Figure 2 . Vegetation PCA biplots. (A ) PCA biplot of all study trees (N = 72) classified by Treatment. (B ) PCA biplot of control trees (N = 24) classified by Farm. The ellipses show the 95% confidence variance for the mean value. The first PCA separates trees the from different treatments: low cover of short grass (Control), high cover of short/medium height grass (one-year exclusion), and high cover of high grass (ten-years exclusion). The second PCA (only control trees) segregates the three farms on basis of their vegetation at their standard livestock densities. Variable arrows are displayed to show differences in grass cover height between farms.