specific experimentally-induced changes to kelp-dominated biotopes across the meso-scale (100 m2). For the first approach, acoustic backscatter mosaics were constructed using sidescan sonar and multibeam echosounder data collected from Church Bay (Rathlin Island, Northern Ireland) in 1999, 2008 and 2009. The mosaics were manually segmented into acoustic facies, which were ground-truthed using a drop-video camera. Biotopes were classified from the video by multivariate exploratory analysis and cross-tabulated with the acoustic facies, showing a positive correlation. These results were integrated with bathymetric data to map the distribution of seven unique biotopes in Church Bay. Kappa analysis showed the biotope distribution was highly similar between the biotope maps, possibly due to the stability of bedforms shaped by the tidal regime around Rathlin Island. The greatest biotope change in this approach was represented by seasonal and annual changes in the growth of the seagrass, Zostera marina. In the second approach, sidescan sonar data were collected before and after the removal of 100 m2 of kelp from three sites. Comparison of the data revealed no differences between the high-resolution backscatter imagery. It is concluded that acoustic seabed classification can be used to monitor change over broad- and meso-scales but not necessarily for all biotopes; its success depends on the type of acoustic system employed and the biological characteristics of the target biotope. 相似文献
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Rosa Freitas Leandro Sampaio Ana Maria Rodrigues Victor Quintino 《Estuarine, Coastal and Shelf Science》2005,65(4):625-632
An acoustic ground discrimination system (QTC VIEW, Series IV) was used to identify and map the bottom acoustic diversity in the bar channel of Ria de Aveiro, Western Portugal. The majority of the survey area presented shallow depth for this type of equipment, ranging mainly from 5 to 15 m. Depth occasionally reached 25 m in specific areas located across the entrance channel, dug by the strong tidal currents, reaching 3 m/s. The acoustic data were submitted to manual and auto-cluster and the results obtained from both procedures were coherent. Using aids to the acoustic classification and ground-truth sediment data, a final solution consisting of four acoustic classes was reached. Their geographical distribution was coincident with the spatial distribution of the major bottom types and sediment groups (hard bottom, coarse sand, medium sand and fine sand), identified through multivariate analysis of the grain-size data, and reflected the complex hydrodynamics of the entrance channel. The acoustic pattern was coincident at the intersections of the acoustic survey lines, assuring the repeatability of the acoustic procedure. Overall, the acoustic approach showed consistent results for the assessment and mapping of the benthic habitats in this shallow-water coastal area, providing a very valuable tool in an area where conventional sediment sampling is less favourable, namely due to strong tidal currents and frequent ship traffic, such as the entrance channel of Ria de Aveiro and the near-shore adjacent shelf. 相似文献
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Gregor Levin 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):45-59
Geografisk Tidsskrift, Danish Journal of Geography 106(2): 45–59, 2006 This paper explores relationships between farm size and landscape composition in terms of densities of uncultivated landscape elements and sizes of agricultural fields. The study is based on national agricultural registers for Denmark and on aerial photo interpretation of three study areas, representing different Danish landscape types. Results indicate significantly smaller fields and significantly higher densities of uncultivated landscape elements on small farms (<25 ha). At national level, current differences between small and large farms are to some extent caused by landscape changes between 1998 and 2004. Analyses of the study areas indicate that current differences between small and large farms mainly evolved between 1982 and 2002, while the influences of changes between 1954 and 1982 are limited. Relationships between farms size and landscape composition are independent of spatial variations in soil type and slope conditions. Consequently, attention must be paid to other parameters linked to farm size. In particular, the effects on landscape composition of part-time and hobby farming, as well as production type, must be considered. 相似文献
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The diversity of life occurs at several hierarchical levels of biological organisation, including the biotope (habitats) diversity. The knowledge of the coastal habitat diversity and its sensitivity to the anthropogenic impact is one of the most important preconditions for the sustainable use and development of the coastal regions. This paper gives a brief overview of a recent study, which was aimed to classify the Lithuanian coastal zone underwater habitats and identify anthropogenic threats to the area. 相似文献
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