Spring burn season, the transitional time from snow melt to when green life returns, can be a frustrating period. We practitioners concentrate most of our efforts to be ready for that small period of time when wind, relative humidity and temperature all align for proper burn conditions. Needless to say, we end up doing a lot of “hurry up and wait.” Saw work is on hold due to sap flow; spot spraying is on hold because plants are not mature enough, so we mentally try to will the weather to cooperate for burning. During these “wait” times between burns, I try to visit as many sites as possible to determine upcoming management needs.
On this March day, I’m looking at an oak savanna we burned in early February. (Refer to the landscape picture immediately below.)
What stands out to you? Yes, there’s a lot of green. Is this good or bad for a savanna? Warm-season grasses (good) are a major plant component of the tallgrass prairie (which includes the oak savanna). As their name suggests, warm-season grasses don't start growing until later in the spring when temperatures have been consistently warm. Cool-season grasses, both native (good) and non-native (bad), grow best during the early spring when temperatures are cool. With this information, we now know our green hillside is covered with cool-season grasses. Many of the non-native, cool-season grasses are invasive species. They compete vigorously with our native grasses and forbs (flowers), and restoration practitioners use a variety of methods to try and control them. One technique is to herbicide the invasive cool-season grass very early in the spring while the majority of native warm-season grasses and forbs are still dormant (not emerged). This technique can be successful if your site does not have native cool-season grasses (and sedges) or early emerging forbs present. Let’s go parse the green for a closer look.
Refer to the photo below.
Next to the coins are June grass and one of the small panic grass species (upper right coin). Both are native cool-season grasses (we want them to prosper). Also present are tall fescue (left half of photo) and smooth brome (right half of photo) – non-native, cool-season invasive grass species (we want them suppressed). Tall fescue is used for both turf (like heavy traffic playgrounds) and agricultural forage. Smooth brome is used for forage. Both of these species wreak havoc on native plant communities.
The photo below shows a small panic grass (left coin) and little bluestem (right coin).
Little bluestem is a native warm-season grass, which hasn't yet emerged. The majority of the green is a mixture of smooth brome grass and quackgrass. Quackgrass is a non-native, cool-season invasive grass brought to this country primarily as an agricultural forage species. It is a serious threat to native plant communities.
The photo below shows native nodding wild onion (left coin), spiderwort (upper right coin) and small panic grass (lower right coin) in a sea of quackgrass. Both nodding wild onion and spiderwort are native forbs.
The photo below shows a just-emerging pasque flower (left of coin) and a wild lupine seedling (above coin).
You can also see many older lupine plants emerging (many purplish leaves radiating out from a central location). Both the pasque flower and lupine are very showy native forbs.
The next photo shows blue-eyed grass next to the coin. Blue-eyed grass is actually a native forb.
And the last photo shows needle grass (left two coins), small panic grass (third coin) and needle grass (fourth coin).
Needle grass is an uncommon native cool-season grass. Also present are non-native quackgrass and Kentucky bluegrass (fine textured leaf). Kentucky bluegrass is a non-native, cool-season invasive grass used everywhere for turf grass in lawns. It can form dense mats that leave little room for anything else.
Now that we have "parsed the green" in our analysis of the hillside, what management practices should we implement? I think it's clear that using an herbicide to control the invasive, non-native cool-season grasses is not a good idea due to all the native species that would also be harmed. For this particular site, we plan to just use dormant-season frequent fire to help tip the balance in favor of the natives.
This little parsing exercise illustrates how important it is to be able to identify plants at all growth stages in order to effectively manage for biodiversity. It's a never-ending learning environment for the inclined practitioner! Hey, I see a ray of sun peaking through the clouds. Got to go check the updated forecast. Maybe we can get in a late afternoon burn?