@article{LuebbeLamarqueDelzonetal.2022,
  author    = {L{\"u}bbe, Torben and Lamarque, Laurent J. and Delzon, Sylvain and Torres Ruiz, Jos{\´e} M. and Burlett, R{\´e}gis and Leuschner, Christoph and Schuldt, Bernhard},
  title     = {High variation in hydraulic efficiency but not xylem safety between roots and branches in four temperate broad-leaved tree species},
  series = {Functional Ecology},
  volume    = {36},
  journal   = {Functional Ecology},
  number    = {3},
  issn      = {0269-8463},
  doi       = {10.1111/1365-2435.13975},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318587},
  pages     = {699 -- 712},
  year      = {2022},
  abstract  = {Xylem hydraulic safety and efficiency are key traits determining tree fitness in a warmer and drier world. While numerous plant hydraulic studies have focused on branches, our understanding of root hydraulic functioning remains limited, although roots control water uptake, influence stomatal regulation and have commonly been considered as the most vulnerable organ along the hydraulic pathway. We investigated 11 traits related to xylem safety and efficiency along the hydraulic pathway in four temperate broad-leaved tree species. Continuous vessel tapering from coarse roots to stems and branches caused considerable reduction in hydraulic efficiency. Wood density was always lowest in roots, but did not decline linearly along the flow path. In contrast, xylem embolism resistance (P50) did not differ significantly between roots and branches, except for one species. The limited variation in xylem safety between organs did not adequately reflect the corresponding reductions in vessel diameter (by ~70\%) and hydraulic efficiency (by ~85\%). Although we did not observe any trade-off between xylem safety and specific conductivity, vessel diameter, vessel lumen fraction and wood density were related to embolism resistance, both across and partly within organs. We conclude that coarse roots are not highly vulnerable to xylem embolism as commonly believed, indicating that hydraulic failure during soil drying might be restricted to fine roots.},
  language  = {en}
}
@article{KumarWaitePaligietal.2022,
  author    = {Kumar, Manish and Waite, Pierre-Andr{\´e} and Paligi, Sharath Shyamappa and Schuldt, Bernhard},
  title     = {Influence of juvenile growth on xylem safety and efficiency in three temperate tree species},
  series = {Forests},
  volume    = {13},
  journal   = {Forests},
  number    = {6},
  issn      = {1999-4907},
  doi       = {10.3390/f13060909},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-278889},
  year      = {2022},
  abstract  = {The evolution of the internal water transport system was a prerequisite for high plant productivity. In times of climate change, understanding the dependency of juvenile growth on xylem hydraulic physiology is therefore of high importance. Here, we explored various wood anatomical, hydraulic, and leaf morphological traits related to hydraulic safety and efficiency in three temperate broadleaved tree species (Acer pseudoplatanus, Betula pendula, and Sorbus aucuparia). We took advantage of a severe natural heat wave that resulted in different climatic growing conditions for even-aged plants from the same seed source growing inside a greenhouse and outside. Inside the greenhouse, the daily maximum vapour pressure deficit was on average 36\% higher than outside during the growing seasons. Because of the higher atmospheric moisture stress, the biomass production differed up to 5.6-fold between both groups. Except for one species, a high productivity was associated with a high hydraulic efficiency caused by large xylem vessels and a large, supported leaf area. Although no safety-efficiency trade-off was observed, productivity was significantly related to P\(_{50}\) in two of the tree species but without revealing any clear pattern. A considerable plasticity in given traits was observed between both groups, with safety-related traits being more static while efficiency-related traits revealed a higher intra-specific plasticity. This was associated with other wood anatomical and leaf morphological adjustments. We confirm that a high hydraulic efficiency seems to be a prerequisite for a high biomass production, while our controversial results on the growth-xylem safety relationship confirm that safety-efficiency traits are decoupled and that their relationship with juvenile growth and water regime is species-specific.},
  language  = {en}
}