Restoration of native early successional plant communities in the eastern United States is a conservation priority because of declining populations of associated plants and wildlife. Restoration typically involves seeding native species and is often fraught with problems including weedy competition, expensive seed, and slow establishment. Pairing seed bank response with strategic herbicide applications may be an alternative approach for restoring these plant communities. We compared early successional plant communities established by seeding (SD) paired with selective herbicide use to natural revegetation (NR) from the seed bank paired with selective herbicide use at 18 locations that were previously row-crop or tall fescue (Schedonorus arundinaceus) fields in Tennessee, Alabama, and Kentucky, the United States. We did not detect differences in species diversity and richness, coverage of non-native grasses and forbs, or number and coverage of native flowering forbs by season between NR and SD treatments at tall fescue or fallow crop sites. Species evenness was greatest in NR and coverage of native-warm-season grasses in SD. Species richness and coverage of native forbs were least in untreated tall fescue units (CNTL). More flexibility to use herbicides with NR reduced coverage of sericea lespedeza (Lespedeza cuneata) in NR units compared to SD units at tall fescue sites. NR was 3.7 times cheaper than seeding. Land managers should consider using an NR approach to establish native early successional plant communities.

Forest fragmentation may negatively affect plants through reduced genetic diversity and increased population structure due to habitat isolation, decreased population size, and disturbance of pollen-seed dispersal mechanisms. However, in the case of tree species, effective pollen-seed dispersal, mating system, and ecological dynamics may help the species overcome the negative effect of forest fragmentation. A fine-scale population genetics study can shed light on the postfragmentation genetic diversity and structure of a species. Here, we present the genetic diversity and population structure of Cercis canadensis L. (eastern redbud) wild populations on a fine scale within fragmented areas centered around the borders of Georgia-Tennessee, USA. We hypothesized high genetic diversity among the collections of C. canadensis distributed across smaller geographical ranges. Fifteen microsatellite loci were used to genotype 172 individuals from 18 unmanaged and naturally occurring collection sites. Our results indicated presence of population structure, overall high genetic diversity (H E = 0.63, H O = 0.34), and moderate genetic differentiation (F ST = 0.14)among the collection sites. Two major genetic clusters within the smaller geographical distribution were revealed by STRUCTURE. Our data suggest that native C. canadensis populations in the fragmented area around the Georgia-Tennessee border were able to maintain high levels of genetic diversity, despite the presence of considerable spatial genetic structure. As habitat isolation may negatively affect gene flow of outcrossing species across time, consequences of habitat fragmentation should be regularly monitored for this and other forest species. This study also has important implications for habitat management efforts and future breeding programs. K E Y W O R D S Cercis canadensis, fine-scale population structure, genetic diversity, habitat fragmentation, redbud S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Ony MA, Nowicki M, Boggess SL, et al. Habitat fragmentation influences genetic diversity and differentiation: Fine-scale population structure of Cercis canadensis (eastern redbud).

Continued reliance on chemical methods for controlling annual bluegrass has resulted in many populations evolving resistance to PRE and POST herbicides, particularly in warm-season turfgrass species such as zoysiagrass. Soil seedbank management is critically important when managing herbicide-resistant weeds. Fraise mowing (also spelled fraze, frase, and fraize) is a new turfgrass cultivation practice designed to remove aboveground biomass while allowing turf to regrow vegetatively. We hypothesized that this process would remove annual bluegrass seed and therefore be a mechanical means of controlling annual bluegrass in turfgrass. Zoysiagrass field plots were fraise-mowed in June 2015 only, June 2016 only, June 2015 and June 2016, or left untreated. The fraise mower was configured to remove the uppermost 25 mm of plot surface (i.e., 15-mm verdure and 10-mm soil). Annual bluegrass infestation was quantified in April following fraise mowing via grid count. Soil cores (10.8 cm diameter) were extracted from each plot after grid count data were collected to assess effects of fraise mowing on the soil seedbank. Moreover, replicated subsamples (7.6 L) of debris generated during fraise mowing were collected to better understand weed seed content removed during the fraise mowing process. Fraise mowing in June offered a slight reduction (24%) in annual bluegrass cover the following April. Whereas 28% of the seed in fraise-mowing debris consisted of annual bluegrass, there was no difference in the quantity of annual bluegrass seed remaining in the soil seedbank among fraise-mowed and non–fraise-mowed plots. Although fraise mowing may help to temporarily reduce existing annual bluegrass infestations via mechanical removal, the frequency and depth we studied did not effectively reduce the seedbank. Fraise mowing is a useful tool for providing mechanical suppression of annual bluegrass but it is not a replacement for properly timed herbicide applications.