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New Paper in ‘Biological Invasions’

Ecotypic diversity of a dominant grassland species resists exotic invasion

Yang, Callaway, Atwater

In this study, Lixue Yang showed that bluebunch wheatgrass (Pseudorogneria spicata) populations with greater within species diversity were pound-for-pound more resistant to invasion by spotted knapweed (Centaurea stoebe) than populations with less species diversity, by an order of magnitude.

Dr. Yang attributed this to two processes: 1) as seen in our previous study,  more diverse bluebunch populations had greater yield, and 2) even accounting for their increased yield, diverse populations were more resistant to invasion than suspected.

The causes of this phenomenon remain mysterious, but they may have something to do with root recognition among related bluebunch or with activity of soil communities.

This paper takes an important step towards demonstrating the extreme–yet cryptic–effects that within-species diversity has on plant communities.

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New Paper in ‘Journal of Plant Ecology’

Evidence for fine-scale habitat specialization in an invasive weed

Atwater, Fletcher, Dickinson, Paterson, Barney (pdf)

In previous studies, we found evidence for striking genetic and phenotypic differentiation in Johnsongrass (Sorghum halepense) populations collected throughout the United States. Here, we report that Johnsongrass may be adapting to local habitat variation.

Johnsongrass from non-agricultural populations competed better in a field community than Johnsongrass from agricultural populations. Agricultural and non-agricultural populations were separated by less than a kilometer, suggesting that this species may be adapting to habitat variation at extremely fine spatial scales.

These results contribute to a growing list of studies revealing the importance of fine-scale habitat specialization in invasive species, with possible ecological and management implications.

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