Control of invasive exotic species in restorations without compromising the native plant community is a challenge. Efficacy of exotic species control needs to consider collateral effects on the associated plant community. We asked (1) if short-term control of a dominant exotic invasive, Lespedeza cuneata in grassland restorations allows establishment of a more diverse native plant community, and (2) if control of the exotic and supplemental seed addition allows establishment of native species. A manipulative experiment tested the effects of herbicide treatments (five triclopyr and fluroxypyr formulations plus an untreated control) and seed addition (and unseeded control) on taxonomic and phylogenetic diversity, and community composition of restored grasslands in three sites over three years. We assessed response of L. cuneata through stem density counts, and response of the plant community through estimates of canopy cover. Herbicide treatments reduced the abundance of the exotic in the first field season leading to a less dispersed community composition compared with untreated controls, with the exotic regaining dominance by the third year. Supplemental seed addition did not provide extra resistance of the native community to reinvasion of the exotic. The communities were phylogenetically over-dispersed, but there was a short-term shift to lower phylogenetic diversity in response to herbicides consistent with a decrease in biotic filtering. Native plant communities in these grassland restorations were resilient to short-term reduction in abundance of a dominant invasive even though it was insufficient to provide an establishment window for native species establishment.

Intraspecific competition is an important plant interaction that has been studied extensively aboveground, but less so belowground, due to the difficulties in accessing the root system experimentally. Recent in vivo and in situ automatic imaging advances help understand root system architecture. In this study, a portable imaging platform and a scalable transplant technique were applied to test intraspecific competition in Arabidopsis thaliana. A single green fluorescent protein labeled plant was placed in the center of a grid of different planting densities of neighboring unlabeled plants or empty spaces, into which different treatments were made to the media. The root system of the central plant showed changes in the vertical distribution with increasing neighbor density, becoming more positively kurtotic, and developing an increasing negative skew with time. Horizontal root distribution was initially asymmetric, but became more evenly circular with time, and mean direction was not affected by the presence of adjacent empty spaces as initially hypothesized. To date, this is the first study to analyze the patterns of both vertical and horizontal growth in conspecific root systems. We present a portable imaging platform with simplicity, accessibility, and scalability, to capture the dynamic interactions of plant root systems.