Sun Changfeng, Liu Yu
Department of Earth and Environmental Science, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, No.28, Xianning West Road, Xi'an, 710049, China.
The State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, No.97 Yanxiang Road, Xi'an, 710061, China.
PLoS One. 2016 Aug 10;11(8):e0160938. doi: 10.1371/journal.pone.0160938. eCollection 2016.
The analysis of the tree radial growth response to climate is crucial for dendroclimatological research. However, the response relationships between tree-ring indices and climatic factors at different timescales are not yet clear. In this study, the tree-ring width of Huashan pine (Pinus armandii) from Huashan in the Qinling Mountains, north-central China, was used to explore the response differences of tree growth to climatic factors at daily, pentad (5 days), dekad (10 days) and monthly timescales. Correlation function and linear regression analysis were applied in this paper. The tree-ring width showed a more sensitive response to daily and pentad climatic factors. With the timescale decreasing, the absolute value of the maximum correlation coefficient between the tree-ring data and precipitation increases as well as temperature (mean, minimum and maximum temperature). Compared to the other three timescales, pentad was more suitable for analysing the response of tree growth to climate. Relative to the monthly climate data, the association between the tree-ring data and the pentad climate data was more remarkable and accurate, and the reconstruction function based on the pentad climate was also more reliable and stable. We found that the major climatic factor limiting Huashan pine growth was the precipitation of pentads 20-35 (from April 6 to June 24) rather than the well-known April-June precipitation. The pentad was also proved to be a better timescale for analysing the climate and tree growth in the western and eastern Qinling Mountains. The formation of the earlywood density of Chinese pine (Pinus tabulaeformis) from Shimenshan in western Qinling was mainly affected by the maximum temperature of pentads 28-32 (from May 16 to June 9). The maximum temperature of pentads 28-33 (from May 16 to June 14) was the major factor affecting the ring width of Chinese pine from Shirenshan in eastern Qinling.
树木径向生长对气候的响应分析是树木年轮气候学研究的关键。然而，不同时间尺度下树木年轮指数与气候因子之间的响应关系尚不清楚。本研究利用中国中北部秦岭华山的华山松（Pinus armandii）年轮宽度，探讨树木生长在日、候（5天）、旬（10天）和月时间尺度上对气候因子的响应差异。本文应用了相关函数和线性回归分析。树木年轮宽度对日和候气候因子表现出更敏感的响应。随着时间尺度减小，年轮数据与降水量以及温度（平均、最低和最高温度）之间最大相关系数的绝对值也增大。与其他三个时间尺度相比，候尺度更适合分析树木生长对气候的响应。相对于月气候数据，年轮数据与候气候数据之间的关联更显著、准确，基于候气候的重建函数也更可靠、稳定。我们发现，限制华山松生长的主要气候因子是第20 - 35候（4月6日至6月24日）的降水量，而非广为人知的4 - 6月降水量。候尺度也被证明是分析秦岭西部和东部气候与树木生长的更好时间尺度。秦岭西部石门山油松（Pinus tabulaeformis）早材密度的形成主要受第28 - 32候（5月16日至6月9日）最高温度的影响。秦岭东部石人山油松年轮宽度的主要影响因子是第28 - 33候（5月16日至6月14日）的最高温度。
