4 pp. / Climate Change and Variability in Southwest Ecosystems Series / Several environmental factors are changing, including the global rise in atmospheric CO2 concentrations and global warming. These environmental changes portend needed changes in the future management of forests in the Southwestern U.S. Therefore, University of Arizona Extension Agents organized a Workshop in Sedona, AZ, in February, 2005, targeted at Southwest forest managers. This paper presents facts from one of the presentations at that workshop and summarizes what the direct effects of the increased CO2 concentrations are likely to be on future tree growth. It is expected that the growth of most trees will be stimulated by the higher CO2 concentrations but variations in response among species will alter competition among species. The fact sheet also speculates about what the implications may be for future forest management. This research benefits the forest industry, as well as the many consumers of forest products.

14 pp. / A primary expression of stocking levels on rangeland vegetation is utilization defined as the proportion or degree of current years forage production that is consumed or destroyed by animals (including insects). Utilization may refer either to a single plant species, a group of species, or the vegetation as a whole. Utilization is an important factor in influencing changes in the soil, water, animal, and vegetation resources. The impact of a specific intensity of use on a plant species is highly variable depending on past and present use, period of use, duration of use, inter-specific competition, weather, availability of soil moisture for regrowth, and how these factors interact. Utilization data can be used as a guideline for moving livestock within an allotment with due consideration to season, weather conditions and the availability of forage and water in pastures scheduled for use during the same grazing season. In combination with actual use and climatic data, utilization measurements on key areas and utilization pattern mapping are useful for estimating proper stocking levels under current management. Utilization studies are helpful in identifying key and problem areas, and in identifying range improvements needed to improve livestock distribution.

4 pp. / Southwest forests are complex systems that are influenced by climate variability. Wildfires naturally occur in these forests and woodlands, but with an increasing population, land management decisions are becoming more difficult. This publication is a result of discussions from the "Workshop on Climate Variability and Ecosystem Impacts" that was sponsored by UA Cooperative Extension in February 2005. It provides a summary of the current situation, a summary of climate change science for land management, and a brief description of suggested future research in climate science as it relates to forests and woodlands.

A strategy for the discovery of new insect growth regulators from arid lands plants was developed. Plant genera with a history of toxicity, medicinal use, or incorporation in native american cultures were selected. Forty-five species from twenty-one families were collected, extracted, and tested for biological activity on the large milkweed bug, Oncopeltus fasciatus. Eight extracts were toxic and the extract of Nama hispidum (Hydrophyllaceae) caused nymphs to undergo precocious metamorphosis to an adult. The active component of N. hispidum was precocene II (6,7-dimethoxy-2,2-dimethyl chromene). Nine Nama species, representing four of the five sections in the genus were gathered from Hawaii, California, Nevada, Arizona, New Mexico, and the Dominican Republic. In addition to the insect anti-hormone, precocene II (PII), present in N. hispidum, N. rothrockii contained at least two different insect juvenile hormone mimics, and N. sandwicense contained insect anti-hormone and insect juvenile hormone mimics. Fifth instar larvae of Heliothis zea were used as model insects to distinguish between post-ingestive intoxication and feeding deterrency during exposure to PII. Larvae fed artificial diet with PII were deterred from eating, and had retarded weight gain, growth, and development. Insects grown on diet with PII consumed less food, could not digest the food, or convert ingested food to body mass. in vivo radiotracer studies with the nutrient, ¹⁴C linoleic acid, show a lower rate of transport and incorporation of radioactivity into fat body tissue. A change in the midgut epithelial cells from PII resulted in reduced transport efficiency and retarded larval growth and development. Scanning electron microscopy of the midgut epithelia indicated that cytotoxic damage is induced by PII. Observed changes in the midgut epithelial cells are consistent with a destructive alkylation of cell structures by PII.

The proposition that environment is of equal importance to time and space in the study of culture suggests that a three-dimensional approach may be a useful method for studying the process of cultural evolution. This possibility is tested by detailed investigations into the history and natural habitat of the prehistoric Hohokam Culture. This culture developed an extensive system of irrigation agriculture in the Gila River valley of southern Arizona about A. D. 1-1400. The study is carried out on the processual as well as analytical level of enquiry whereby primary attention was given to the relationship between environment and culture. This emphasis is particularly relevant in the case of the arid conditions of the region in which the Hohokani Culture developed. The interaction of the primary environmental agents, water and soil, and the cultural agent, prehistoric man, is delineated in terms of the natural processes of soil development and movement of water in the region as well as the cultural process of irrigation agriculture. During all phases of the River liohokarn Culture the relationship between soil, water, and man was interdependent and their functional interaction was exposed to the forces of the active environment, which may have become critical. An attempt is made to arrive at an interpretation along these lines for the terminal period of the Hohokam Culture at Snaketown, a major prehistoric site near Chandler, Arizona. While no definite conclusions are derived, the evidence, presented by means of inferential analysis, points strongly towards environmental causation. The impact of the prevailing climatic conditions at the end of the 13th century may have upset the precarious balance between water and soil and thus the livelihood of the desert dwellers. These events led inevitably to the termination of the Hohokam Culture.

Elderly recreational vehicle campers are attracted to the Lower Colorado River area during the winter season. Their numbers have grown in recent years and many are seeking alternatives to the usual practice of establishing residence in private trailer parks. As a result, various public land sites in the region are being subjected to concentrated winter use. Units in these camping areas represent users who are retired couples or individuals on fixed or limited incomes, living in "self-contained" campers, travel trailers or motor homes. Some of these visitors are utilizing designated campgrounds; others are squatting on the public domain where there are few, if any, sanitary or other facilities. The impact of elderly winter visitors on the public land resource of the Lower Colorado River basin area is varied. An understanding of environmental effects is important, but proposed solutions depend upon our ability to understand the people causing environmental deterioration. Answers have been sought to basic questions about winter visitor characteristics and behavior. The findings were applied toward the development of basic policy recommendations pertinent to appropriate public land management for the desert areas of the Southwest. Of theoretical interest was the evaluation of the relative importance of camping socialization experiences in explaining user behavior. Data were gathered from 580 visitor units during the winter of 1973-74 with a personal interview schedule. Important classes of variables included socio-economic characteristics, camping experience, and users' campground behavior and preferences. Interviews were conducted in seven sites representing various kinds of public and private camping facilities in the region. Discriminant function, correlational, multiple regression and bivariate analyses were utilized to render the collected data meaningful. The basic sub-groups in the sample were distinguished by significant differences in various socio-economic and experiential characteristics. The most important of these were income, education, age, value of mobile quarters, and pre-retirement adult camping experience. Length of stay in public land camping areas was not explained by differences in site characteristics. Differences in visitor characteristics accounted for 40-50% of variation in length of stay. Important predictor variables included income, age, average annual pre-retirement camping experience and the amount of previous recreational vehicle camping without utility and sewerage hookups. Support was evidenced for a basic theoretical orientation: that post-retirement behavior is, in part, a reflection of pre-retirement recreational socialization and leisure life style patterns and persistence. The results suggested certain implications for public land management. Recommendations include the desirability of moving elderly winter camper use to sites away from the Colorado River. High fees imposed along the river would discourage extended-stay winter use and restore a unique resource to the short-term water-oriented visitor. The establishment of a spectrum of "inland" camping sites with varying levels of facilities and fees would serve as a positive inducement to the older winter camper, and restore some order to what has been, in some areas, an uncontrolled camping environment. A public campground on Bureau of Land Management land in Why, Arizona, offers a possible solution to the problems posed by the limited resources available to most public land management agencies. There a parcel of public land has been leased by a non-profit community association and developed into a public campground with basic facilities for elderly winter visitors. Management expenses are met through the imposition of a modest graduated fee schedule which favors the extended-stay camper. In this case a squatting problem has been resolved through local initiative; the public land management agency, with its limited budget, has been spared the expense of development and that of direct management responsibility.

An important part of the process of assessing the environmental impacts of coal-fired energy development in the Southwest is the transfer of information between electric utilities, federal agencies, and the interested public. There are, however, several problems associated with the transfer of information among the different groups. The acquisition of factual material on power projects by the interested public, for example, is adversely affected by the sufficiency, convenience, and credibility of present sources. Efforts of electric utilities and federal agencies to effectively communicate impact information are hindered by the inability of existing sources to selectively transfer information and to rapidly transmit information on the cumulative impacts of many combinations of power plants. This research concerns the development and evaluation of a computerized information system designed to selectively transfer information on both the cumulative and individual impacts of several electric generating facilities located in the southwestern United States. The information system incorporates features of management information systems, environmental information systems, and an issue-oriented system developed at The University of Illinois, making it a hybrid system capable of communicating impact information derived from a variety of sources. Specifically, the system is able to either retrieve textual material stored in a base information file or to execute on-line simulation models and routines in order to describe environmental impacts. Interactions with the information system are performed at a remote computer terminal by an information specialist who, with the assistance of supporting documents, helps users select information of interest. Evaluation of the system was carried out by demonstrating it to prospective users from electric utilities, government agencies, and the interested public in Arizona. The response of the users to the system shows that this type of communications technology is a viable means of transmitting environmental information. The results of the evaluation also indicate that the system's usefulness is more likely to depend on its credibility than on its convenience and that computer models are an effective way of describing cumulative impacts caused by a series of power plants.

Axelrod (1958) suggested that the late Tertiary shift in regional climate -- the elimination of summer rains -- had a profound influence on the evolution of biotic provinces in the American southwest. In particular, the taxa endemic to biotic provinces characterized by summer drought, e.g., the Mojave Desert, should be derived from ancestors that likely inhabited regions of summer rain, e.g., the Chihuahuan Desert. Further, the derived features of summer-drought taxa should be related to water stress. I examined Axelrod's thesis, using a combination of phylogenetic systematics, physiological ecology, and vicariance biogeography. The first chapter is a cladistic study of the pinyon pines, 13 taxa of small trees that range from the summer-wet regions of Mexico to the summer drought regions of Nevada and California. A parsimony analysis using twenty morphological characters showed that the most recently derived pinyons are from regions of summer drought. The "summer-drought" taxa are characterized by relatively few needles per fascicle. Because fewer needles per fascicle results in a reduction in the needle surface-to-volume ratio, Haller (1965) hypothesized that fewer needles in pines is an adaptation to reduce transpirational water loss. The second chapter reports on a two year study of the xylem pressure potentials of single- and double-needled fascicles of hybrid pinyons in central Arizona. The results showed no significant differences between single- and double-needles. I concluded that either needle morphology does not effect water relations, or that the relatively high precipitation during the study did not allow significant water stress to occur. The third chapter uses the methods of vicariance biogeography to search for a common pattern of relationship between southwestern biotic provinces, as indicated by the relationships of their endemic taxa. Using a biogeographic parsimony analysis, I compared the area cladograms of six taxa -- junipers, pinyon pines, the composite Palafoxia, hedgehog cactus, desert tortoises, and gecko lizards. The most parsimonious area cladogram supports Axelrod's (1958) hypothesis, but also shows that some taxa, notably the junipers, support other patterns of area relationships, e.g., summer-drought primitive. I suggest that there is no single pattern of area relationships because of the effects of the Pleistocene (including dispersal and extinction) and vicariance events other than the Tertiary climatic change, e.g., the separation of the Baja peninsula from mainland Mexico during the Miocene.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Revised; Originally Published: 2006 / 4 pp.