DOI: 10.5061/dryad.z8w9ghx83
title: Biodiversity effects on grape quality depend on variety and management intensity

description: Interactions between plants can be beneficial, detrimental or neutral. In
 agricultural systems competition between crop and spontaneous vegetation
 is a major concern. We evaluated the relative support for three
 non-exclusive ecological hypotheses about interactions between crop and
 spontaneous plants based on competition, complementarity or facilitation.
 The study was conducted in Swiss vineyards with different vegetation
 management intensities. Thirty-three vineyards planted with two different
 grape varieties were studied over 3 years to determine whether
 low-intensity vegetation management might provide benefits for grape
 quality parameters. Management intensity varied with the degree of control
 of spontaneous inter-row vegetation. Features of spontaneous vegetation
 measured included total cover, total species richness and abundance of
 nitrogen fixing plants. Grape quality parameters of known importance to
 wine-making (yeast assimilable nitrogen, sugars, tartric acid, and malic
 acid) were determined by Fourier-transform infrared spectroscopy (FTIR).
 Using structural equation modeling, we evaluated hypotheses about the
 multivariate responses of grape quality parameters as well as the direct
 and indirect (plant-mediated) effects of management.  Observed
 effects of management differed between grape varieties. Management
 intensity and abundance of N-fixing plants significantly influenced grape
 quality parameters, while total richness of spontaneous plants did not
 have detectable effects. Abundance of N-fixing plants was enhanced by
 low-intensity management resulting in increased N content in the red grape
 variety (Pinot noir), potentially enhancing grape quality, while measured
 soil N content did not explain the increase. Synthesis: Our study shows
 that crop quality can be enhanced by spontaneous plants, in this case by
 the abundance of a key functional group (N-fixers), most likely through
 plant-plant or plant-microbe facilitation. However, beneficial
 interactions may have a high specificity in terms of facilitation partners
 and may have contrasting effects at low taxonomic resolutions such as crop
 varieties. Generally increasing plant biodiversity in agricultural systems
 may increase competition with crops. Thus, the identification of suitable
 interaction partners and a careful balance between crop variety and
 spontaneous plant species may be necessary to utilize beneficial
 interactions and to reduce the trade-off between agricultural production
 and biodiversity to achieve a sustainable ecological benefit in
 agricultural systems.
description: Name data file:<br> "Management and
 grapes" Attached R code
 ("Grape_qualities_rawdata_prep_archive") decribes the
 preprocessing of thr raw data before analysis.
 Keywords: "grape qualities", "ecological
 intensification", "YAN", "facilitation",
 "non-crop plants", "management intensity"
 Authors: Steiner, Magdalena<br>
 magdalena.steiner1@hotmail.com<br> Affiliation:<br> University
 of Fribourg, Ecology and Evolution, Department of Biology, Ch. du Musée
 10, CH-1700 Fribourg Grace, James B.<br>
 gracej@usgs.gov<br> Affiliation:<br> US Geological Survey,
 National Wetlands Research Center, Lafayette, 70506, Louisiana,
 USA<br> shared senior authorship Bacher,
 Sven<br> sven.bacher@unifr.ch<br> Affiliation:<br>
 University of Fribourg, Ecology and Evolution, Department of Biology, Ch.
 du Musée 10, CH-1700 Fribourg <br> Description of
 the data The data sheet contains raw untransformed data
 from three sampling years (2015-2017). The year of sampling is indicated
 as a suffix to the column name.<br> Data describes measured grape
 quality parameters measured from Grape juice and variables describing
 viticultural ground management.<br> Columns:<br>
 "site" = number of vineyard site identification<br> Grape
 Qualities columns: parameter were measured by FTIR analysis of grape
 juice<br> "sug"    = a measure of grape sugar content;
 measured by refractometer in °Oechsle<br> "pH"     =
 measured pH<br> "TotA"   = describes total
 acidity<br> "TartA"  = amount of tartric acid
 (g/l)<br> "Malic"  = amount of malic acid (g/l)<br>
 "Grape_N"= amount of yeast available nitrogen (YAN) as
 (mg/l) Other variables<br>
 "pinot"       = dummy variable describing whether site belongs
 to the grape variety Pinot noir (=1) or Chasselas (=0)<br>
 "treatment"   = indicates the ground treatment within the
 vineyard Rem = vegetation removal, AltR = vegetation removal in every
 other row and NoR = no removal of vegetation<br>
 "disturbance" = assigned level of disturbance (= management
 intensity); derived from treatment<br> "soil_N"      =
 total soil N in percent measured in vineyard soil sample; Dumas Combustion
 method; analysed by CNS-Elemental analyser<br>
 "plantsdiv"   = averaged number of plant species assessed within
 1m^2 on each row (n=2) in 5 surveys<br> "plantscov"   =
 averaged percentage of plant cover assessed within 1m^2 on each row (n=2)
 in 5 surveys<br> "covNfix"     = averaged percentage of
 legume (N-fixing plants) plant cover assessed within 1m^2 on each row
 (n=2) in 5 surveys<br> "longitude" &
 "latitude"  = x, y coordinates indicates site location
 <br> Funding: European joint project PromESSinG 
 (Promoting  Ecosystem  Services  in  Grapes),  funded through the
 2013-2014 BiodivERsA/FACCE-JPI joint call for research proposals and the
 Swiss National Science Foundation [Grant Number 40FA40_158390]