@article{Stangler-2021,
  year = {2021},
  publisher = {MDPI},
  volume = {12},
  number = {3},
  pages = {274},
  doi = {10.3390/f12030274},
  issn = {1999-4907},
  abstract = "{Research Highlights: Our results provide novel perspectives on the effectiveness and collapse 
of compensatory mechanisms of tracheid development of Norway spruce during intra-seasonal 
drought and the environmental control of intra-annual density fluctuations. Background and 
Objectives: This study aimed to compare and integrate complementary methods of investigating 
intra-annual wood formation dynamics to gain a better understanding of the endogenous and 
environmental control of tree-ring development and the impact of anticipated climatic changes on forest 
growth and productivity. Materials and Methods: We performed an integrated analysis of xylogenesis 
observations, quantitative wood anatomy and point-dendrometer measurements of Norway spruce 
(Picea abies (L.) Karst.) trees growing along an elevational gradient in south-western Germany during 
a growing season with an anomalous dry June followed by an extraordinary humid July. Results: 
Strong endogenous control of tree-ring formation was suggested at the highest elevation where the 
decreasing rates of tracheid enlargement and wall thickening during drought were effectively compensated 
by increased cell differentiation duration. A shift to environmental control of tree-ring 
formation during drought was indicated at the lowest elevation, where we detected absence of compensatory 
mechanisms, eventually stimulating the formation of an intra-annual density fluctuation. Transient 
drought stress in June also led to bimodal patterns and decreasing daily rates of stem 
radial displacement, radial xylem growth and woody biomass production. Comparing xylogenesis 
data with dendrometer measurements showed ambivalent results and it appears that with decreasing 
daily rates of radial xylem growth, the signal-to-noise ratio in dendrometer time series between 
growth and fluctuations of tree water status becomes increasingly detrimental. Conclusions: Our 
study provides new perspectives into the complex interplay between rates and durations of tracheid 
development during dry-wet cycles, and thereby contributes to an improved and mechanistic understanding 
of the environmental control of wood formation processes leading to the formation of 
intra-annual density fluctuations in tree-rings of Norway spruce.}",
  author = {Dominik F. Stangler and Hans-Peter Kahle and Martin Raden and Elena Larysch and Thomas Seifert and Heinrich Spiecker},
  title = {Effects of intra-seasonal drought on kinetics of tracheid differentiation and seasonal growth dynamics of Norway spruce along an elevational gradient},
  journal = {Forests},
  user =	 {mmann}
}