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James Evans

Publications and source records attributed to James Evans.

6 recordsLinked to original sources
USGS2002

Composition of the Rex Chert and associated rocks of the Permian Phosphoria Formation: Soda Springs area, SE Idaho

This study, one in a series, reports bulk chemical and mineralogical compositions, as well as petrographic and outcrop descriptions of rocks collected from three measured outcrop sections of the Rex Chert member of the Phosphoria Formation in SE Idaho. The three measured sections were chosen from ten outcrops of Rex Chert that were described in the field. The Rex Chert overlies the Meade Peak Phosphatic Shale Member of the Phosphoria Formation, the source of phosphate ore in the region. Rex Chert removed as overburden comprises part of the material disposed in waste-rock piles during phosphate mining. It has been proposed that the chert be used to cap and isolate waste piles, thereby inhibiting the leaching of potentially toxic elements into the environment. It is also used to surface roads in the mining district. The rock samples studied here constitute a set of individual chert beds that are representative of each stratigraphic section sampled. The informally named cherty shale member that overlies the Rex Chert in measured section 1 was also described and sampled. The upper Meade Peak and the transition zone to the Rex Chert were described and sampled in section 7. The cherts are predominantly spicularite composed of granular and mosaic quartz, and sponge spicules, with various but minor amounts of other fossils and detrital grains. The cherty shale member and transition rocks between the Meade Peak and Rex Chert are siliceous siltstones and argillaceous cherts with ghosts of sponge spicules and somewhat more detrital grains than the chert. The overwhelmingly dominant mineral is quartz, although carbonate beds are rare in each section and are composed predominantly of calcite and dolomite in addition to quartz. Feldspar, mica, clay minerals, calcite, dolomite, and carbonate fluorapatite are minor to trace minerals in the chert. The mean concentrations of oxides and elements in the Rex Chert and the cherty shale member are dominated by SiO2, which averages 94.6%. Organic-carbon contents are generally very low in the chert, but are up to 1.8 wt. % in cherty shale member samples and up to 3.3% in samples from the transition between the Meade Peak and Rex Chert. Likewise, phosphate (P2O5) is generally low in the chert, but can be up to 3.1% in individual beds. Selenium concentrations in Rex Chert and cherty shale member samples vary from <0.2 to 138 ppm, with a mean concentration of 7.0 ppm. This mean Se content is heavily dependent on two values of 101 and 138 ppm for rocks from the transition zone between the Meade Peak and Rex Chert. Without those two samples, the mean Se concentration would be <1.0 ppm. Other elements of environmental interest, As, Cr, V, Zn, Hg, and Cd, are generally near or below their content in average continental shale. Stratigraphic changes (equivalent to temporal changes in the depositional basin) in chemical composition of rocks are notable either as uniform changes through the sections or as distinct differences in the mean composition of rocks that compose the upper and lower halves of the sections. Q-mode factors are interpreted to represent the following rock and mineral components: chert-silica component consisting of Si (± Ba); phosphorite-phosphate component composed of P, Ca, As, Y, V, Cr, Sr, and La (± Fe, Zn, Cu, Ni, Li, Se, Nd, Hg); shale component composed of Al, Na, Zr, K, Ba, Li, and organic C (± Ti, Mg, Se, Ni, Fe, Sr, V, Mn, Zn); carbonate component (dolomite, calcite, silicified carbonates) composed of carbonate C, Mg, Ca, and Si (± Mn); tentatively organic matter-hosted elements (and/or sulfide-sulfate phases) composed of Cu (± organic C, Zn, Mn Si, Ni, Hg, and Li). Selenium shows a dominant association with the shale component, but correlations and Qmode factors also indicate that organic matter (within the shale component) and carbonate fluorapatite may host a portion of the Se. Consideration of larger numbers of factors in Qmode analysis indicates that native Se (a factor containing Se (± Ba)) may also comprise a minor component of the Se compliment.

Idaho↗
USGS1999

Evaluations of plastic mesh tubes for protecting conifer seedlings from pocket gophers in three western states

The efficacy of plastic mesh tubes for protecting conifer seedlings from pocket gopher damage was evaluated on three national forest lands in three states. In each area, cohorts of 640 protected seedlings and 640 unprotected seedlings (3,840 total) were individually monitored for damage, survival, and growth twice each summer for 5 yr after planting. Substantial differences were found between protected and unprotected seedlings for time until occurrence of damage, survival time, proportion damaged and proportion surviving, as well as differences in growth. Over the three forest study sites, the proportion of unprotected seedlings damaged ranged from 60-89%, whereas the proportion of protected seedlings damaged after 5 yr ranged from 18-27%. The proportion of unprotected seedlings that died of gopher damage over 5 yr ranged from 46-64%, versus 1-19% for protected seedlings. Height growth was 25% greater for protected seedlings. Even when only undamaged seedlings were considered, protected seedlings exhibited superior height growth, possibly due to a more favorable microclimate provided by the tubes. These results were reflected in the higher and more uniform stocking rates for protected seedlings.

Western Journal of Applied Forestry↗
USGS1998

Double-stocking for overcoming damage to conifer seedlings by pocket gophers

A 5-yr study was conducted on national forests in Idaho and Oregon to evaluate how doubling the seedling stocking rate of lodgepole pine ( Pinus contorta ) would relate to 5-year survival and the uniformity of distribution of seedlings in the presence of northern pocket gopher ( Thomomys talpoides ) damage. Either 4 or 8 seedlings were planted in 40-m 2 subplots (1000 or 2000 seedlings/ha) and monitored for gopher damage. We found that the number of seedlings attacked by gophers, and consequently, the number of seedlings surviving for 5 years, were directly proportional to the stocking rate, but the consistency of seedling distribution within each site (as measured by the proportion of 40-m 2 subplots with ≥ 2 surviving seedlings) did not double with stocking rate. In some situations, increasing the stocking rate should be considered as a method for overcoming pocket gopher damage.

Idaho, Oregon↗
USGS1997

The effects of Vexar® seedling protectors on the growth and development of lodgepole pine roots

The effects on the growth and development of lodgepole pine roots from the Vexar ® tubes used to protect seedlings from pocket gopher damage were studied in the Targhee National Forest, Idaho and the Deschutes National Forest, Oregon. At each site, Vexar-protected and unprotected seedlings, with and without above-ground gopher damage were examined after six growing seasons for root deformities and growth. Undamaged seedlings exhibited greater growth, reflecting the importance of non-lethal gopher damage as a deterrent to tree growth. Protected seedlings with similar damage history as unprotected seedlings had greater root depth than unprotected seedlings, although unprotected seedlings with no above-ground damage generally had the greatest root weight. In general, the percent of seedlings with root deformities was greater for the unprotected seedlings than for the Vexar-protectd seedlings, although this could be largely due to the greater care required to plant protected seedlings. Acute deformities were more common for unprotected seedlings, whereas root deformities with less severe bending were more common for protected seedlings. The incidence of crossed roots was similar for protected and unprotected seedlings on the Deschutes site, where enough occurrences of this deformity permitted analyses. Protected seedlings were similar in root abundance, root distribution, root size and vigor to the unprotected seedlings, with some indication from the Deshutes study site that root distribution was improved with Vexar protection.

Idaho, Oregon↗
USGS1970

About nutria and their control

Wild animals are generally classed as beneficial or pest species, depending on the variable interests of man. Those that provide him with earnings, recreation, or enjoyment are considered beneficial; those that compete with him for food, or ruin his possessions or environment, are quickly dubbed pests. But all men do not have the same interests or the same environment, so many animals attain both a beneficial and a pest status. The wild nutria in the United States is one of these animals with a dual nature. It is most numerous in the Gulf States, particularly in Louisiana and Texas, where the sale of nutria fur and meat in some years is a several-million-dollar industry. Although it is a valuable resource, it sometimes causes so much agricultural damage that it is also classified as a pest. In the late 1950's, nutria damage to sugarcane and rice became so acute that the people of Louisiana and Texas asked the Federal Government for help. Research on the problem was assigned to the Division of Wildlife Research, Bureau of Sport Fisheries and Wildlife, which is responsible, among other things, for developing methods to control damage by wild animals. The Division's Denver Wildlife Research Center established field stations at Houma, Louisiana, and Beaumont, Texas, and in 1963 work was begun under congressional appropriation to fulfill this public request. The goal of the Houma and Beaumont stations was to develop a sound, scientific solution to the problem of controlling nutria damage. IT WAS NOT A PROGRAM OF ERADICATION. Because of the involvement of the fur and meat industry, the beneficial aspects of nutria had to be continuously recognized when potential methods of control were evaluated. Especially sought were workable control procedures that could be readily used by laymen. These would have to be relatively selective for nutria and safe for humans, domestic animals, and other wildlife. In 1967, four years after our studies were begun, we had found methods to solve the current and immediately foreseeable problems of nutria damage. This report presents much of the information we gathered during this four-year period about nutria and how to control them. Because it is meant primarily for the general public, it omits the specific references to the scientific literature that pepper most technical reports, but it does present background information on the history, biology, and behavior of nutria, particularly those in the Gulf Coast Region. The control methods presented, when used as directed, are safe and effective and provide solutions for most situations, including those where people want to alleviate nutria damage without killing the nutria. Though we were pleased with these results, research still continues, directed toward discovering new and better methods of control that will solve any future problem with nutria.

Resource Publication↗