DOI: 10.5061/dryad.kprr4xhf2
title: Stable isotope analysis indicates partial mycoheterotrophy in arbuscular mycorrhizal woody seedlings in tropical forests

description: Chlorophyllous plants exhibiting partial mycoheterotrophy obtain carbon
 through mycorrhizal interactions in addition to photosynthesis. In
 arbuscular mycorrhizal (AM) plants, the Paris-morphotype (i.e.
 hyphal coils) is considered essential for mycoheterotrophic carbon gains.
 Numerous tree species in tropical lowland forests form this morphotype,
 and under light- and nutrient-limitation, additional carbon gain would be
 beneficial. However, if seedlings of woody species in the understory of
 tropical lowland forests exhibit partial mycoheterotrophy remains
 unexplored. Here we (a) examined the AM morphotype (Paris- or Arum-type)
 in seedlings of 41 tropical woody species, and (b) to determine if any of
 the target Paris-type species are partially mycoheterotrophic, we compared
 their multi-element stable isotope natural abundance (13C, 2H, 18O, 15N)
 to neighbouring autotrophic non Paris-type reference seedlings. 50 % of
 the investigated species (and 80 % of the genera) exhibited
 the Paris-type, expanding the number of tropical plant genera
 with Paris-type AM. Enrichment in 13C, but not in 18O in target compared
 to neighbouring reference plants indicated partial mycoheterotrophy in
 seedlings of 6 of the 21 investigated Paris-type AM species. Our results
 indicate for the first time that carbon gain through mycoheterotrophy
 occurs in seedlings of AM tropical tree species. In tropical forests,
 partial mycoheterotrophy during seedling establishment may confer so far
 unrecognised ecological advantages influencing seedling recruitment and
 ecosystem dynamics.
description: # Stable isotope analysis indicates partial mycoheterotrophy in arbuscular
 mycorrhizal woody seedlings in tropical forests
 [https://doi.org/10.5061/dryad.kprr4xhf2](https://doi.org/10.5061/dryad.kprr4xhf2) ## Description of the data and file structure The data were collected to identify if seedlings of woody species in the understory of tropical lowland forests exhibit partial mycoheterotrophy. We (a) examined the AM morphotype (*Paris*- or *Arum*-type) in seedlings of 42 tropical woody species, and (b) to determine if any of the target *Paris*-type species are partially mycoheterotrophic, we compared their multi-element stable isotope natural abundance to neighbouring autotrophic non *Paris*-type reference seedlings. The multi-element stable isotope natural abundance of potentially partially mycoheterotrophic target *Paris*-type species and their neighbouring autotrophic non *Paris*-type reference seedlings are displayed as figures (jpeg for single figures and pdf-file for all figures combined in one file). Comparison of the δ values of the respective stable isotope (13C, 2H, 18O, 15N) and N concentration of the individuals of ’*Paris*-type’ target species compared to the mean δ values of the respective stable isotope (13C, 2H, 18O, 15N) and N concentration of all ‘non *Paris*-type’ reference plants in the respective plot. The lines connect the individual δ values of the respective stable isotope (13C, 2H, 18O, 15N) and N concentration values of a ’*Paris*-type’ target species to the mean δ values of the respective stable isotope (13C, 2H, 18O, 15N) and N concentration of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε = δS – δREF, where δS is a single δ value of an individual plant (i.e. ‘*Paris*-type’ target), and δREF is the mean value across all ‘non *Paris*-type’ reference plants in the respective plot.  Figure R1. File name = R1_13C.jpg — Comparison of the δ 13C values of the individuals of ’Paris-type’ target species compared to the mean δ 13C of all ‘non Paris-type’ reference plants in the respective plot. The lines connect the individual δ 13C values of a ’Paris-type’ target species to the mean δ 13C of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε 13C = δS – δREF, where δS is a single δ 13C value of an individual plant (i.e. ‘Paris-type’ target), and δREF is the mean value across all ‘non Paristype’ reference plants in the respective plot. Figure R2. File name = R2_2H.jpeg — Comparison of the δ 2H values of the individuals of ’Paris-type’ target species compared to the mean δ 2H of all ‘non Paris-type’ reference plants in the respective plot. The lines connect the individual δ 2H values of a ’Paris-type’ target species to the mean δ 2H of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε 2H = δS – δREF, where δS is a single δ 2H value of an individual plant (i.e. ‘Paris-type’ target), and δREF is the mean value across all ‘non Paris-type’ reference plants in the respective plot. Figure R3. File name = R3_18O.jpeg — Comparison of the δ 18O values of the individuals of ’Paris-type’ target species compared to the mean δ 18O of all ‘non Paris-type’ reference plants in the respective plot. The lines connect the individual δ 18O values of a ’Paris-type’ target species to the mean δ 18O of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε 18O = δS – δREF, where δS is a single δ 18O value of an individual plant (i.e. ‘Paris-type’ target), and δREF is the mean value across all ‘non Paris-type’ reference plants in the respective plot. Figure R4. File name = R4_15N.jpeg — Comparison of the δ 15N values of the individuals of ’Paris-type’ target species compared to the mean δ 15N of all ‘non Paris-type’ reference plants in the respective plot. The lines connect the individual δ 15N values of a ’Paris-type’ target species to the mean δ 15N of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε15N = δS – δREF, where δS is a single δ 15N value of an individual plant (i.e. ‘Paris-type’ target), and δ REF is the mean value across all ‘non Paris-type’ reference plants in the respective plot. Figure R5. File name = R5_TotN.jpeg — Comparison of the N-concentration values of the individuals of ’Paris-type’ target species compared to the mean N-conc. of all ‘non Paris-type’ reference plants in the respective plot. The lines connect the individual N-conc. values of a ’Paris-type’ target species to the mean N-conc. of all ‘non Paris-type’ reference plants in a respective plot and illustrate the calculation principle of the enrichment factor ε N-conc. = N-conc.S – N-conc.REF, where N-conc.S is a single N-conc. value of an individual plant (i.e. ‘Paris-type’ target), and N-conc.REF is the mean value across all ‘non Paris-type’ reference plants in the respective plot.