Hi everybody, I have some questions about Unconstrained ordination (GNMDS) and Constrained Ordination (CCA) and use of ordisurf() in both method. I am working on soil fungal sequence data (presence-absence matrix). I have quite a few environmental variable to test with fungal community. Repeated sampling was done for 9 weeks. Julian day was not related with fungal community where as factorial time variable showed relationship with fungal community. Which indicated that there is no direct relation ship with time, but significantly related env variable (Moisture, NO3 and K) drive this community. This is fine. I run GNMDS analysis and it shows there is considerable variation due to spatial heterogeneity. (Factor spatial variable shows approx 30% and when I used UTM cordinate, Northing shows approx 10% variation, sampling distance is within 1.5 x 1.5 km area, Can some one tell me which variable is more appropriate for space, Factor variable or Cordinate). Therefore i need to use appropriate method by which i can remove variation due to space and then i want to test impact of env variable on community.
Partial DCA can be good approach but i have no idea how to do it in R. Suggestion would be helpful! Therefore in order to solve my purpose i used CCA where i removed the variation due factorial space variable and and then used Ordisurf to find the pattern. It was observed that soil water content and NO3 content drive this community shift. The CCA ordination shows highly significant and perfectly ecologically interpretable results. I would like to know is this OK to use ordisurf with CCA or it is not appropriate and ordisurf should only be used with unconstrained ordination. Thanks a lot for your help! Best regards, -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/Ordisurf-in-CCA-is-appropriate-tp7579056.html Sent from the r-sig-ecology mailing list archive at Nabble.com. _______________________________________________ R-sig-ecology mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
