Ordination
- Ordination (序列化)
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Apparent complexity of techniques for analyzing vegetation data (Kent & Coker 1992)
Plant community data are multivariate in nature= Crude data matrix
Aims of multivariate analysis
1. Summarizing plant community data
2. Defining environmental gradient ↓Multivariate analysis: to decrease complicated information content by a few components that summarizes the information
- Indirect ordination
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Modified after Kent & Coker (1992)
Method Note Application Bray and Curtis (polar ordination) (PO) Originally calculated and drawn using compass construction Widely used between 1960 and 1970. Now superseded by more sophisticated techniques Principal component analysis (PCA) Relatively complex, requiring computing facilities for calculation Widely used from 1966-present. However, now not recommended due to distortion ('horseshoe') effects Reciprocal averaging/ correspondence analysis (RA/CA) Simple calculation for one axis. Requires computer for full analysis Used extensively from 1973-1985. Now replaced by DCA Detrended correspondence analysis (DCA) 'Improved' version of RA/CA. Requires computer program DECORANA (or R) for analysis Widely used 1980-present Multi-dimensional scaling (MDS) requiring computing facilities NMDS is becoming popular - Direct ordination
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Method Note Application (Detrended) canonical correspondence analysis ([D]CCA) Not strictly indirect ordination since it is a revised version of DCA with ordination axes constrained by multiple regression with environmental factors. Use CANOCO / CANOPLOT / CANODRAW (Micor$oft Windows version available) for analysis (ter Braak et al. 2002) Becoming widely used
Fig. 1. Algorithms for (A) correspondence analysis, (B) detrended correspondence analysis, and (C) canonical correspondence analysis, diagrammed as flowcharts. LC scores are the linear combination site scores, and WA scores are the weighted averaging site scores. (Palmer 1993) - Weighted average
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Example of Klinka Weighted average method
Moisture score 1 (dry) 2 3 4 5 6 (wet) Total Cover 36.81 14.32 8.94 0.28 0.16 0.32 60.83 Weight 36.8 28.6 26.8 1.1 0.8 1.9 96.0 Soil moisture indicator index =[Weight/Cover] × 10 = 15.8
- References
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- Advanced course in environmental conservation (環境保全学特論)
- canonical correspondence analysis
- cluster analysis
- Kent M & Coker P. 1992. Vegetation description and analysis: A practical approach. CRC Press, Boca Ration
- Palmer MW. 1993. Putting testings in even better order: the advantages of canonical correspondence analysis. Ecology 74: 2215-2230
- ter Braak CJF & Smilauer P. 2002. CANOCO reference manual and CanoDraw for Windows user's guide. Software for canonical community ordination (version 4.5). Microcomputer Power, Ithaca, NY
- ordination LINK