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Exploring Montana’s Sea of Grass

In prairie ecosystems, it is difficult to see the biodiversity that is there from the window of a vehicle, even for people who are plant nerds like my husband Lars and me. Who can really distinguish different grass species without walking out into the prairie? Once we throw on our boots on and take off across the Reserve with our dog, Husker, there are so many types to see as spring emerges: annual or perennial, tall or short, sod or bunch, warm-season or cool-season. It really is amazing that there are so many characteristics of something we just usually think of as “grass.”

American Prairie Reserve is a mixed-grass prairie containing both short and tall grasses. For example, little barley is one of the smallest cool-season grasses growing up to 15 inches while green needlegrass is one of the tallest cool-season grasses, growing up to 36 inches. One of my favorite cool-season grasses is bluebunch wheatgrass, which also happens to be the state grass of Montana.

Here on the Reserve, grass isn’t ornamental – it’s an important part of the circle of life. It nourishes, provides cover and building material, and keeps soil from eroding away. By getting down on your hands and knees, you might discover a vesper sparrow nest hidden in the tall grasses. Or perhaps you’ll stumble upon a prairie dog town, where grasses give way to dusty burrows thanks to the little lawnmowers of the prairie. Bison like to graze around the edges of towns because the constant clipping by prairie dogs means that there are always new green things to eat.

The first plants to signal the beginning of spring are the cool-season grasses. Because these grasses evolved in temperate regions with cooler day and night temperatures and shorter day lengths, they begin growing much earlier than warm-season grasses, which evolved in tropical climates. Right now, cold-season grasses are in the process of using last summer’s reserve of carbohydrates to prepare new shoots for this year’s growth cycle. Cells are growing, expanding, and dividing, pushing out roots and a tube-like structure through which the first blade of grass will emerge from the soil surface.

With the emergence of this single leaf, the process of photosynthesis will support the growth and development of the seedling from here on out. This new growth will break the soil surface within the next few weeks as air and soil temperatures increase. Gazing across the landscape, at first you’ll notice just a gradual tinge of green, and before you know it, an ocean of green grass surrounds you. It’s a lot of fun to look for the first green plants of the year – a scavenger hunt for plant nerds like us.

The next time you have the chance to go for a prairie walk, see if you can distinguish the difference between sod-grass and bunchgrass. The bunchgrasses have distinct clumps of grass leaving space in between each island of green. Sod-forming grasses have either rhizomes or stolons by which they produce new plants, and these extensions of their root systems expand without needing to produce seeds – how energy efficient!

Within weeks, the browns and yellows of American Prairie Reserve will give way to brilliant green just in time for all of the life that emerges as winter fades away. Don’t forget to spend time looking down, even in Big Sky Country. You might be surprised by the biodiversity that you find.