DOI: 10.5061/dryad.sn02v6xcr
title: Weed community change from the 1980s to 2020s, South France

description: Spontaneous plant communities have undergone considerable constraints due
 to human-mediated changes. Understanding how plant communities are
 shifting in response to land management and climate changes is necessary
 to predict future ecosystem functioning and improve the resilience of
 managed ecosystems, such as agroecosystems. Using Mediterranean weed
 communities as models of managed plant communities in a climate change
 hotspot, we quantified to which extent they have shifted from the 1980s to
 the 2020s in response to climate and management changes in vineyards. The
 weed communities of the same 40 vineyards in the Montpellier region were
 surveyed using the same protocol in spring, summer, and autumn, for two
 years, with a 40-year interval (1978-79 versus 2020-21). In four decades,
 the annual range of temperatures (i.e. the difference between the warmest
 month's and the coldest month's mean temperatures) increased by
 1.2°C and the summer temperatures by 2°C. Weed management diversified over
 time with the adoption of mowing that replaced the chemical weeding of
 interrows. Chemical weeding is now mostly limited to the area under the
 row. Current weed communities were 41% more abundant, 24% more diverse and
 with a less even distribution of abundance across species than the 1980s
 communities at the vineyard level. Modern communities were composed of
 more annual species (57% of annual species in the 1980s versus 80% in the
 2020s) with lower community-weighted seed mass and were composed of fewer
 C4 species. They had higher community-weighted specific leaf area, higher
 leaf dry matter content and lower leaf area than the 1980s weed
 communities. At the community level, the onset of flowering was earlier
 and the duration of flowering was longer in the 2020s. Climate change
 induced more stress-tolerant communities in the 2020s while the
 diversification of weed management practices favoured less ruderal
 communities. This study shows that plant communities are shifting in
 response to climate change and that land management is a strong lever for
 action to model more diverse and eventually more desirable plant
 communities in the future.
description: # **Weed community change from the 1980s to 2020s near Montpellier,
 France**
 [https://doi.org/10.5061/dryad.sn02v6xcr](https://doi.org/10.5061/dryad.sn02v6xcr) #### Description of the data and file structure The table includes all the explaining variables and response variables necessary to analyze the dataset. Each row is the change in weed community structure of a vineyard at a given season which is the **ID_plot_season** column.  Thus, "ID_plot_season= 76_june" describes the functional changes of the weed community of plot 76, from the 1980s to the 2020s. The dataset contains all the following information : -        Community Weighted mean and functional PCA coordinate shifts -        Phylogenetic and functional diversity shifts -        Abundance, richness, Shannon and Pielou shifts -        CSR score shifts -        Climate PCA coordinate shifts -        Climate variable shifts -        Weed management shifts All these shifts were computed following this equation : ΔIndice = (Indice2020s – Indice1980s)/(Indice2020s + Indice1980s) (Eq.1) Thus, these shifts are unitless. The table below lists the different variables of the dataset with their description. We did not specify the units as the whole dataset is unitless. | **Variables** | **Description** | | :--------------------- | :------------------------------------------------------------------------------------------------------------------------- | | ID\_plot\_season | weed community of a vineyard at a given season | | ID\_plot | Vineyard plot | | Season | Season | | delta.dim.1.trait | Shifts in weed communities along the first axis of the functional Principal Component Analysis (PCA) | | delta.dim.2.trait | Shifts in weed communities along the second axis of the functional PCA | | delta.dim.3.trait | Shifts in weed communities along the third axis of the functional PCA | | delta.dim.4.trait | Shifts in weed communities along the fourth axis of the functional PCA | | delta.SLA | Shifts in the weed community weighted mean specific leaf area | | delta.LDMC | Shifts in the weed community weighted mean leaf dry matter content | | delta.Seed\_mass | Shifts in the weed community seed mass | | delta.Max\_Height | Shifts in the weed community maximum height | | delta.EIV\_L | Shifts in the weed community Ellenberg light indicator value | | delta.EIV\_T | Shifts in the weed community Ellenberg temperature indicator value | | delta.EIV\_F | Shifts in the weed community Ellenberg soil moisture indicator value | | delta.EIV\_N | Shifts in the weed community Ellenberg nitrogen indicator value | | delta.Flow\_dur | Shifts in the weed community flowering duration | | delta.Flow\_on | Shifts in the weed community flowering onset | | delta.Lateral\_spread | Shifts in the weed community lateral spread | | delta.C4 | Shifts in the weed community C4 photosynthesis | | delta.LA | Shifts in the weed community leaf area | | Dim.1.mean.trait\_1980 | Coordinates of weed communities along the first axis of the functional PCA, during the 1980s | | Dim.1.mean.trait\_2020 | Coordinates of weed communities along the first axis of the functional PCA, during the 2020s | | Dim.2.mean.trait\_1980 | Coordinates of weed communities along the second axis of the functional PCA, during the 1980s | | Dim.2.mean.trait\_2020 | Coordinates of weed communities along the second axis of the functional PCA, during the 2020s | | Dim.3.mean.trait\_1980 | Coordinates of weed communities along the third axis of the functional PCA, during the 1980s | | Dim.3.mean.trait\_2020 | Coordinates of weed communities along the third axis of the functional PCA, during the 2020s | | Dim.4.mean.trait\_1980 | Coordinates of weed communities along the fourth axis of the functional PCA, during the 1980s | | Dim.4.mean.trait\_2020 | Coordinates of weed communities along the fourth axis of the functional PCA, during the 2020s | | delta.ab | Shifts in the weed community abundance | | delta.rich | Shifts in the weed community richness | | delta.shannon | Shifts in the weed community Shannon index | | delta.pielou | Shifts in the weed community Pielou index | | C\_1980s | Competitive score in the CSR triangle of weed communities in the 1980s | | C\_2020s | Competitive score in the CSR triangle of weed communities in the 2020s | | S\_1980s | Stress-tolerance score in the CSR triangle of weed communities in the 1980s | | S\_2020s | Stress-tolerance score in the CSR triangle of weed communities in the 2020s | | R\_1980s | Ruderal score in the CSR triangle of weed communities in the 1980s | | R\_2020s | Ruderal score in the CSR triangle of weed communities in the 2020s | | C\_shift | Shifts in Competitive score of weed communities from the 1980s to the 2020s | | R\_shift | Shifts in Ruderal score of weed communities from the 1980s to the 2020s | | S\_shift | Shifts in Stress-tolerance score of weed communities from the 1980s to the 2020s | | delta.dim.1.climate | Shifts in weed communities along the first axis of the climate PCA | | delta.dim.2.climate | Shifts in weed communities along the second axis of the climate PCA | | delta.T.Summer | Shifts in summer temperature from the 1980s to the 2020s | | delta.T.range | Shifts in annual range of temperatures from the 1980s to the 2020s | | delta.dim.1.pra | Shifts in practices along the first axis of the practice PCA from the 1980s to the 2020s | | delta.dim.2.pra | Shifts in practices along the first axis of the practice PCA from the 1980s to the 2020s | | Nb.decades.C | Number of decades with herbicide use from the 1980s to the 2020s | | Nb.decades.stop.C | Number of decadres since herbicides were abandoned | | Diver | Weed management diversification: number of additional weed management practices applied in the 2020s compared to the 1980s | | Nb.decades.start.M | Number of years since mowing was adopted | | Nb.Mow\.IR.20 | Annual frequency of mowing of the interrow in the 2020s | | Nb.Mow\.R.20 | Annual frequency of mowing of the row in the 2020s | | Nb.Till.IR.20 | Annual frequency of tillage of the interrow in the 2020s | | Nb.Till.R.20 | Annual frequency of tillage of the row in the 2020s | | Nb.Chem.IR.20 | Annual frequency of herbicide sprayings of the interrow in the 2020s | | Nb.Chem.R.20 | Annual frequency of herbicide sprayings of the rows in the 2020s | | rao\_20 | Rao quadratic entropy of weed communities in the 2020s | | rao\_80 | Rao quadratic entropy of weed communities in the 1980s | | delta.rao\_phyl | Shifts in phylogenetic diversity of weed communities from the 1980s to the 2020s | | Nb.Chem.IR.80 | Annual frequency of herbicide sprayings of the interrow in the 1980s | | Nb.Chem.R.80 | Annual frequency of herbicide sprayings of the rows in the 1980s | | delta.rao | Shifts in functional diversity of weed communities from the 1980s to the 2020s |