Sum of monthly Tavg where Tavg >=5 deg C 0.243908 Solar interception 0.250168 Integer number of consecutive months where Tavg >= 5 deg C (Length of potential growing season) 0.317111 Precipitation during the driest quarter 0.483837 Carbon content of soil 0.484799 Precipitation during the coldest quarter 0.503849 Bulk density of soil 0.551181 Precipitation during the hottest quarter 0.554645 Precipitation during the wettest quarter 0.593992 Nitrogen content of soil 0.594284 Ratio of precipitation to potential evapotranspiration 0.736274 Day/night diurnal temperature difference 0.753235 Compound topographic index (relative wetness) 1.05024 Available water holding capacity of soil 1.29341 Temperature during the hottest quarter 1.78394 Temperature during the coldest quarter 2.43044