Vertical gradients in photosynthetic physiology diverge at the latitudinal range extremes of white spruce

• DOI: 10.1101/2022.05.06.490824
• Publication Date: 2022-05-06T21:50:12Z
• Authors: Stephanie C. Schm...; Kevin L. Griffin; Natalie T. Boelman; Lee A. Vierling; Sarah G. Bruner; Elizabeth Min; Andrew J. Maguire; Johanna Jensen; Jan U. H. Eitel
• Keywords: Temperate rainforest; Photosynthetic capacity; Black spruce; Shade tolerance

ABSTRACT Light availability drives vertical canopy gradients in photosynthetic functioning and carbon (C) balance, yet patterns of variability these remain unclear. We measured light availability, CO 2 response curves, foliar C, nitrogen (N) pigment concentrations, the photochemical reflectance index (PRI) on upper lower needles white spruce trees ( Picea glauca ) at species’ northern southern range extremes. combined our data with previously published respiratory to compare contrast C balance between latitudinal found steep irradiance, photosynthesis, leaf traits limit, but a lack variation across positions limit. Thus, unlike many tree species from tropical mid-latitude forests, high latitude may not require metabolic activity optimize gain. Consequently, accounting for self-shading is less critical predicting gross primary productivity relative latitudes. Northern also had significantly smaller net positive than suggesting that, regardless position, low rates coupled costs ultimately constrain limit this widely distributed boreal species. SUMMARY STATEMENT Canopy capacity diminish compared Low determine extent treeline.