RESUMO
We established 340-year chronologies of total ring width, early wood width, and late wood width with tree-ring samples of Pinus taiwanensis at high altitude collected from the western Tianmu Mountain in northern Zhejiang Province. According to the criterion that subsample signal strength (SSS) should be larger than 0.8, the reliable period was from 1810 to 2019. Through the correlation analysis between chronologies and climatic factors, we examined the responses of tree ring growth to climate. The results showed that radial growth of P. taiwanensis was more sensitive to temperature than to precipitation. Comprehensively considering the correlation analysis results for the raw and first-order difference series, early wood width was significantly correlated with the early growing season mean and maximum temperatures of the prior year, while late wood width with prior May and current September mean and maximum temperatures. The correlation pattern of total ring width was similar to that of early wood width, although at a low level. The optimal correlation was between early wood width and prior April-July mean temperature. Based on this relationship, April-July mean temperature of the Tianmu Mountain, East China was reconstructed for the period of 1809-2018 with an explained variance of 61.5%. Both the raw and first-order difference series passed the split sample calibration-verification test. The warm periods were 1809-1833 and 1965-2018, with a cold period in 1834-1964. Temperature had risen rapidly since the 1960s. From the standpoint of low frequency, it reached an unprecedented level since the 1980s over the past 210 years. Spatial correlation analysis showed that the reconstructed temperature series could represent temperature variations of East China, which had a good agreement with a reconstructed regional temperature series from East China. Our results showed that P. taiwanensis had a great potential for paleoclimate reconstruction in East China.
Assuntos
Pinus , Árvores , China , Clima , TemperaturaRESUMO
The knowledge about the existence of annual tree rings in tropical trees, which was already found at the beginning of the last century, was ignored by many scientists for a long time. Wood samples of 80 tree species from seven different sites belonging to Satipo and Chanchamayo provinces in Central Forest, Perú. Wood slices were taken at 1.30m height, following the Peruvian Technical Norms (NTP) 251-008, COPANT norms 30:1-019 and IAWA (1989). Results showed that 24 of the 80 tree species analyzed showed a potential for dendrocronological studies, 25 had problems for growth-rings analysis, and 31 did not have potential. The problems most frequently found were: barely visible or irregular ring growth, parenchyma bands and multiseriate rays difficult to be identified in rings growth. The “T” Student test showed that the significant variation in vessel and fiber diameters between growth zones (Early-wood and late-wood) of species with potential for dendrocronology, do have a periodic cells production, so is possible to suggest the annual formation of each growth-ring. However, those species without potential to dendrocronology may be influenced by of a lot of factors, such as biotic and abiotic conditions of environment, as well as the genetic aspect of each species.
El conocimiento acerca de la existencia de anillos anuales en árboles tropicales, se conoce desde principios del siglo pasado, pero fue ignorado por muchos científicos durante largo tiempo. La investigación fue realizada en el Laboratorio de Tecnología de la Madera e Industrias Forestales de la Universidad Nacional del Centro del Perú, con la finalidad de caracterizar anatómicamente los anillos de crecimiento de 80 especies arbóreas potenciales para estudios dendrocronológicos; provenientes de las provincias de Satipo y Chanchamayo en la Selva Central del Perú. Para el estudio se consideraron las normas COPANT 30:1-019, Normas Técnicas Peruanas (NTP) 251-008 y la Lista Estándar de la IAWA 1989. Entre los resultados más sobresalientes tenemos: el 30% de las ochenta especies estudiadas tienen buen potencial para estudios dendrocronológicos. La mayoría de estas especies, están delimitadas por una banda de fibras acortadas radialmente. Entre los problemas encontrados, se puede destacar la presencia de anillos con dificultad para ser visualizados, la presencia de anillos irregulares y la presencia de parénquima en bandas. Las características microscópicas, muestran que la variación significativa en dimensiones de fibras y vasos entre zonas de crecimiento (madera temprana y madera tardía), de las especies potenciales para dendrocronología, tienen una producción de células en forma periódica, lo que podría sugerir la formación anual de cada anillo.
