Grasslands & Grazing (mowing)

We see grass and grasslands everywhere: in our yards, in pastures, and in the wild. Let's learn a bit more about the Grass Family - Poaceae and learn some ID techniques and common species.

The Lab ACtivity

In general grasses tend to look like little green leaves that all look alike...but that is because we are not looking close enough! Your first step is to look at the diagram below in the background info. Take note of the terminology relating to different parts of grass. You may need to google some structures to make sure you know what you are looking at (i.e. what is a tiller, a stolon, etc.?). Then, with your newfound vocabulary, watch the video directly after the diagram. This will show you how to go about identifying some common cool season grass species. I know the video is from the UK but we have many of the same species here in the USA as well thanks to introductions from colonists so it is likely you will see some of these species around you. In any case take special note of his approach (i.e. what traits he is using) to distinguish between species. We also have a Multi Access Key for UK grasses based on grass inflorescence. When you are using it take special note that when you click on the name of each trait (Inflorescence, Spikelet arrangement, Spikelet shape, Glumes, Floret number, Awns, Awn length, Awn type) there is a a diagram and/or description that will lead you through how to use the trait. Always remember that it doesn't matter grading-wise if you get the ID correct - we are more interested in a correct and developed process for trying to ID grasses using the data at hand.

You will now use your knowledge (diagram and video) and tools (video, key, smartphone apps) to identify grasses near you. This is a VERY challenging thing to try and do...grasses are NOT easy! It can be super challenging if the grass does not yet have any inflorescence showing. If all you have is a mowed yard or it is too cold to see grass seeds and flowers yet - you will have to go with the leaf, collar, and ligule approach. Your ID apps may not be of much use as these are hard differences for them to pick up...but it is worth a try! Also, please note that the resources I have referenced are to do with cool season grasses. If you have access to a prairie and are trying to do IDs there you will want to look in the videos down in the "other resources" category. Remember warm season grasses start growing later in the summer while cool season grasses take off right away in the early spring.

I would like you to try and identify 10 specimens. I know this is pretty hard given the constraints listed above so I am going to ask you to do at least 3 from live specimens. For the remaining 7 feel free to either use live specimens OR pictures from a Google image search for "grass seed heads", etc.

Finally, since not all of you have ruminants handy we cannot examine the effects of grazing. Instead, we will examine the effects of mowing! Go into a field or yard (a place you could imagine animals grazing... even if it would have to be a motorized one.. aka lawn mower). If you have access to an area that is grazed/mowed regularly AND a grassy margin that is mowed/grazed infrequently (ditches, woods edge, etc.) that is even better. Compare the regularly grazed/mowed patch to the infrequently grazed/mowed patch. What differences do you notice in estimated plant morphotype diversity? What about differences in the proportion of grasses vs. broad-leafed plants? Why do you think you these observed differences exist?

Now, get on your hands and knees on the ground and look at a grass patch you have handy before and after grazing/mowing. What happened? How does mowing/grazing affect the sunlight conversion (photosynthetic capacity) in your grass patch? Soil cover? What do you think is happening to the plant community as a result of the mowing? How does managing plant/animal (lawn mower) relationships affect the ecosystem?

What to hand in on your website

• 10 identified grass specimens (at least 3 hand specimens) - that include the following [50 points]:

  • • species name - note: If you can't get all the way to species that is fine. Just list the level at which you were able to identify (genus, etc.). I am more interested in your process rather than your ID

    • annotated picture(s) with specific attention to what structures and traits you are using in your ID

    • detailed description of how you went about identifying using your resources and the traits you could see

• one paragraph comparing the plant communities in the frequently mowed/grazed area vs. the infrequently mowed/grazed area and why they appear how they do [5 points]

• one paragraph describing the grass-level view of what is different before and after the mowing/grazing event [5 points]

background

Multi Access Key for UK grasses using the following terms:

• Inflorescence

• Spikelet arrangement

• Spikelet shape

• Glumes

• Floret number

• Awns

• Awn length

• Awn type

other resources....

Fun children's book - We are Growing

https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=295987

https://www.sciencedaily.com/releases/2019/12/191219074744.htm