Weeds! Tricks of the Trade How weeds got to where they were going

Tricks of the trade Dispersal Traits: Seed banks: Landscapes: The plant characteristics that help them move Seed banks: Your plots have made a withdrawal Landscapes: How the world around us affects how weeds move 3 individual vignettes about the ways that weeds get to where they end up.

What is a weed? ? ? ? All these species are widespread in the U.S. Left: Prairie cordgrass – native grass important to native wetlands; Middle: crabgrass – non-native weed of lawns, etc.; Right: maize – important food crop . . . How do we define a weed? “. . . a plant not intentionally sown, whose undesirable qualities outweigh its good points.” (from the Introduction to Weeds of the North Central States)

Dispersal Traits Plants have evolved several “strategies” for getting their seeds away from the mother plant. . . First show the description, and ask the class to to describe what it would look like By birds and other animals Sticking to animal fur On the wind

Dispersal Traits Plants have evolved several “strategies” for getting their seeds away from the mother plant. . . On the water Explosive seed pods Being nutritious And so on . . . Left to right: Lotus (water), jewelweed (explosive), acorns (nutritious)

Graphing Activity Dispersal Traits

Seed banks Seeds can “disperse through time” by remaining dormant in the soil for . . . How long? William J. Beal buried 20 jars of seed in the ground in the 1880s, and we are still digging them up and germinating them! KBS researchers conducted research on the persistence of weeds in agricultural seed banks CC = continuous corn; RC = rotational ag in corn; RW = rotational ag in wheat (Weed Science 54(6):1094-1100. 2006. Rapid change in the germinable fraction of the weed seed bank in crop rotations)

More Graphing Seed Viability

Seed banks Seeds can “disperse through time” by remaining dormant in the soil for . . . How long? William J. Beal buried 20 jars of seed in the ground in the 1880s, and we are still digging them up and germinating them! KBS researchers conducted research on the persistence of weeds in agricultural seed banks CC = continuous corn; RC = rotational ag in corn; RW = rotational ag in wheat (Weed Science 54(6):1094-1100. 2006. Rapid change in the germinable fraction of the weed seed bank in crop rotations)

Landscapes How do the weeds get there? Land use history can influence the abundance of weeds Land uses that surround a site also are important Relative abundance of invasive species Bar graph – abundance of invasive species in prairie restorations with different land use histories (shows existence of variation)

Farms that used to be Forest Farms that used to be Prairie Note – farm areas that reflect red are former prairies, those that reflect gray are former forest Forest Residential Wetlands

Corridor Project Corridors increase dispersal of plants and animals. Corridor effects on dispersal can be predicted from knowledge of smaller-scale movement behavior of animals. Corridors increase plant diversity. Corridor project in S. Carolina: openings in longleaf pine forest as above are replicated in landscape

Tricks of the trade Traits: Explains some success The plant characteristics that help them move Seed banks: Explains a little more Your plots have made a withdrawal Landscapes: Explains a little more How the world around us affects how weeds move Have we explained all of the noise?

Clonal Species Kentucky bluegrass Crabgrass Quackgrass

Seedbank?