Study design
During the summer of 2019 in Wyoming, we established 5 blocks each forB. arvensis and B. tectorum along 10 natural invasion
gradients. Each block consisted of 5, 1 m2 plots with
different invasion levels (1 – very low, 2 - low, 3 - moderate, 4 -
high, and 5 – very high cover) of either B. arvensis or B.
tectorum (50 total plots). During the summer of 2020 in Montana, we
established blocks along 8 natural invasion gradients of B.
arvensis only. Each block consisted of 6, 1 m2 plots
across 3 levels of invasion abundance (1- very low, 3 – moderate, 5 –
very high cover) by B. arvensis . In 2020, we collected data from
a total of 48 plots, but in 2021 and 2022, we only present data from
half (24) of these plots as the other plots were allocated for an
additional treatment not presented here. At both sites, invasion levels
represent aerial cover categories of the invasive compared to the rest
of the plant community.