Principal Component Analysis on eight community metrics of benthic macroinvertebrate data collected from 47 sites in the Tongariro National Park, New Zealand, Feb-April 2007

<p>Biplot of Principal Component (PC) 1 as a function of PC2 performed on the eight macroinvertebrate metrics collected from 47 streams in the Tongariro National Park, New Zealand, 2007. The main plot shows the spread of the 47 sites and the inset displays the loadings of the eight metrics. Two principal components were able to adequately explain the variation in metric data (Eigenvalues: PC1 – 4.17, PC2 – 2.04). This Principal Component Analysis (PCA) was performed using the princomp() function in R.</p> <p> </p> <p>Five 0.1 m2 Surber samples (500 micron mesh) were taken from random locations in riffles throughout approximately 50 m reaches at each site.