Nitrogen content of soil 1.23636 Sum of monthly Tavg where Tavg >=5 deg C 1.29999 Precipitation during the wettest quarter 1.59173 Precipitation during the driest quarter 1.6898 Carbon content of soil 1.69651 Bulk density of soil 1.92385 Day/night diurnal temperature difference 1.97685 Integer number of consecutive months where Tavg >= 5 deg C (Length of potential growing season) 2.32028 Available water holding capacity of soil 2.49144 Temperature during the hottest quarter 2.86066 Compound topographic index (relative wetness) 3.49793 Solar interception 3.79663 Precipitation during the coldest quarter 4.24135 Ratio of precipitation to potential evapotranspiration 4.9537 Temperature during the coldest quarter 6.39678 Precipitation during the hottest quarter 6.61816