DOI: 10.5061/dryad.h9w0vt4q4
title: Field testing a 13C labeling method in an East African ant-plant

description: Tree carbon allocation is a dynamic process that depends on the
 tree's environment, but we know relatively little about how biotic
 interactions influece these dynamics. In central Kenya, the loss of
 vertebrate herbivores and the savanna's invasion by the ant Pheidole
 megacephala are disrupting mutualisms between the founational tree Acacia
 drepanolobium and its native ant defenders. Here we piloted a 13Carbon (C)
 pulse-labeling mathod to investigate the influece of these biotic
 interactions on C allocation strategies by adult trees in situ. Trees
 withstood experimental conditions and took up sufficient labeled 13CO2 for
 13C to be detected in various C sinks, including ant mutualists. The 13C
 in ants collected shortly after labeling suggested that trees exposed to
 herbivores allocated relatively more newly assimilated C to native ant
 defenders. Our results demonstrate the viability of the pulse-labeling
 method and suggest the C allocation to ant partners depends on the biotic
 context of the tree, but further investigation with replication is needed
 to characterize such differences in relation to invasion and herbivore
 loss.
description: Biological samples were collected at Ol Pejeta Conservancy by
 Grabriella Mizell, John Mosiany, and John Lemboi. Samples were analyzed
 for 13C content at the University of California, Davis Stable Isotope
 Facility.  Gabriella Mizell and Elizabth Pringle conducted data analyses
 at the University of Nevada, Reno. No other processing was done beyond
 transformations and manipulations outlined in the data files, R script,
 and associated article.
description: # Field testing a 13C labeling method in an East African ant-plant ##
 GENERAL INFORMATION 1. Title of Dataset: Field testing a 13C labeling
 method in an East African ant-plant 2. Author Information A. Principal
 Investigator Contact Information Name: Elizabeth Pringle Institution:
 University of Nevada, Reno Address: 1664 N Virginia St. ms 0314 Reno, NV
 89557 Email: epringle@unr.edu B. Associate or Co-investigator Contact
 Information Name: Gabriella Mizell Institution: University of Nevada, Reno
 Address: 1664 N Virginia St. ms 0314 Reno, NV 89557 Email:
 gmizell@nevada.unr.edu 3. Date of data collection (single date, range,
 approximate date): 2020-03-07 - 2020-09-09 4. Geographic location of data
 collection: 0.003036 N, 36.96572 E. Ol Pejeta Conservancy, Laikipia, Kenya
 5. Information about funding sources that supported the collection of the
 data: U.S National Science Foundation to Elizabeth Pringle (NSF
 DEB-1935498) ## DATA & FILE OVERVIEW 1. File List: * `Licor
 Data.zip` \- contains 8 csvs of environmental variables measured in the
 labeling tent\. There is one csv per labeling event\. isotope.time.csv -
 data for solid samples analyzed for 13C, including tree tissue and ants. *
 `CO2_efflux_calcs.csv` \- data for gas samples analyzed for 13C\,
 including branch and soil respiration\, and atmospheric gas samples *
 `13C_stem_investment.xlsx` \- contains stem 13C data and calculations for
 scaling stem samples to whole tree stem 13C * `13C_ant_investment.xlsx` \-
 contains ant 13C data and calculations for scaling ant samples to whole
 ant colony 13C 2. Relationship between files, if important: In licor Data
 folder: Files that begin with the same 3 letters are labeling events for
 the same tree. There are 2 labeling events per tree. 3. Additional related
 data collected that was not included in the current data package: NA 4.
 Are there multiple versions of the dataset? No ## METHODOLOGICAL
 INFORMATION 1. Description of methods used for collection/generation of
 data: See article in Plant Ecology: Carbon allocation in an East African
 ant-acacia: field-testing a 13C-labeling method for evaluating biotic
 impacts on the carbon cycle. 2. Methods for processing the data: The data
 in the Licor data folder came directly from the LI-8100 gas analyzer - all
 data processing is documented in the associated R script. The raw data we
 received from UC Davis Stable Isotope Facility included the delta 13C
 values. This file was widened to include a new column for each
 experimental treatment. Columns that were not used in our analyses (e.g.,
 total C and total N in each sample) were removed. 3. Instrument- or
 software-specific information needed to interpret the data: R version
 4.1.1 (2021-08-10) with RStudio interface Necessary packages: plyr, dplyr,
 tidyverse, ggplot2, ggbreak, gg.gap, ggpubr, glmmTMB, DHARMa, MuMIn,
 magrittr, car, lmtest, emmeans, multcompView, FSA 4. People involved with
 sample collection, processing, analysis and/or submission: Gabriella
 Mizell, Elizabeth Pringle, John Lemboi, John Mosiany ### DATA-SPECIFIC
 INFORMATION FOR: Licor\_data.zip Each csv in the zipped file contains the
 same information 1. Number of variables: 8 2. Number of cases/rows:
 MUE\_L2\_1: 14568, MUE\_L2\_2: 11230, MUO\_L1\_1: 18069, MUO L1\_2: 17825,
 MIE\_L1\_1: 20794, MIE\_L1\_2: 2976, MIO\_L3\_1: 17329, MIO\_L3\_2: 13134
 3. Variable List: * Date - the date and time the reading occurred * CO2 -
 the CO2 level (ppm) inside the tent * Tbench - the temperature (Celsius)
 of the IRGA - it need to be at least 50C before it was ready to record CO2
 data. * V1 - Photosynthetically active radiation (PAR), measured in micro
 moles per meter squared per second * V2 - relative humidity (%) * V3 -
 Temperature (Celsius) * Hour - The hour of the day the measurement was
 taken * DOY - the day of the year the measurement was taken ###
 DATA-SPECIFIC INFORMATION FOR: isotope.time.csv 1. Number of variables: 13
 2. Number of cases/rows: 141 3. Variable List: * sample.id - a unique code
 for each sample used as a descriptive name for isotope analysis. * tree -
 the tree that the sample came from * time.hours - the timepoint at which
 the sample was collected, in hours * delta.13C - the proportion of 13C to
 12C in each sample, expressed in delta notation * time.days - the
 timepoint at which the sample was collected, in days * treatment - the
 labeling treatment of the tree from which the sample comes from. Either
 control or label * meta.material - the broadest classification of the
 material of the sample. Either tree or ants * material - the type of
 sample. Ants, thorns, stems, new.stems, or leaves * sub.material -
 additional material classification * ant.treatment - the invasion status
 of the tree from which the sample comes from. Either control or invaded *
 herbivore.treatment - whether or not herbivores were present or excluded
 from the tree from which the sample comes from * ant.species - the species
 name of the ant samples. C.mimosae, P.megacephala, or T.penzigi * notes -
 if there was any additional information about the sample that was not
 captured by the other columns. This only applied to leaf data. first.event
 means the leaf sample was collected after the first labeling event, while
 second.event means the leaf sample was collected after the second labeling
 event. 4. Missing data codes: na - data is not necessary for a column for
 a sample ### DATA-SPECIFIC INFORMATION FOR: CO2\_efflux\_calcs.csv 1.
 Number of variables: 11 2. Number of cases/rows: 46 3. Variable List: *
 tree - the tree from which the sample came from * sample.type - the type
 of gas sample that was collected. Either branch, soil, or atmospheric *
 treatment - the labeling treatment of the tree from which the sample was
 collected. Either control or label * time - the timepoint that the sample
 was collected at, in hours. * 10 - the CO2 concentrtation at 10 minutes,
 in ppm * 20 - the CO2 concentration at 20 minutes, in ppm * 30 - the CO2
 concentration at 30 minutes, in ppm * delta.13C.30min - the proportion of
 13C to 12C in each sample at 30 minutes, expressed in delta notation *
 intercept - the intercept calculated after fitting a linear model through
 the three timepoints (10, 20, 30) for each sample * r2 - the fit of the
 linear model for each sample, using r2 * CO2.efflux - the calculated
 efflux value, using the delta.13C.30min + the intercept multiplied by
 1/the CO2 concentration of the sample. 4. Missing data codes: na - data
 not necessary for a column for a sample ### DATA-SPECIFIC INFORMATION FOR:
 13C\_ant\_investment.xlsx 1. Number of variables: 16 2. Number of
 cases/rows: 8 3. Variable List: * treatment- whether the sample comes from
 a control tree or labeled tree * sample - the name of the sample *
 labeling treatment - whether the tree that the sample comes from was
 labeled with 13CO2 or unlabeled (control) * ant treatment - whether the
 tree that the sample came from was at the uninvited site or invaded site *
 herbivore treatment - whether the tree that the sample came from was
 exposed to herbivores or not * at-% 13C - the atom % 13C of the sample *
 prop13C - the proportion of the sample that is 13C relative to 12C * total
 C\_ug - the total amount of C in the sample in micrograms * ug 13C in
 sample - the amount of micrograms in the sample * sample weight\_g - the
 weight of the sample in grams * estimated ant biomass\_g - the estimated
 total ant biomass of the labeled tree based on allometry * ug 13C in ants
 per tree - the total amount of 13C in the ant colony in micrograms * g 13C
 in ants per tree - the total amount of 13C in the ant colony in grams *
 difference\_control\_label - the difference in g of 13C in the ants on the
 tree between the control tree and labeled tree. Only trees in the label
 labeling treatment contain a value because this column
 (difference\_control\_label) shows the difference between g 13C in ants
 per tree in the labeled tree and paired control, which is located one row
 below each labeled tree. * 13C\_uptake\_g - the amount of g of 13C that
 the labeled tree took up. This only applies to trees in the label labeling
 treatment, as 13CO2 was not added to control trees. *
 percent\_newC\_to\_ants - the percentage of the added 13C that is in ants
 on the labeled tree. This only applies trees in the label labeling
 treatment, as 13CO2 was not added to control trees. ### DATA-SPECIFIC
 INFORMATION FOR: 13C\_stem\_investment.xlsx 1. Number of variables: 17 2.
 Number of cases/rows: 6 3. Variable List: * treatment- whether the sample
 comes from a control tree or labeled tree * sample - the name of the
 sample * labeling treatment - whether the tree that the sample comes from
 was labeled with 13CO2 or unlabeled (control) * ant treatment - whether
 the tree that the sample came from was at the uninvited site or invaded
 site * herbivore treatment - whether the tree that the sample came from
 was exposed to herbivores or not * at-% 13C - the atom % 13C of the sample
 * prop13C - the proportion of the sample that is 13C relative to 12C *
 totalC\_ug - the total amount of C in the sample in micrograms *
 ug\_13C\_in\_sample - the amount of 13C in micrograms in the sample *
 g\_13C\_in\_sample - the amount of 13C in grams in the sample * sample
 weight\_g - the weight of the sample in grams * 13C\_prop\_sample - the
 proportion of 13C to sample weight in the sample *
 estimated\_stem\_biomass\_g - the estimated total stem biomass of the
 labeled tree based on allometry * g\_13C\_stem - the total amount of 13C
 in the stem of the whole tree * difference\_control\_label - the
 difference in g of 13C in the ants on the tree between the control tree
 and labeled tree. Only trees in the label labeling treatment contain a
 value because the it is the difference between g\_13C\_stem in the labeled
 tree and paired control, which is located one row below each labeled tree.
 * 13C\_uptake\_g - the amount of g of 13C that the labeled tree took up.
 This only applies to trees in the label labeling treatment, as 13CO2 was
 not added to control trees. * percent\_newC\_to\_stem - the percentage of
 the added 13C that is in stem on the labeled tree. This only applies trees
 in the label labeling treatment, as 13CO2 was not added to control trees.