Vorschläge zur multivariaten Strukturanalyse varianzreicher Tiergemeinschaften : am Beispiel von Makroinvertebraten-Zönosen landwirtschaftlicher Fließgewässer in Südostniedersachsen
The present study investigates the statistical options for separating macroinvertebrate communities in a zoogeographical way. The communities investigated inhabit three different natural landscapes. 145 taxa were collected with the so-called SURBER-sampler-method at 40 sampling sites in the Hanover area (Germany) during five periods, each lasting six-weeks, during autumn 1998 until spring 2000. In addition to these samplings, data of 52 abiotic parameters were gathered. In order to reveal relevant ecological interrelationships between the abiotic and biotic data it was necessary to apply multivariate methods, including the Two-Way Indicator Species Analysis, both the direct and indirect form of the Correspondence Analysis, the Principal Components Analysis and derived from that the Principal Response Curve. Furthermore, there was an additional need to use multivariate methods as a result of the data. The collected data exhibited a large variance, as many outdoor samples often do. The study begins with a description of its genesis. Several questions are raised concerning the structure of the communities investigated and the existence of 'bioareas'. Next, a presentation of several multivariate statistical tools is provided, since the major task of the present study was their use in an ecologically meaningful way. The problem of the correct application of multivariate tools to community data is demonstrated und discussed with reference to the choice of abundance classes. Then the investigated landscape areas are described. Criteria for the choice of sample sites, the used materials, and methods of data collection, as well as the characteristics of the data are discussed. The first results are described using simple univariate means to show the main aspects of data variability. They give an overview of the structural surroundings of the sample sites and the temporal, spatial, and structural diversity of the macro-invertebrate samples. Thirty-three from 145 taxa were defined as 'Leitformen' (indicator species sensu lato) because of their permanent occurrence over time. Following this, 52 environmental gradients and the coenoses are multivariate analyzed. Despite the large variance, a zoogeographical differentiation of the three landscape areas could be achieved over the whole period of the investigation. However, from all used parameters, only the twenty water-related parameters correlate with the three areas as well as with the macroinvertebrate community structure. After a statistical confinement, a reduced combination of representative parameters were found, comprising pH-value, conductivity, dissolved organic carbon and velocity of stream flow. These parameters are forming a syndrome, which allows the assignment of an unknown water sample to its landscape area. In addition, three groups of five to seven taxa are established that represent their respective area. The last results section contains two multivariate analyses with special design. The first one describes seasonal aspects of the coenotic structure. It shows which physicochemical parameters could play an important role for the explanation of the variation of associated taxa groups during single seasons. The second one demonstrates how seasonal fluctuations of the coenotic composition can be described in a quantitative manner from a group of constantly found taxa along ten most important gradients. Finally, the questions of the coenotic structures raised in the beginning are discussed. There is evidence to suggest the existence of three 'bioareas' in the investigated region, although these areas overlap somewhat. Furthermore, the stability of the freshwater communities in the 'bioareas', the necessity of analyzing them in a neutral way, and the difficulties of detecting a coenotic recovery on long-term adapted communities is discussed. Lastly, the findings are compared with those of two studies of comparable contents, and the integrative concept of the present study is contrasted with the concept of index-based biocoenosis research.
info:eu-repo/classification/ddc/570, Biowissenschaften, Biologie, multivariat, Fließgewässer, Makroinvertebraten, Tiergemeinschaften, Zönosen, Strukturanalyse, Varianz, Südostniedersachsen
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