Читать книгу One Best Hike: Grand Canyon. Everything You Need to Know to Successfully Hike from the Rim to the River—and Back онлайн

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These vegetation zones can be identified by just a few dominant shrubs and trees, but more than 900 species occur below the canyon rims and in spring a diligent botanist might locate several hundred species along this walk. Any attentive hiker will notice many tens of distinctive and, when flowering, colorful species. Such diversity exists because the landscape is complex, creating many unique combinations of physical, chemical, and biological conditions. Each species prefers a certain soil depth, soil made from a specific rock, a specific small-scale climate, and a specific topographic position. Your walk will take you past geographic features that include solid rock, washes, steep slopes, seeps, small dunes, river terraces, the Tonto Platform, stream banks, ridges, and valleys, each home to a different collection of species.

DESERT ADAPTATIONS

Colorful flowers attract your attention—and that of pollinators—but stare also at the leaves and stems of plants, for they you will remind you what life is like for plants in the region. For instance, shrubs and perennial herbs that grow in a desert environment must have traits that minimize water loss: Lack of leaves (e.g., cactus), drought-deciduous leaves (leaves that fall off in summer; e.g., blackbrush), small leaves (e.g., Mormon tea) and hairy leaves (e.g., brittlebush and big sagebrush) are all common desert adaptations. Most water loss occurs because plants need to cool their leaves by transpiring (evaporating) water, a process much like humans sweating. Minimizing leaf area and having leaf hairs to reflect light and keep leaves cooler are two very effective ways to preserve water.