[MUSIC] I'm Erika Zavaleta and this is Ecosystems of California. And today we're visiting California's alpine ecosystems above Virginia Lakes in the Hoover wilderness and the eastside of the Sierras. So we're at about 3,200 meters right now. Still just below treeline, and we'll be climbing up out of here to check out some of what's up above. Now, because alpine ecosystems occur above treeline, that's the simplest definition. That means that their vegetation is going to be shrubs, grasses, and graminoids, and other herbs, and then mosses and lichens. In most alpine ecosystems, you have mainly perennial plants. Things with a lifespan of more than one year, because it's a really, really difficult environment in which to have an annual life cycle. The Sierras have more annuals than a lot of continental alpine systems. And that's even though they have to do all of their growing in this really, really short period and complete their entire lifecycle then. So in California, it's a little bit warmer than in alpine areas and places like the Rockies. And that may be part of why annual plants are able to make it here. And although alpine ecosystems include vegetation, they also include a lot of habitats that are characterized by rock. Or what are called lithic environments like this talus slope. But also cliffs, boulder fields, and rock glaciers, which are sort of a matrix of rocks embedded in ice that move down slope. And then tarns, large and small lakes and glaciers and snowfields. And although there aren't a lot of plants in these lithic environments, there are lithic-adapted flora. Including lichens that grow on rocks and certain perennial and annual species adapted to really unstable substrates. There isn't a lot of vertebrate diversity in the alpine. But there are some really interesting animals that lived in lithic environments and have a variety of adaptations to deal with these settings. Yellow-bellied marmots are an important mammal species in the alpine, in both the Sierra Nevada and the White Mountains. And they breed in both alpine and subalpine meadows. Another important alpine mammal is the American pika which is actually a lagomorph or a relative of rabbits. It's about this big and it's a specialist on these talus slopes and broken rock environments. And pikas have a really interesting lifecycle. Even though they live in these really, really extreme environments with very, very short summers and a long year under snow, and with cold temperatures, they don't hibernate. What they do is they will cull and harvest plant parts all summer and build them into a bed, food storage area underneath the rocks. And then pikas are preyed upon by a variety of things, but weasels are big predator and raptors are another one. And so they have alarm cries that are really distinctive that are higher pitched than the marmots. [SOUND] The Sierra Nevada yellow legged frog was once an important part of alpine and subalpine lakes throughout this region. The yellow legged frog began to decline quite a while ago. And it was first thought that that was due to introduced trout and other fishes into these high alpine lakes, and maybe to pollution. However, people noticed that the frogs were continuing to disappear even from lakes that weren't polluted and didn't have introduced fishes in them. And it's now understood better that chytrid fungus, which is a fungal disease of amphibians that has spread throughout much of the world, is affecting these frogs. Because they were so abundant, and because they are predators. Sierra Nevada yellow legged frogs are thought to have been an important part of the cycling of energy and matter in both aquatic and terrestrial ecosystems in this Sierra Nevada alpine. A second species of once common amphibian in the alpine and environments of the Sierra Nevada is the Yosemite toad. The Yosemite toad is a resident of alpine and subalpine meadows, and it's declined a lot in recent decades. One interesting thing about it is that its lifespan, up to 15 or 20 years, is really unusual for a toad. And it's thought to be an adaptation to this environment, where growing seasons are so short that to complete its life cycle it really has to be able to survive for a long time. And, to be able to capture optimal conditions for breeding, it may need to wait a long time, for a good year. Wow, so this is Moat Lake, and this sort of amphitheater shaped basin behind me is called a cirque. And it's formed by glacial action, and you'll get little ponds or lakes called tarns at the bases of some cirques. And then this one is a little bit bigger and gets called a lake proper. So here we're at about 3,500 meters in elevation now about 10,500 feet. And you can see great examples of some of the different lithic environments that characterize the alpine. Including boulder fields, talus, cliffs, and then you can also see some patches of vegetation here and there even on some of the really steep unstable habitats. One of the things about the Sierra Nevada's alpine that's really unusual is that it really doesn't have a long period of overlap between water availability and warm weather. This is still that mediterranean type climate, so we have summer drought. So this is a system up on the slopes that's getting all of it's moisture essentially from snow. And so there's a very brief period when that snow melts and that time overlaps with the availability of temperatures warm enough during the day to photosynthesize and grow. So alpine environments everywhere, in the Alps and the Rockies and the Himalayas, have slow growing, low productivity vegetation. And in the Sierra Nevada it's even more acute. Its tempered a little bit by the warm temperatures here. So it's warmer, the growing season's a little bit longer, but it's really dry. One of the things that is exceptional about the Sierras is that because it has this Mediterranean type climate and these alpine environments, and they don't occur anywhere else, it has a lot of endemics. So a lot of species that aren't found anywhere in the world besides the Sierra Nevada alpine. It's also definitely gotten colder as we've come up slope, just from 3,000 meters to 3,500 meters. And above us in little spots, even though it's August and it was a very dry winter, there is a little bit of snow here and there. Which is pretty remarkable and just reflects how quickly it's cooling idiomatically as we go up. Only about 3% of the world's land surface consists of alpine ecosystems. But they play an important role in the hydrology of mountain regions throughout the world. And that's especially true here in California. Where the role that alpine ecosystems play in maintaining snowpack and delivering gradual snow melt helps attenuate the long summer droughts for ecosystems downstream of here. One of the challenges that organisms face in the alpine here is that there is very little overlap between moisture availability, and warm temperatures. And so as climate change reduces snowpack in the Sierras by some accounts by as much as 90%. It's going to have really important implications not only for the state's water capture, storage and transport systems. But also for ehses ecosystems and for the subalpine and montane ecosystems downstream of here. [MUSIC]
