title: RDA visualisation - plot Species abundance according to RDA1
body: <p>I have sampled 87 plots and identified overall 9 earthworm species. My aim is to investigate changes in species richness and abundance across my site (sampled across 87 plots), which is known to be polluted (mainly by Cu, Zn, and Pb but I also considered 2 composite measure of soil environment extracted by a PCA). </p>
  
  <p>For that I have performed an RDA (species data were hellinger-transformed):</p>
  
  <pre><code>rda(formula = species.hel ~ Cu + Zn + Pb + PCA_axis1 + PCA_axis2, data = env)
  </code></pre>
  
  <p>the model is significant, I do have an effect of my studied pollutants on species community and the variance explained by my explanatory variables reach 37%. All is ok so far except that now, I would like to plot how individual species abundance varies with RDA1 such as in Oksanen online course (<a href="http://cc.oulu.fi/~jarioksa/opetus/metodi/ordination101.html#33" rel="nofollow noreferrer">http://cc.oulu.fi/~jarioksa/opetus/metodi/ordination101.html#33</a>): 
  <a href="https://i.stack.imgur.com/Sm1LK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Sm1LK.png" alt="enter image description here"></a></p>
  
  <p>If my understanding of how RDA proceeds is correct, from the RDA object i should potentially extract (non) linear species response to environmental variable with one model for each species. However, in the summary object of the RDA, I cannot figure out which data to extract. I any of you has a suggestion on that I would be very grateful.</p>