title: multiple ggplot linear regression lines
body: <p>I am plotting the occurrence of a species according to numerous variables on the same plot. There are many other variables but I've only kept the important ones for the sake of this post: </p>
  
  <pre><code> &gt; str(GH) 
   'data.frame':  288 obs. of  21 variables: 
   $ Ee       : int  2 2 1 7 6 3 0 9 3 7 ... 
   $ height   : num  14 25.5 25 21.5 18.5 36 18 31.5 28.5 19 ... 
   $ legumes  : num  0 0 55 30 0 0 55 10 30 0 ... 
   $ grass    : num  60 50 30 35 40 35 40 40 35 30 ... 
   $ forbs    : num  40 70 40 50 65 70 40 65 70 70 ... 
  </code></pre>
  
  <p>I've managed to plot this fine and get it looking nice using (where Ee is the species in question): </p>
  
  <pre><code>ggplot(data=GH,aes(y=y,x=x),ylab="Number of individuals (N)",xlab="Percentage cover (%); OR  Height(cm))+
  geom_jitter(aes(legumes,Ee),colour="blue")+ 
  geom_jitter(aes(grass,Ee),colour="green")+ 
  geom_jitter(aes(forbs,Ee),colour="red")+ 
  geom_jitter(aes(height,Ee),colour="black") 
  </code></pre>
  
  <p>However, I want to add regression lines for each of the variables (and calculate the R squared value), and have had no luck so far. Also the axes labels refuse to change from X and Y which I have never encountered before. Could anybody give me any help on this? Cheers</p>