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Fig. 4. Distribution of site index as a function of five selected mine soil properties across 14 mined study sites. Figure 4F shows the nontransformed, general functions for the soil properties that are non-linear with site index.
Regression depicts predicted site index based on observed values of each soil variable while others held constant at their average. 
Available water-holding capacity (AWHC) represents centimeters of water held between field capacity and wilting point for the total profile depth on each site.
