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.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Orman Mühendisliği Anabilim Dalı, 2009. / Kaynakça var.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 121-134). Also available on the World Wide Web.

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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.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 59-67). Also available on the World Wide Web.

Thesis (M.S.)--Southern Oregon University, 2005. / "A thesis submitted to the Department of Biology of Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science in Environmental Education." Includes bibliographical references (p. 36-50) Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 107-118). Also available on the World Wide Web.

abstract: ABSTRACT The February 2008 study of a Snowflake, Arizona site measured changes in soil organic carbon, total nitrogen, extractable phosphorus, and soil moisture, to determine what affect One-seed Juniper (Juniperus monosperma) trees have on surrounding soil, thus affecting native grass growth. Increasing juniper densities in grasslands also decrease populations of some grassland bird species. Measurements were taken each meter along a twelve meter line transect, moving from juniper trees, through a bare soil area and into a grassland. Non-linear relationships were examined, in regard to distance from the tree and juniper root mass. Relationships were examined to determine any affect of the juniper tree on soil characteristics along the transect. Organic carbon decreased as distance increased from the trees (F=4.25, df=46, p=0.020). Soil moisture increased with distance from the trees (F=5.42, df=46, p=0.008), and juniper root mass, of roots less than 1 mm diameter, significantly decreased with distance away from the trees (F=11.29, df=46, p=0.0001). Total nitrogen and extractable phosphorus did not significantly change with distance from the tree, or presence of juniper roots. This data is important as grassland restoration projects rely on the availability of soil nutrients and water for reestablishment of native grass species. / Dissertation/Thesis / M.S. Applied Biological Sciences 2010

Objectives were (1) to evaluate the seasonal and daily use by mule deer (Odocoileus hemionus) of adjoining converted and natural pinyon pine-Utah juniper woodland (P-J) winter range, and (2) to determine the major factors influencing mule deer use of converted P-J range to provide criteria for deer management. The study was conducted on 3 sites in central, eastern, ar.d southeastern Utah between 1969-72. Data for 1969-72 on physiographic, climatic, and vegetational attributes of the three Utah study areas were related to data from approximately 10,000 deer observations, 5,000 0.01-acre pellet-group count plots, feeding observations of 1,100 deer, 220 miles of track counts on trails, and 450 radio locations of nine adult female deer. Conclusions were: (1) In the initial 12 years post-treatment, no increase in deer numbers X was correlated with P-J conversion. (2) Increasing deer use during the study was concentrated on natural P-J. (3) The bulk of the use on chainings occurred in March and April. (4) Radio telemetry indicated that, from November to May, about 55 percent of the deer within 0.5-mile of the chaining edge used the chainings at night, and 5 percent in the day. (5) Deer fed and bedded in alternate 2-hour periods. Thus, the Mayfield chainings contributed 25 to 30 percent of the deer forage, but comprised over 50 percent of the land area. (6) The greatest overwinter deer use occurred in shallow valleys and on slopes of 10-20°. Least preferred by deer were flats and hilltops. Chaining decreased the relative deer use on hilltops, increased it on hillsides, and had no effect on the use of valleys. (7) Deer use was greatest on north exposures in the natural P-J and on south exposures on chainings. (8) No edge effect existed in the initial mile of P-J away from the chaining edge, whereas, deer use of chainings declined 50 percent in the initial 0.2-mile. (9) Radio telemetry showed a mean home range radius of 0.6- mile between November and May for nine adult female deer. (10) Moon phase effected deer use on the chainings but with reversed influence between November and May. (11) Snow cover over 10 inches and wind velocity greater than 20 miles-per-hour each decreased considerably deer use of chainings. (12) An increase in shrub density increased deer use of chainings more than any other variables measured. (13) Chaining of P-J apparently decreased Cercocarpus montanus, Quercus gambelii, and Pinus edulis shrub density but increased Juni£eru~ osteosperma and Artemisia spp. Forb cover did not markedly change post-chaining, while grass cover increased by 400 percent. (14) Total forage crown cover increased 25 percent 3-12 years post-treatment. However, total palatable browse cover was less on treated than untreated range. (15) Juniperus spp., Artemisia spp. and green grasses comprised 60 to 75 percent of the over-winter diet; the remainder was composed largely of Quercus gambelii and Cercocarpus montanus. (16) Optimum tree density for deer use of P-J appears to be 50 to 100 per acre, depending upon maturity of the stand. Management recommendations are that P-J chainings should: (1) be less than 0.4-mile wide, compose no more than 20 percent of the winter range 1n a 25 year period, (2) be single chained only, (3) be confined to small valleys and gentle slopes, (4) have 20 percent slash cover, 5-10 percent grass cover, and many of the pushed-over tree tops ~eft alive, (5) be confined largely to south and west exposures, (6) be grazed in a spring- fall rotation by cattle.