Rim Environment Pinyon - Juniper Community Microhabitats Plants Living on the Edge The arid environment of the South Rim Within each landscape are microhabitats, poses a number of challenges for the Both pinyons areas with conditions ideal for a plant or Grand Canyon National Park plants living here. The rim averages only 16 and junipers community that otherwise would not be able inches/41 cm of rain a year, which varies illustrate to flourish. Walk the Hermit Road portion entire trail or only a portion of it, picking up widely from year to year. Periods of drought adaptations of the Greenway Trail to learn the free shuttle bus at Pima Point along the are common. Half of the precipitation to this dry As you walk along the Greenway Trail environment. about the South Rim’s plant way. Enjoy the quiet overlooks and rest on falls as winter snow, when many plants are west of Monument Creek Vista and benches along the trail. Water, snacks, and dormant and cannot use the moisture. The Short, stout leave the canyon’s rim, notice several communities and how they thrive restrooms are available only at Hermits Rest. other half arrives with summer monsoon trees better ponderosa pines towering along the trail. in this challenging environment. storms starting in July. Huge thunderclouds withstand the Ponderosas have tall, straight trunks and Carry water and snacks and wear clothing build as the day heats up, often producing strong winds long needles. Generally found at higher This section of the Greenway Trail starts at appropriate for the weather. The exposed violent torrents of rain. Since much of the battering the elevations than pinyons and junipers, here Monument Creek Vista and ends at Hermits rim becomes hot in the summer and quite ground surface is rock, only a portion of rim. Small, they grow together. Why would that be? Rest, a distance of 2.8 miles/4.5 km. The cold with sharp winds in the winter. Be the rainwater penetrates the soil while the wax-coated First, by leaving the rim, you are leaving needles use paved trail is relatively level with some slight prepared and enjoy your learning adventure rest rushes away. Fractures within the rocks Pinyon pine (left), Utah juniper (right) the rim effect, the strong winds and hotter up and downhill sections. Walk along the against the backdrop of Grand Canyon. draw water deep into the ground, below the less water. air temperatures that would prevent a roots of the plants. Woodlands dominated by pinyon pine and Evergreen ponderosa from living right along the rim. various species of juniper grow throughout trees retain Also, the trail traverses a drainage that holds The rim effect influences local environments. the Southwest and dominate the vegetation their needles Ponderosa pines more moisture below the ground surface Warm, dry, summer air rising from the along the edge of Grand Canyon’s South for years and do not expend precious water than other areas, providing ponderosas depths of the abyss spills over the rim, Rim. and energy replacing all their foliage each sufficient moisture to live. You have stunting trees that grow tall and stately just year. These long-lived trees grow very encountered a microhabitat suitable for a few hundred feet back from the edge. Pinyon pine is easily recognized by its dark slowly. Even the smaller trees are decades ponderosas. Winter storms laden with snow and ice bark, short, curved needles in groups of two, old and can survive more than 600 years. sweep across the canyon, blasting the plants and small cones. The Utah juniper has Microhabitats can be much smaller in scale, close to the rim and exacting a toll on foliage shaggy bark, small scale-like needles, and Temperature increases and rainfall becomes such as a crack in the rock. While at first and the next season’s leaf and stem buds. light blue-green cones that look like, and are more scarce as you descend into the canyon. glance a crack seems like an impossible called, berries. A rich variety of shrubs, Desert plants replace pinyons and junipers. habitat, it is flowers, and grasses grow beneath these Biologist C. Hart Merriam documented actually quite trees, comprising a complex, fascinating this pattern of changing plant and animal favorable. community. communities with changes in elevation Cracks trap more that 100 years ago. He introduced the and hold soil concept of life zones—broad bands of plant and moisture, and animal species that could be associated giving plants with certain latitudes, elevations, and growing exposures. within them a better habitat At elevations higher than those found on than available most of the South Rim, ponderosa pines nearby. replace the pinyon-juniper community. At even higher elevations on the North Rim, Engelmann spruce, subalpine fir, and aspen Pinyon cones (left) and juniper berries (right) replace the ponderosa pine community. National Park Service Adaptations to the Environment Interactions with other Plants and Animals Past, Present, and Future U.S. Department of the Interior Grand Canyon National Park Like pinyons and junipers, many plants have adapted to Plants often develop symbiotic relationships Fungi form an Today the pinyon-juniper community A healthy pinyon-juniper community Arizona this challenging environment in a variety of ways. with animals, benefitting both the plant and elaborate transfer prospers along the South Rim and partway consists of a large variety of plants that the animal. You may be surprised by the system with pinyon down the canyon, but its range has changed provide rich wildlife habitat. This important complexity of these interrelationships and pine roots. The through the millennia. During the most community needs to be protected and the dependency of the participants on each fungi grow thin, recent ice age (35,000 – 11,000 years ago), nurtured at Grand Canyon National Park Plants Living other. root-like hyphae when the region was cooler and moister, and throughout the Southwest. Tree cutting, that transfer water pinyon-juniper communities spread introduction of non-native plants, and and minerals from to the bottom of the canyon. Scientists overgrazing have degraded the community. on the Edge the soil to the tree. determined this from plant evidence left The combination of recent droughts and Watch for The tree, in turn, in caves and alcoves by packrats. As global insect infestations has killed many trees. Prickly pear cactus roots extend well beyond the plant and spread close to the surface, poised to scrub jays contributes sugars climate continues to warm, the pinyon- We must work to preserve this vibrant rapidly absorb as much moisture as possible during short-lived monsoon storms. Cacti store large collecting Along the to the fungi. With juniper habitat type may become established collection of plants and animals so that it amounts of water for use during droughts. pinyon this association, tree roots need to grow less at higher elevations. Plants within this continues to be a widespread component of Hermit Road nuts extensively, while fungal hyphae (the thin community may find the South Rim the Southwestern landscape. Yucca (left) and agave Claret-cup cacti have ripening Greenway Trail lines) extend to areas far beyond the roots. uninhabitable. (right) grow thick, fluted, accordion-like in the fall. waxy leaves that store stems that expand Jays cache the moisture. Although for maximum water seeds in the they have very storage. ground away different leaf edges, from the tree. In both plants form as the spring they a rosette of tough, remember where spine-tipped leaves. they left the nuts and return to eat them. Seeds the birds do not retrieve are left to sprout as future trees. Yucca plants and yucca moths cannot survive without each other. Adult moths lay eggs in a flower, then pollinate the same flower. The larvae eat only the mature seeds, which developed because the moth fertilized the flower. Larvae do not eat all the seeds, leaving the yucca sufficient to reproduce. Many plants—cliffrose (left above), Mormon tea (middle), and sagebrush (right)—have small leaves to minimize water loss. The green stems of Mormon tea take on the Tiny hairs cover the stems and foliage of food-producing function of leaves. Silvery Navajo fleabane (left) and cheatgrass (right) sagebrush leaves reflect the sun’s rays, contributing to the plants’ light color and Coyotes and birds eat juniper berries and leave the seeds in their droppings. The keeping them cooler. helping to reduce moisture loss. undigested seeds may germinate at some distance from the parent tree. Photographs and illustrations © Lisa Kearsley 0617