Browsing by Subject "Chihuahuan Desert (N.M.)"
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Item Fire effects on small mammals and vegetation of the Northern Chihuahuan Desert(Texas Tech University, 1997-12) Monasmith, Tony JohnThe role of fire in the Northern Chihuahuan Desen has been of great interest and also heavily debated for 40 years. However, few replicated studies have documented the changes brought about by fire. .My study documented the short term effects of fire on a creosotebush (Larrea tridentata) dominated community and associated small mammal community. Prescribed burns were ignited during 13-15 June 1995 on 10 pairs (10 bumed. 10 unbumed) of 25- ha study sites. The 1995 bums reduced shmb (P = '» 006) and grass (P < 0.000) canopy cover to 64 and 16% of the preburn cover, respectively Complete recovery' of the canopy cover had not taken place 1 year post bum Densities of shrubs, primarily creosotebush. tarbush (Flourencia cemua). and cacti species (Opuntia) were reduced 1 year post bum. Mortality of creosotebush (25.6%) was lower than previously reported for summer burns. Tarbush monality (26 3°o) was similar to creosotebush on the study sites. Above average precipitation during June and July 1996 and lower competition by shmbs for available resources promoted an 1160% increase in forb canopy cover on the bumed sites.Item Home range, habitat use, and denning characteristics of kit foxes in the northern Chihuahuan Desert(Texas Tech University, 1997-05) Hansen, Paul J.Zoellick and Smith (1992) noted that information regarding kit foxes' ecology in the Chihuahuan Desert is lacking. In 1993 I initiated a study on the ecology of desert kit foxes on NMR. The objectives of my Investigation were to gather information on the home range, habitat use, and denning characteristics of kit foxes in the northern Chihuahuan Desert ecosystem. Specifically, I examined kit foxes' annual and seasonal home range size, home range core areas measured by a 50% harmonic mean (HM) home range estimator, and compared fidelity to home range on a seasonal and annual basis. I compared the observed versus expected number of relocations in different habitats and ecotones to gain insight into range use and compared the observed versus expected relocations on roads, arroyos, and trails to gauge kit foxes' use of travel corridors. Finally, I compared the observed versus expected number of den site locations in different habitat types and collected data on the physical characteristics at den sites to gain insight into kit foxes' denning preferences.Item Influence of biosolids application on growth, nitrogen uptake, and photosynthesis of two desert grasses(Texas Tech University, 1999-12) Mata-Gonzalez, RicardoThis research is an evaluation of the effects of different rates and dates of biosolids application, as well as irrigation levels on biomass production, nitrogen absorption, and gas exchange characteristics of blue grama {Bouteloua gracilis) and tobosagrass {Hilaria mutica) in the Chihuahuan Desert, Individuals of blue grama and tobosagrass were transplanted into pots and grown under greenhouse conditions, Biosolids were applied in March (spring application) or Jime (summer application) at rates of 0, 7, 18, 34, and 90 dry Mg ha"'. Plants were irrigated at 40 or 80% soil field capacity. Treatments were combined in a factorial experiment and plants were arranged in a completely randomized block design. Application of biosolids produced an increase in available soil nitrogen, which favored an increase in shoot biomass of blue grama and tobosagrass. As biosolids rates and irrigation levels increased, biomass allocation increased in the shoots of the grasses. As biosolids rates and irrigation levels decreased, biomass allocation to the roots increased. Spring application of biosolids promoted greater soil nitrogen availability and higher plant growth than summer application of biosolids. Biosolids promoted higher nitrogen uptake and higher nitrogen concentrations in the shoots. Higher plant nitrogen concentrations were particularly favored by biosolids application when irrigation was not a limiting factor. Plant nitrogen concentrations were not strongly correlated with photosynthetic rates in both species. Leaf area, nitrogen concentrations, and photosynthesis rates in tobosagrass irrigated at 80% field capacity increased as biosolids rates increased. Increasing rates of biosolids in tobosagrass under the low irrigation level and in blue grama irrespective of irrigation level produced increases in leaf area, which corresponded with decreases in stomatal conductance and photosynthetic rates. Except for tobosagrass at high levels of irrigation, blue grama and tobosagrass seemed to have a mechanism of stomatal regulation to avoid excessive water loss in response to increments in leaf area.Item Microsite and habitat boundary influences on small mammal capture, diversity, and movements(Texas Tech University, 1997-08) Root, J. JeffreyHabitat, habitat edges, and microhabitat are important components for theories and concepts of community ecology. However, their effects have not been examined in many locations. Replicated studies in different ecosystems are necessary to determine the generality of the effects of these habitat variables. The effects of trap-site disturbance and microhabitat on small mammal capture rates were examined in the Tularosa Basin of south-central New Mexico during 7-14 April, 1996. The study was conducted in a mixed desert scrub habitat characteristic of the Chihuahuan Desert. Small mammals were live-trapped on 32 study plots. Soil disturbance and microhabitat treatments were assigned to study plots in a completely randomized factorial design to test the hypothesis that trap-site disturbance can influence small mammal captures between microhabitats. Thirteen species of small mammals were captured, including four species of Heteromyidae, eight species of Muridae, and one species of Sciuridae. Peromyscus eremicus was captured more frequently at undisturbed sites (P=0.004) and was recaptured more frequently under shrubs j[P=0.048). Neotoma micropus was captured less frequently at undisturbed sites in the open (P=0.035). No other species were affected by microhabitat, trap-site disturbance, or interactions (P>0.05). These results provide limited support to the hypothesis that trap-site disturbance can influence small mammal captures between microhabitats.Item Quantity and quality of runoff from two biosolids-amended Chihuahuan Desert grassland soils(Texas Tech University, 1997-05) Moffet, Corey AllenWater is a precious resource in the arid west. Communities, both plant and animal, depend on it for basic life functions. Land application of biosoHds on arid and semi-arid rangeland has led to growing interest in determining the hydrologic consequences of this practice. Water, in the form of precipitation, is partitioned into runoff, interception, or infiltration at the active surface. Because the application of biosolids alters the active surface it may be expected that biosolids also will affect infiltration, runoff and erosion. The objectives of this work were to: (1) evaluate the effects of varied rates of biosolids on infiltration, and erosion; (2) examine some of the mechanisms whereby biosolids application affect infiltration and erosion; and (3) find environmental conditions that maximize or minimize the response of infiltration or erosion to biosolids application. A portable single-nozzle rainfall simulator was used to simulate rainfall on 0.5 m^ plots to determine infiltration and erosion. Many factors are considered including soil type; season of simulation; the period of time biosolids are in plots before simulation; vegetative cover: the rate of biosolids applied; and antecedent soil water. Measurements recorded to characterize each plot included canopy cover, surface cover, surface roughness, plot standing crop and liter, and soil morphology to 35 cm depth. Experimentally manipulated factors included soil type, vegetation cover, rate of biosolids applied, and antecedent soil water. Application of biosolids affects infiltration rate, cumulative infiltration and erosion. Biosolids provides ground cover and adds organic matter to the soil. The hydrologic response to biosolids depends on site factors, including soil type and cover and biosolids factors such as rate and batch. Topical application of biosolids has important hydrologic consequences in desert grasslands that depend upon the rate of biosolids applied and is modified by the environment to which the biosolids are applied.