Does natural root grafting make trees better competitors?
Data files
Aug 26, 2022 version files 167.72 KB
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Data_Oikos.csv
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README_file.txt
Abstract
Methods
Field work was performed in summer 2017. At each site, distance between trees were measured then all trees were felled with a chainsaw and cross-sectional disks were collected at ground level (0 m). Cross-sectional disks were air dried and sanded (80-400 grit) to reveal growth rings. Tree ring widths series were measured on cross-sectional disks from the stem base using a Velmex “TA Unislide” measurement system with ACU-Rite linear encoder and QC10V digital readout device (Velmex, Inc., Bloomfield, New York) interfaced with Measure J2X (Version 5.0x) ring-reading software (Project J2X, Voortech Consulting, Holderness, NH). Ring-width series were measured with 0.001 mm precision along two rays per wood disk when possible (i.e. when the rings were clearly visible) and visually cross-dated. To obtain a single series per tree, chronologies were averaged for each tree when two of them were available. A total of 110 tree ring width series were obtained.
We converted tree ring width series into basal area increment (BAI) to calculate annual tree growth (Biondi and Qeadan 2008) following equation (1) :
BAIt = πRt2- πR2t-1 (1)
Where Rt is the stem radius at year t and Rt-1 is the stem radius at year t-1.
Intraspecific competition between trees was estimated using distance-independent (BAL: Basal area of the Larger tree) and distance-dependent (HEG: Hegyi competition index) competition indices. The first index (BAL) was developed by Wykoff et al. (1982) and corresponds to the sum of the of the basal area of neighbor trees that are larger than the subject tree: The second index (HEG) was developed by Hegyi (1974) and corresponds to the sum of the ratios of diameters of a subject tree and its competitors, weighted by the distance from the subject tree. We considered that each tree found in a radius of 6 m or less around the subject tree was a potential competitor.
Usage notes
Excel software is required to open the data files (.csv).