Little evidence of native and non‐native species influencing one another's abundance and distribution in the herb layer of an oak woodland

Abstract

Question: To what extent are species, including native and non-native species, influencing one another's distribution and abundance in the herb layer of a Minnesota oak woodland?Location: Oak woodland succeeding into a more mesic forest, on bluffland of the Mississippi River, east-central Minnesota. Methods:We collected plant composition and species cover data in 182 1.0 9 0.5 m quadrats regularly spaced on a 6-ha study grid in the oak woodland. We also recorded slope, slope position, aspect, elevation and photosynthetically active radiation (PAR) at each quadrat.Results: Presence and abundance of other plant species, topographic variables and light availability explained only a small portion of the variation (5-19%) in the distribution and abundance of individual species. The most common strongest predictor of cover for the ten most common species was species richness, with the association being positive. The non-native species, garlic mustard (Alliaria petiolata) exhibited the strongest positive association with species richness. Only one of the 45 pair-wise comparisons of the ten species resulted in a negative relationship between the species. Abundance and distribution of two species were associated with topographic features, but this accounted for much less of the variation in abundance than did species richness. Conclusion:We found little evidence that competition or any other interactions among common herb layer species, including the non-native Alliaria petiolata, play an important role in determining the abundance and the distribution of herb layer species in this oak woodland. Topographic factors may explain a small amount of the distribution and abundance patterns of a few species. But, for the most part, species are more likely to be present when other species are present, suggesting that they are simply establishing in microsites favourable to plants in general.

Genomic signatures of rapid adaptive evolution in the bluespotted cornetfish, a Mediterranean Lessepsian invader

“…; Davis et al . ), most biological invasions result in significant negative ecological and economic impacts (Simberloff & Rejmánek ; Vitule et al . ).…”

Comparison of the non‐native herbAlliaria petiolatawith dominant native herbs in microhabitats of a Midwestern forest

“…In a prior study in the same site that did not differentiate quadrats based on density, we observed largely positive correlations among species and guilds, which we attributed to overlapping habitat preferences among herb species, including Alliaria (Davis et al. ). Our main motivation for differentiating quadrats based on cover in the present study was to attempt to isolate this possibility, which should generate positive correlations and be strongest at the lowest cover levels, from negative correlation‐generating mechanisms such as competition, which should be strongest at the highest overall cover.…”

“…Details of the location and ecology of the station have been described elsewhere (Davis et al. , ). Briefly, the woodland habitat is dominated by oak species (primarily Quercus rubra L., Q. ellipsoidalis E.J.…”

“…In prior studies (Davis et al. , ), we have determined that the ten most common species (hereafter focal species) in the herb layer are as follows: two shrubs, Ribes missouriense Nutt. and Rubus spp.…”

A novel mechanism to explain success of invasive herbaceous species at the expense of natives in eastern hardwood forests

“…(a) Garlic mustard co‐existing among native species of the herbaceous layer of a deciduous forest of east‐central Minnesota (Davis et al ., ). Note encircled cordate basal leaf in center, typical of vegetative first year of this obligate biennial (photograph credit: Mark Davis).…”