Biotic Response to Climate Variability
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1955 E 6th St, Tucson AZ 85719
520.670.6821 (voice)
520.670.6806 (fax)
Biotic responses to climatic change or human manipulation are inherently complex because of wide differences in organism sensitivities and response times, the influence of history and scale, and the various interactions between organisms and with the physical system. In arid and semi-arid lands, which cover about 12.5 percent of the Earth's land surface, the effects of climatic variability on vegetation are greatly magnified, particularly because most plants exist near their physiological limits. How arid land vegetation might in turn affect climate is uncertain, though there is some indication that decreasing cover and increasing albedo could promote regional drought. Whether in response to projected Greenhouse climates or intensified land use, vegetation in such critical watersheds as the Rio Grande and Colorado River basins is apt to change in the near future. There is a need to understand the direction and rate of this change and how it might affect water use and availability in the region. The objectives of this project are to achieve a dynamic understanding of vegetation change and its relation to water resources; to develop such an understanding in a manner appropriate to the hierarchy of spatial and temporal scales implicit in a study of global change; and to determine whether the responses of dryland vegetation to global change are predictable from past and present behavior of vegetation.
Faculty and Staff
Landscape Change in the Southwest
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520 N Park Ave, Tucson AZ 85719
520.670.6671 (voice)
Understanding the effects of climatic variability is important to development of water resources, mitigation of flood hazards, and interpretation of geomorphic surfaces. Climatic variability, which is characterized by temporal changes in variability of seasonal climate that spans decades or centuries, may be more important to water-resources evaluations than changes in mean climatic conditions. Changes in variability of climate has a large effect on the probability of occurrence of extreme events, such as floods or droughts. Understanding of climatic variability and its effect on the landscape is of paramount importance for estimation of flood frequency, sediment transport rates, and long-term watershed and channel changes. The objectives of this project are to define historic climatic variability in the western United States over the past century; to identify specific time periods of statistically stationary precipitation, discharge, flood frequency, and sediment transport; to assess the net effects of climatic variability on watershed conditions and fluvial systems; and to determine the extent that historic changes reflect Holocene climatic fluctuations.
Research Projects
Faculty and Staff
Sediment Impacts from Disturbed and Undisturbed Lands
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1955 E 6th St, Tucson AZ 85719
520.670.6821 (voice)
520.670.6806 (fax)
The acquisition and meaningful interpretation of sediment data from areas disturbed by land-use activities or natural processes are two of the most deficient areas of recognizing nonpoint-source pollution in the United States. The comparison of sediment data from disturbed and undisturbed areas provides a means to (1) evaluate the effects that land-use activities cause, (2) investigate the geomorphic processes that regulate the detachment and transport of sediment, and (3) develop strategies for remedial action to reduce excessive sediment discharges. This information is especially necessary to minimize sediment discharges and sorbed chemical loads from surface-mine, industrial, agricultural, and urban areas. Objectives of this project are to (1)evaluate the extent and utility of sediment data from a variety of land-use areas; (2) predict the movement of sediment from drainange basins affected by those land uses; and (3) assess existing techniques and develop new ones based on geomorphic principles and the application of statistics, geochemistry, and botany to the limited data available as aids in improving our interpretive capabilities.
