Collector's curves of the observed and estimated phylotype richness of 16S rRNA gene libraries. Collector's curves of the observed (blue) and estimated (ACE (pink) and Chao1 (yellow)) phylotype richness calculated for IN (A), OUT (B) and IR (C) at 99% level. Each curve reflects observed or estimated richness values obtained as more clones are added to the data set. After an initial steep rise, the curves level out suggesting that a majority of clones in the treatment groups have been sampled. Differences between the estimates and observed phylotype richness were highest in the IR group. Novel phylotypes continued to be identified up to the end of sampling in this group.