Call:  glm(formula = grow ~ soilanom + pre_forest + rmin + tmin + wind + 
    I(pre_forest^2), family = binomial(link = "logit"), data = dtab)

Coefficients:
    (Intercept)         soilanom       pre_forest             rmin  
     -0.8236615       -0.5895372        0.0575013       -0.0440670  
           tmin             wind  I(pre_forest^2)  
      0.1428048        0.0803416       -0.0006205