Adapted from Yosemite National Park by Jeffrey P. Schaffer

Who can forget his or her first visit to Yosemite-the enormous granite cliffs of El Capitan and Clouds Rest, the leaping, dashing waterfalls, the domes of Yosemite Valley, Tenaya Canyon, and Tuolumne Meadows, the rusty, metamorphic peaks above Dana Meadows? Of these features only the waterfalls move, and none are living. For most visitors, memories of living forms-except for giant sequoias (Hikes 18, 19, 92, and 93)-are likely to take a back seat to the inanimate landscape, although many out-of-state visitors will be duly impressed with the size of some conifers. But despite the barren peaks, cliffs, and canyon walls, Yosemite is predominantly a landscape of forest green. Along all but a few of the Park's trails, conifers shade your way. In this chapter we'll delve into the "Living Yosemite"-the assemblage of plants and animals which we too often take for granted. We'll look at its ecology, the relations between organisms and their environment. Because humans too are an organism, we'll also look at them.

Driving up Highway 41, 120, or 140, you can't help noticing that the natural scene changes with elevation. The most obvious changes are in the trees, because they are the largest organisms and unlike most animals they are readily observable. When you pay close attention, you notice that not only the trees but the shrubs, wildflowers, grasses, and animals also change with elevation. You might wonder why you don't see the same species in Tuolumne Meadows that you saw in Yosemite Valley. Climate is probably the foremost limiting influence on species' distributions, but there are others. In the following pages we'll also look at the roles that topography, soil, fire, and organisms play in regulating the distribution of plant and animal species.