Data from publication: Castillioni, K., & Isbell, F. (2023). Early positive spatial selection effects of beta-diversity on ecosystem functioning. Landscape Ecology, 1-15.
Spatial beta-diversity may increase landscape productivity if there are positive spatial selection effects. Alternatively, dominant species in mixtures might not be the most productive species in monoculture leading to negative or neutral spatial selection effects. However, these hypotheses remain untested experimentally. Seedling survival can determine species establishment, influencing productivity later. To address this knowledge gap, we experimentally tested whether transplanted seedlings of dominant species optimally sort among habitat types (grassland dominated by Andropogon gerardii, savanna by Quercus macrocarpa, deciduous forest by Acer rubrum, coniferous forest by Pinus strobus, bog by Larix laricina), creating positive effects of landscape diversity on seedling survival and net biodiversity effects at Cedar Creek Ecosystem Science Reserve (CCESR) in Minnesota, USA. The study is named BetaDIV and consists of 100 plots (20 plots per habitat × 5 habitats). Each of the five habitats includes two true replicate monocultures for each of the five species and two true replicates for each of the five possible mixture compositions of four species (leaving each one out in turn to eventually explore the effect of species identity). Each plot is 1.5 by 1.5 m, with 12 seedlings planted 0.5 m apart in a 4 × 4 square grid, except in the plot corners. In the early June 2022, we tagged and planted all seedlings (i.e., bareroot seedlings for trees and plugs for the grass A. gerardii). Two weeks after the initial transplanting, we started tracking seedling survival (presented here) to investigate how seedlings responded to local habitat conditions. We conducted a seedling census for each of the 1200 tagged seedlings (12 seedlings per plot×100 plots), in early September 2022, which was two months at the end of the growing season of the first year of this experiment. We also measured soil moisture, soil temperature and light availability as environmental variables that could influence seedling survival. We did five measurements of soil moisture (m3 of water/ m3 of soil) and soil temperature (°C) in the upper 10 cm of each plot (averaging across five measurements per plot: four in the plot corners and one in the center) using a Decagon 5TM probe (METER Group, Pullman, WA, USA). We measured light interception by taking two-point measurements of photosynthetically active radiation (PAR, μmol m−2 s−1) above the plant canopy (i.e., below adult trees canopy) and below the plant canopy (i.e., just above litter layer) in each plot and using a Meter Accupar—LP-80 (METER Group, Pullman, WA, USA). Each light measurement represents eighty sensors that are averaged in an 80 cm long probe. We then averaged the two-point measurements to obtain an overall averaged plot-level PAR.