干旱对庐山日本柳杉径向生长量的影响

Effects of Drought on Radial Growth of Cryptomoria japonica

【目的】研究选用SPEI(标准化降水蒸散指数)分析庐山自然保护区干旱状况,及其对日本柳杉(Cryptomoria japonica)径向生长的影响,为庐山日本柳杉的生长和林分经营等提供一些理论依据。【方法】通过建立STD(树轮年表)的树轮宽度指数来反映庐山日本柳杉的径向生长量情况,计算分析SPEI来反映庐山自然保护区近几十年来的干旱变化情况。采用Mann-Kendall突变检验、相关性检验分析、小波分析、多元回归等方法探讨研究庐山日本柳杉径向生长量以及干旱变化。【结果】研究发现:(1)在1967—1970年、1977—1981年、2004—2012年庐山日本柳杉生长情况低于预期标准;(2)标准化降水蒸散指数随时间尺度的增大,波动周期越来越长较长,相对而言,SPEI12更为集中、波动较小,能够更好更准确的反映干旱年变化特征。SPEI12反映出庐山1967—1970年达到重旱程度,1978—1980年特旱,2002—2003年中旱,2005—2013年中旱至重旱;(3)树轮宽度指数与月尺度、半年尺度标准化降水蒸散指数呈显著正相关,与年尺度标准化降水蒸散指数呈极显著正相关关系。同时树轮宽度指数与上年8月至当年6月年尺度标准化降水蒸散指数呈显著正相关,其中与当年5月呈极显著正相关。【结论】日本柳杉生长量的周期变化与干旱周期变化接近,日本柳杉生长量变化相对干旱的变化会持续一到两年左右。

[Objective]In this study,SPEI(The Standardized Precipitation Evapotranspiration Index)was used to analyze the drought status of the Lushan Nature Reserve and its influence on the radial growth of Cryptomoria japonica,and provide some theoretical basis for the growth and forest management of the Cryptomoria japonica.[Method]The tree-ring width index of the standardized chronology(STD)was established to reflect the radial growth of the Cryptomoria japonica,the calculation and analysis of SPEI were conducted to reflect the drought changes in the Lashaun Nature Reserve in recent decades.Mann-Kendall mutation test,correlation test analysis,wavelet analysis,multiple regression and other methods were used to investigate the radial growth of Cryptomoria japonica changes in drought.[Result]The results showed that:(1)the growth of Cryptomoria japonica in Lushan was lower than expected in 1967-1970,1977-1981 and 2004-2012;(2)the standardized precipitation evapotranspiration index increased with time scale,and the fluctuation period was relatively long.Relatively speaking,SPEI12 is more concentrated and less volatile,and can better reflect the characteristics of drought years.SPEI12 reflects the degrees of drought in Lushan from 1967 to 1970,the extreme drought in 1978-1980,the drought in 2002-2003,and the drought to heavy drought in 2005-2013;(3)tree-ring width index showed a significant positive correlation with monthly scale and semi-annualized scale of SPEI,and it was significantly positively correlated with the annualized scale of SPEI.At the same time,the tree-ring width index was significantly correlated with the annual SPEI from August of last year to June,which was significantly correlated with the positive electrode in May of that year.[Conclusion]The periodic change of growth of Cryptomoria japonica is close to that of drought,and the changes in Cryptomoria japonica growth relative to the drought will last about one to two years.