神农山白皮松不同龄组年轮-气候关系及PDSI重建

Abstract

We found that the tree rings have higher mean sensitivity( MS) via comparisons among tree-ring width chronologies of Pinus bungeana in different age-class from Shennong Mountains in Henan Province. The MS is standard deviation( SD) particularly high for the older trees. While the signal-to-noise ratio( SNR) and expressed population signal( EPS) for the young trees are higher than these of the older age-class trees. The SNR and EPS of the entire age-class is higher than individual age-class. We investigated the climate-growth responses for chronologies at different age-classes. It is revealed that there are some different responses to temperature and limiting influence to the younger age-class and the older age-class trees are more than the middle age-class trees( especially in current May). The tree-ring chronology explained53. 7% and 48. 3% of the instrumental variances of the mean temperature and precipitation in current May and previous September. This indicates that the correlation with temperature and precipitation of current May and previous September is the main limiting factor of growth of trees.The higher correlation between chronology and PDSI from previous November to current October than that to each month PDSI indicates that the correlation with temperature and precipitation during a year is stronger than that of individual month. The result of PDSI reconstructed from 1805 to 2005 a of all Pinus bungeana shows there lies a serious drought period from 1820's to 1840's. Significant multidecadal spectral peaks of 2. 3—5. 1a、36. 6a and 78. 7a were identified,and 2. 7a,2. 8a and 78. 7a were most significant with 0. 01 level. The periodic variation of dry and wet may potentially be the fingerprints of some climate change forcings such as solar activity,summer monsoon and ENSO activity.