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University of Minnesota
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Methods for Experiment 199 -

Carbon Dioxide Treatment

E199 experiments take place within the e141 BioCON rings to utilize existing CO2 treatments and are conducted in BioCON plots, or in areas outside the plots, but within the CO2 treatments associated with each ring. If the attribute 'PLOT' is not present in the data-set, plants were grown in containers within BioCON rings, but not planted in BioCON plots.

Elevated CO2 treatment rings 1, 3 and 5 receive air with a target CO2 concentration set at 550 ppm in 1997, gradually rising to 565 ppm in 2013 to address rising carbon dioxide concentrations in the atmosphere. The ambient CO2 treatment rings 2, 4 and 6 are 'fumigated' with ambient air with no experimental CO2 addition in order to protect against erroneous results caused by the FACE equipment. Elevated CO2 treatments are applied seven days per week, during daylight hours, for the full growing season (roughly May 1 to October 15).

FACE Technology

BioCON uses a unique Free Air CO2 Enrichment (FACE) technology to elevate the atmospheric concentration of CO2 in the experimental plots. The FACE system used in the BioCON experiment was developed at Brookhaven National Laboratory. It uses natural wind conditions to carry CO2 enriched air across the vegetation. Because the plants are outside in a more natural environment, the chamber effects normally created by enclosures such as greenhouses are reduced or eliminated.

Wind direction, wind velocity, and [CO2] are measured at the center of each plot and this information is used by a computer-controlled system to adjust CO2 flow rate to maintain the target elevated [CO2] (FACE System Schematic). Only pipes on the upwind side of the plots release CO2, unless wind velocity is very low, at that time CO2 is released alternately from adjacent release points. Fast feedback algorithms avoid large overshoots in response to fluctuations in [CO2] and provide a stable elevation of [CO2].

aahe199 - Phenology, growth, and fitness of Arabidopsis under ambient and elevated CO2 and in the presence/absence of competitors

Growth measures

We measured rosette diameter (mm) before plants were moved to the field. We recorded flowering date and measured rosette diameter (mm) and counted the # of leaves and # of leaves damaged by herbivores on 22 June 2006. We harvested plants as they senesced and measured height (cm) and counted the number of stems and saliques (fruits) produced. Aboveground biomass was weighed after drying for 2 days at 60C. We also measured several growth traits on the competitors, including mean height, mean culm number, and total aboveground biomass (g).

Sampling Method

We planted seeds from 19 different Arabidopsis thaliana accessions into 164mL conetainers and placed these potted plants into racks set up in the margins of the BioCON rings, where they were exposed to either ambient or elevated CO2 concentrations. Competition treatments were applied to individual Arabidopsis plants: none = no competition, intraspecific competition = a second A. thaliana individual was planted into the pot, Bromus = two Bromus seeds were planted into the pot, C4 = two Andropogon seeds were planted into the pot.

aaie199 - Arabidopsis Tolerance to herbivory

Growth measures

We measured rosette diameter (mm) before clipping treatments were imposed and estimated the proportion of leaves with insect herbivore damage. We also recorded flowering date and date of re-flowering for clipped plants. We harvested plants as they senesced and measured height (cm) and counted the number of stems and saliques (fruits) produced. Aboveground biomass was weighed after drying for 2 days at 60C.

Sampling Method

We planted seeds from 18 different Arabidopsis thaliana accessions into 164mL conetainers and placed these potted plants into racks set up in the margins of the BioCON rings, where they were exposed to either ambient or elevated CO2 concentrations. Insecticide (Eight) was applied to half of the racks, and half of the plants within each CO2 x Insecticide treatment were clipped to simulate browsing from vertebrate herbivores.

aaje199 - Phenology, growth, and fitness of Arabidopsis under ambient and elevated CO2

Growth measures

We measured rosette diameter (mm) and counted the number of leaves and the number of leaves with flea beetle damage on 31 May 2005. On 8 June, we measured rosette diameter (mm) and visually estimated the percentage of leaf area damaged by Plutella xylostella. We recorded flowering date, and from half of the plants in each RIL in each ring, we collected a single fully expanded leaf at time of flowering to estimate SLA. After harvest, we measured height (cm) and counted the number of stems and saliques (fruits) produced. We also counted the number of aborted fruits. Aboveground biomass was weighed after drying for 2 days at 60C.

Sampling Method

We planted seeds from a Recombinant Inbred Line (RIL) mapping population of Arabidopsis thaliana into 164mL conetainers and placed these potted plants into racks set up in the margins of the BioCON rings, where they were exposed to either ambient or elevated CO2 concentrations.

aaxe199 - Lespedeza herbivory census

Herbivory and Plant Trait Census

We censused damage from three types of herbivores: 1) generalist chewing herbivores (primarily grasshoppers), 2) Pachyscheulus laevigatus (leaf beatles), and 3) Tortriedon spp. (webworms) by visually estimating the proportion of leaf area damaged by each type of herbivore on 10 haphazardly selected leaves per plant. Pathogen damage was estimated as present/absent based on the presence of leaf browning/curling and stem curling. Herbivore and pathogen damage data was collected by Joachim Strengbom in 2004 and by Jen Lau in 2005. In 2005, we also estimated plant traits including plant height, pubescence (scale of 0-3 with 0, no obvious trichomes; 1, trichomes present but sparse; 2, trichomes abundant; 3, leaf surface entirely covered with trichomes), and SLA. SLA was estimated by collecting the youngest fully expanded leaf with no herbivore damage, measuring leaf area using SCION image anlalysis software and weighing the leaf after drying for 2 days at 60C.

Sampling Method

Herbivore and pathogen damage was estimated on 50 haphazardly selected Lespedeza capitata plants growing within the monoculture plots in E141 and all available L. capitata plants growing within the 16 species plots in July of 2004 and August 2005.

acoe199 - Arabidopsis thaliana, Bromus inermis phenotypic selection analysis

Arabidopsis thaliana, Bromus inermis phenotypic selection analysis

Data was used to test how genotype, CO2 concentration, and competition affect plant traits and to conduct phenotypic selection analyses and test how genotype, CO2 concentration, and competition affect the strength of natural selection on plant traits. This dataset standardized traits and relativized fitness within treatments, following common conventions.

Attributes 19 through 27 are relative fitness (?fruit?/mean fruit production within the appropriate CO2 x competition treatment) and standardized trait values calculated as (trait ?mean trait value within the appropriate CO2 x competition treatment)/standard deviation. The means and standard deviations are calculated based on plants within a single treatment (i.e., averaged across all plants within a single CO2 and competition treatments).

This data package includes plant trait and fitness data organized for use in analyses presented in:
Lau, Jennifer A.; Shaw, Ruth G.; Reich, Peter B.; Tiffin, Peter; Indirect effects drive evolutionary responses to global change; New Phytologist, 201: 335?343. doi: 10.1111/nph.12490 2014.
All questions about this dataset should be directed to: Jennifer Lau, jenlau@msu.edu.

acpe199 - Arabidopsis thaliana, Bromus inermis phenotypic selection analyses standardized across trtmnts

Arabidopsis thaliana, Bromus inermis phenotypic selection analyses standardized across treatments

Data was used to conduct phenotypic selection analyses and test how genotype, CO2 concentration, and competition affect the strength of natural selection on plant traits. This dataset standardized traits and relativized fitness across rather than within treatments.

Attributes 19 through 27 are standardized trait values calculated as (trait minus grand mean trait value)/standard deviation trait and relative fitness values. The mean and standard deviation are calculated based on all plants (i.e., averaged across all CO2 and competition treatments) included in the experiment.

This data package includes plant trait and fitness data organized for use in analyses presented in:
Lau, Jennifer A.; Shaw, Ruth G.; Reich, Peter B.; Tiffin, Peter; Indirect effects drive evolutionary responses to global change; New Phytologist, 201: 335 - 343. doi: 10.1111/nph.12490 2014.
All questions about this dataset should be directed to: Jennifer Lau, jenlau@msu.edu.