NOAA/WDS Paleoclimatology - Fischer - Nordrhein-Westfalen/Eifel dre07 - QUPE - ITRDB GERM179

Growth responses to twentieth century climate variability of the three main European tree species Fagus sylvatica, Quercus petraea, and Pinus sylvestris within two temperate low mountain forest sites were analyzed, with particular emphasis on their dependence upon ecological factors and temporal stability in the obtained relationships. While site conditions in Central (~51°N, 9°E, KEL) and West (50.5°N, 6.5°E, EIF) Germany are similar, annual precipitation totals of ~700 mm and ~1,000 mm describe a maritime-continental gradient. Ring-width samples from 228 trees were collected and PCA used to identify common growth patterns. Chronologies were developed and redundancy analysis and simple correlation coefficients calculated to detect twentieth century temperature, precipitation, and drought fingerprints in the tree-ring data. Summer drought is the dominant driver of forest productivity, but regional and species-specific differences indicate more complex influences upon tree growth. F. sylvatica reveals the highest climate sensitivity, whereas Q. petraea is most drought tolerant. Drier growth conditions in KEL result in climate sensitivity of all species, and Q. petraea shifted from non-significant to significant drought sensitivity during recent decades at EIF. Drought sensitivity dynamics of all species vary over time. An increase of drought sensitivity in tree growth was found in the wetter forest area EIF, whereas a decrease occurred in the middle of the last century for all species in the drier KEL region. Species-specific and regional differences in long-term climate sensitivities, as evidenced by temporal variability in drought sensitivity, are potential indicators for a changing climate that effects Central-West German forest growth, but meanwhile hampers a general assessment of these effects.

本研究针对欧洲三大主要树种——欧洲山毛榉（Fagus sylvatica）、无梗花栎（Quercus petraea）与欧洲赤松（Pinus sylvestris），在德国两处温带低山森林样地内，对其20世纪气候变异的生长响应开展分析，重点探讨其对生态因子的依赖性以及所得关联的时间稳定性。两处样地分别位于德国中部（约51°N，9°E，记为KEL）与德国西部（约50.5°N，6.5°E，记为EIF），立地条件相似，但年降水量分别约为700 mm与1000 mm，呈现出海洋性-大陆性气候梯度。研究采集了228株树木的年轮宽度样本，采用主成分分析（PCA, Principal Component Analysis）识别共同生长模式；构建树轮年表，通过冗余分析（redundancy analysis）与简单相关系数计算，检测树轮数据中记录的20世纪气温、降水与干旱信号指纹。夏季干旱是森林生产力的主导驱动因子，但区域与物种特异性差异表明，树木生长受到更为复杂的调控影响。欧洲山毛榉展现出最高的气候敏感性，而无梗花栎的耐旱性最强。KEL样地的生长环境更为干旱，导致所有物种的气候敏感性均有所增强；EIF样地中的无梗花栎在近数十年间，其干旱敏感性从不显著转变为显著水平。所有物种的干旱敏感性动态均随时间发生变化。湿润林区EIF的树木生长干旱敏感性呈上升趋势，而较干旱的KEL区域在20世纪中期，所有物种的干旱敏感性均出现下降。以干旱敏感性的时间变异性为佐证的物种与区域长期气候敏感性差异，是影响德中西部森林生长的气候变化的潜在指示因子，但同时也阻碍了对这类影响的统一评估。