兴隆山油松树轮宽度与太阳年辐射总量的关系分析

Analysis on the relationship between tree ring width of Pinus tabulaeformis Carr. and solar annual average radiation in Xinglong Mountain

利用采自兰州市榆中县兴隆山自然保护区的油松树轮资料,建立了研究区域的树轮STD年表。并利用1960—2016年该区域的太阳年辐射总量资料,将油松树轮宽度与太阳年辐射总量的年际变化趋势相比较,利用Pearson分析初步探究其相关性。采用滑动相关分析等方法,探讨了研究区域油松树轮宽度与太阳年辐射总量的关系随时间的变化。结果表明:树轮宽度与太阳年辐射总量在年际上存在较为一致的变化趋势,且该树轮宽度标准化年表对研究区域太阳年辐射总量具有一定的指示意义。在此基础上设计转换方程,利用多元回归技术重建了研究区1640—2015年的太阳年辐射总量变化历史,重建序列的方差解释量为36.9%(F=15.206,p <0.0001)。在过去的376年中,太阳年辐射总量表现出明显的年际间频繁波动,并且极值年出现的频率较高,其中极高辐射总量年有70年,极低辐射总量年有68年,分别占整个时段的18.67%和18.04%。

Background,aim,and scope Radiation research is essential for better understanding past climate change,and in various climatic factors,the amount of radiation is also an important indicator of the growth of trees.However,involving the tree-ring data and radiation changes in the research results are still relatively rare.Tree-rings have been considered as one of the best known archives in the past climate research with their features such as strong continuity,high resolution and easy access to duplicate.Materials and methods Employing the standard methods sponsored by the International Tree-Ring Data Bank(ITRDB),44 Chinese pine tree(Pinus tabulaeformis Carr.)cores were collected from 22 trees in Mt.Xinglong in north-central China(103°50′-104°10′E,35°38′-35°58′N,annual average radiation is 5122 MJ?m?2)during November 2016.In the laboratory,the standard dendrochronological processes were employed,and the ring-widths of each core were measured with a precision of 0.001 mm.After cross-dating,the COFECHA program was used to control the quality of cross-dating.Three tree ring chronologies(STD,RES and ARS chronologies)were carried out with the ARSTAN program.To clarify the climatic conditions in our study area,the total annual radiation data from 1960 to 2016 were extracted from the Yuzhong station(104.15°E,35.87°N,1875 m a.s.l.).The treering widths and the total annual radiation were compared by Pearson correlation analysis to preliminarily identify their relationship.The changes of tree-ring chronology and total radiation were also explored by sliding correlation analysis.Based on the correlation analysis,multivariate regression analysis was used to establish the conversion equation of the annual total radiation of the STD chronology.And the conversion equation was used to reconstruct the annual total radiation from 1640 to 2015 in the historical period.Results In the sliding correlation analysis,11-year is chosen for the sliding window.Since the solar sunspot activity period is 11 years,if the sunspots are relatively large,the sun activity will be more intense,the radiation sunshine hours and the solar radiation all will increase.Therefore,the sliding correlation coefficient calculated by the 11-year sliding window can better represent the effect of radiation intensity on tree-ring width.The correlation coefficient r(r0=0.338,p<0.01,n=57)between tree-ring width and annual radiation in the region from 1960 to 2016 is tested by the confidence degree<0.01,indicating that the total annual radiation and the tree-ring width have a more significant positive correlation.The sliding correlation coefficient shows that the relationship between tree-ring width and total annual radiation is always positive correlation between 1970 and 2016.The positive correlation in 1970-1991 reaches the significance level of 0.05,and the positive correlation is significant,which shows that the change of total annual solar radiation is always the main factor affecting the variation of tree-ring width.From 1992 to 2016,the sliding correlation coefficient fluctuates between 0.3-0.5 and tends to be stable.The factors influencing the radial growth of Pinus tabulaeformis Carr.tree-ring width become more complicated,but the relationship between the change of annual total radiation and the radial growth of tree-ring width reaches a steady state.It is significant to indicate the change of the annual total radiation by Pinus tabulaeformis Carr.tree-ring width in this region.Using multivariate regression technique,the history of the change of annual total radiation is reconstructed in the study area from 1640 to 2015.During the past 376 years,the annual total amount of radiation shows significant inter-annual fluctuations.There are periods below average during the reconstruction period:1646-1668,1705-1727,1739-1751,1758-1774,1832-1846,1856-1875,1923-1944,1984-2010;there are higher periods:1683-1704,1728-1738,1752-1757,1775-1812,1876-1922,1945-1983.The rest years’values are close to the average.At the same time,there is a high frequency of extremes,of which 70 years are very high and 68 years are very low,accounting for 18.67%and 18.04%of the total period(1640-2016)respectively.Discussion During the study years,tree-ring width and total annual radiation always have positive correlation.The growth of Pinus tabulaeformis Carr.is sensitive to the change of total annual radiation.From view of physiology,when in a certain radiation intensity range,adequate light provides the heat required for tree growth and promotes the plant photosynthesis,which is conducive to the accumulation of organic matter,and nutrients reserved for the next year while ensuring the growth consumption,thus it is easy to form a wide tree-ring.Meanwhile,the total annual solar radiation can affect the radial growth of trees by affecting the temperature and precipitation.According to the geographical location and climate characteristics,Mt.Xinglong is located in the east,the most western end of the monsoon region,the boundary between semi-arid and semi-humid areas,which has a temperate and semi-humid climate.Water is the main limiting factor of plant growth in this area.When the amount of precipitation is constant,if the amount of solar radiation increases,it will accelerate the evaporation of water and reduce the soil water content,thus limiting the normal growth of plants.In addition,changes in the total annual solar radiation will cause changes in temperature.Changes in temperature will directly affect photosynthesis,but also indirectly adjust the plant’s respiratory and transpiration,therefore,it also has an impact on the physical activity of trees.Thus,the width of tree-rings can truly record the favorable or unfavorable changes of solar radiation to its growth,and reflect the change of total annual solar radiation.Conclusions The tree-ring width chronology of Mt.Xinglong can indicate the change in the total amount of annual radiation in the region for a period of 1970-2016.The radial growth of Pinus tabulaeformis Carr.is more sensitive to the change of total annual radiation.It further indicated that the tree chronology has a certain significance to the total annual radiation in the study area.According to the reconstruction results in the study area from 1640 to 2015,the annual total amount of radiation shows significant inter-annual fluctuations during the past 376 years.And there are periods below average during the reconstruction period:1646-1668,1705-1727,1739-1751,1758-1774,1832-1846,1856-1875,1923-1944,1984-2010;there are higher periods:1683-1704,1728-1738,1752-1757,1775-1812,1876-1922,1945-1983.The rest years’values are close to the average.At the same time,there is a high frequency of extremes,of which 70 years are very high and 68 years are very low,accounting for 18.67%and 18.04%of the total period(1640-2016)respectively.Recommendations and perspectives Due to the shortage of historical data related to annual radiation in this area,historical records can not be used to corroborate the reliability of the results.Therefore,future research on historical solar radiation in this region is still very necessary.