Climatic Signal in Earlywood and Latewood in Conifer Forests in the Monarch Butterfly Biosphere Reserve, Mexico

Abstract Earlywood (EW) and latewood (LW) chronologies can be used to analyze seasonal climatic variation. We constructed and analyzed total ring (RW), EW, and LW ring growth in Abies religiosa and Pinus pseudostrobus trees from the Monarch Butterfly Biosphere Reserve and evaluated their climatic signal (monthly precipitation and mean average, minimum and maximum temperatures) in the growth of tree rings by correlation and response function analyses. Precipitation during October and December of the previous year and during January, February, April, and May of the year of growth had a positive influence in the growth of both P. pseudostrobus and A. religiosa. Mean maximum temperatures had a negative effect on tree growth in both species. Additionally, growth of A. religiosa was more sensitive to variations of mean, minimum, and maximum temperatures in comparison with P. pseudostrobus, and monthly mean minimum temperature was positively correlated with EW and LW series in A. religiosa. We conclude that EW and LW growth of A. religiosa and P. pseudostrobus might be reduced by lower precipitation during the winter-spring season. Consequently, in the eventuality of warmer and drier climate during the latter season as projected by climate change scenarios, growth rates of A. religiosa could become severely affected, negatively impacting the overwintering habitat of the monarch butterfly (Danaus plexippus L.).