NOAA/WDS Paleoclimatology - Copenheaver - Raystown Lake - QUAL - ITRDB PA015

The objective of this study was to track changes in growth and dendroclimatic response of white oak (Quercus alba) trees that established in the forest interior and, following the creation of an artificial lake, continued living along the lake edge. Twenty-one white oaks from the lake edge were cored and 91% of the trees exhibited a growth response to the creation of the lake - most commonly a suppression. Two 32 y segments (pre-lake and post-lake) were compared for differences in dendroclimatic response. The tree-ring chronology from the pre-lake time period had significant negative correlations between ring width index (RWI) and temperature in Jun.; significant positive correlations between RWI and precipitation from Jun. of the previous year; significant positive correlations between RWI and precipitation in Mar. of the current year; and significant positive correlations between RWI and Palmer Drought Severity Index (PDSI) in Jul. After lake construction, the same trees exhibited significant positive correlations between RWI and Jul. temperature from the previous year; significant negative correlations between RWI and temperature in Feb. and May; significant positive correlations between RWI and precipitation in Sep.; and significant positive correlations between RWI and PDSI in Jun., Jul., Aug. and Sep. Most trees that experienced transitions from interior to edge positions responded with a decline in growth rate and a moderate change in dendroclimatic responsiveness.

本研究旨在追踪原本定植于森林内部、在人工湖修建后存续于湖岸带的白栎（Quercus alba）的生长变化及其树轮气候响应（dendroclimatic response）。研究人员对21株湖岸带的白栎开展了钻芯取样，其中91%的个体对人工湖修建产生了生长响应，最普遍的响应类型为生长受抑。本研究选取两个各持续32年的时段（湖前期与湖后期），对比二者的树轮气候响应差异。湖前时段的树轮年表（tree-ring chronology）显示，轮宽指数（ring width index, RWI）与当年6月气温呈显著负相关，与前一年6月降水量呈显著正相关，与当年3月降水量呈显著正相关，且与7月帕尔默干旱严重指数（Palmer Drought Severity Index, PDSI）呈显著正相关。人工湖建成后的湖后期，该批个体的相关特征发生显著变化：轮宽指数（RWI）与前一年7月气温呈显著正相关，与2月、5月气温呈显著负相关，与当年9月降水量呈显著正相关，且与6、7、8、9月的帕尔默干旱严重指数（PDSI）均呈显著正相关。多数从林内生境转变为湖岸生境的个体，其生长速率出现下降，且树轮气候响应特征发生了中等程度的改变。