Environmental variable Contribution (%) Importance (%)
Variation coefficient of air temperature 2.3 4.2
The highest temperature in the hottest month 1.3 10.6
The lowest temperature in the coldest month 12.2 19.4
Annual range of temperature 0.2 1.7
Precipitation of the wettest month 53.8 40.3
The driest monthly precipitation 5.7 5.8
Altitude 20.9 11
Cation exchange capacity of topsoil 0.5 1.4
Electrical conductivity of topsoil 1.3 2.3
Gravel volume in topsoil 0.5 0.6
Organic carbon content in topsoil 0.8 1
Silt content in topsoil 0.7 1.7