Milti-Scale Detrended Partial Cross-Correlation Analysis of Tree Ring Width and Climate Variations: Revealing Heat and Drought Stress Resilience Factors in a Forest Ecosystem

In a changing climate, forest ecosystems become increasingly vulnerable to the continuously exacerbating heat and drought stress conditions. Climate stress resilience is governed by a complex interplay of global, regional and local factors, with hydrological conditions among the key roles. Using a modified detrended partial cross-correlation analysis (DPCCA), we analyse the interconnections between long-term tree-ring width (TRW) data and regional climate variations at various scales and time lags. By comparing dendrochronological series of Scots pine trees near the southern edge of the boreal ecotone, we investigate how local hydrological conditions affect heat- and drought stress resilience of the forest ecosystem. While TRW are negatively correlated with spring and summer temperatures and positively cor-related with the Palmer drought severety index (PDSI) in the same year indicating that heatwaves and droughts represent the limiting factors, at interannual scales remarkable contrasts can be observed between areas with different local hydrological conditions. In particular, for the sphagnum bog area positive TRW trends over several consecutive years tend to follow negative PDSI trends and positive spring and summer temperature trends of the same duration with a time lag between one and three years, indicating that prolonged dry periods, as well as warmer springs and summers appear beneficial for the increased annual growth. In contrast, for the surrounding elevated dry land area a reversed tendency can be observed, with pronounced negative long-term correlations with temperature and positive correlations with PDSI. Moreover, by combining detrending models and partial correlation analysis, we show expicitly that the long-term temperature dependence could be partially attributed to the spurious correlations induced by coinciding trends of the trees ageing and climate warming, while contrasts in correlations between TRW and PDSI become only further highlighted, indicating the major impact of the local hydrological conditions on the drought stress resilience. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/542825v1_ufig1.gif" ALT="Figure 1"> View larger version (75K): org.highwire.dtl.DTLVardef@e37c34org.highwire.dtl.DTLVardef@ef6a97org.highwire.dtl.DTLVardef@3ef47forg.highwire.dtl.DTLVardef@125fe99_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIClimate stress resilience of forest ecosystems is largely driven by local hydrology C_LIO_LIMultiscale analysis reveals reversed climate stress response in dry and wetland areas C_LIO_LIWarmer springs and summers are favorable for tree growth under nondrought conditions C_LIO_LIWarm and dry periods improve trees growth in the peat bog area with 1-3 year time lag C_LIO_LIClimate stress response and ageing effects can be understood from partial correlation C_LI