There are several unique riparian areas in the Prime Desert Woodland Preserve that are very important in sustaining a diverse and healthy wildlife population. First of all, what is a riparian habitat?
There are many strict definitions because of the term’s use by the various natural sciences and by government. However, for the purpose of this article riparian habitat is defined as a stream channel or low area where water flows or ponds, either continuously or intermittently, and supports vegetation that is dependent on this water. Thus, plants that grow in riparian habitats are usually different species than the plant species growing nearby whose roots do not reach the water. This environmental uniqueness created by water together with plants that are dependent on this water makes up a riparian habitat. Notable examples of vegetation found in riparian habitats on the Preserve are the Fremont Cottonwood tree, willow, and cattail reed. The wetness of the soil also discourages growth of Joshua trees and other desert species that thrive in the drier soils.
The desert riparian habitat benefits both the bird and animal life by increasing the diversity of food sources and by providing dense cover for nesting. In the dry desert environment (averaging less than 7 inches per year), riparian areas are often the only source of water for many wildlife species. Many of the desert’s natural riparian habitats are dependent on storm water runoff or receive their water from sources in distant mountains. The Amargosa Creek is a good example. It has its source, also called headwaters, in the southern mountains surrounding the Antelope Valley. It receives much of its flow from a wide area of natural and man-made tributary channels that spread like tree branches across the southern Antelope Valley, including carrying the runoff from the Preserve during winter storms. Many of these tributary channels support riparian habitat important to the local and migrating wildlife.
Riparian areas in the Preserve are even more unique, in that most of the water flow, in the dry season, is street runoff from the urban areas outside the boundaries of the Preserve. As the water enters the Preserve, it often carries with it street litter and impurities. The flowing water is “more or less” filtered by the lush riparian vegetation growing in and along the stream channels. Most of this water is soaked up by the desert soil and is finely filtered by many layers of soil and geology before it enters the underground water basin which is tapped for domestic and agriculture uses. In this way, the Preserve serves an important function of allowing water to enter the soil, as pavement does not allow the water to soak in the ground. This is referred to as the “hydrologic cycle”, in which water is used and reused again, using nature as the transport method and as the filter to supply clean water for many uses.
The riparian habitat provides food and cover during the winter bird migrations. Some of these birds migrate short distances from the nearby mountains to the valley floor, as our winter residents, to escape the harsh weather at the higher elevations. Others are on very long migration journeys and rest at the Preserve to replenish themselves with food and water. Birds such as the red-shafted flicker and some of the warbler species can be seen foraging in the riparian areas of the Preserve throughout the winter months. Other birds frequently seen in the riparian habitat in the Preserve are the great blue heron, common snipe, California quail, and red-winged blackbird. The branches of the tall Fremont Cottonwood tree, whose roots require much water, are leafless during the winter and serve as perfect lookout perches for a variety of raptor species. In fact, the riparian habitat is one of the best areas in the Preserve to observe birds as they perch, nest, or forage for food. Be sure to ask a volunteer Docent where some of the best examples of riparian habitat are during your next visit to the Prime Desert Woodland Preserve.