Piecewise Regression for Blackbrush (Desert Shallow Sandy Loam and Desert Sandy Loam)

I was "messing around" with piecewise regression and Mark's CANY/BLM data, exploring patterns between vegetation and soil stability for Blackbrush dominated ecological sites. It didn't take long to find an interesting pattern and after running a piecewise regression, I was able to calculate the breakpoint (threshold?) and confidence level around it (standard error). I plotted the data coding the observations by "grazed" or "ungrazed". These are very preliminary, but I thought this was interesting. Someone might argue that because soil stability is measured categorically you would expect this kind of "saturating" relationship. But, I thought I would go ahead and share in case anybody actually looks at this.