Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought

Research output: Research - peer-reviewJournal article

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DOI

  • Marceau Guerin
    Marceau GuerinColumbia Univ, Columbia University, Dept Earth & Environm Engn
  • Dario Martin-Benito
    Dario Martin-BenitoColumbia Univ, Columbia University, Lamont Doherty Earth Observ, Tree Ring Lab
  • Georg von Arx
    Georg von ArxInst Environm Sci, Climat Change & Climate Impacts
  • Laia Andreu-Hayles
    Laia Andreu-HaylesColumbia Univ, Columbia University, Lamont Doherty Earth Observ, Tree Ring Lab
  • Kevin L. Griffin
    Kevin L. GriffinColumbia Univ, Columbia University, Lamont Doherty Earth Observ, Dept Earth & Environm Sci
  • Rayann Hamdan
    Rayann HamdanEcole Polytech Palaiseau, Ecole Polytechnique, Centre National de la Recherche Scientifique (CNRS), Universite Paris Saclay (ComUE), CEA, Lab Solides Irradies, CEA, Inst Rayonnement Matiere Saclay IRAMIS
  • Nate G. McDowell
    Nate G. McDowellPacific Northwest Natl Lab, Pacific Northwest National Laboratory, United States Department of Energy (DOE), Atmospher Sci & Global Change Div
  • Robert Muscarella
  • William Pockman
    William PockmanUniv New Mexico, University of New Mexico, Dept Biol
  • Pierre Gentine
    Pierre GentineColumbia Univ, Columbia University, Earth Inst, Dept Earth & Environm Engn

In the southwestern USA, recent large-scale die-offs of conifers raise the question of their resilience and mortality under droughts. To date, little is known about the interannual structural response to droughts. We hypothesized that pinon pines (Pinus edulis) respond to drought by reducing the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7-year experiment in central New Mexico with three watering treatments (irrigated, normal, and rain exclusion). We analyzed how variation in evaporative structure (needle length, stomatal diameter, stomatal density, stomatal conductance) responded to watering treatment and interannual climate variability. We further analyzed annual functional adjustments by comparing yearly addition of needle area (LA) with yearly addition of sapwood area (SA) and distance to tip (d), defining the yearly ratios SA:LA and SA:LA/d. Needle length (l) increased with increasing winter and monsoon water supply, and showed more interannual variability when the soil was drier. Stomatal density increased with dryness, while stomatal diameter was reduced. As a result, anatomical maximal stomatal conductance was relatively invariant across treatments. SA:LA and SA:LA/d showed significant differences across treatments and contrary to our expectation were lower with reduced water input. Within average precipitation ranges, the response of these ratios to soil moisture was similar across treatments. However, when extreme soil drought was combined with high VPD, needle length, SA:LA and SA:LA/d became highly nonlinear, emphasizing the existence of a response threshold of combined high VPD and dry soil conditions. In new branch tissues, the response of annual functional ratios to water stress was immediate (same year) and does not attempt to reduce the drop of water potential. We suggest that unfavorable evaporative structural response to drought is compensated by dynamic stomatal control to maximize photosynthesis rates.

Original languageEnglish
JournalEcology and Evolution
Volume8
Issue number3
Pages (from-to)1655-1672
Number of pages18
ISSN2045-7758
DOIs
StatePublished - Feb 2018

    Research areas

  • functional ratio, Huber value, isohydricity, leaf area, stomatal conductance, xylem, PINYON-JUNIPER WOODLAND, MAXIMUM STOMATAL CONDUCTANCE, TREE DIE-OFF, SCOTS PINE, HYDRAULIC ARCHITECTURE, WATER-STRESS, LEAF-AREA, CARBOHYDRATE DYNAMICS, VEGETATION MORTALITY, BIOMASS ALLOCATION

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