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Table 4 Results of GAMs applied to inventory data from Germany

From: Tree species richness enhances stand productivity while stand structure can have opposite effects, based on forest inventory data from Germany and the United States of America

   Germany
Term Intercept a Std. error Sig. R-sq. (adj)
QI/QII f1 (Lon × Lat) 12.24 0.04 *** 0.19
f2 (Precip × Temp) ***
f3 (R × CVd) ***
f4 (SDI × dq) ***
QIII f1 (Lon × Lat) 0.32 0.00 *** 0.29
f2 (Precip × Temp) ***
f3 (SDI × R) ***
  1. Lon longitude, Lat latitude, Precip annual precipitation, Temp mean annual temperature, R species richness, CVd coefficient of variation of diameter, SDI stand density index, dq quadratic mean diameter (cm). Sig. Significance values: 0 ‘***’, 0.001 ‘**’, 0.01 ‘*’, 0.05