Comparison of inter- and intra-annual growth dynamics and drought response of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) along an altitudinal gradient
Final Report Abstract
The impact of anticipated climate change on growth and productivity of Norway spruce and European beech and their future role in the forest and wood sector in Central Europe are still discussed controversially. This study is based on a unique time series of ~ 20 years of precision point-dendrometer data collected at three dendroecological field sites along an altitudinal gradient in south-western Germany. By the intergrated analysis of the dendrometer time series with measured wood anatomical variables from the same years and detailed studies of cambial activity and wood formation, this project aimed to provide a better understanding of and new insights in the different environmental factors that control the short-, medium- and long-term growth dynamics of these two important tree species in Central-European forestry. To estimate growth phenology (annual onset and cessation of xylem cell production) of the two tree species based on the long-term dendrometer data, algorithms with accuracies of ~ 7 days for growth onset (both tree species) and ~ 4 days (European beech) and ~ 9 days (Norway spruce) for growth cessation were developed and calibrated by combining xylogenesis data of weekly sampled microcores with dendrometer data measured on the same trees in 2014 and 2015. Based on these algorithms, we could retrospectively extract onset, cessation and duration of xylem cell production for the 1997 – 2016 dendrometer time series. We found for both tree species the growth onset to be delayed by ~ 3 days 100 m^-1 increase in altitude. However, for growth cessation, we could detect a significant interaction effect between altitude and tree species. This was demonstrated by an earlier growth cessation of ~ 2 days 100 m^-1 increase in altitude for European beech compared to a later growth cessation of ~ 0.5 days 100 m^-1 increase in altitude for Norway spruce, indicating that in comparison to European beech, growth cessation of Norway spruce is frequently limited by drought on the low elevation site and less temperature limited on the high elevation site. The xylogenesis data collected on Norway spruce trees in 2014 were also used to model the kinetics of tracheid development and the seasonal dynamics of woody biomass production. This analysis contributed new insights into the complex interplay of the rate and duration of cell enlargement during a drought period in the second half of June and contributed to a more mechanistic understanding of the processes that control the formation of intra-annual density fluctuations in tree-rings of Norway spruce. This study also contributed a new methodological framework, which integrates complementary techniques of tree-ring research with the innovative approach of the Multiple Interval-based Curve Alignment (MICA) for a more advanced and accurate temporal annotation of wood anatomical profiles. Based on this framework, the dendrometer data was used to convert spatial scales of ~ 20 years of wood anatomical profiles of the two tree species along the altitudinal gradient to seasonal time scales. We found vessel size and vessel density of European beech on the lower and medium elevation sites to be closely correlated with soil water content in July and August, providing new and detailed insights into the plastic responses and adaptive capacity of European beech hydraulic architecture to intraseasonal variability in the hydroclimatic conditions.
Publications
- (2017) Simulation study to determine necessary sample sizes for image analysis-based quantitative wood anatomy of vessels of beech (Fagus sylvatica). Dendrochronologia 45 35–38
Diaconu, Daniela; Hackenberg, Jan; Stangler, Dominik Florian; Kahle, Hans-Peter; Spiecker, Heinrich
(See online at https://doi.org/10.1016/j.dendro.2017.07.002) - (2016) Seasonal wood formation dynamics and tree-ring structure of selected tree species in response to climate and forest management. PhD Thesis. Albert-Ludwigs-University Freiburg
Stangler DF
- (2016) Spatiotemporal alignment of radial tracheid diameter profiles of submontane Norway spruce. Dendrochronologia 37: 33–45
Stangler DF, Mann M, Kahle HP, Rosskopf E, Fink S, Spiecker H
(See online at https://doi.org/10.1016/j.dendro.2015.12.001) - (2016) Vessel plasticity of European beech in response to thinning and aspect. Tree Physiology 36: 1260–1271
Diaconu D, Stangler DF, Kahle HP, Spiecker H
(See online at https://doi.org/10.1093/treephys/tpw053) - (2017) A heat wave during leaf expansion severely reduces productivity and modifies seasonal growth patterns in a northern hardwood forest. Tree Physiology 37: 47-59
Stangler DF, Hamann A, Kahle HP, Spiecker H
(See online at https://doi.org/10.1093/treephys/tpw094)
