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Introduction: Basal area increment (BAI) is an indicator of forest productivity that varies with tree age and site factors such as soil and climate. Objective: To generate tree-ring width index (RWI) and BAI chronologies of Pinus hartwegii Lindl., relate them to climatic variables, and study the variation in BAI at different altitudes and aspects. Materials and methods: Four observation sites were identified, combining northwest (NW) and southwest (SW) aspects, as well as altitudes of 3 800 and 3 700 m. At each site, the temperature was recorded every four hours for 435 days and 32 growth ring segments were collected using a Pressler´s increment borer. Tree-ring width was measured and BAI was calculated; the correlation index between these indicators and the climatic variables was Pearson’s correlation coefficient. Results and discussion: The RWI series from the four observation sites had an intercorrelation of 0.33 (P < 0.01). Two low-growth periods were detected, one between 1950 and 1960 and the other between 1990 and 2005. Site SO-3700 had a different growth pattern, due to a second growth phase beginning in 1978, possibly a benefit resulting from increased temperature. The previous autumn temperature, spring temperature and April-September precipitation of the current year explained the variation in BAI (P < 0.05). Conclusion: The BAI of P. hartwegii could respond favorably to the predicted increases in temperature at an altitude of 3 700 m with southwest aspect.

Introduction: Geomorphological processes, such as flash floods, affect the natural growth of trees. From the dating of disturbances in growth rings, historical events useful for the prevention and mitigation of natural hazards were reconstructed. Objectives: To determine the dendrogeomorphological potential of Pinus ponderosa Douglas ex C. Lawson to date and reconstruct flash floods in Los Picos de Davis, Coahuila. Materials and methods: Samples were collected from 19 dead and living trees with evidence of disturbance (impact scars, growth suppression and compression wood). The samples were prepared, dated and analyzed based on dendrogeomorphological techniques. The reconstructed flash floods were related to historical climate information from hurricanes, tropical cyclones and precipitation. Results and discussion: We were able to date 68 % of the samples with evidence of disturbance; the correlation between growth series was significant (r = 0.403; P < 0.001). The most common anomalies were in the form of scars (72 %), growth suppression (20 %) and compression wood (8 %). Ten flash floods were reconstructed. The causative processes were flash floods, caused by extreme hydrometeorological phenomena, including hurricanes “Alex” in 2010, “Dolly” in 2008 and “Claudette” in 2003. There is synchrony between geomorphological processes and hydrometeorological phenomena. Conclusions: P. ponderosa ring disturbances are useful to reconstruct the frequency and distribution of geomorphological processes.

Introduction: In the United States of America, forest pests are associated with climate variability. Such studies are scarce in Mexico. Objectives: To create a data base of historical outbreaks of bark beetles and analyze their relationship with drought. Materials and methods: Historical records of outbreaks of bark beetles were obtained from official documents in Mexico, Guatemala, and Honduras. Dendroclimatic indices were used as a climate proxy. The relationship between pest outbreaks and climate was analyzed with the Superpose Epoch Analysis (SEA). Results and discussion: A database of 120 years (1895-2015) of bark beetle outbreaks was created. The most frequent species were Dendroctonus mexicanus Hopkins, Dendroctonus frontalis Zimmermann and Dendroctonus adjunctus Blandford. A total of 106 records of outbreaks in 15 states of Mexico were recorded during the period 1903-2015; 16 outbreaks in Guatemala during the period 1895-2013, and 15 outbreaks in Honduras during the period 1962-2015. Historically, outbreaks were recorded in years with below-average precipitation (550 mm) and have increased since 1970. The SEA determined that bark beetle outbreaks in Mexico, Guatemala and Honduras were recorded during dry years (P 0.05) of NINO 3 and PDSI (Palmer Drought Severity Index) and significant negative indices (P Conclusion: A significant relationship was determined between bark beetle outbreaks and drought conditions for the last 120 years.

La reconstrucción histórica de los regímenes del fuego, fundamentada en métodos dendrocronológicos, aporta información para el entendimiento de este fenómeno. Con el objetivo de reconstruir la historia de incendios en un bosque de pino-encino en Mezquital, Durango, se colectaron 78 muestras de Pinus durangensis , P. ar i z o n i c a, P. ayacahuite, P. teocote y Pseudotsuga menziesii con cicatrices de incendios; 73 y 27 % de las muestras se tomaron de árboles vivos y muertos, respectivamente. Se fecharon 75 muestras (96 %) y 535 cicatrices. Los regímenes se reconstruyeron de 1746 a 2013; el año 1779 representó el primer registro de incendio. Se reconstruy ó un intervalo medio de frecuencia de incendios (MFI) de 2.0 años y un intervalo medio de probabilidad de Weibull (WMPI) de 1.8 años, cuando todas las cicatrices fueron incluidas; al considerar 25 % o más (incendios extensos) se determinaron MFI y WMPI de 7.0 y 5.9 años, respectivamente. En primavera se categorizó 92.2 % de los incendios y solo 7.8 % en el verano. No hubo inf luencia significativa ( P < 0.05) de la lluvia y de El Niño Oscilación del Sur (ENSO) en la frecuencia; sin embargo, los incendios extensos se asociaron positivamente a la disminución de lluvia y eventos ENSO (fase La Niña).

Las especies forestales como Pseudotsuga menziesii (Mirb.) Franco son sensibles al clima y muestran anillos de crecimiento claramente definidos. La selección cuidadosa de árboles dominantes con fuste circular permite el análisis de tendencias de crecimiento arbóreo. En este estudio se utilizaron mediciones directas del incremento del área basal (IAB) para explicar las periodicidades biológicas y elaborar predicciones del crecimiento en el abeto Douglas-fir que crece en el oeste de México. Para eliminar el efecto de la edad en el crecimiento de los árboles se hizo un análisis en términos de la edad del cámbium. Los resultados mostraron correlación significativa (P < 0.05) entre IAB y la precipitación de enero a julio. Además, se encontraron periodicidades de 7, 21, 27 y 60 años en el crecimiento de los árboles; el periodo de 60 años fue determinante para la construcción de un modelo ARIMA (0,1,1) para realizar predicciones del IAB en las próximas décadas. Las proyecciones del crecimiento proponen una reducción del IAB en árboles maduros dominantes en las próximas décadas. Dicha reducción es un resultado inesperado, debido a que el IAB en árboles dominantes permanece constante hasta una edad biológica de senescencia. Los resultados concuerdan con una tendencia general de reducción en el crecimiento en otros bosques del mundo debido a estrés hídrico, lo cual sugiere que la variabilidad climática futura puede empeorar la condición de salud del abeto Douglas-fir de los bosques del norte de México.

The drought of the past few years in north-central Mexico underscores the need for extensive hydroclimatic data that can reveal fluctuations and trends over time, in order to establish water resource planning and mitigation measures. Using dendrochronological techniques, an 800-year streamflow reconstruction was developed for the upper Nazas River watershed in Durango. The reconstruction showed high inter-annual and multiannual hydroclimatic variability and decadal droughts were detected in the 1250s, 1320-1340s, 1370-1380s, 1440-1450s, 1460-1470s, 1650-1660s, 1710-1730s, 1790-1810s, 1920-1940s, 1970-1980s, and 1990s. Some of the droughts were longer and of higher intensity than ones observed in climate records. Extreme flow events were detected in the years 1212, 1229, 1242, 1245, 1271, 1313, 1404, 1427, 1451, 1504, 1520, 1563, 1566, 1620,1671, 1681, 1735, 1816, 1833, 1869, 1920, 1956, 1959, and 1992, and they were linked with the El Nino–Southern Oscillation (ENSO) warm phase. Water decision-makers in the Comarca Lagunera region could use this information to establish probabilities of droughts and occurrence of extreme runoff events for management purposes.

Resumen es: Se reconstruyo la precipitacion invierno-primavera de 219 anos (1792-2010) de la Reserva de la Biosfera Sierra de Manantlan (RBSM), Jalisco, Mexico, empl...

Pico de Tancitaro National Park is the most important source of water for the collection and recharge cycle of the aquifers located in western region of the state of Michoacan. Understanding the precipitation variability throughout time is crucial. Nonetheless, there is a lack of extensive and quality series on climatic data. For this reason, this work established the following objectives: 1) to reconstruct the precipitation variability for Pico de Tancitaro National Park based on the Abies religiosa growth rings, and 2) to analyze the drought frequency during the XXth century and the first decade of the XXIst century. Thus, some A. religiosa samples were taken and dated using standardized dendrochronological techniques. The quality of the dating as well as the quality of its climatic response were verified with the COFECHA software. These series presented a significant correlation (r=0.473; P < 0.01), which indicates their potential to generate dendroclimatic series. The precipitation of the last 127 years (1884-2010) was reconstructed. The severest droughts were reconstructed for the 1890-1896, 1948-1956, 1967-1971, 1982-1989, and 1998-2004 periods. It was also found that the Paricutin volcano eruption (1943) had a significant effect on regional climate.

Se reconstruyó la precipitación invierno-primavera de 219 años (1792-2010) de la Reserva de la Biosfera Sierra de Manantlán (RBSM), Jalisco, México, empleando los anillos anuales de Pinus douglasiana (Mtz.) como “proxy”. La sequía de mediados del siglo XX (1941-1963) fue la más severa del periodo estudiado. El índice multivariado de El Niño Oscilación del Sur (ENSO; 1959-2010) y el índice de ancho del anillo de P. douglasiana mostraron correlación significativa (r = 0.4542; P < 0.05) de los meses de enero-junio, con mayor correlación en los meses de enero (r = 0.4337; P < 0.0001) y marzo (r = 0.4310; P < 0.0001). Las teleconexiones de ENSO en la región varían a través del tiempo; de enero a junio, los eventos El Niño están asociados con precipitaciones mayores que el promedio, mientras que los eventos La Niña muestran lo contrario.

Con el objetivo de conocer el impacto de El Niño Oscilación del Sur en la parte alta del Nazas, se relacionaron las series de precipitación reconstruida y los índices de El Niño 3.4. Para tal efecto, se utilizaron gráficos de resolución anual y sus espectros potenciales de ondeleta. Los resultados indican que durante los últimos 100 años El Niño ha influido de manera significativa (P