Are ordination and constrained ordination alternative or complementary strategies in general ecological studies?

Økland, Rune Halvorsen

doi:10.2307/3236330

Cited by 235 publications

(104 citation statements)

References 33 publications

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“…We applied Detrended Correspondence Analysis (DCA) to analyze variation in species compositions, species turnover (from the main matrix) and struc-tural and environmental variables (from the second matrix). The efficacy of this technique has been well established (Okland 1996). Using PC-ORD 6.0 MjM Software (Gleneden Beach, OR, USA), we carried out detrending by segments (default of 26 segments) and did not downweight rare species, because important indicator tree species may be rare in the data set.…”

Section: Fine-scale Ecological Niche Analysismentioning

confidence: 99%

Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany

et al. 2017

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Ch., Sutcliffe L., Leuschner Ch., 2017. Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany. Ann. For. Res. 60(1): 101-126. Abstract.We compared results derived using three different approaches to assess the suitability of common tree species on the Franconian Plateau in southern Germany under projected warmer and drier climate conditions in the period 2061-2080. The study area is currently a relatively warm and dry region of Germany. We calculated species distribution models (SDMs) using information on species' climate envelopes to predict regional species spectra under 63 different climate change scenarios. We complemented this with fine-scale ecological niche analysis using data from 51 vegetation surveys in seven forest reserves in the study area, and tree-ring analysis (TRA) from local populations of five tree species to quantify their sensitivity to climatic extreme years. The SDMs showed that predicted future climate change in the region remains within the climate envelope of certain species (e.g. Quercus petraea), whilst for e.g. Fagus sylvatica, future climate conditions in one third of the scenarios are too warm and dry. This was confirmed by the TRA: sensitivity to drought periods is lower for Q. petraea than for F. sylvatica. The niche analysis shows that the local ecological niches of Quercus robur and Fraxinus excelsior are mainly characterized by soils providing favorable water supply than by climate, and Pinus sylvestris (planted) is strongly influenced by light availability. The best adapted species for a warmer and potentially drier climate in the study region are Acer campestre, Sorbus torminalis, S. aria, Ulmus minor, and Tilia platyphyllos, which should therefore play a more prominent role in future climate-resilient mixed forest ecosystems.

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Section: Fine-scale Ecological Niche Analysismentioning

confidence: 99%

Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany

et al. 2017

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“…The two methods were applied to data matrices for all values. Parallel ordination offers an opportunity for controlling if the two different methods reveal the same structure, which is regarded as an indication that the true underlying structure has been found [18]. Congruence between parallel DCA and GNMDS ordinations (i.e., ordinations based on a specific range of the abundance scale) was assessed by means of Procrustes analysis [38,40], and by calculating pairwise Kendall's rank correlation coefficients between corresponding DCA and GNMDS axes.…”

Section: Discussionmentioning

confidence: 99%

“…Like other models for relating response variables to independent variables, constrained ordination thus only summarises variation in species composition that is explained by the supplied variables. This has several important implications [18]: (1) compositional variation due to unmeasured, but important, variables is lost in a black box of "unexplained variation"; (2) compositional variation not linearly related to the supplied variables is lost as residual variation; and (3) being (linear) combinations of environmental gradients, axes of direct gradient analysis are complex-gradients, not gradients in species composition. Økland [18] therefore argues that indirect gradient analysis should be used to generate hypotheses about species-environment relationships, while direct gradient analysis should be used for testing hypotheses or for partitioning the variation in species abundances in a set of sites or on sets of explanatory variables [18].…”

Section: Indirect Versus Direct Gradient Analysis and Weightmentioning

confidence: 99%

“…The methodological approach used in this study is to apply indirect gradient analysis (i.e., unconstrained ordination methods such as DCA and NMDS) in a generalpurpose, inductive study [18] with the main aim to generate hypotheses about species-environment relationships. Our results demonstrate that the chosen method gives us new insight into the structuring of species composition by environmental complex-gradients.…”

Section: Indirect Versus Direct Gradient Analysis and Weightmentioning

confidence: 99%

“…One reason for this is that the axes of NMDS ordinations as implemented in PRIMER, are unscaled and thus not interpretable in terms of compositional turnover. Such interpretation is essential for identification of coenoclines, for relating these to complex-gradients, and for hypothesising about ecoclines [18].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Identification of Fine-Scale Marine Benthic Ecoclines by Multiple Parallel Ordination

Son

Halvorsen

Norling

et al. 2014

Journal of Marine Biology

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The species-environment relationship is a fundamental structural property of natural ecosystems. Marine sedimentary macrofauna is known to be structured by a range of environmental variables; however, the mechanisms by which environmental variables covary to form complex-gradients (i.e., groups of intercorrelated environmental variables), and how these are related to coenoclines (i.e., gradients in species composition), remain poorly understood. We classified our study area into geomorphological features that were used for stratified sampling of macrofaunal polychaetes, molluscs, and echinoderms. The resulting species-by-site matrix was subjected to indirect gradient analysis by a multiple parallel ordination strategy, using detrended correspondence analysis and nonmetric multidimensional scaling. One major and one minor coenocline were identified. Based on the correlation between complex-gradients and the main coenocline we hypothesise the existence of two ecoclines that we have termed Periodic hypoxia and Periodic physical forcing. We conclude that a combination of recurrent (periodical) and extreme events is likely to determine the variation found in the species composition of marine sedimentary ecosystems. Based on the results of our study, we conclude that indirect gradient analysis is a useful tool for enhancement of our basic mechanistic understanding of the processes governing the compositional structure of marine sediment communities.

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Riparian vegetation and channel change in response to river regulation: a comparative study of regulated and unregulated streams in the Green River Basin, USA

Merritt

Cooper

2000

Regul. Rivers: Res. Mgmt.

316

278

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Are ordination and constrained ordination alternative or complementary strategies in general ecological studies?

Cited by 235 publications

References 33 publications

Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany

Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany

Identification of Fine-Scale Marine Benthic Ecoclines by Multiple Parallel Ordination

Riparian vegetation and channel change in response to river regulation: a comparative study of regulated and unregulated streams in the Green River Basin, USA

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