Intepreting a plot from a "constrained" NMDS

Dear list members,

Is there any reference or document on how to interpret a "constrained" 
non-metrical multidimensional scaling using ecological data?  By 
"constrained" I mean after fitting environmental covariables, using, for 
example, the "envfit" function in the vegan package.  Is it possible to 
interpret the resulting plot in the same way that a constrained 
ordination, for example CCA?
Thank you very much in advance.
Best,

Manuel

Manuel Sp?nola, Ph.D.
Instituto Internacional en Conservaci?n y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspinola at una.ac.cr
mspinola10 at gamil.com
Tel?fono: (506) 2277-3598
Fax: (506) 2237-7036