2 pp. / Other Forest Health Publications / Cypress bark beetles are native insects that often impact ornamental Arizona cypress and Leyland cypress trees. Healthy, vigorous cypress trees can usually withstand substantial beetle pressure. However, significant mortality of host tree species often occurs during periods of extended drought. Tree vigor can easily be maintained through deep, infrequent irrigation during drought periods.

5 pp. / Pine Bark Beetles, Cypress Bark Beetles / Hosts, description and life cycle of the pinon ips and signs of infection. Management practices include maintaining tree health, sanitation and chemical sprays. Thinning is the long term solution to stressed stands. Many ecological factors are significant when managing for pinon ips.

Revised; Originally Published: 2003 / 2 pp.

Revised; Original Published: 2006 / 5 pp.

The impetus for this research was the increasing threat of catastrophic wildfires resulting from the accumulation of fuels across the West. Guided by the priorities, goals, and guiding principles outlined by the national fire plan (NFP), the objective was to identify those areas within a pinyon-juniper woodland-dominated landscape with the highest hazard of catastrophic wildfire. The intent was to help managers prioritize proactive fuels management efforts outside of the wildland urban interface (WUI). Based on a management paradigm, constraints were placed on the data collection, analysis, and model development. A geographic information system (GIS) was used to create a hazard assessment at a landscape scale in Tintic Valley, Utah. Hazard categories were a classification of fuels based on crown cover of pinyon-juniper trees, utilizing remotely sensed data. The data set consisted of digital orthophoto quadrangle (DOQ) images from 1993. The methods were developed in three phases. Phase One resulted in a hazard assessment protocol. In Phase Two, data layers were created to further divide the hazard categories into more tractable management units. Phase Three, through the retrospective examination of recent wildfires, indicated the limitations and utility of the assessment technique. The protocol presented provides a relatively fast, inexpensive, and timely hazard classification technique for pinyon-juniper woodlands at a watershed level. It is intended to be used for coarse-scale assessments of fuel hazards for strategic planning purposes. While not appropriate for fire behavior predictions, this assessment can focus managerial efforts for additional tactical planning.

With the dramatic expansion of pinyon-juniper woodlands over the last century, improved understanding of how these woodlands modify infiltration properties is needed, in order for land managers to make informed decisions on how to best manage their specific resources. However, current methods for measuring soil infiltration are often limited by low sample sizes and high experimental error, due to constraints associated with remote, non agricultural settings. This thesis first presents a scheme for automating and calibrating two commercially available infiltrometers, which allows collection of a large number of precise unsaturated infiltration measurements in a relatively short period of time. Secondly, a new method to precisely determine saturated hydraulic conductivity from small intact soil cores collected in the field is demonstrated. This method removes bias due to measurement error using a multiple head linear regression approach. Finally, hundreds of fine spatial scale measurements of soil sorptivity, unsaturated hydraulic conductivity, saturated hydraulic conductivity, soil water content, and other soil descriptive measurements along radial line transects extending out from the trunk of juniper (Juniperus osteosperma) and pinyon pine (Pinus edulis) trees. Within the subcanopy of these trees, interactions among litter material, root distributions, and hydrophobic soil significantly influence ecohydrologic properties by limiting and redirecting infiltration below the soil surface. Consequently, hydrophobicity appears to be a mechanism that promotes survival of woody vegetation in arid environments, through decreasing evaporation rates from the soil surface. We further demonstrate how differences in unsaturated infiltration and soil water content between the subcanopy and intercanopy zones are not discrete. Unsaturated infiltration was significantly lower within the subcanopy than in the intercanopy, and increased by eight-fold across a gradient extending outward from near the edge of the canopy to approximately two times the canopy radius. This gradient was not strongly related to soil moisture. In the intercanopy, increasing structural development of biological soil crust cover beyond this gradient was positivity correlated with infiltration capacity. Consequently, these results indicate that the spatial location of the trees should be considered in the assessment and modeling of woody plant and biological soil crust influence on infiltration capacity in a pinyon-juniper ecosystem.

There was a period during the early history of Utah when grasses in some areas grew so tall that it hid grazing cattle and sheep from view. However, mismanagement caused this to change and depleted grassland was invaded by noxious weeds, sagebrush, and pinyon-juniper. This deterioration of choice grassland to less desirable range cover was aided by the attitude of stockmen that pasture was available on a first come first serve basis. As a result of such an attitude and the unsatisfactory condition of ranges. the era of free, uncontrolled use of grazing lands came to a close with the introduction of the Taylor Grazing Act in 1934. This act provided for classification of all unappropriated and unreserved lands. Grazing districts were organized and regulations were established for the distribution of grazing permits and the setting of fees to be charged for the use of public lands (9, p.14).1

The objectives of this study were to 1) determine the effects of livestock grazing and periods of rest from grazing on infiltration and erosion rates of unchained woodland; chained, debris-in-place; and chained, debris-windrowed pinyon-juniper sites; and 2) utilize these measurements in developing guidelines for grazing management of pinyonjuniper rangelands that protect or improve the hydrologic condition of the watershed. The study was conducted on sandy loam soils in southeastern Utah during the summers of 1971 and 1972. Runoff and erosion were artificially induced from small plots by simulating rainfall with the Rocky Mountain infiltrometer. Infiltration rates, erosion rates, and selected vegetative and edaphic parameters were measured on each plot. Forage removal by clipping and soil compaction subtreatments were applied to randomly selected plots in an effort to simulate the forage removal and trampling activities of livestock. Analysis of variance techniques were used to determine the effect on infiltration and erosion rates of forage removal and soil compaction subtreatment, grazing and varying periods of rest from grazing, and chaining treatments with similar grazing histories. Multiple regression techniques were used to evaluate the influence of vegetative and edaphic factors on infiltration and erosion. Forage removal and soil compaction subtreatments had no consistent effect on infiltration rates. However, the clipping and compaction subtreatments were an instantaneous application of forage removal and soil pressure and thus may not adequately represent long term, accumulative conditions imposed by actual grazing. Areas rested from livestock grazing since 1967 had significantly higher infiltration rates than grazed areas on unchained woodland and chained, debris-in-place sites. Grazed plots consistently had the lowest infiltration rates although this lower rate was not significantly different from infiltration rates measured on areas protected from grazing since 1969 or 1971. Grazing did not consistently affect infiltration measured on chained, debris-windrowed sites. Infiltration rates increased on all three vegetative conditions as the period of rest from grazing increased. None of the 21 soil and vegetative variables included in this study were identified by multiple regression models as consistently explaining significant amounts of variation in infiltration rates. Results of this study indicate that the primary value of multiple regression models is not to predict changes that will occur in infiltration because one management alternative is selected over another, but to help explain significant differences measured between treatments. Erosion rates were not significantly affected by forage removal subtreatments, but a trend indicates that erosion increases on plots when above ground vegetation is removed by clipping. No consistent relationship between -erosion rates and soil compaction subtreatments was found. A trend toward increased erosion rates on grazed areas was found. No consistent relationship between erosion rates and the various periods of rest from grazing was recorded. Thus, any rest from grazing appears to reduce the erosion potential from pinyonjuniper sites. In summary, pinyon-juniper rangelands can be improved for livestock by chaining and seeding without causing a deterioration in watershed condition. However, to achieve these objectives, the sites to be treated must be carefully evaluated and the appropriate chaining, plant debris disposal, and seeding techniques identified. And following vegetative conversion, the areas must be properly grazed.

Wooded plant encroachment has dramatically changed the composition of rangelands in the arid and semiarid rangelands of the southwestern United States and may have significantly affected hydrologic and biogeochemical process in these environments. In particular, suspicions that encroaching species waste an undue amount of water through evapotranspiration (ET) has prompted much discussion concerning the possibility of using brush control to enhance water supplies in Texas. This study focuses on two broad goals for evaluating the effects of wooded growth in rangelands. The first of these is the assessment of wooded cover with the use of remotely sensed imagery. A methodology for delineating differing land cover classes, including different levels of brush cover, is described, applied, and validated for the Upper Guadalupe River watershed, Texas. This portion of the research resulted in an 81.81% success rate for correctly matching land cover varieties and showed that 88.8% of the watershed was covered with various amounts of woody plant growth. The second portion of this study incorporated the previously developed land cover product along with a number of other highly detailed data sources to model the North Fork of the Upper Guadalupe River watershed using the Soil and Water Assessment Tool (SWAT). The role of topography, brush cover, and soil slope, which are hypothesized to contribute to successful implementation of brush removal for water yield, were tested in a scientifically conscious and practical experiment to determine their influence upon water availability at a watershed scale. The effects of brush removal were found to be comparable to the quantities documented in field experiments, but less than the levels presented in previous modeling studies. Brush density was found to be the most important factor in determining locations for successful brush removal in regards to reducing ET. Slope was also found to have significant effect in increasing lateral flow while shallow soil had lesser effects on hydrology than other criteria. Large quantities of deep recharge simulated by the model raise questions concerning measurement of ET in the Edwards Plateau region and the extent of deep water recharge to the Trinity Aquifer.

Intermittent headwater streams serve important functions in semi-arid rangelands, both for humans and wildlife. However, few studies have assessed species-environment relationships for fish and benthic macroinvertebrate assemblages in these systems. Additionally, no published studies could be found that addressed the influence of juniper coverage in watersheds on assemblage structure of these taxa. Increased juniper coverage in recent decades is believed to be associated with decreased water yields in central Texas streams. During summer 2003 and spring 2004, I examined potential effects of juniper cover on aquatic ecology. Fishes, benthic macroinvertebrates, and the physicochemical habitat were investigated in spring-fed headwater tributaries of the Pedernales River. My objectives were to: 1) describe the typical fish and benthic macroinvertebrate assemblages in headwater creeks of the Pedernales River basin; 2) compare seasonal variability of fish and benthic macroinvertebrate assemblages; 3) identify species-environment relationships in this river basin; and 4) evaluate the influence of juniper coverage in the watershed, relative tolocal and landscape-level environmental factors, on the structure of fish and benthic macroinvertebrate assemblages. A total of 4,181 individual fish were collected in summer 2003 samples, 551 fish were collected in spring 2004, 59,555 macroinvertebrates were captured in summer 2003 samples, and 51,500 macroinvertebrates were collected in spring 2004. Assemblages were typical for the area and habitat conditions. Faunal richness was lower in spring than in summer, possibly due to a combination of sampling after a relatively dry period in the spring, and lack of winter refugia in the form of deep pools. Fish assemblages may structure based principally on abiotic factors in spring, the harsher season (less available water), whereas predation pressure may influence structure in summer. Another important environmental gradient for both fish and invertebrate assemblages contrasts pool and run mesohabitats. In general, juniper cover was weakly associated with fish and invertebrate assemblages, although it tended to be associated with relatively high quality habitat for sensitive taxa (flowing runs with coarse substrate; deep, connected pools). In these intermittent streams, local-scale environmental factors probably are the dominant influences on fish and benthic macroinvertebrate assemblages. Implications for future studies are discussed.