Andrew R. Jakubowski

Genetic evidence suggests a widespread distribution of native North American populations of reed canarygrass

Reed canarygrass is an important agricultural crop thought to be native to Europe, Asia, and North America. However, it is one of the worst wetland invaders in North American wetlands. The native North American status has been supported by the circumstantial evidence of early botanical records and the dating and location of herbarium specimens. The lack of empirical evidence has left the North American native status of the species in doubt and prevented comparisons between native North American and Eurasian populations of the species. We utilized genetic markers to compare a wide range of European and Asian collections to DNA extracted from 38 early North American herbarium specimens. The genetic data confirm the presence of a distinct population present throughout North America in the early twentieth century, but not present in Europe or Asia, ranging from Alaska, USA to New Brunswick, Canada. These native North American populations of reed canarygrass are likely present throughout Alaska today, as one specimen was collected as recently as 1996, and may still be present in other regions of North America. Future research can utilize this dataset to determine the origin of present-day invasive populations in North American wetlands.

Population genetic structure of N. American and European Phalaris arundinacea L. as inferred from inter-simple sequence repeat markers

Phalaris arundinacea L. (reed canarygrass) has become one of the most aggressive invaders of North American wetlands. P. arundinacea is native to temperate N. America, Europe, and Asia, but repeated introductions of European genotypes to N. America, recent range expansions, and the planting of forage and ornamental cultivars complicate the resolution of its demographic history. Molecular tools can help to unravel the demographic and invasion history of populations of invasive species. In this study, inter-simple sequence repeat markers were used to analyze the population genetic structure of European and N. American populations of reed canary grass as well as forage and ornamental cultivars. We found that P. arundinacea harbors a high amount of genetic diversity with most of the diversity located within, as opposed to among, populations. Cluster analyses suggested that current populations are admixtures of two formerly distinct genetic groups.

Landscape context predicts reed canarygrass invasion: implications for management.

Understanding the landscape distribution of invasive species has become an important tool to help land managers focus their efforts. We used land cover data to predict the proportion of wetlands in a watershed dominated by reed canarygrass (Phalaris arundinacea L.), one of the most dominant wetland invaders in North America over the past century. Our results indicated that the landscape configuration of a watershed was a better predictor than the landscape composition of a watershed, with the adjacency of wetlands to agriculture and open water identified as the best predictors of the proportion of wetlands in a watershed dominated by reed canarygrass. In contrast, proportion of agriculture and open water were identified as the next best predictors in our regression tree, but explained significantly less variability. These results suggest that the risk of invasion by reed canarygrass varies among watersheds, and further that the potential for restoration success may similarly vary across the landscape. We argue that it is essential to understand the landscape context of a wetland before attempting a restoration project because success may be mediated by factors outside the local site.

Genetic diversity and population structure of Eurasian populations of reed canarygrass: cytotypes, cultivars, and interspecific hybrids.

Reed canarygrass (Phalaris arundinacea L.) is an important forage crop and potential biofuel feedstock due to its wide environmental adaptation. The P. arundinacea ‘species complex’ is made up of three cytotypes, 2x, 4x, and 6x, with the 4x cytotype (P. arundinacea L.) most common. Active breeding programs have developed cultivars since the early 20th Century, but little is known about the genetics of the species complex. With the aid of DNA markers, we evaluated the population structure of 83 wild accessions collected throughout Eurasia, 24 cultivars, and the genetic relationship between 4x and 6x cytotypes. Seven subpopulations were present in Europe with a high level of admixture, suggesting that reed canarygrass germplasm has spread throughout Eurasia, either naturally or by humans for use in agriculture. Our results indicate that cultivars have incorporated much of the diversity found in wild populations, although modern low-alkaloid cultivars appear to come from a relatively small gene pool. We also found some evidence that the 6x cytotype is made up of three sub-genomes that are a combination of genomes present in 4x P. arundinacea and 4x P. aquatica, although the 6x cytotype does not appear to be a direct hybrid between the species.

Regional Gene Pools for Restoration, Conservation, and Genetic Improvement of Prairie Grasses

Switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), and Indiangrass (Sorghastrum nutans) are native warm-season grasses that have been identified as potential cellulosic bioenergy feedstock crops due to their potential for high yields, perennial life habit, and nutrient use efficiency. This chapter outlines the role that improved cultivars and unimproved locally collected ecotypes can play in meeting agronomic and conservation goals. Improved cultivars grown for use as a bioenergy feedstock will be established in areas where introgression will occur with native populations. The concerns regarding the introgression of transgenes or non-adaptive alleles are outlined along with several avenues for mitigating these concerns. The agronomic and breeding history of each species is reviewed, as well as their importance in the conservation and restoration efforts of the prairie ecosystems of North America. We argue that both improved and locally collected ecotypes can coexist on the landscape and help to jumpstart the shift to a bioenergy based economy that provides sufficient biomass to meet cellulosic bioenergy goals, restore native ecosystems, and provide an array of regulating, cultural, and supporting ecosystem services while increasing the sustainability of agriculture.

Renovation and management effects on pasture productivity under rotational grazing.

Renovating permanent pasture to replace existing cool-season perennial grasses with improved varieties has potential risk and reward. Improved grasses may increase long-term productivity, but these increases should offset costs associated with replacing an existing stand. We eliminated existing perennial grass stands with tillage and herbicides and sowed a mixture of improved orchardgrass and meadow fescue in 2006 on five Wisconsin farms that used a range of rotational grazing systems. Paddocks were also subject to either typical producer management or recommended agronomic management. Despite considerable farm-to-farm variation, annual forage yield of improved varieties was greater than that of existing grasses the next two years. The yield advantage of improved varieties was greater when managed according to recommended agronomic practices in 2007, but management had no effect in 2008. Forage nutritive value was not influenced by grasses or management at any time during the growing season. Our results suggest that renovation with improved grasses increases pasture productivity, but producers should also consider their management and pasture production goals before renovating.