DATA:      Fricke & Steubing (1984)
DIRECTORY: \CANOCO\SAMPLES\UNIMODAL\ALGAE
PROBLEM:   Effect of pollution on algae distribution in rivulets
BOOKLET:   pp 68-69
ILLUSTRATION OF:
+ How to obtain a DCCA
+ How to interpret canonical coefficients
+ How to test the significance of ordination axes
+ How, given the first axis, a second ordination axis is extracted and tested
+ How to define powers of explanatory variables using the Define Interaction 
  Terms option
+ Detrending-by-polynomials algorithm in DCCA
_______________________________________________________________________________
FILE TYPE    |  FILE NAME    |         DESCRIPTION
-------------+---------------+-------------------------------------------------
 SPECIES     | algae.dta     | 34 algae species (scale 0-5) in 25 sites within
             |               |  rivulets
ENVIRONMENT  | pollutio.dta  | 7 pollution variables (of which 6 are 
             |               |  ln-transformed)
 DERIVED     | alg_cca.xxx   | solution file of alg_cca.con with text Sample 
             |               |  scores modified to Xample scores
             | alg_dcca.xxx  | solution file of alg_dcca.con with text Sample 
             |               |  scores modified to Xample scores
             | ax1pol2.dta   | AX1 and AX1-squared of SamE: scores of solution 
             |               | file from pol_dcc2.con, made for the test of 
             |               | the second axis of a DCCA with detrending by 
             |               | second order polynomials
             | ax1pol2z.xxx  | made by the recipe in section 8.2.9 to test for
             |               |  the second axis of a DCCA with detrending by 
             |               |  second order polynomials
             | weight.txt    | default sample weights of (DC)CA used to modify 
             |               |  the unweighted RDA project rda_ini.con
 PROJECTS    | alg_dca.con   | DCA of algae, interpreted as pollution gradient
             | alg_cca.con   | CCA of algae on pollution
             | alg_dcca.con  | DCCA of algae on pollution (detrending by 
             |               |  segments)
             | pol_dcc2.con  | DCCA of algae on pollution (detrending by second
             |               |  order polynomials)
             | ax1_cca.con   | significance test of the first CCA-axis
             | ax2_cca0.con  | wrong test of second CCA-axis
             | ax2_cca1.con  | correct test of second CCA-axis
             | ax2_comm.con  | significance test of second CCA-axis in the 
             |               | command version of CANOCO
             | ax2_dcca.con  | approximate test of second DCCA-axis (detrending 
             |               | by segments)
             | rda_ini.con   | RDA of ax1pol2.dta on pollutio.dta
             | rda_samw.con  | weighted version of rda_ini.con (sample weights 
             |               | from weight.txt)
             | ax2pol2z.con  | correct test of second DCCA-axis (detrending by
             |               |  second order polynomials)
-------------+---------------+-------------------------------------------------

Fricke, G. & Steubing, L.(1984): Die Verbreitung von Makrophyten und 
Mikrophyten in Hartwasser-Zufl¸sse des Ederstausees. 
Archiv f¸r Hydrobiologie, 101: 361-372.