Revisiting the relationship between common weather variables and loblolly-shortleaf pine seed crops in natural stands

Seed production was monitored during 24 years using seed-collection traps i n loblolly-shortleaf pine (Pinus taeda L.-P. echinata Mill.) stands located in southeast Arkansas, north-central Louisiana, and southwest Mississippi on the southeastern Coastal Plain, USA. Sound seed production was correlate d with mean monthly precipitation and temperature from National Oceanic and Atmospheric Administration weather stations located near the seed-collecti on areas to determine the potential of weather factors in forecasting pine seed crops. Correlations were restricted to three critical periods in the p ine reproductive cycle - strobili primordia differentiation, pollination, a nd fertilization. The most important (P less than or equal to 0.05) variabl es correlated with pine seed production for combined locations were cumulat ive precipitation (r = +0.60) during July, August, and September at 27 to 2 5 months before seed dispersal and mean temperature (r = -0.45) in August a t 26 months before seed dispersal. Because multiple environmental factors c an negatively impact pine seed development during the two years following s trobili primordia differentiation, seed-production forecasts based on weath er variables should be verified by on-site cone counts during the summer pr eceding autumn seed dispersal.