摘要
对天目山两株柳杉(分别简称CF-1与CF-3),分别测定了不同方位上的树轮δ13C年序列。方差分析表明:天目山柳杉树轮δ13C值存在显著的方位差异和年际变化。不同方位上δ13C序列年际变化趋势基本一致,但极值出现的方位存在明显的年际漂移。同一树体各方位之间及两树体对应方位之间δ13C值均存在较好的相关性,表明区域环境背景条件对树轮δ13C值方位变化及年际变化趋势的影响是共同的。重点分析了局部环境差异对树轮δ13C方位变化的影响。不同坡向及树冠不同方位光照条件的差异是造成树轮δ13C值方位变化的主要原因。
The δ^13C annual series in different azimuths of two Cryptomeria fortunei Hooibrenk ex Otto et Dietr （for short CF-1 and CF-3, respectively） tree discs collected from west Tianmu Mountain,Zhejiang Province were determined based on cross-dated tree ring age. The analysis of variance shows that the δ^13C values in Cryptomeria fortunei tree rings varied along with azimuths significantly. At the same time, we found the differences of the average δ^13C values among azimuths were up to 0.56‰（for CF-3）-1. 34‰（for CF- 1） and the inter-annual variations in each azimuth were up to 0.9‰ - 1.63‰ （for CF-1） and 0.6‰-1. 1‰（for CF-3）. The δ^13C variability in space was the same as to the interannual. This indicates the study on the azimuth variation of δ^13 in tree rings has the same significance to that on the inter-annual variation. The statistical analysis proved that correlation coefficients are highly correlated, ranging from 0.4 to 0.87 for CF-1 and from 0.59 to 0.89 for CF-3 at significance level of α ： 0. 001 among different azimuths, respectively, as well as from 0.48 to 0.89 for the same azimuths between CF-1 and CF-3 tree discs at significance level of α ： 0. 001. This indicates that local environmental factors resulting in the δ^13C values varying along with azimuths significantly were similar for the two tree rings. In our study, we mainly analyzed the causes that resulted in the differences in the δ^13C values at the same azimuths for CF-1 and CF-3 as well as between the different azimuths for both CF-1 and CF-3. The differences of the solar radiation on different tilted surfaces and of the radiant condition （such as radiant intensity and efficient sunlight hours） at the different azimuths on crown of a tree were the most important factors leading to the δ^13C variations along with azimuths. The site conditions where the trees stand including latitude, longitude and altitude as well as gradient and slope orientation can affect the variations of the sunlight, microenvironment temperature, humidity and soil nutrient along the different radials and thus affect the variations of δ^13C values of tree rings along the azimuths. So the site conditions where the trees were collected are important factors leading to the azimuth variations of the δ^13C values in tree rings.
出处
《地理研究》
CSCD
北大核心
2006年第2期242-254,共13页
Geographical Research
基金
国家重点基础研究发展计划(2003CB415201)
国家自然科学基金资助项目(49771001)
关键词
天目山
树轮
Δ^13C
方位分布
成因探讨
Tianmu Mountain
tree ring
δ^13C
azimuth distribution
cause investigation
