Canopy cover and soil moisture influence forest understory plant responses to experimental summer drought

Extreme droughts are globally increasing in frequency and severity. Most research on drought in forests focuses on the response of trees, while less is known about the impacts of drought on forest understory species and how these effects are moderated by the local environment.
We assessed the impacts of a 45-day experimental summer drought on the performance of six boreal forest understory plants, using a transplant experiment with rainout shelters replicated across 25 sites. We recorded growth, vitality and reproduction immediately, two months, and one year after the simulated drought, and examined how differences in ambient soil moisture and canopy cover among sites influenced the effects of drought on the performance of each species.
Drought negatively affected the growth and/or vitality of all species, but the effects were stronger and more persistent in the bryophytes than in the vascular plants. The two species associated with older forests, the moss Hylocomiastrum umbratum and th..., Experimental set-up and site-level variables
We experimentally induced a summer drought at 25 sites, representing a range of ambient canopy cover and soil moisture levels, in a managed forest landscape in central Sweden (Ekopark Färna, Västmanland, Sweden). We experimentally induced a 45-day drought during the summer 2021 (2th of June - 16th of July), by installing rainout shelters that completely intercepted all rainfall during this period over one of the plots at each site. The rainout shelters were 2 × 2 m, to allow for a 0.5 m buffer zone on each side of the drought-treated plots. The control plots received ambient rainfall, which added up to 87 mm.
In all treatment and control plots, we tracked soil moisture levels using TMS-4 loggers (TOMST). These loggers recorded soil moisture of the topsoil in the middle of each plot every 15 minutes. Raw soil moisture measures, which are based on conductivity pulses, were calibrated to percentage soil moisture volume. We calculated site-level ..., , # Data from: Canopy cover and soil moisture influence forest understory plant responses to experimental summer drought

## Dataset 1: sitelevel data

Provides site-level data for the 25 sites

Site_ID: Unique ID for each site
Latitude: Latitudinal coordinate
Longitude: Longitudinal cordinate
gap_fraction: The % gap in the canopy (inverse of canopy cover).
Canopy_cover: The % canopy cover
TMS_may: Proportional soil moisture in May before the drought treatment

## Dataset 2: All_species_growth_sc

Provides data on the scaled growth of the species over the different time intervals

Site_ID: Unique ID for each site
Treatment: Two level factor: drought treatment and ambient control
Transplant: Transplant ID within each plot (3 transplant patches for each species)
Species: Abbreviations of the six study species: Gr = Goodyera repens, Lp =Luzula pilosa, Oa = Oxalis acetosella, Hs = Hylocomium splendens, Hu = Hylcomiastrum umbratum, Bl = Barbilophozia lycopodioides
Group: Two level factor: vasc...