The robustness of Correspondence, Detrended Correspondence, and TWINSPAN Analysis

Groenewoud, H. van

doi:10.2307/3235685

Cited by 77 publications

(26 citation statements)

References 15 publications

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“…In interpretation of the results presented, the emphasis is on sample ordinations. Van Groenewoud (1992) cautions against the temptation to pack too much into the analysis, and he recommends restricting sampling mainly to one gradient at a time.…”

Section: Methodsmentioning

confidence: 99%

Plant Communities of Archaeological Sites, Abandoned Dwellings, and Trampled Tundra in the Eastern Canadian Arctic: A Multivariate Analysis

Forbes¹

1996

ARCTIC

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ABSTRACT. Arctic terrestrial ecosystems subjected to anthropogenic disturbance return to their original state only slowly, if at all. Investigations of abandoned settlements on three islands in the eastern Canadian Arctic Archipelago have detected striking similarities among contemporary and ancient human settlements with regard to their effects on tundra vegetation and soils. Ordination procedures using 240 quadrats showed the plant assemblages of Thule (ca. 800 B.P.) winter dwellings on northern Devon and southern Cornwallis Islands to be floristically similar to pedestrian-trampled meadows on northeast Baffin Island last used ca. 1969. Comparisons from the literature made with other North American sites in the Low Arctic reveal similar findings. The implication is that the depauperate flora of the Arctic has a limited number of species able to respond to disturbance, and that anthropogenically disturbed patches may be extremely persistent.Key words: Thule culture, phytoarchaeology, High Arctic, trampling, anthropogenic disturbance, growth forms, ordination RÉSUMÉ. Les écosystèmes terrestres arctiques soumis à une perturbation anthropique ne retournent que lentement -lorsqu'ils le font -à leur état initial. Des études faites sur des établissements abandonnés dans trois îles de l'archipel Arctique canadien oriental ont permis de constater des ressemblances frappantes entre les établissements humains contemporains et anciens en ce qui concerne leurs effets sur la végétation et les sols de la toundra. Les procédures d'ordination portant sur 240 quadrats ont montré que les communautés végétales des habitations d'hiver de Thulé (v. 800 BP) situées dans le nord de l'île Devon et le sud de l'île Cornwallis, sont similaires au plan de la flore aux prairies piétinées par l'homme v. 1969 dans le nord-est de la terre de Baffin. Des comparaisons établies à partir de documentation réalisée sur d'autres sites nord-américains dans le Bas-Arctique révèlent des constatations similaires. L'implication est que la flore souffreteuse de l'Arctique possède un nombre limité d'espèces capables de réagir aux perturbations, et que les endroits perturbés anthropiquement pourraient demeurer tels quels très longtemps.Mots clés: culture de Thulé, phytoarchéologie, Extrême-Arctique, dommages dus au piétinement, perturbation anthropique, formes de croissance, ordination Traduit pour la revue Arctic par Nésida Loyer.

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Section: Methodsmentioning

confidence: 99%

Plant Communities of Archaeological Sites, Abandoned Dwellings, and Trampled Tundra in the Eastern Canadian Arctic: A Multivariate Analysis

Forbes¹

1996

ARCTIC

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“…The objective of DCA in this research was to determine more precisely the relationship between the pollen in the surface sample data and the taxa within the surrounding vegetation. Although the program has a weakness in the analysis of two equally strong gradients (Van Groenewoud, 1992 ;Belbis & McDonald, 1993), it has proved to be successful for hypothesis generation (Birks & Gordon, 1985). For example, output from the ordination can be interpreted in terms of a causal factor; in our case this factor is how representative of the surrounding taxa is the pollen in surface sediments.…”

Section: Establishing a Modern Pollen-vegetation Relationshipmentioning

confidence: 99%

Pollen representivity of montane forest taxa in south‐west Uganda

Marchant

Taylor

2000

New Phytologist

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Results presented in this paper demonstrate the relationship between two data sets from Mubwindi Swamp, south-west Uganda. The first data set is from a survey of dryland montane forest within the immediate catchment and the second is in the form of pollen spectra recovered from surface samples of sediment. Numerical analysis grouped pollen types encountered into five categories, according to their level of representivity when compared with abundances of the same taxa in the sampled vegetation : under representative, moderately under representative, representative, moderately over representative, and over representative. The northern part of Mubwindi Swamp also yielded a 5-m-long sequence of organic-rich sediments (core MB6) from which sub-fossil pollen and radiocarbon data have been previously obtained. This provides an opportunity to apply calibration factors derived from modern pollen-vegetation relationships to sub-fossil pollen data that were obtained from the same site. These calibration factors effectively down-weighted the influence of over representative pollen types and permitted the discrimination of a phase of forest disturbance that had not previously been so clearly visible in subfossil pollen data.

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“…However, Eyre, Ball & Foster {1986) found considerable overlap of TWINSPAN groups on Axes 1 and 2 of the DCA ordination, but consideration of group centroids, and DCA Axis 3, fadlitated interpretation. The tendency of TWINSPAN to produce inappropriate divisions has been discussed recently in relation to the analysis of simulated ecological data {van Groenewoud, 1992;Beibin & McDonald, 1993). An alternative classification strategy was adopted by Verdonschot {1987, 1992 who used the program FLEXCLUS {van Tongeren, 1986).…”

Section: Site Groupingsmentioning

confidence: 99%

Relationships between macroinvertebrate communities and environmental variables in metal‐contaminated streams in south‐west England

et al. 1994

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1. Macroinvertebrate species and information on thirty-nine variables were recorded at forty-six sites on twelve Cornish streams affected to varying extents by past metalliferous mining. 2. Relationships between macroinvertebrate communities and environmental variables were examined using canonical correspondence analysis (CCA). Copper was the strongest correlate with Axis 1 of the analysis, suggesting that it may have a major role in determining community structure. There were also strong correlations between Axis 1 and aluminium, alkalinity, pH, dissolved organic matter and algal cover, and between Axis 2 and discharge.3. CCA distinguished four site groupings. In spite of seasonal changes in position on the ordination, as revealed through CCA and detrended correspondence analysis (DCA), sites retained their group membership. There were differences in the proportions of the major taxa within the four CCA-derived groups. In the group with the highest copper concentration, Ephemeroptera were absent, but triclads and chironomids were abundant, with Orthocladiinae the dominant group. 4. Changes in the occurrence of spedes along the metal gradient reflected changes in sensitivity. 'Tolerance' plots of selected species based on the CCA site ordination diagram were used to identify environmental thresholds. 5. As well as direct toxic effects of copper and aluminium on invertebrate communities, co-precipitation of these two metals could be an important physical factor. Further modifying influences resulting from interactions between toxic metals and pH, alkalinity, hardness and dissolved organic matter contributed to the complexity of conditions affecting the faunat community in metal-contaminated streams. 6. The most severely contaminated sites, with mean copper concentration exceeding 500(xgp', were all characterized by a reduced community dominated by the flatworm Phagocata vitta, the chironomids Chaetocladius melaleucus and Eukiefferielia claripennis and the net-spinning caddis Plectrocnemia conspersa. The necessity for spedes identification is demonstrated in relation to variation in metal tolerance.

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The robustness of Correspondence, Detrended Correspondence, and TWINSPAN Analysis

Cited by 77 publications

References 15 publications

Plant Communities of Archaeological Sites, Abandoned Dwellings, and Trampled Tundra in the Eastern Canadian Arctic: A Multivariate Analysis

Plant Communities of Archaeological Sites, Abandoned Dwellings, and Trampled Tundra in the Eastern Canadian Arctic: A Multivariate Analysis

Pollen representivity of montane forest taxa in south‐west Uganda

Relationships between macroinvertebrate communities and environmental variables in metal‐contaminated streams in south‐west England

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