What indicators of phenological stage would you use to decide when grazing should start and how would you decide when to remove livestock? This would be in North Dakota, in the northern great plains, USA. Here Kentucky bluegrass often goes dormant in the summer but will green up again in the fall with cooler temperatures if we get fall rains.
Has exotic animal grazing ever been shown to make the change you are looking for in your area, because unfortunately it has never worked here in California.
You do not mention what species you want to replace the KBG with, but you might check soil nutrient thresholds needed for seedling survival for each of the natives plus the KBG.
What I have found out here, is that soil nutrient levels for native seedling survivals are below the threshold for natives species, so no matter how much you try to hammer back the exotics, the natives cannot recolonize soils too poor for their seedling survival.
For example, decades of research and tens of millions of dollars spent on finding ways to fight cheatgrass in the Great Basin, without realizing the cheatgrass is just a symptom of soil nutrient levels too low for native seedling survival, like you can see at http://www.ecoseeds.com/good.example.html, and see the fix when fertilizer was added for the 600 acre project at http://www.ecoseeds.com/greatbasin.html.
Another example is the 100 year old battle in the Franklin Basin, Idaho vs the solid stands of tarweeds in the Rocky Mountains, where three generations of researchers failed to find any answer, until we set up test plots in 1997 with fertilizer, and now native grow there again.
Hope this answer is helpful. You can go for decades fighting weeds, and until you look close at the soil nutrient requirement of the native seedlings you desire, then 100 years can go by without results, like in Idaho.
We will be grazing with beef cattle. We have been turning them out early in the spring and grazing intensively for a short time and then removing them when the natives start to grow. And this does seem to reduce the Kentucky bluegrass somewhat. So we are considering a fall grazing as well. I haven't looked at soil nutrients, but I have heard that high nitrogen levels may encourage the Kentucky bluegrass. The natives we would be hoping to encourage would be things like western wheatgrass, green needlegrass, needle and thread, short bristle needle and thread, and big bluestem.
Ignore whatever you have ever heard about high nitrogen levels and weeds vs natives, unless you have data from test plots you have actual measured yourself. And I am doubtful that any form of grazing is going to make a major impact with any form of grazing, especially if the underlying cause is a soil nutrient problem.
Nitrogen favoring weeds over natives is the biggest scientific myth in uplands ecological restoration that has been around for almost 20 years now. This concept got started from the erroneous observations of a researcher from the Southwest, and has become part of the popular land management mythology like an urban myth.
The http://www.ecoseeds.com/good.example.html shows the whole story of when you have low soil levels that have dropped below native seedling survival levels, then the native seedlings die of starvation. See Howard Sprauge’s classic book “Hunger Signs in Crops” (three editions).
You could go out and gather some soil samples in spring, take only from the top 2 inches below the duff, and I use 1 x 2 foot wood boxes, or even as small as 6-8" square plastic pots.
Then sow the different native grass seeds, each into their own individual pots, and also have a control pot with potting soil for each species. If you get good germination and growth in the potting soil only, and if any of the species of native grass seedlings die at two inches tall like they did in the photo on the web page, then fertilizers will be needed.
You did not say how big this area is---what percentage cover is there of the bluegrass and what percentage do you have of the other weed and native species---and do you still have some wildflower percentage cover, like annuals and herbaceous perennials---and whose land is it---and why is there a need to control the bluegrass, like it is Endangered Species habitat?
Some ranchers graze it hard early in the season before the native grasses have made much growth. I guess fall grazing, in addition, may also help, although the native C3 grasses also have a secondary peak at the same time.
Don't allow it to reach seed stage by grazing or cutting. This will eliminate it's abundance.
- Badges
- Science topic