> summary(sem.didelphis)
    rich.end         ab.end        rich.n.end     ab.n.end.     paisag  
 Min.   :0.000   Min.   : 0.00   Min.   :1.00   Min.   : 5.00   tap:15  
 1st Qu.:2.000   1st Qu.: 8.25   1st Qu.:2.00   1st Qu.:11.00   cau:20  
 Median :4.000   Median :21.50   Median :2.25   Median :19.00   rg :15  
 Mean   :3.830   Mean   :23.28   Mean   :2.41   Mean   :21.96           
 3rd Qu.:5.375   3rd Qu.:33.00   3rd Qu.:3.00   3rd Qu.:30.75           
 Max.   :7.500   Max.   :60.00   Max.   :6.00   Max.   :57.00           
> summary(dri[1:2])
 paisag        area       
 tap:15   Min.   :  1.95  
 cau:20   1st Qu.:  6.75  
 rg :15   Median : 19.64  
          Mean   : 46.10  
          3rd Qu.: 43.36  
          Max.   :374.32