Study On Japanese Yew (Taxus Cuspidata) Dendrochronology

Japanese yew(Taxus cuspidata) was a national key protective and endangered wild plant. Based on tree ring index datas,studied those meteorological factors which affected tree growth and the response to global climate change.Understanding the biological characteristics and the response to climate change was very significant,as well as the endangered mechanism of Japanese yew.A 300-year Japanese yew chronology was developed in Muling Japanese yew Nature Reserve(1700-2005 year).Over the 300 years,the tree growth had two peaks,one was about 1770,and the other was about 1930.In addition,two low-value growth areas,about 1748 and 1813.Through the archives we only found the floods record in 1931 and 1932 years. It was a downward fluctuations of the radial growth pattern,which had reached a natural mature in 160 years,and reached the maximum age of 370 years in the samples.DBH,tree height and age had an obvious synchronization changes on the overall,but differences between single wood.Correlation analysis between tree ring index and climatic variables indicated that the minimum and mean monthly temperature in winter and spring were the mainly limited factors of Japanese yew radial growth.The cloud cover in growing season and vapor press in dormancy season had positive effect on radial growth of Japanese yew while relative sunshine hour and wind speed had negative influence on radial growth of Japanese yew,those revealed the biological characteristics of Japanese yew.Suitable habitat had a direct impact on changes in the structure of natural populations and the development of species,climate warming may caused a recession in the growth.In addition,human poaching,deforestation accelerated the species endangered would be another important reason.Used standard chronology reconstructed over the past 300 years of summer precipitation in June,it showed that,since the mid 18th century,which was large fluctuations in precipitation,and gentle after mid 20th century,but it did found the existence of slow drying trend in this region.Obvious characteristics of droughts and floods with stage and mass characteristics,the interval stage of severe droughts and floods was relatively short and concentration,while mild drought and flood events was scattered.It had 2-4,10-32 and 8-10 yr prominent periodicities,which had a similar cycle with global climate events such as ENSO,sunspot etc.It indicated that precipitation in this region was affected by the regional and global large-scale impacts of climate change.Comparison between Japanese yew tree-ring index and Wilson reconstructed northern hemisphere temperature,it could not adapt to rapid changes in temperatures.At the same time,human factors impact led to a loss of suitable habitat and deforestation a large had accelerated the process of endangered species.By MTM and Morlet 6 analysis,the radial growth of Japanese yew had 86,60,29 and 3.4 yr prominent periodicities,which mainly focused on two fast growth periods of 1740-1830 and 1900-1960 year.Japanese yew radial growth could be related to the influences of global climate events such as ENSO,sunspot etc.