Dendroclimatic analysis of Pinus pseudostrobus and Pinus devoniana in the municipalities of Áporo and Zitácuaro (Michoacán), Monarch Butterfly Biosphere Reserve | Análisis dendroclimático de Pinus pseudostrobus y Pinus devoniana en los municipios de Áporo y Zitácuaro (Michoacán), Reserva de la Biósfera de la Mariposa Monarca

Inglés. This article presents the first study on dendroclimatology of Pinus pseudostrobus and Pinus devoniana in the state of Michoacán (Mexico), specifically in the municipalities of Áporo and Zitácuaro, both municipalities within the Monarch Butterfly Biosphere Reserve (MBBR). The sampling in Áporo, northwest of the MBBR, was held in Los Ejidos del Rincón del Soto and Arroyo Seco, in Sierra Chincúa (May 2011). In Zitácuaro, southwest of the reserve, a sampling was performed in the Ejido de San Juan de Zitácuaro, in the area of Ocotal and Palma, and Meso Sedano (June 2011). There were a total of 38 Pinus pseudostrobus and 12 Pinus devoniana sampled in both areas of the study and distributed in 28 trees in the municipality of Áporo and 22 in Zitácuaro. Two samples per tree were taken at 1.3 m height, resulting in a total of 100 tree cores. The dendrochronological series in Áporo for the species Pinus pseudostrobus were extended to 62 years (1949-2010) and for Pinus devoniana 86 years (1925-2010); and the series in Zitácuaro for Pinus pseudostrobus and Pinus devoniana were extended to 47 years (1964-2010) and 44 years (1967-2010), respectively. The ring chronologies were validated using the program COFECHA, which calculates the cross correlations between individual series of the tree-growth, five series were eliminated due to very low or negative correlations. The climate data from Zitácuaro were obtained from two weather stations located in the same municipality. And, in the case of Áporo, the data was obtained from stations located in Senguio. The growth rates related to the climate were obtained by removing the growth trend of each tree due to the age, size and other factors such as the competition, using the program ARSTAN. The following statistics were used to evaluate the quality of the residual chronologies and to determine the potential dendrochronology of species for the different populations: the average correlation between series (Rbar), the signal expressed by the population (EPS), medium sensitivity (MS), and the auto-correlation of first order (AC). To analyze the correlation and the function of response between the radial growth and climate variables, the waste medium chronologies of the growth rates for both species, and the records of temperature and precipitation, were evaluated through the Dendroclim2002, which determines the period of the year that most influences the radial growth of Pinus in relation to monthly climate data. In order to establish the climatic parameters that control the radial growth of the studied species, the Pinus pseudostrobus was found to be the potential series to perform the dendrochronological study in Zitácuaro. The value of the series of Pinus devoniana is slightly lower (0.81) than the acceptance value (0.85). The series of radial growth were compared with the climate records of monthly precipitation, average monthly temperature, and average maximum and minimum monthly temperatures. Correlation functions indicate that the width of the rings of both species is regulated significantly by rainfall and the average maximum temperature in Zitácuaro. Both species react similarly to the climate, but with some differences. There is a positive relationship between radial growth of Pinus pseudostrobus and the increasing rainfall in April of the current year; and there is a negative relationship between radial growth and the increasing average maximum temperature in August the previous year. For Pinus devoniana there is a negative relationship between radial growth and the increasing rainfall in November of the previous year, and a positive relationship in February of the current year; and there is a negative relationship between radial growth and the increasing average of maximum temperature in July and August last year.

Español; castellano. Se presenta el primer estudio sobre dendroclimatología de Pinus pseudostrobus y Pinus devoniana en el estado de Michoacán (México). El estudio se realizó en los municipios de Áporo y Zitácuaro de la Reserva de la Biosfera de la Mariposa Monarca (RBMM). Se colectaron cien testimonios de madera tomados a 1.3 m de altura del árbol, repartidas en los ejidos del Rincón del Soto y Arroyo Seco (Áporo), y en el ejido de San Juan de Zitácuaro. Las series dendrocronológicas en Áporo para la especie Pinus pseudostrobus se extendió a 62 años (1949-2010) y para Pinus devoniana 86 años (1925-2010); y las series en Zitácuaro para Pinus pseudostrobus y Pinus devoniana se extendieron a 47 años (1964-2010) y 44 años (1967-2010), respectivamente.Con el objetivo de establecer los parámetros climáticos que controlan el crecimiento radial de las especies estudiadas, se encontró que la serie potencial para hacer estudios dendrocronológicos es la de Pinus pseudostrobus en Zitácuaro. El valor de la serie de Pinus devoniana se encuentra ligeramente por debajo (0.81) del valor de aceptación (0.85). Las series de crecimiento radial se compararon con datos climáticos de precipitación mensual, temperatura media mensual, temperatura máxima y mínima medias mensuales, de estaciones meteorológicas cercanas al área en estudio. Las funciones de correlación indican que la anchura de los anillos de ambas especies está regulada significativamente por la precipitación y la temperatura máxima media en Zitácuaro. Ambas especies reaccionan semejantemente con el clima, pero con algunas diferencias. Para Pinus pseudostrobus hay una relación positiva del crecimiento radial con el aumento de precipitación en el mes de abril del año actual; y hay una relación negativa del crecimiento radial con el aumento de temperatura máxima media en el mes de agosto del año previo. Para Pinus devoniana hay una relación negativa del crecimiento radial con el aumento de precipitación en el mes de noviembre del año previo, y una relación positiva en febrero del año actual; y hay una relación negativa del crecimiento radial con el aumento de temperature máxima media en los meses de julio y agosto del año previo.