R: adding biplot arrows to CCA plot
<p>Starting with the following code:</p>

<pre><code>library(vegan)
data(dune)
data(dune.env)
Ordination.model1 &lt;- cca(dune ~ Management,dune.env)
plot1 &lt;- plot(Ordination.model1, choices=c(1,2), scaling=1)
</code></pre>

<p>I get a plot with sites, species, centroids, and biplot arrows.  I want to build up a plot with just the sites depicted by points, and the arrows with customized labels.
So far, I have:</p>

<pre><code>colvec &lt;- c("red", "green", "blue")
plot(Ordination.model1, type="n", scaling=1)
with(dune.env, points(Ordination.model1, display ="sites", col=colvec[Use], scaling=1, pch =16, bg = colvec[Use]))
</code></pre>

<p>I am stuck as far as how to put the arrows in.  Thanks in advance!</p>