ECONOMIC FEASIBILITY OF USING BRUSH CONTROL TO ENHANCE OFF-SITE WATER YIELD

A feasibility study of brush for off-site water yield was undertaken in 1998 on the North Concho River near San Angelo, Texas. Subsequently, studies were conducted on eight additional Texas watersheds. Economic analysis was based on estimated control costs of the different options compared to the estimated rancher benefits of brush control. Control costs included initial and follow-up treatments required to reduce brush canopy to between 3 and 8%, and maintain it at the reduced level for 10 years. The state cost-share was estimated by subtracting the present value of rancher benefits from the present value of the total cost of the control program. The total cost of additional water was determined by dividing the total state cost-share if all eligible acreage were enrolled by the total added water estimated to result from the brush control program. This procedure resulted in present values of total control costs per acre ranging from $33.75 to$159.45. Rancher benefits, based on the present value of the improved net returns to typical cattle, sheep, goat, and wildlife enterprises, ranged from $8.95 to$52.12 per acre. Present values of the state cost-share per acre ranged from $21.70 to$138.85. The cost of added water estimated for the eight watersheds ranged from $16.41 to$204.05 per acre-foot averaged over each watershed.Resource /Energy Economics and Policy,

Effects of Brush Management on Water Resources

For several decades, land managers have cleared brush species, such as mesquite and juniper (cedar), and observed increases in spring and streamflows. Scientists have also conducted numerous studies in which they have measured the effects of brush removal on different aspects of rangeland hydrology. These include the amount of rainfall that is intercepted and held by the plant leaves, surface runoff, spring flow, water use by individual plants and plant communities, fluctuation of shallow water tables, and streamflows. Considering this very diverse information, many scientists agree on several points: 1. The roots of some brush species extract water from greater depths than do grasses and forbs, and brush control can reduce the total amount of water used by vegetation. 2. Brush and other deep-rooted vegetation growing over shallow aquifers near streams can be expected to use large amounts of groundwater, likely reducing the amount in both the interconnected stream and aquifer. 3. Removal of brush like juniper and live oak from upland areas some distance from streams may increase streamflow and/or recharge aquifers especially when: 1. The brush canopy is dense and intercepts substantial amounts of rainfall (for example: dense juniper [cedar] or live oak stands), effectively reducing the amount of rainfall reaching the soil surface, and 2. Soils, subsoils and/or geologic strata are permeable, and streams in the area are fed by seeps and springs. Water can quickly percolate below the roots of grasses and forbs and move through subsurface pathways to local streams or aquifers. 4. Brush control in upland areas is unlikely to increase significantly water yields if soils and geologic formations are not conducive to increased runoff and/or subsurface flows to streams or to aquifers. 5. For brush control to have substantial long-term impacts on water yield, most or all of the woody vegetation in the treated area should be killed, and regrowth of brush and herbaceous vegetation should be controlled so that it is less dense and more shallow rooted than the pretreatment vegetation. 6. New science-based tools can help pinpoint locations where brush control should substantially increase water flows in streams. 7. A geographically targeted brush control program with careful scientific verification of impacts is needed to guide long-term brush control policies

Effects of Brush Management on Water Resources

For several decades, land managers have cleared brush species, such as mesquite and juniper (cedar), and observed increases in spring and streamflows. Scientists have also conducted numerous studies in which they have measured the effects of brush removal on different aspects of rangeland hydrology. These include the amount of rainfall that is intercepted and held by the plant leaves, surface runoff, spring flow, water use by individual plants and plant communities, fluctuation of shallow water tables, and streamflows. Considering this very diverse information, many scientists agree on several points: 1. The roots of some brush species extract water from greater depths than do grasses and forbs, and brush control can reduce the total amount of water used by vegetation. 2. Brush and other deep-rooted vegetation growing over shallow aquifers near streams can be expected to use large amounts of groundwater, likely reducing the amount in both the interconnected stream and aquifer. 3. Removal of brush like juniper and live oak from upland areas some distance from streams may increase streamflow and/or recharge aquifers especially when: 1. The brush canopy is dense and intercepts substantial amounts of rainfall (for example: dense juniper [cedar] or live oak stands), effectively reducing the amount of rainfall reaching the soil surface, and 2. Soils, subsoils and/or geologic strata are permeable, and streams in the area are fed by seeps and springs. Water can quickly percolate below the roots of grasses and forbs and move through subsurface pathways to local streams or aquifers. 4. Brush control in upland areas is unlikely to increase significantly water yields if soils and geologic formations are not conducive to increased runoff and/or subsurface flows to streams or to aquifers. 5. For brush control to have substantial long-term impacts on water yield, most or all of the woody vegetation in the treated area should be killed, and regrowth of brush and herbaceous vegetation should be controlled so that it is less dense and more shallow rooted than the pretreatment vegetation. 6. New science-based tools can help pinpoint locations where brush control should substantially increase water flows in streams. 7. A geographically targeted brush control program with careful scientific verification of impacts is needed to guide long-term brush control policies

Ecoregions of Texas

A report on the the development of areas known as ecoregions in Texas with environmental information for each region

Mixed Hydrologic Recovery of a Degraded Mesquite Rangeland

Land degradation and anthropogenic change is widespread on rangelands in Texas. Over the last 150 years, noticeable change has occurred as a direct result of agricultural practices and human activity. As novel ecosystems and permanently altered landscapes become more common, an understanding of these new environments becomes essential. The ability of rangelands to rebound from past degradation is a factor of interest and one this study attempts to quantify. How a localized hydrologic cycle responds to disturbance can be indicative of the health of an ecosystem. This study characterized the hydrology of a mesquite rangeland at Fort Hood, Texas and assessed the current hydrologic regime compared to similar rangeland sites. The site at Fort Hood is unique because it has undergone recent high intensity vehicular traffic and low intensity grazing. Additionally, the site was cultivated until Camp Hood was established in 1942. Presented within this paper are the results of a series of seven large-scale rainfall simulations, which quantified the hydrologic variables present at the Fort Hood site. Variables of interest included infiltration, runoff, and sediment loads. Key quantitative findings of the study include: (1) Runoff values accounted for 28.7% - 64.9% of the total application of water applied to the plot. (2) Infiltration rates ranged from 15.1 mm/hr to 70.1 mm/hr at the site and (3) sediment loads ranged from 1.7 kg/ha to 4.2 kg/ha. These findings potentially indicate that the site has undergone a mixed recovery to its past hydrologic regime because erosion amounts are minimal, but infiltration rates are lower than comparable locations. This is important because it describes the ability of these landscapes to recover from past degradation

Effects of Woody Vegetation Removal on Soil Water Dynamics in a South Texas Shrubland

Ecosystem changes from grassland to shrubland in the Rio Grande Plains are thought to have negative effects on the hydrology of the region. The increase in woody plants, known as woody encroachment, may alter the amount of water moving beyond the root zone of plants. Water moving beyond the root zone is referred to as deep drainage, and has potential to become aquifer recharge. A vegetation manipulation project was designed to understand the effects of woody vegetation removal on soil water dynamics in the recharge zone of the Carrizo-Wilcox aquifer of south Texas. The primary objective of the project was to determine the potential to increase groundwater recharge through woody vegetation removal. To understand the effects of vegetation removal on various soil textures we studied changes in soil water, rooting depth, and the role of water redistribution by woody vegetation. Woody vegetation was removed using common methods of cut-stump and roller chop across three soil types. Soil water contents and changes were measured using neutron moisture meter to a depth of 180 cm. Average rooting depth was determined across three soil types. Soil and stem water stable isotopes were used to understand soil water movement. Rooting depth was determined to between 140 and 160 cm for all soil textures. Soil water content and changes were analyzed at three depth increments: 0-60, 60-120 and 120-180 cm. ANOVA analysis showed that there was no treatment response in average soil profile water in the sandy or sandy loam soils. There was a significant decrease in soil profile water for clay loam soil in response to roller chopping. Changes in soil profile water were the greatest in the sandy roller chopped soils. Below 120 cm, three months had significant differences in change in soil water in the sandy roller chop plot. During dry conditions, Honey mesquite shifts water use to deeper in the soil profile. In clay loam soils under dry conditions there is evidence of water being moved up from below 2 m soil depth to drier shallow soils. Roller chopping in sandy soils is the vegetation removal treatment and soil type most likely to result in water moving beyond the root zone. Although treatments had significant effects on soil moisture dynamics that interacted with soil type, we did not find support for deep drainage effects over the Carrizo-Wilcox aquifer from woody vegetation removal

Weed and Brush Control for Pastures and Rangeland.

54 p

The Ecology and Sociology of the Mission-Aransas Estuary : An Estuarine and Watershed Profile

watershed profileThe Mission-Aransas National Estuarine Research Reserve (NERR) is one of 28 national estuarine reserves created to promote the responsible use and management of the nation's estuaries through a program combining scientific research, education, and stewardship. The purpose of this document is to provide researchers and resource managers with an adequate basis of knowledge to further development of scientific studies and applied management investigations. This document describes the different physical ecosystem components, ecological processes, habitats, and watersheds of the Reserve. The Mission-Aransas NERR is a complex of wetland, terrestrial, and marine environments. The land is primarily coastal prairie with unique oak motte habitats. The wetlands include riparian habitat, and freshwater and salt water marshes. Within the water areas, the bays are large, open, and include extensive wind tidal flats, seagrass meadows, mangroves, and oyster reefs. This site profile describes each habitat by their location, type, distribution, abundance, current status and trends, issues of concerns, and future research plans. Research within the Mission-Aransas NERR seeks to improve the understanding of the Texas coastal zone ecosystems structure and function. Current research includes: nutrient loading and transformation, estimates of community metabolism, water quality monitoring, freshwater inflow, climate change and fishery habitat. Harmful algal blooms, zooplankton, coliform bacteria, submerged aquatic vegetation, and marsh grass are monitored through the System- Wide Monitoring Program (SWMP). This document also describes the climate, hydrography and oceanography, geology, water quality, and endangered species within the Mission-AransasUniversity of Texas Marine Science InstituteMarine Scienc

A Fifty-Year History of the Weed and Brush Program in Texas and Suggested Future Direction.

36 p