[R] gam and ordination (vegan and labdsv surf and ordisurf)

[stephen sefick]

I have a general question about using thin plate splines in the surf
and ordisurf routines.  My rudimentary knowledge of a gam is that with
each predictive variable there is a different smooth for each one and
then they are added together with no real interaction term (because
they don't handle this well?).  Now,  If I have two variables that
have a high D^2 score and a low GCV score (I am thinking of this as a
goodness of fit which may be wrong) I would like to add these together
to produce one surface fitted to the ordination.  Is this possible?
Am I going down the right track?  Any help is greatly appreciated.

-- 
Stephen Sefick
Research Scientist
Southeastern Natural Sciences Academy

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis