Data from: Species patch size at seeding affects diversity and productivity responses in establishing grasslands

1. Species interactions in diverse plant communities affect
community-scale functions such as above-ground biomass production,
diversity and invasion resistance. While the strength of these formative
interactions can be affected by the balance of inter- and intraspecific
interactions among the resident species, it is unclear over what distances
individuals typically interact in grasslands and whether or not species
interactions at seeding can be effectively manipulated to improve these
responses. 2. In a three-year study, we tested whether manipulating the
size of seeded species patches affected above-ground biomass, diversity
and invasion resistance in experimentally restored grassland plots (16
m2). Plots were divided into patches that were 1, 0.5, 0.25 or 0.125 m on
a side, and the equivalent of 1 m2 in each plot was seeded with one of 16
grassland species (1728 seeds/m2). A final treatment involved mixing and
broadcasting all seeds into an undivided plot to mimic typical restoration
approaches. 3. Using successively smaller initial seed patches resulted in
plots that were less diverse and initially more productive (~25%
difference in second-year biomass production) than larger patch
counterparts. Smaller patch plots also had a greater selection effect and
experienced increases in resident species connectivity, suggesting that
diversity declines and productivity gains resulted from the enhanced
establishment and spread of more productive seeded species. 4. Plots
seeded with larger patches of the resident species were initially more
invaded than those seeded with smaller patches, but this effect diminished
over time. This likely reflects the ability of the non-seeded species to
more effectively colonize larger patches with poor seeded species
establishment. 5. Mixed seeding plots were most similar to the smallest
patch plots in their metrics of resident species spatial pattern,
diversity and invasion resistance. However, these plots were initially
less productive and had a weaker selection effect, which reflects a
different compositional outcome, than the structured seeding plots. 6.
Synthesis: Species interact over sub-metre scales in establishing
tallgrass prairie and, once established, their patterns may change over
time. Given these dynamics, structured seeding approaches may be used over
traditional mixed seeding approaches to control species dominance and
preserve seeded species diversity within grassland systems.