Sap flow, leaf gas exchange, and micrometeorological parameters were evaluated during 1997 in riparian forest at perennial and ephemeral stream sites on the San Pedro River in southeastern Arizona, USA. At the perennial stream site, measurements of sapwood area based transpiration and sapwood area/canopy area of clusters of Populus fremontii and Salix goodingii were used to estimate transpiration across the stand. Stand structural heterogeneity resulted in as much as 30% variation in mean transpiration across the stand. Transpiration of cottonwood was more dependent upon vapor pressure deficit at the ephemeral stream site which had an open, less dense canopy compared to that at the perennial stream site. This may be due to differences in advection properties and canopy feedback processes between sites. Conversely, transpiration in willow was less dependent upon vapor pressure at the ephemeral stream site than that at the perennial stream site. This may be due to water stress associated with deeper depth to groundwater.

Yellow bluestem (Bothriochloa ischaemum (L.) Keng.) cultivars are used in conservation plantings in New Mexico, Texas and Oklahoma. The recommended cultivar in southern Arizona is Ganada. However, a population from Saudi Arabia P.I. 237110, may be better adapted to the Sonoran Desert environment. This study was conducted to determine why P.I. 237110 may be better adapted to this environment than Ganada. Morphological and physiological characteristics of P.I. 237110 and Ganada were compared in five experiments. Evaluations revealed significant differences in combined stomate densities on both leaf surfaces, leaf surface area, and water use efficiency but not in apparent photosynthesis or dark respiration. Combined average stomate density was significantly lower for P.I. 237110 than Ganada (107 vs. 136 stomates mm⁻²). P.I. 237110 had a significantly higher leaf surface area (40.5 cm²) than Ganada (25.3 cm²). Apparent photosynthetic rates were not significantly different between the populations (Ganada: 12 mumol m⁻² s-1 and P.I. 237110: 10 mumol m⁻² s⁻¹). Dark respiration rates for Ganada were not significantly different (1.4 mumol m⁻² s⁻¹) from those of P.I. 237110 (1.9 mumol m⁻² s⁻¹). P.I. 237110 required 88.9 g of water per 1 g of dry matter than Ganada which required 52.3 g of water.

<p> It is difficult to assess rangeland management practices at a hillslope scale because of the spatial and temporal variability of ecohydrological processes across a landscape. The Conservation Effects Assessment Project (CEAP) aims to provide a cost-effective method for quantifying benefits of conservation practices on rangelands. This study uses the Rangeland Hydrology and Erosion Model (RHEM) to develop a framework to assess rangeland management practices by quantifying sediment yield and runoff. Kaler Ranch, located in Eastern Arizona, was used as a study site because of their recently implemented rangeland conservation practices. Vegetation parameters were developed based on field data collected across the ranch and used to represent various rangeland management scenarios in RHEM. Peak flow and sediment yield rates were determined for each scenario using RHEM and were used as metrics to evaluate rangeland condition. RHEM provided an adequate method to evaluate the relative differences between upland rangeland management scenarios; however, it was less effective at evaluating changes in management practices within a riparian area.</p>

<p> The vegetation associations in the Eastern San Cristobal Valley of Barry M. Goldwater Range-East (BMGR) were mapped using a combination of field surveys (relev&eacute;s) and interpretation of aerial imagery in order to contribute to ongoing mapping efforts of Barry M. Goldwater Range -East. Throughout the San Cristobal Valley, 149 relev&eacute; samples were collected to characterize the vegetation associations. Seventeen vegetation associations were identified and mapped, including a new <i>Larrea tridentata/Ambrosia dumosa/Grusonia kunzei</i> (Creosote bush-White bursage-Devil's cholla) association. Accuracy assessment of the map was conducted using a contingency table finding the map to be 82% accurate.</p><p> Route proliferation in the San Cristobal Valley of Barry M. Goldwater Range-East (BMGR) was also mapped and measured using remotely sensed imagery in geographic information systems and modeled with geographical variables in a multivariate regression. Throughout the San Cristobal Valley study site, 6,878 km of unauthorized routes were identified. Geographic explanatory variables distance from slopes greater than 34% (b = -3.252e-5, <i>p</i> &lt; 0.001) and the most influential variable distance from unauthorized routes (b = -0.006568, <i>p</i> &lt; 0.001) were tested for significance and influence in predicting unauthorized route density. The resulting model, built from the two significant geographic variables in a multivariate regression, was able to explain 57% of the variability in the data. The results from this study have shown that through the use of GIS and remote sensing, unauthorized route density can be predicted by geographic variables which can then be used to make future route management decisions.</p>

<p> The United States increasingly calls upon elite teams of Special Operations Forces, like the Navy SEALs, to respond to the evolving asymmetric threats posed by terrorists and extremists. These teams must have the capacity to adapt as a collective unit in the most dynamic circumstance. This research explored the nature of collective adaptation by these exceptional action teams using a qualitative case study methodology and a lens of complexity theory. Specifically, data gathered from official documents and interviews with retired Navy SEALs expanded the understanding of dynamic instability as it relates to team adaptation in uncertain environments. A greater understanding of this phenomenon contributed to the scholarly literature by identifying and describing the critical factors used by teams to promote adaptive capacity through the appropriate usage of structure and innovative flexibility in a dynamically changing situation. The study produced the following conclusions: 1. Individuals in an action team mentally reference a combination of general simple rules and situation-specific simple rules when they adapt in an uncertain environment. &bull; Varying application of different types of simple rules correspond with different levels of environmental uncertainty. &bull; Simple rules provide the basis for a shared cognitive structure that enables greater collective adaptation. 2. Previous experience plays an important role in the adaptive capacity of an action team. &bull; Experience provides an individual with context to determine how simple rules can and should be applied. &bull; Experience strengthens the relationship (trust and familiarity) between team members which allows them to adapt more quickly and effectively as a collective. 3. Relationships between team members, grounded in previous experience and a shared culture, play an important role in the adaptive capacity of an action team. &bull; Trust between team members gives each individual the freedom and permission to take initiative and adapt as necessary. &bull; Familiarity between team members enables the action team to collectively adapt more quickly and effectively because they can predict how another teammate will react given a specific set of parameters without the need for extensive communication. 4. The ability of individual team members to control emotions, slow and simplify reactions, and focus communication promotes more effective adaptation by an action team in an uncertain environment. &bull; Individual decision-making is enhanced when individuals are able to control their reactions and react calmly in the midst of an uncertain environment. &bull; As environmental uncertainty increases, individuals who react by slowing down and simplifying their actions are capable of more effective adaptation. &bull; In an uncertain environment, action teams that focus communication, reduce potential distractions for team members. This reduced, but effective communication is possible because of trust and familiarity between team members. 5. An action team's ability to adapt is dependent upon its dynamic instability (the interplay between morphostatic and morphogenetic factors). &bull; Morphostatic factors that promote structure include simple rules, selection of team members, familiarity between team members, and perpetuation of a structured culture that regulates behavior. &bull; Morphogenetic factors that promote flexibility include previous experience, distributed leadership, trust between team members, and perpetuation of a permissive culture that encourages innovation.</p>

All plants contain primary and secondary compounds. Primary compounds are needed by plants and herbivores for maintenance, growth, and reproduction, while secondary compounds play roles as diverse as protecting plants from ultraviolet radiation, defenses against herbivores, pollination attraction, and stress resistance. Secondary compounds have nutritional and medicinal benefits for herbivores as well, especially when eaten in diverse combinations that complement one another. While complementarities among secondary compounds are an important but little understood area of plant-herbivore interactions, even less is known about how the sequences of eating plants with different compounds affects foraging behavior, though they may be critical. In three trials, I determined if the sequence in which lambs ate endophyte-infected tall fescue (alkaloids), birdsfoot trefoil (tannins), and alfalfa (saponins) affected their foraging behavior. When lambs grazed on monocultures they spent similar amounts of time grazing regardless of which forage they grazed. Lambs that grazed in a sequence of different forages tended to subsequently eat less alfalfa pellets in pens than lambs that grazed a monoculture, which suggests they better met their nutritional needs on mixtures than on monocultures. Likewise, lambs that grazed a monoculture of alfalfa or fescue spent more time grazing during the first 45 min than in the subsequent 45 min, while lambs that grazed alfalfa during the first 45 min and then fescue spent more time grazing in the subsequent 45 min, suggesting lambs satiate faster when they have fewer choices. While the foraging sequences I examined generally allowed animals to consume more than they would if they grazed in monocultures, there is still a need to further explore how different plants and foraging sequences influence the level of consumption by livestock of forages on pastures that contain various secondary compounds.

Master of Science / Department of Agronomy / Walter H. Fick / Kevin Price / Caucasian bluestem [Bothriochloa bladhii (Retz) S.T. Blake] is a perennial, C4 warm-season bunchgrass that was first introduced in 1929 from Russia as a potential forage crop in the Great Plains. Due to its invasiveness and tolerance of drought and grazing pressure, Caucasian bluestem can out-compete native prairie species. Research has shown that this species, when compared to native tallgrass species in the Flint Hills of Kansas causes decreased cattle weight gains because of its poor forage quality relative to tallgrass prairie species. Traditional methods of plant data measurements and mapping are costly and time consuming. Use of remotely sensed data to map and monitor the distribution and spread of this plant would be most useful in the control of this aggressive invader. Spectroradiometer data were collected over the 2009 growing season to determine if and when Caucasian bluestem was spectrally unique from native tallgrass prairie species. Observations were made from June through September as the plants were going into a senescent state. Reflectance data were measured approximately every two weeks or when clear/near clear sky conditions prevailed. Statistical analyses for differences in spectral characteristics were conducted to determine the optimal spectral bands, indices and timing for discriminating Caucasian bluestem from native tallgrass species. Difference in reflectance for spectral reflectance of bands 760 nm, 940 nm, 1,070 nm, and 1,186 nm were found to be statistically significant on the June 17th and June 30th sampling dates. The following band ratios and indices were found to be significantly different between Caucasian bluestem and native range on the June 17th collection date: Simple Ratio, Modified Normalized Difference Index, Normalized Phaeophytinization Index, Plant Index 1, Normalized Water Difference Index, Water Band Index, Normalized Difference Nitrogen Index, and the Normalized Difference Lignin Index. Findings of this study suggest that Caucasian bluestem can be spectrally discriminated from native tallgrass prairies of the Flint Hills in Kansas if the measurements are collected in mid to late June. Statistical analyses also showed differences between treatments for percent litter, grass, and forb basal cover.

Master of Science / Department of Animal Sciences and Industry / Dale A. Blasi / An experiment was conducted to evaluate the effects of dry matter intake (DMI) restriction on early receiving performance by steers in a drylot and subsequent grazing performance, feedlot performance, and carcass characteristics. During the backgrounding period, crossbred, weanling steers (n = 329; initial BW = 191± 5.52 kg ) were randomly assigned to 1 of 4 DMI levels corresponding to ad libitum, 2.50% of BW (2.50%), 2.25% of BW (2.25%), and 2.00% of BW (2.00%) for 62 d. During the subsequent grazing period, the same steers were randomly assigned to 13 paddocks to graze for 90 d. Paddocks were stocked at 281 kg live weight per hectare. Initial steer BW were similar on each pasture and each backgrounding treatment was equally represented within a paddock. During the feedlot period, steers were finished at a commercial feedlot and were assigned to 1 of 4 pens according to their rank in BW. Entire pens were harvested when average steer BW reached 545 kg. During the backgrounding period, ad libitum-fed steers had greater (P < 0.001) ADG and final BW than other treatments; steers fed at 2.50 and 2.25% of BW had similar ADG and final BW and were greater (P < 0.001) than steers fed 2.00% of BW. During the grazing period, compensatory gain was observed in restricted DMI treatments. Steers fed at 2.00% of BW had greater (P = 0.006) ADG than ad libitum-fed steers but an ADG similar to that of the other restricted DMI treatments. Steers fed ad libitum, 2.50% of BW, and 2.25% of BW had similar final BW and steers fed 2.00% of BW had lesser (P < 0.001) final BW than other treatments. During the feedlot phase, steers fed 2.00% of BW were on feed longer (P < 0.05) than other treatments. Growth compensation during grazing illustrated that restricted feeding immediately prior to pasture grazing can reduce backgrounding costs.

The objective of this work is to estimate the effect of floods on the riparian vegetation communities of the Gila Box, Arizona, based on historical maps, satellite images, and GPS-referenced airborne video. The condition and extent of selected riparian vegetation communities in 1973, 1982, and 1991 are documented. Changes in riparian vegetation communities for the time period from 1973 to 1982 and from 1982 to 1991 are analyzed to assess the potential effect of floods that occurred in 1978 and 1983, respectively. The results indicate that the floods in 1978 and 1983 may have had an impact on the mesquite riparian community. The effect of floods on riparian vegetation is most apparent in the downstream portion of the Gila River. The information collected and presented in this work can be used to formulate effective management plans to the Gila Box area.

A case study is used to illustrate and assess the applicability of participatory democracy theory to public participation in public land decision-making. In this case, public outcry against a Bureau of Land Management acquisition plan resulted in adoption of a coordinated resource management process, an application of participatory democracy theory which is purported to improve public acceptance of administrative decisions by providing improved access and representation, information exchange and learning, continuity of participation, and shared decision-making authority. The study suggests that in order to satisfy the public, a participatory democracy approach to public participation should give participants tangible evidence that their input will influence agency decisions, preferably by giving them the authority to collectively make decisions that will be binding on all participants, including agencies. Furthermore, organizational and decision-making rules, as well as legal and bureaucratic limitations on the process, must be explicit.