Hello, students. This is Plants and Animals in Southern Cal and we're at Cheeseboro Canyon, is our example of a savannah. A savannah is like a prairie, and a prairie is like a grassland, and so you can sort of think of all those as the same. I don't use the word grassland so much, because even though it's dominated by grasses now, we think that once upon a time, California's prairies were not nearly as grassy. Like almost all of this grass that you see is annual, alien grass that came from the Mediterranean Basin, and it now is responsible for a huge proportion of the cover. But before this invasion happened, then the prairies would have had some grasses, a few annual grasses which probably weren't very dominant, maybe more bunch grasses, which are perennial grasses that form kind of an underground thing, and then send up leaves every year and then die back, and then lots of annual, leafy plants called forbs, and then also probably a lot of geophytes, things like onions and lilies and stuff like that. The reason why they are prairies instead of shrublands I think is because the water table is so low. Like there's a lot of soil on the top before you can get to groundwater that exists during the summer, and so any plant that had to have water during the summer would have to get through a lot of soil before it would be able to survive. Now, what makes it a savannah is that it's dotted with these trees, like this one. This is a valley oak, and you can see it's got a beautiful sort of spherical look to it. The valley oaks, I think they are typically pretty old. Like when you see a bunch of valley oaks, that's because they're pretty old, and they don't easily recruit. Recruitment is when you have a new individual that's established. So these valley oaks, they dump a ton of acorns on the ground, but almost all of those acorns don't make it past their first year. It's only a very, very lucky acorn, maybe it was shed in a year that was really wet or something like that, and so it grew down, and of course acorn is well fortified, and so then it grew down a root, and then the next year was a really great year, too, and it was also really wet. And so then it got its roots down deep enough to make it through like the third season. Once they get big like this and have roots that go down deep, then they're fine and they can live out here. But I think that's why there's not that many other things. It's just that there's a very acute seasonality to how moist the soil is. So once upon a time, there were lots and lots of places in California that were these oak savannas, and they were dominated by some bunch grasses and lots of forbs and a few annual grasses, and then they got greatly invaded. They were like the first thing to get invaded really heavily. And the invaders include all these annual grasses, which kind of interestingly have seeds that don't last very long in the seed bank, and then there are a lot of individuals anyway, a few species of geraniums, including storksbill, Erodium cicutarium, which is maybe one of our most common invaders and then more recently we're getting a lot of invasion of a couple species of mustards and star thistle. And those mustards and star thistle, they do have seeds that can last a long time. I think a lot of those leafy forbs, native leafy forbs, they have seeds that last a very long time in the seed bank, so they kind of can wait until they sense that the weather's just right, and then they come and bloom out. And so you'll have some years that are just fantastic, beautiful sort of blankets of flowery fields, and then you'll have other years that tend not to be so much. Another really important feature of these California prairies is that they have lots and lots of disturbance. See, there's lots of gopher mounds that are dotting all over the landscape. And if you look at the California flag, it has a grizzly bear on it. The grizzly bear is standing in a California prairie, and there's gopher mounds on the flag. Now, the grizzly bears would have been the top predators out here. They're not like the mountain bears that we've already studied. These are bears that would have dug up things to try to get at those onions and bulbs and at ground squirrels. Ground squirrels are another really important component of this ecosystem because they're also churning the soil constantly, digging things up. And then in other places -- not here, but in other California prairies and savannas, there's kangaroo rats and burrowing owls, lots of other types of burrowing animals, maybe a badger. And so what that means is that at a very local level there's all sorts of stages of succession caused by these local disturbances where there's fresh dirt and then there's dirt that's not quite as fresh and so on. And that buries the seeds but it also stimulates things. And so the biodiversity of the plants out here includes species that, like the mounds when they're just fresh and then species that like the mounds a little bit later, species that like the -- after you can't even tell that they're mounds and species that are in between the mounds, that hate the mounds. And so that then causes another -- it's another reason why you don't end up with just complete monocultures of one species and instead you have a very high diversity within the plot that you might say is 10 x 10 meters. Like 10 x 10 meters you can find a lot of species out here. So that's about all I had to say about that.