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CALS Current Research

Criteria for Defining Site Conservation Thresholds for Arizona Rangelands

E. L. Smith and P. R. Ogden, SRNR, College of Agriculture and Life Sciences. 1994 - 1997

OBJECTIVES: Characterize pattern and proportion of soil/vegetation attributes related to thresholds of soil stability. Define and describe pattern of erosion cells on clay loam ecological sites.

PROGRESS: A test of the soil surface condition assessment method of Tongway (Australia) was completed in Southeastern Arizona. Twenty 100m transects were run on 5 different range sites and 2 National Resource Conservation Service condition classes on each range site. Range sites and condition classes were assessed in 2 different watersheds. Variables measured were: average obstruction length, total obstruction width, average fetch length, total number of obstructions, & percent perennial cover. Also 9 soil surface assessments; soil, litter, cryptogam cover, crust brokenness, erosion features, deposited materials, soil microtopography, surface nature, stake test. Also 3 synthetic variables: stability, infiltration/runoff, nutrient cycling. Vegetation data included % composition by weight, NRCS condition score, and percent of quadrants (40x40cm) containing no perennial plants. Correlation analysis of all soil variables vs NRCS range condition score showed no relationship. There was no relationship of soil variables measured and range site. Soil variables will be analyzed using a "skewness" test to see if these relate to "stability". Percent unoccupied quadrants appears to be a quick method of evaluating soil surface condition. Complete results will be included in a MS Thesis entitled "Effects of Ecological Site and Vegetation State on Assessment of Rangeland Soil Surface Condition."

Development of a Spatial Decision Support System for Rangeland Watershed Management

D. P. Guertin, SRNR, College of Agriculture and Life Sciences.

OBJECTIVES: The primary objective of this project is to develop a GIS-based integrated watershed-scale Spatial Decision Support System (SDSS) that will provide land managers with recommendations for Best Management Practices (BMPs) based on site specific conditions. The SDSS will be deployed via the Internet, which provides access to GIS technology and models not currently available to most land managers. The SDSS will provide estimates of erosion resulting from user-defined land-use conditions and incorporate available BMPs and economic concerns to allow the user to design watershed-based management systems that meet user's land-use needs along with reducing non-point source pollution and addressing Total Maximum Daily Loads (TMDLs).

SUMMARY: The impact of livestock grazing on water quality, especially related to erosion and sedimentation, is becoming a major concern in the southwestern United States due to the U.S. Environmental Protection Agency designating Total Maximum Daily Loads (TMDLs) as criteria to evaluate pollution contribution from land use impacts and other non-point sources. In response to the need to comply with these Federal and State mandated criteria, Best Management Practices (BMPs) for rangeland management are being developed and implemented in many western states, although the efficacy and economic impact of many practices have not been examined. Tools are needed to assist in the evaluation and implementation of BMPs for non-point source pollution at a watershed-level. This project will evaluate current BMPs and develop a Spatial Decision Support System (SDSS) to recommend BMPs for livestock management by integrating water quality, livestock management and economic concerns. The SDSS will recommend the type and location of BMPs based on site-specific data and will be deployed via the Internet providing access through a web browser to both land managers and local ranchers. The results from this project will provide land managers in the southwestern United States with a means to identify critical locations causing water quality degradation and design and implement watershed management measures to improve water quality by incorporating cost effective management practices and recommended BMPs.

IMPACT: 2000/01 TO 2000/12. Effective water management is of utmost importance in the arid and semiarid southwest. This project addresses the development of tools for integrating information, at the watershed scale, to assist in the decision-making process.

Development of Satellite Derived Vegetation Measures Specific to Arid/Semiarid Regions

A. R. Huete, SRNR, College of Agriculture and Life Sciences. 1999 - 2002

OBJECTIVES: In this project we will conduct a sensitivity analysis of existing vegetation index equations over the transitional environments of the U.S and Mexico border area. We will then simulate the complex canopy conditions encountered in arid regions with a three dimensional canopy radiant transfer model. Remote sensing methodologies will then be refined for maximum discrimination of sparse arid and semiarid vegetation dynamics. Finally, we will calibrate and validate both models and remote sensing equations over the range of vegetation conditions encountered in transitional arid and semiarid regions.

IMPACT: 2000/01 TO 2000/12. The MODIS image products were found to be highly reliable in quantitative assessments of arid and semiarid region vegetation cover. This will be quite useful in the use of satellite data in land degradation studies, soil erosion, and changes in biogeochemical cycling of nutrients.

Effects of Human Activities on Wildlife Populations in Forested and Desert Landscapes

R.J. Steidl, SRNR, College of Agriculture and Life Sciences. 2000 - 2003

OBJECTIVES: Describe and experimentally assess the effects of physical and aphysical human activities on the behavior, activity budgets, and distribution of a suite of wildlife species. Use these data to model and predict effects of these activities on reproductive success and viability of these wildlife populations. Lastly, develop scientifically-based recommendations and guidelines that can be implemented by land managers to minimize or ameliorate the effects of these human activities on wildlife.

SUMMARY: The types, intensity, and number of human disturbances affecting wildlife are pervasive and increasing. Further, agencies are only beginning to reintroduce natural physical disturbances that are important mechanisms that influence the composition and trajectory of many communities. I propose to assess the effects human activities on the behavior, activity budgets, and distribution of a suite of wildlife species, with the goal of developing guidelines to minimize these effects

IMPACT: 2000/01 TO 2000/12 As a result of our research activities have provided managers information by which to minimize or ameliorate the effects of humans on wildlife in wilderness settings (Mexican spotted owls and songbirds) and in a newly developed cave (bats).

Evolution of Adaptation in Plants of Southwestern Rangelands

S. E. Smith, Department of Plant Sciences, College of Agriculture and Life Sciences. 2001 - 2005

OBJECTIVES: Assess variation in bud, tiller and plant survival following cool-season drought among populations of Arizona cottontop native to environments differing in average cool-season precipitation. Evaluate the potential for natural selection to affect response to cool- season drought in Arizona cottontop populations from southern Arizona.

SUMMARY: Improved understanding of the basic biology of rangelands, and of the natural processes that control productivity and promote their stability, should improve our ability to manage these environments effectively. We propose to investigate the potential that adaptive evolution may occur in a perennial grass native to the desert grasslands of Arizona in response to less than average amounts of winter precipitation.

Fate and Efects of Pollutants in Arid West Surface Waters and Riparian Ecosystems

D. G. Baumgartner, E. P. Glenn, K. M. Fitzsimmons, Department of Soil, Water, and Environmental Sciences, College of Agriculture and Life Sciences. 1997 - 2000

OBJECTIVES: Determine the effects of treated municipal effluent on the quality of surface waters needed to protect aquatic, terrestrial, and plant communities in ephemeral an deffluent-dependent watercourses of the arid west, as well as water that infiltrates through tyhe vadose zone to be subsequently used for irrigation, aquaculture and individual water supplies. The results are intended to be used by state and federal regulatory agencies to improve scientific basis for regulatory standards and case-by-case decisions on waste discharges and to aid in separating beneficial and deleterious impacts of irrigation return flows from impacts due to municipal wastewater discharges.

IMPACT: Land disposal of centrate can alleviate mechanical problems associated with return of the liquid stream to the head of the treatment plant and reduce pumping costs. In addition, removal of this large nitrogen load from the plant stream can reduce the cost for nitrogen removal from the effluent that would otherwise be necessary prior to discharge of the effluent into the receiving water. Plant biomass created in a wetland or an alternative plant use system can provide benefits for the nearby community, e.g., dust control, small animal habitat, and beautification.

Fluvial Material Budget in a Changing Forest Environment

V. L. Lopes, SRNR, College of Agriculture and Life Sciences.

OBJECTIVES: 1. Develop a modeling system to explore the long-term impacts of land use and climatic variability on steam-borne sediment, P, and C fluxes in southwestern watersheds. 2. Apply the modeling systems to improve understanding of how sediment and nutrient fluxes from southwestern watersheds might respond to future land use and climatic variability.

PROGRESS: 1999/01 TO 1999/12. Research efforts have concentrated on the hydrology of forested watersheds in north-central Arizona. Primary work explored the implications of forest harvesting practices on in-stream sediment concentrations from ponderosa-pine and pinyon-juniper watersheds. Preliminary results of the study were published in Lopes et al (1999a) and Lopes et al (1999b). Additional work involved analysis of particle-size characteristics and superficial armoring in a brush-covered watershed in northeast Arizona. Results of the study were presented in Canfield et al. (1999). Future research will continue focusing on data analysis, hydrologic impact assessment, and modeling of catchment runoff and sediment yield from forested watersheds in Arizona. Primary emphasis will be on integrating models and field experiments with a view to improve understanding of scale-process interactions and catchment response to land management practices and climate change.

Hydrology of Oak Woodlands in Arizona

P. F. Ffolliott, SRNR, College of Agriculture and Life Sciences. 2000 - 2003

OBJECTIVES: 1) Create a bibliographic database of material related to the history of Arizona's rivers and streams; 2) Determine the historical conditions on major rivers and streams in Arizona; 3) Assess and categorize the nature of major human-induced impacts on Arizona's riparian reaches; 4) Develop policy options for the management of riparian areas.

PROGRESS: 1995/07 TO 1997/06
Management of riparian areas is one of the most pressing issues facing the Western United States. Although these areas comprise approximately 1% of the total land area in the West, they perform essential ecological functions including maintaining water quality, controlling erosion, and providing habitat for fish and wildlife. These areas are also an important indicator of ecosystem health. The following publications previously reported were a result of this research project; the University of Arizona Water Resources Research Center (WRRC) convened a major conference on riparian management in the West, and in cooperation with the USDA Forest Service, published the proceedings. The WRRC also published a bibliography of materials focusing on Arizona rivers (Where to Find Information About the History of Arizona's Rivers, in hard copy and on disk), and published an issue paper, Arizona's Changing Rivers: How People Affected Arizona's Rivers, that provides an overview of the history of Arizona's rivers and how they have changed over the last century.

Hydrology of Southwestern Wetlands and Riparian Areas

D. P. Guertin, SRNR, College of Agriculture and Life Sciences.

OBJECTIVES: The objective of this proposed research is to investigate the hydrological and vegetation relations of southwestern riparian and wetland systems.

IMPACT: 1996/10 TO 2000/09. This study linked GIS and models to develop tools for relating watershed and channel condition. The results from this project will assist natural resource managers better manage watersheds, while still preserving riparian and aquatic habitat.

Improved Erosion Prediction Technology for Sediment TMDL Compliance on Rangeland Watersheds

V. L. Lopes, SRNR, College of Agriculture and Life Sciences. 2001 - 2005

OBJECTIVES: The primary objective of this study is to develop an improved technology consisting of a process-based runoff-erosion model and a semi quantitative sediment yield prediction approach embedded within a knowledge-based system (KBS) to assist end-users to achieve compliance with state and EPA-set TMDL standards.

SUMMARY: The successful implementation of the sediment TMDL guidelines set by the Clean Water Act, depends critically on the ability of the state to identify sediment sources and pathways. This project will develop an improved technology to assist land managers with sediment TMDL compliance on rangeland watersheds of Arizona and the southwest.

Interactions Between Mesquite and Lehmann Lovegrass: Geomorphic Control on Plant and Soil Water Balance

D. G. Williams, SRNR, College of Agriculture and Life Sciences. 1999 - 2002

OBJECTIVES: 1) Determine the extent to which Lehmann lovegrass alters seasonal patterns of soil moisture on different aged geomorphic surfaces. 2) Characterize seasonal patterns of water use, photosynthesis, and growth of mesquite on different aged geomorphic surfaces. 3) Determine the influence of mesquite plant size on potential interference from Lehmann lovegrass on different aged geomorphic surfaces.

SUMMARY: The African grass Lehmann lovegrass has altered the structure of semi-desert grassland and mesquite savanna. Interaction between this grass mesquite is potentially altered as well, especially related to water use on different soil types. The purpose of the project is to understand how the Lehmann lovegrass shapes the pattern of water availability for seedling, sapling and adult mesquite on a range of sites that vary in soil characteristics. The information will help us understand the processes affecting mesquite encroachment on grassland that has been altered by non-native African grasses.

IMPACT: Our initial findings from this Hatch project on mesquite water relations and leaf carbon isotope ratios were incorporated into a successful grant proposal to USDA-NRIGCP. We are now investigating the interaction of geomorphic substrate and precipitation seasonality on mesquite seedling establishment potential using rain-out shelters in an experimental framework. Our results will provide a mechanistic explanation for the propensity of mesquite to establish on loamy, Holocene geomorphic surfaces in the Sonoran desert grassland, and the impact of potential climate changes on mesquite spread.

Land Use Effect in Rainfall Runoff Response

R. H. Hawkins, SRNR, College of Agriculture and Life Sciences. 2001 - 2004

OBJECTIVES: 1.Determine watershed response characteristics and interpret them in hydrologic terms with accent on Arizona and the southwest. 2. Delineate de-facto hydrologic response groups for small watersheds from available data, with accent on Arizona and southwest. Test the outcomes for clustering into hydrologic groups. 3. As available, identify land characteristics associated with the watersheds the response types. 4. Determine effects of land use, seasonal variation and establish catalog classifications and coefficient values or application. 5. Develop identities of hillslope-channel combinations with the already observed de-facto groups. 6. Identify rainfall and runoff data attributes that are characteristic of each type. 7. Examine internal, regional, and general relationships for rainfall-runoff events. Relate the CN method to general hydrology questions. 8. Make data and metadata available to external users.

SUMMARY: Arizona's watersheds respond to rainfall with floods, erosion, and streamflow. Our land use and water resources management depends on understanding how this happens, and how land use affects it. The rainfall-runoff characteristics of Arizona small watersheds will be studied, characterized, and summarized, and the information made available to users in the engineering and land management communities.

PROGRESS: 2000/01 TO 2000/12
The large assembly of event rainfall and runoff data for agricultural, rangeland, forested, and urban watersheds continues to be further expanded, developed, analyzed, shared, and archived. Several new data sources have been identified and included in the master collection. This reduced data resource has permitted the clear identification and scaling of land use effects on rain event runoff for a variety of land uses.

Policy Options for Managing Arizona's Riparian Areas

H. J. Cortner, SRNR, College of Agriculture and Life Sciences. 1995 - 1997

OBJECTIVES: 1) Create a bibliographic database of material related to the history of Arizona's rivers and streams; 2) Determine the historical conditions on major rivers and streams in Arizona; 3) Assess and categorize the nature of major human-induced impacts on Arizona's riparian reaches; 4) Develop policy options for the management of riparian areas.

PROGRESS: Management of riparian areas is one of the most pressing issues facing the Western United States. Although these areas comprise approximately 1% of the total land area in the West, they perform essential ecological functions including maintaining water quality, controlling erosion, and providing habitat for fish and wildlife. These areas are also an important indicator of ecosystem health. The following publications previously reported were a result of this research project; the University of Arizona Water Resources Research Center (WRRC) convened a major conference on riparian management in the West, and in cooperation with the USDA Forest Service, published the proceedings. The WRRC also published a bibliography of materials focusing on Arizona rivers (Where to Find Information About the History of Arizona's Rivers, in hard copy and on disk), and published an issue paper, Arizona's Changing Rivers: How People Affected Arizona's Rivers, that provides an overview of the history of Arizona's rivers and how they have changed over the last century.

Significance of Local Adaptation in Rangeland Revegetation with Native Species

S. E. Smith, Department of Plant Sciences, College of Agriculture and Life Sciences. 1994 - 1998

OBJECTIVES: Using four ecotypes of Arizona cottontop (Digitaria californica) we will evaluate: germination and seedling establishment under a range of moisture regimes; and plant morphology, and vegetative and reproductive success of transplanted seedlings on disturbed and undisturbed sites.

PROGRESS: Our research evaluated germination and emergence in response to variable moisture among 10 ecotypes of Arizona cottontop (Digitaria californica [Benth.] Chase.) from Arizona, Texas and northern Mexico that represented a wide range of mean summer precipitation (140-377 mm). We observed significant variation among ecotypes in response to variable water application. A close positive association was seen between summer precipitation at the site of collection and the amount of water required for emergence. The amount of water required for emergence was also negatively associated with the soil water holding capacity at the site where plants were collected. These data suggest that using ecotypes of Arizona cottontop from sites with the lowest mean summer precipitation should result in higher levels of seedling establishment, regardless of precipitation regime.

Social, Economic and Institutional Influences on Rangeland Management

M. P. McClaran, D. A. King, SRNR, College of Agriculture and Life Sciences. 1993 - 1997

OBJECTIVES: The purpose of this project is to understand the factors underlying the adoption of Best Management Practices (BMP's) intended to reduce soil erosion on Arizona rangelands. Specific objectives are to: 1) describe the relationship between rancher and agency attitudes and the adoption of soil conservation practices; 2) estimate the benefits and costs to the rancher and society of adopting soil conservation practices; and 3) describe the institutional factors underlying the implementation of soil conservation practices.

PROGRESS: Our assessment of the US Forest Service public participation process used questionnaire responses from 435 Forest Plan participants across 13 national forests nationwide. The respondents supported the agency, but only marginally. Nearly 55 percent were satisfied, 54 percent trusted, and 63 percent felt the local Forest employees were effective. Support for the Forest Service was most strongly related to perceptions of procedural fairness and changes in personal benefits that would follow the implementation of the new Forest Plan.

Southwest Rangeland Invasive Plants Initiative

L. Howery, M. Fernandez Gimenez, M. Brunson, N. Haynes, R. Lee, J. Gleason, SRNR, College of Agriculture and Life Sciences. 2000 - 2004

OBJECTIVES: Three primary goals are defined for this project: 1) Raise public awareness of the economic and ecological threats of invasive plant species in the Southwest U. S., 2) Organize citizens to participate in invasive plant monitoring, control and prevention efforts, and 3) Strengthen the institutional infrastructure for invasive plant management in the Southwest. Research and extension programs will be designed to address economic, social, psychological, cultural, and institutional infrastructure questions and issues that are pertinent to the development of community-based, grassroots weed management efforts. Research findings will contribute to the evaluation of the overall success of the project, and will help guide future Extension efforts.

SUMMARY: This is a multi-disciplinary research and cooperative extension project that will promote and evaluate low-cost, community-based approaches to managing invasive plants in the Southwestern U.S. Research projects are designed to answer economic, psychological, and cultural questions pertinent to the development of collaborative stewardship for integrated weed management. Research results will guide the development and expansion of extension and outreach programs that are specifically tailored to local constituencies, policy contexts, and invasive plant threats affecting range and forestlands in the Southwestern U.S. However, our general conclusions and methodologies can be applied throughout the U.S., wherever incipient or imminent plant invasions have not yet reached epidemic proportions.

Vegetation Monitoring Program for the Santa Rita Experimental Range

M. P. McClaran, SRNR, College of Agriculture and Life Sciences. 1997 - 2001

OBJECTIVES: Develop and implement a vegetation/soil monitoring program for Santa Rita Experimental Range.

PROGRESS: Measurements of grass density made every 3 yrs from 1972-84 and 1991-2000 described the influence of livestock grazing intensity on the non-native perennial grass, Lehmann lovegrass (Eragrostis lehmanniana). The grazing intensities ranged from 40-65% forage utilization across all these years. The rate of increase and amount of lovegrass was not related to the intensity of livestock grazing, which is contrary to most models predicting the spread of nonnative plant species. We examined the re-sprouting potential of velvet mesquite (Prosopis velutina) following those 2 wildfires in 1994. Mesquite mortality decreased as a function of increasing tree size and with increasing number of basal stems on the original tree. Re-sprout biomass after burning was not related to tree size or number of basal stems. In comparison, cut trees were very unlikely to die no matter the size or number of stems, and re-sprout biomass was negatively related to number of basal stems. These results suggest that multiple-stems are a benefit for surviving fires, but they hinder the production of re-sprout biomass. A complete set of repeat photographs was taken for over 110 permanent photo- stations on the Experimental Range. Some original photographs were taken in 1903, some photo-stations include photos for multiple directions. The entire photographic collection is available at http://cals.arizona.edu/SRER.

IMPACT: The impact of this work is in showing the value of repeating long term research to evaluate vegetation change on arid rangelands, and the role of multiple basal stems in the response of velvet mesquite to fire and cutting. Economically, this research should advise producers and lending institutions that measurements of range conditions in a single year could be misleading because single-year weather patterns can mask long-term trends in conditions. Instituting a long-term, repeated measurement plan of monitoring is essential to providing the most accurate assessment of management influences on range conditions.

Water Use Along A Semiarid Riparian Continuum

D. G. Williams, SRNR, College of Agriculture and Life Sciences. 1996 - 1999

OBJECTIVES: The principle objective of the proposed research is to gain an understanding of water utilization and root allocation patterns in semiarid riparian environments. Specific objectives are to determine how variation in groundwater depth influences vertical patterns of rooting activity, measure costs of root and leaf production, patterns of root water uptake and leaf photosynthesis to test a cost-benefit model of root allocation and examine inter and intraspecific variation in cost-benefit relationships to evaluate how these properties collectively control species distribution and function along a semiarid riparian habitat continuum.

IMPACT: This work has uncovered some fundamental factors associated with riparian tree function within the context of ecosystem water balance. Variability in water sources of riparian trees has inter- and intraspecific components. Intraspecific variation is controlled by site conditions and plant internal resource levels. This knowledge forms the foundation for building process models of riparian evapotranspiration that incorporates future global changes.
Last Reviewed and Updated: March 19, 2003
Questions/Comments: spater@cals.arizona.edu