Prepared by the Arid Lands Information Center, Office of Arid Lands Studies, University of Arizona ; Mark W. Speece, compiler.

Prepared by the Arid Lands Information Center, Office of Arid Lands Studies, University of Arizona ; Dr. James Silliman, compiler.

Riparian ecosystems are valued for ecosystem services which have impacts on the well-being of humans and the environment. Anthropogenic disturbances along rivers in arid and semiarid regions have altered historical flow regimes and compromised their integrity. Many rivers are hydroecologically deteriorated, have diminished native riparian forests, and are pressured for their water supplies. My first study is founded on the premise that river restoration has increased exponentially with little documentation on effectiveness. We designed a conference to discuss lessons learned from past restoration activities to benefit future efforts. Participants, including scientists, managers, and practitioners, agreed that creating measureable objectives with subsequent monitoring is essential for quantifying success and employing adaptive management. Attendees stated that current projects are local and have limited funding and time, whereas future efforts must have longer funding cycles, larger timeframes, should contribute to regional goals, and address factors responsible for ecological decline. Bridging gaps among science, management, and policy in the 21st century is a key component to success. My second study focused on the benefits of long-term monitoring of local riparian restoration. Many efforts include revegetation components to re-establish native cottonwood-willow communities, but do not address how high-density establishment impacts vegetation dynamics and sustainability. Over five years, we documented significantly higher growth rates, lower mortality, and higher cover in cottonwood compared to non-native tamarisk. Cottonwood height, diameter at breast height, growth rates, and foliar volumes were reduced at higher densities. Herbaceous species decreased every year but native shrubs volunteered after two years resulting in a reduction of overall plant diversity from 2007-2009 with a slight increase from 2009-2011.My third study focused on improving basin-scale evapotranspiration (ET), a large component of the water budget, to better inform water resource allocation. My research suggests that multiple models are required for basin-scale ET estimates due to vegetation variability across water-limitation gradients. We created two empirical models using remote sensing, a multiplicative riparian ET model (r²=0.92) using MODIS nighttime land surface temperature (LST(n)) and enhanced vegetation index, and an upland ET model (r²=0.77) using multiple linear regression replacing LST(n) with a precipitation input.

Prepared by the Arid Lands Information Center, Office of Arid Lands Studies, University of Arizona ; Mark W. Speece, compiler.

Prepared by the Arid Lands Information Center, Office of Arid Lands Studies, University of Arizona ; Mark Speece, compiler.

Distributional and ecological dynamics of Neotropical migratory birds at stopover sites where they maintain critical fat reserves during migration remain poorly understood in North American aridlands. I examined spatiotemporal abundance and timing of migrants relative to 1) upland and riparian habitats, 2) post-fire landscape mosaics, and 3) phenological synchrony and overlap of migration with tree flowering in southeastern Arizona's Madrean Archipelago (2009-2011), and 4) abundance, habitat breadth, and foraging substrates relative to tree flowering along the Colorado River in southwestern Arizona and northwestern Sonora, Mexico (2000-2003). I explored these dynamics relative to local weather conditions and El Niño Southern Oscillation (ENSO) climate phenomena. In Madrean habitats, migrants showed three non-exclusive responses to high precipitation, snowfall, and low minimum temperatures associated with El Niño in 2010; migration timing adjustments, habitat shifts, and reduced abundances suggesting migration route shifts. Foliage-gleaning insectivores were most abundant in high severity burns, disproportionate to their availability, and decreased with time since fire (TSF); flycatchers were most abundant in low-moderate severity and increased with TSF. Migrant abundance increased with tree flowering. Phenological overlap declined with increasing difference in timing of these events. Overlap was lowest in 2011 in riparian habitat due to low willow (Salix goodinggii) flowering, despite high migrant abundance, but lowest in 2010 in montane conifer, despite high pollen cone production by Douglas-fir (Pseudotsuga meziesii), suggesting temperature limitation of insect abundance at high elevations, but water limitation of plant phenology at lower elevations. Along the Colorado River, migrant abundance and habitat breadth had inverse positive and negative quadratic relationships, respectively. Abundance increased with tree flowering, but only in 2003 during severe drought. Habitat breadth increased with monsoon precipitation. Foraging substrate use tracked flowering, shifting from willow to mesquite (Prosopis sp.); the overlap coincided with peak abundance and narrowest habitat breadth. Maintenance of diverse vegetation and post-fire landscape mosaics in the Madrean Archipelago should benefit migratory bird diversity. Flowering phenology likely provides large-scale cues of local-scale stopover habitat condition associated with interannual climatic variation. Management and restoration of upland habitats and large riparian woody perennials will be critical for migratory bird conservation in aridlands.

No description available.

Shallow water bathymetry is important for both safe navigation and natural resource management purposes. Extracting depth information from spectral imagery allows identification of benthic features and characterization of coral reef habitats, especially in remote islands. Techniques have been developed to extract water depth from multispectral imagery (Lyzenga, 1978; Philpot, 1989). These techniques can be difficult to apply in optically shallow waters with heterogeneous bottom types and varying albedo, and require tuning of multiple parameters. An improved algorithm to extract water depth from multispectral satellite imagery was proposed by Stumpf et al. (2003) to generate bathymetric maps with limited a priori information. The algorithm is based on the ratios of transformed reflectance values in the visible bands, retrieving greater depths than previous algorithms and compensating for variable bottom type and albedo. This method requires fewer tunable parameters and can be applied to low-albedo features. Although Stumpf et al. (2003) conclude that the method is robust and works well over variable bottom types, recent studies have pointed out limitations, mostly attributable to varying albedo (Clark, 2005; Densham, 2005). This research attempts to quantify the contribution of variable benthic substrates to the algorithmâ s accuracy by classifying the scene into its main bottom types and tuning the coefficients separately. The algorithm is evaluated using a QuickBird high resolution multispectral image of the remote Midway Atoll, in the Northwestern Hawaiian Islands. Classifying the image into two main bottom types and tuning the coefficients separately produced a small improvement in the accuracy of the bathymetric estimates when bottom reflectance is included as a factor. This result indicates that Stumpf et al. (2003)â s ratio method is not insensitive to variable bottom type, and that knowledge of the distribution and extent of different benthic substrates in optically shallow waters has the potential to improve bathymetric derivation in remote coastal areas such as coral reef environments in the Pacific.

The combination of price inflation and historical cost-based depreciation for tax purposes has been shown in the finance literature to reduce the present value of depreciation deductions. Since tax depreciation deductions are limited to a nominal dollar amount, when inflation occurs a future tax deduction has less real value. This effect is pedagogically presented in a capital budgeting context. In the economic literature Hotelling and Herfindahl have contributed models describing natural resource production changes in response to changes in demand, production cost, and cost of capital. Parts of the inflation-explicit capital budgeting model and the Hotelling and Herfindahl models are combined. The result is a partial equilibrium model which yields the conclusion that production from a natural resource is reduced if inflation is increased. Copper industry data from 1947-1978 are examined for empirical confirmation of the theoretical model. A copper industry production function, which contained demand, real price and labor strike variables, gained in descriptive capability by inclusion of inflation as an additional multiple regression variable. The dissertation reviews literature on the relationship between capital investment and inflation. The cases of hyper-inflation in Germany and medium inflation in Latin America are considered. Other literature review topics include the inflation effects in the securities markets, inflation-caused wealth transfers and inflation adjustments in accounting statements.

In terrestrial habitats with a history of mining activity and previous or ongoing reclamation efforts, understanding the effects of acidification on the ecology of amphibians is an important part of the restoration process and the conservation of local amphibian populations. Pond-breeding amphibians spend much of their post metamorphic life history in direct contact with the soil in upland habitat adjacent to aquatic breeding sites. I reared recently metamorphosed marbled salamanders (Ambystoma opacum) to evaluate the role of soil acidity on determinants of fitness such as growth and survival. My results indicate that a substrate of pH 4 was lethal to recent A. opacum metamorphs. Among animals surviving the higher pH treatments, we found that individuals reared on a pH 5 substrate suffered a reduction in total length and snout vent length by the end of the experiment. The mechanisms of acidity are complex; both hydrogen ions and anions contribute to negative effects on amphibians. Sulfuric acid has larger negative effects than other acids and sulfates can cause reductions in growth without a change in pH. I reared larval spotted (Ambystoma maculatum) and Jefferson salamanders (Ambystoma jeffersonianum) to evaluate the effects of pH and sulfates on two species with differential acid resistances. My results indicate that a pH of 4 is lethal to larval salamanders of both species. In high sulfate treatments there was an early reduction in growth in the spotted salamander, but not in the Jefferson salamander showing that acid resistance applies to the effects of sulfates as well as hydrogen ions. Together, our results suggest that acid and sulfate deposition can affect the fitness of Ambystoma salamanders through direct mortality and a decrease the growth rate of salamanders both as larvae and subsequent to metamorphosis.