Precipitation during the wettest quarter 0 Day/night diurnal temperature difference 0.00586 Compound topographic index (relative wetness) 0.01138 Temperature during the hottest quarter 0.019548 Ratio of precipitation to potential evapotranspiration 0.10618 Carbon content of soil 0.128019 Precipitation during the coldest quarter 0.136126 Precipitation during the driest quarter 0.156563 Sum of monthly Tavg where Tavg >=5 deg C 0.160824 Nitrogen content of soil 0.204333 Bulk density of soil 0.224209 Integer number of consecutive months where Tavg >= 5 deg C (Length of potential growing season) 0.244939 Temperature during the coldest quarter 0.446246 Elevation 0.517553 Precipitation during the hottest quarter 0.556864 Solar interception 0.559521 Available water holding capacity of soil 0.7277