By Donald Edward McHenry, Junior Naturalist.
NESTLED here and there among the stately trees of the Kaibab Forest on the North Rim of Grand Canyon are beautiful open grasslands known as parks. These parks offer a series of delightful surprises to the visitor and unexpected variety to the scenery as one drives along the interesting forest roads.
Many a person has asked the reason for these parks; and why the trees of the forest do not close in upon them. To the writer it seems evident that these open areas fall into three distinct categories.
One type of park is represented by such areas as V. T. Park, found just outside of the National Park boundary, and by Little Park, through which the highway runs after it passes the checking station. Here we find the broad, flat floor of a shallow valley into which drains the water from the surrounding slopes. Running the length of such a valley usually is found a series of sink holes, some stopped up and forming small lakes,* others still open to the passage of water. The floor of such a valley is composed of a layer of alluvial material resting upon the surface of Kaibab limestone. Thus there is a very shallow water table. With the melting snows this alluvial soil becomes saturated with drainage water. As the season advances the water from the meadow soil either evaporates or drains off to the sink holes. The ground then reaches an extreme in dryness.
Conditions of extreme wetness and dryness are unfavorable to natural reforestation on the Kaibab Plateau. During the spring and early summer the excessive moisture and cold temperature of the soil make germination of seeds from the surrounding trees unlikely. With the arrival of warm weather the soil becomes as dry as it had been wet, a condition hardly more favorable to the germination of these seeds, It is noteworthy that the floral structure of such parks is largely composed of plants best adapted to a very dry environment. Sedges are conspicuously absent in these areas except about water holes. There is no evidence that trees ever grew in these open places.
In a few cases limited attempts at natural reforestation may be seen. Here and there a small vanguard of the seedlings of the Engelmann Spruce and the Blue Spruce reaches down the slope, encroaching upon the grass-lands. These trees are hardly more then eight or ten years old at the most, and probably indicate a recent and very slowly changing condition in that restricted environment. In most oases, however, these parks are bounded very definitely by stands of mature trees with practically no reproduction. It is in such parks then, as the dusk of evening advances, that the visitor today will see bands of deer numbering around a hundred or so. Not many years ago herds of deer numbering as high as 1,400 were seen in these same parks.
Another category into which the writer would place woodland parks is one which would include definite drainage valleys. On the North Rim of Grand Canyon, drainage take a place from the region of the National Park checking station southward to the Colorado River. This has resulted in the formation of a number of drainage valleys leading into side canyons just below the North Rim. In many of these, intermittent streams resulting from the waters of melting snow and from rains not infrequently assume the proportions of raging torrents. Nor are such drainage basins always confined to restricted areas at the bottoms of narrow valleys. Sometimes they appear as broad areas, as the Coconino Basin, where are found slopes draining from three directions over a rock surface which is sparsely covered by a thin layer of soil. Frequently, also, otherwise narrow valley parks will be broadened in places by alluvial fans at the mouths of tributary draws.
Where park and forest meet
In parks having the type of drainage origin described above, water is usually overly abundant at a time when conditions would otherwise be favorable to germination of seeds from the trees of the forest. Any seedling which might get a slight start is likely to be washed along with the shifting soil. These parks are covered with a characteristic vegetation of grasses and a few semi-arid flowers. Such vegetation is able to establish itself during the dryer part of the season after the conditions favorable for the development of tree seedlings have passed. In these valley-drainage parks one finds now and then localized areas of sedges. Somehow these have become established during the wet part of the season.
One more category into which we should place woodland parks, includes areas located on south facing slopes in drainage valleys. Examples of such parks are to be seen along the road leading to Point Sublime as it passes through Kanabownits Canyon. Here and there along this delightful woodland road one finds these grass lands reaching up the side of a south-facing slope to the forest above. The north-facing slope opposite will be heavily wooded with a substantial stand of spruce and fir almost to the very bottom of the valley.
In places of the type just described, the natural drainage of the south-facing slope will be greatly aided by the drying effect of the hot, direct rays of the sun and possibly the hot, dry winds from the southwest. Any seed of the trees above which might begin successful germination on such a slope during the moist part of the season would quickly succumb to an advancing drought condition. Occasionally we do find on such slopes a very slow encroachment of the forest from above, as the trees along the forest rim afford a rather meager fringe of protective shade to a sparce reproduction.
Visitors to the North Rim of the Grand Canyon have abundant opportunity to enjoy the delightful woodland parks of the Kaibab Forest, for all the principal roads follow along valleys in which these picturesque meadows are enclosed by the somber green walls of surrounding spruce and fir.
|<<< Previous||> Cover <||Next >>>|