Nitrogen content of soil 1.15321 Precipitation during the driest quarter 1.45801 Precipitation during the wettest quarter 1.53756 Carbon content of soil 1.6272 Sum of monthly Tavg where Tavg >=5 deg C 2.00447 Bulk density of soil 2.11469 Integer number of consecutive months where Tavg >= 5 deg C (Length of potential growing season) 2.65784 Available water holding capacity of soil 2.84476 Compound topographic index (relative wetness) 2.88046 Day/night diurnal temperature difference 3.03177 Temperature during the hottest quarter 3.11033 Precipitation during the coldest quarter 3.68645 Precipitation during the hottest quarter 4.07305 Ratio of precipitation to potential evapotranspiration 4.47812 Temperature during the coldest quarter 5.87054 Solar interception 6.11429