DOI: 10.5061/dryad.qbzkh18tx
title: Data for: Warming increases negative interactions of a juvenile fescue and nearby plants in a tundra, moss facilitates mycorrhizae

description: In systems where low temperatures limit plant productivity, facilitative
 effects of surrounding vegetation on juvenile plants may outweigh effects
 of competition for resources, mainly through temperature buffering but
 also via increased availability of root mutualists such as mycorrhizal
 fungi. Climate warming could cause this balance between facilitation and
 competition to shift. We investigated how first-year plant performance,
 biomass allocation, and mycorrhizal colonization were affected by
 neighboring vegetation, both under ambient temperatures and under
 experimental warming. Juveniles of the grass species Festuca ovina (L.,
 Poaceae) were planted into an alpine tundra ecosystem in central Norway,
 into one of four microsite types: a moss and lichen layer, other
 graminoids, both groups, or neither (bare soil). Half of the microsites
 experienced ambient conditions and half were located within open-top
 warming chambers. Warming increased shoot biomass of F. ovina, but only if
 planted in bare soil. Our results suggest that when abiotic stress was
 reduced by warming, the importance of competition among F. ovina juveniles
 and neighboring vegetation increased, in line with the Stress Gradient
 Hypothesis. These results indicate that climate warming may shift the
 balance from facilitation to competition among plants in cold ecosystems,
 although the resource(s) competed for remain to be identified. We also
 found that when moss and lichen were present, planted F. ovina were more
 likely to form mycorrhizae, yet had a significantly lower root biomass,
 both absolute and relative to their total biomass. Thus, at the juvenile
 stage, belowground competition and/or increased mycorrhization may
 decrease plant root production yet without detectable benefits to
 aboveground growth.
description: # Data for: Warming increases negative interactions of a juvenile fescue
 and nearby plants in a tundra, moss facilitates mycorrhizae
 [https://doi.org/10.5061/dryad.qbzkh18tx](https://doi.org/10.5061/dryad.qbzkh18tx) ## Description of the data and file structure This dataset contains all the data and software necessary to recreate the analyses and figures presented in our manuscript entitled "Warming increases negative interactions of a juvenile fescue and nearby plants in a tundra, moss facilitates mycorrhizae". In brief, in central Norway (The study site is located at 62.30553 °N, 9.65095 °E, at 1352 m a.s.l. on a west-facing slope in the Dovrefjell mountains of Norway), we planted individuals of the perennial grass *Festuca ovina* into four types of naturally occurring microsites (characterized by presence/absence of grass and moss-lichen complexes). Within each of these microsites, we implemented an experimental warming treatment using open-top chambers. Each microsite class received both a warming treatment and an ambient control. After one growing season, all experimental *F. ovina* individuals were harvested and measured for biomass, functional traits, and presence of mycorrhizae. Analyses examine the individual and interactive effects of grass and moss-lichen presence and warming on these responses. ### Files and variables **Note:** Empty cell values in the data files signify that the associated data for that individual sample was not collected, and therefore the value is missing (N/A). These cell values have been left blank so as not to interfere with the scripts to analyze the data. Reasons for missing values include trampling by ungulates which destroyed the samples before they could be collected, or loss of material during sample processing in the lab. For more information, see *Results* in the main manuscript. #### File: DATA.csv **Description:** All data required for analyses other than comparing soil surface temperatures in OTCs vs. adjacent ambient plots (see the DATA_temp.csv file below) ##### Variables * ID: An individual identifier randomly assigned to each plant * Plot: The study site had three plots, each of which had four replicates of each treatment/microsite combination. Each plant was haphazardly assigned to one of these plots. * Warming: Temperature regime that plants experienced. Ambient = no manipulation (i.e., plants experienced ambient temperatures for the entire duration of the experiment). Warmed = experimental warming (i.e., plants had an open-top warming chamber for the entirety of the experiment). * LICH (0/1): Presence/absence of naturally occurring lichens and/or mosses (moss-lichen). Presence of moss-lichen was defined as &gt;75% cover of &gt;1 cm tall lichen and/or moss within an 8 cm diameter circle centered around the juvenile. Absence of either group occurred when no aboveground biomass of that group was visible within the treatment area. 0 = absent. 1=present. * GRASS (0/1): Presence/absence of naturally occurring grasses. Presence of established* *grasses was defined as grass stem density of &gt;5 stems/cm2 occurring within 1 cm of the planted *F. ovina* juvenile. 0 = absent. 1=present. * Fresh_shoot (g): Fresh weight of all aboveground biomass for the *F. ovina i*ndividual * Fresh_root (g): Fresh weight of all belowground biomass for the *F. ovina i*ndividual * Dry_shoot (g): Dry weight of all aboveground biomass for the *F. ovina i*ndividual * Dry_root (g): Dry weight of all belowground biomass for the *F. ovina i*ndividual * Mycorrhizae (0/1): Presence of mycorrhizal structures (hyphae, vesicles, and/or arbuscules) on *F. ovina* roots. * Bare (0/1): If the microsite was classified as absent of both moss-lich and grass (as defined above), the microsite was classified as Bare present. 0 = absent. 1=present. * mosslichcov (%): Absolute cover of moss-lich within an 8cm diameter diameter circle centered around the focal *F. ovina*. See *Methods: Treatments and microsites* section within the manuscript for more information. * grasscov: Absolute cover of grasses (not including the experimental plant) within an 8cm diameter diameter circle centered around the focal *F. ovina*. See *Methods: Treatments and microsites* section within the manuscript for more information. #### File: DATA_temp.csv **Description:** Data for comparing soil surface temperatures in OTCs vs. adjacent ambient plots. Each row represents one temperature measurement from one logger at a single timepoint (presented in *Methods: Warming Treatments* within the manuscript). ##### Variables * ID_Tlog: the unique identification number given to each temperature logger * Date, year, month, Hour, full_date: Calendar year/date/hour/month at which the measurement took place. * Warming_treatment: Temperature regime that the logger experienced. 0 = no manipulation (i.e., ambient temperatures for the entire duration of the experiment). 1 = experimental warming (i.e., logger within an experimental open-top warming chamber for the entirety of the experiment). * temperature (degrees C): The recorded temperature. Variables within the file not used in the analysis presented in this manuscript: * Sunrise: the time at which the sun rose on the date during which the temperature was recorded * Sunset: the time at which the sun set on the date during which the temperature was recorded * DayNight: Day = the temperature was recorded during the daytime (between sunrise and sunset). Night = the temperature was recorded during the nighttime (between sunset and sunrise). Uses data from the full_date, Sunrise, and Sunset columns. ## Code/software All analyses were performed in R version 4.2.2 (R Core Team, 2022). The associated R project (PROJECT.Rproj) and script (CODE.R) are provided in this submission and includes the packages and workflow as well as all other code required to complete the analyses. ## Access information Other publicly accessible locations of the data: * NONE