Undergraduate Abstract

Kevin Clarke
August 1996

Salt Cedar Eradication and Native Revegetation of a Desert Riparian Area: The Pilot Study of the Hidden Valley Dairy Salt Cedar Eradication Project

A Thesis submitted in partial satisfaction
of the requirement for the degree of

BACHELOR OF ARTS

In

Environmental Studies Program
University of Nevada Las Vegas

by

Kevin Clarke
and
Robert M. Nelson

Summer1996

Thesis Adviser:
Environmental Studies Program
University of Nevada, Las Vegas

Abstract

The purpose of this paper is to present a brief history of the salt cedar problem in the southwestern U.S. and to provide an analysis of the pilot study on the Muddy River salt cedar eradication project. The paper was divided into two parts, the first is a brief overview of salt cedar biology and ecology and the second is the analysis of the pilot study.

Salt cedar is a deciduous plant that was introduced from Asia in the mid 1800's. It was used for ornamental wind breaks and shade in the southwestern United States. For the past thirty years salt cedar has infested well over a million acres of desert riparian habitat. These areas are some of the most valuable habitat because of the limited water availability in such harsh desert climates. Salt cedar has several adaptive advantages that allow them to out compete native riparian vegetation for this valuable habitat, with a limiting factor being water Salt cedar is a facultative phreatophyte, this means that they do not need to constantly be in the water table for survival. Unlike salt cedar, native vegetation are obligate phreatophytes, which means they have to be rooted in the water table in order to survive. Another advantage salt cedar has over native vegetation is that it is capable of living in highly saline soils. This is helpful for salt cedar because native vegetation can not survive in such conditions. Salt cedar can also produce several hundred thousand seeds in a single growing season. Salt cedar plants are also vigorous sprouters and can take advantage of natural disasters. Because of these competitive advantages salt cedar is causing serious ecological problems in the southwest. Salt cedar has been known to use high amounts of water leading to a high rate of evapotranspiration. They also drop salt saturated leaves on the ground causing highly saline soils in which native vegetation can not grow. Salt cedar is also known to change flow rates, river channels, and increase sedimentation that can lead to the widening and narrowing of floodplains. In contrast to all of the problems that are caused by salt cedar, there are only a few benefits.

The second part of this paper is an analysis of a pilot study of the Muddy River salt cedar eradication program. This study was conducted from March 1996 to the beginning of August 1996. The study area was one half mile along the Muddy River in Moapa, Nevada. The objectives of this project were twofold. First was to find a suitable method for salt cedar eradication and the second was to revegetate the site with native desert riparian plants. The site area was divided into 40 one hundred and fifty foot plots. Theses plots were labeled and marked in position with the river. Several methodologies for herbicide application were tested for efficiency and effectiveness. The methodologies include a handheld sprayer, a wick applicator and the hypohatchet. In addition to the methodologies, two chemicals were tested for their effectiveness (2,4-D amine and roundup ultra). The second objective of this pilot study was to effectively revegetate the site with native vegetation. The species used for revegetation include mesquite (Proposis spp.), quailbush (Atriplex lentiformis), willow (Salix spp.), and cottonwood (Populus spp.). Both the quailbush and mesquite were purchased as one gallon seedlings from the Nevada Division of Forestry (NDF) nursery. The cottonwood and willows were harvested as pole cuttings and planted along the water's edge. A very interesting aspect of the pilot study was the irrigation system, a product named Dri-Water. This product is an environmentally safe gel that is composed of 97.85% water and the rest an alum and aluminum sulfate mix. This product releases water as it comes in contact with soil microbes. The Dri-Water product produces a drip irrigation process that can last up to three months in favorable conditions.