Descriptive statistics for the nineteen pairs of TRW and MXD tree-ring data from Siberia

Table 1. Descriptive statistics for the nineteen pairs of TRW and MXD tree-ring data from Siberia. Species codes: PISY (Pinus sylvestris), LAGM (Larix gmelinii), PIOB (Picea obovata), LASI (Larix sibirica), LACA (Larix cajanderi). n: number of cross-dated tree-ring series at each site. rTRW|MXD: correlation between the TRW and MXD chronologies over the years in the period column. \bar {r}: mean interseries correlation of pre-whitened series. EPS: expressed population signal. : first-order autocorrelation. Abstract Different methods have been developed for measuring carbon stocks and fluxes in the northern high latitudes, ranging from intensively measured small plots to space-based methods that use reflectance data to drive production efficiency models. The field of dendroecology has used samples of tree growth from radial increments to quantify long-term variability in ecosystem productivity, but these have very limited spatial domains. Since the cambium material in tree cores is itself a product of photosynthesis in the canopy, it would be ideal to link these two approaches. We examine the associations between the normalized differenced vegetation index (NDVI) and tree growth using 19 pairs of tree-ring widths (TRW) and maximum latewood density (MXD) across much of Siberia. We find consistent correlations between NDVI and both measures of tree growth and no systematic difference between MXD and TRW. At the regional level we note strong correspondence between the first principal component of tree growth and NDVI for MXD and TRW in a temperature-limited bioregion, indicating that canopy reflectance and cambial production are broadly linked. Using a network of 21 TRW chronologies from south of Lake Baikal, we find a similarly strong regional correspondence with NDVI in a markedly drier region. We show that tree growth is dominated by variation at decadal and multidecadal time periods, which the satellite record is incapable of recording given its relatively short record.表1. 西伯利亚地区19组树木年轮宽度（TRW, Tree-Ring Width）与最大晚材密度（MXD, Maximum Latewood Density）数据的描述性统计量。物种代码：PISY（欧洲赤松 *Pinus sylvestris*）、LAGM（兴安落叶松 *Larix gmelinii*）、PIOB（西伯利亚云杉 *Picea obovata*）、LASI（西伯利亚落叶松 *Larix sibirica*）、LACA（卡氏落叶松 *Larix cajanderi*）。$n$：各采样点经交叉定年的树木年轮序列数量。$r_{ ext{TRW|MXD}}$：时段列中各年份TRW与MXD年表的相关系数。$ar{r}$：预白化序列的平均序列间相关系数。$ ext{EPS}$：种群信号表达量（Expressed Population Signal）。$phi_1$：一阶自相关系数。摘要 已开发出多种方法用于北极高纬度地区的碳储量与碳通量测定，涵盖从密集采样的小型样地，到利用反射率数据驱动生产效率模型的星基遥感方法。树轮生态学领域通过径向生长增量样本量化生态系统生产力的长期变异，但此类研究的空间覆盖范围极为有限。由于树芯中的形成层材料本身是冠层光合作用的产物，将这两类研究路径相结合堪称理想方案。本研究借助西伯利亚广大区域内的19组树木年轮宽度（TRW）与最大晚材密度（MXD）数据，探究归一化差分植被指数（NDVI, Normalized Difference Vegetation Index）与树木生长的关联。研究发现NDVI与两种树木生长指标均存在稳定相关，且MXD与TRW之间未呈现系统性差异。在受温度限制的生物区域中，我们观测到树木生长的第一主成分与MXD、TRW对应的NDVI值之间存在极强的对应关系，表明冠层反射率与形成层生长存在广泛关联。借助贝加尔湖以南地区的21条TRW年表网络，我们在显著更为干旱的区域也发现了与NDVI类似的强区域对应关系。本研究表明，树木生长的变异主导性地表现为年代际及多年代际尺度的波动，而卫星观测记录因时长相对较短，无法捕捉这类尺度的变化。