Peter F. Ffolliott

Integrated watershed management : connecting people to their land and water

Conservation in protected areas has focused on preserving biodiversity of ecosystems and species, whereas conserving the genetic diversity contained within species has historically often been ignored. However, maintaining genetic diversity is fundamental to food security and the provision of raw materials and it is best preserved within plants natural habitats. This is particularly true for wild plants that are directly related to crop species and can play a key role in providing beneficial traits, such as pest or disease resistance and yield improvement. These wild relatives are presently threatened due to processes of habitat destruction and change and methodologies have been adapted to provide in-situ conservation through the establishment of genetic reserves within the existing network of protected areas.Providing a long awaited synthesis of these new methodologies, this book presents a practical set of management guidelines that can be used for the conservation of plant genetic diversity of crop wild relatives in protected areas.

Ecology and management of oak and associated woodlands: Perspectives in the southwestern United States and northern Mexico

This symposium focused on technologies that bridge the gap between research and its application in the management of woodlands. Topic areas include: ecology and silvicutural practices; growth, yield, and utilization potentials; livestock and grazing practices; wildlife habitat and values; and hydrology and watershed management. The proceedings include titles and abstracts of all papers in Spanish, a bibliography, and a summary of research needs.

Snowpack-runoff relationships for mid-elevation snowpacks on the Workman Creek watersheds of Central Arizona

Snowpacks in the southwestern United States melt intermittently throughout the winter. At some mid-elevation locations, between 7,000 and 7,500 ft, snowpacks appear and disappear, depending on the distribution of storms during relatively dry winters. Some winter precipitation can occur as rain during warm storms and is not reflected in the snow course data. The USDA Natural Resources Conservation Service (NRCS) maintains a system of measuring stations to index snow conditions and predict snowmelt runoff. The three Workman Creek watersheds in the Sierra Ancha Experimental Forest north of Globe were instrumented in late 1938 to study the hydrology of southwestern mixed conifer forests and to determine changes in streamflow and sedimentation resulting from manipulating the forest cover. The watersheds were deactivated in 1983, but they were re-instrumented in June 2000 after the Coon Creek wildfire to measure fire effects on forest hydrology and sediment dynamics. The Rocky Mountain Research Station would like to use NRCS data from the Middle Fork of Workman Creek to reinforce its hydrologic data acquisition and interpretation efforts. Snow water equivalent data can be used to characterize past winter runoff volumes and peak mean daily runoff. Significant regressions were developed between the data sets with coefficients of determination values ranging from 0.40 to 0.77. The relationships defined by these regressions will allow researchers and managers to ascertain the impacts of fire on snowmelt-related hydrologic processes and to estimate winter flows for the years when the installations were closed. They also provide an insight into the snowpack runoff relationships for intermittent snowpacks that are common at intermediate elevations throughout Arizona.

Dynamics of a pinyon-juniper stand in northern Arizona: a half-century history

This paper adds to the limited knowledge of stand dynamics in pinyon-juniper woodlands by reporting on the changes in species composition, numbers of trees, arrangements of trees, and total height and volume in a stand from late 1938 to early 1991. This information should be helpful in managing pinyon-juniper woodlands to sustain their productivity and maintain their multiple-use values. The annual increase of 1.2 trees per acre does not reflect the massive invasion of trees suspected by many people.

The 2002 Rodeo-Chediski Wildfire's impacts on southwestern ponderosa pine ecosystems, hydrology, and fuels

The Rodeo-Chediski Wildfire burned nearly 462,600 acres in north-central Arizona in the summer of 2002. The wildfire damaged or destroyed ecosystem resources and disrupted the hydrologic functioning within the impacted ponderosa pine (Pinus ponderosa) forests in a largely mosaic pattern. Impacts of the wildfire on ecosystem resources, factors important to hydrologic functioning, peak stormflow events and water quality constituents, and loadings of flammable fuels were evaluated on two watersheds in a ponderosa pine forest that was exposed to the burn - one experienced a high severity (stand-replacing) fire (Watershed A), and the other was exposed to only a low severity (stand-modifying) fire (Watershed B). Cumulative impacts of the wildfire on ecosystem resources, hydrologic functioning, and flammable fuels were more pronounced on Watershed A. Recovery of the Stermer Ridge watersheds from the Rodeo-Chediski Wildfire has been related to the respective fire severities that the two watersheds experienced. Watershed A converted from ponderosa pine to grasses, forbs, and a few shrubs. Recovery of the hydrologic functioning on this watershed has begun on a limited scale, but it is anticipated that the overall hydrologic functioning of Watershed A will not approach pre-fire conditions for many years. Flammable fuels represented by standing trees have been eliminated on Watershed A, but there has been an increase in stem sections, branches, twigs, and herbaceous fuels on the forest floor. While the possibility of a future crown fire has declined, the potential for surface fire remains. Much of Watershed B is slowly recovering from the impacts of the wildfire. Much of the hydrologic functioning of this watershed is also returning slowly to its pre-fire level. The post-fire loadings of flammable fuels were largely unchanged from their pre-fire estimates. Watershed B remains vulnerable to future wildfire events as a consequence.

Fire effects on tree overstories in the oak savannas of the Southwestern Borderlands Region

Effects of cool-season and warm-season prescribed burning treatments and a wildfire on tree overstories in oak savannas on the Cascabel Watersheds of the Southwestern Borderlands Region are reported in this paper. Information on the initial survival, levels of crown damage, species compositions and densities, annual growth rates, and basal sprouting following these burning events is presented. Impact of the fires on spatial distributions of trees in the overstories is also described. These events were all of low fire severities. As a consequence, effects of the prescribed burning treatments and the wildfire on tree overstories of the watersheds were similar and, therefore, the data sets were pooled. Effects of these fires on the tree overstories were mostly minor and often insignificant in terms of management implications.

Fire Effects on Herbaceous Plants and Shrubs in the Oak Savannas of the Southwestern Borderlands

Much has been learned in recent years about the ecological, hydrologic, and environmental characteristics of the oak (encinal) woodlands of the Southwestern Borderlands. Comparable information for the lower-elevation oak savannas, including the impacts of fire on ecosystem resources, is also necessary to enhance the knowledge of the oak ecosystems in the region. Oak savannas are more open in stand structure than are the oak woodlands and, as a consequence, a higher level of herbaceous production might be expected in this ecosystem than in the oak woodlands. The effects of prescribed burning treatments and a wildfire on species compositions, production of grass and forb components, growth of shrubs, utilization of forage and browse plants by herbivores, and ecological diversity in a oak savanna are described in this paper.

Hydrologic processes in the pinyon-juniper woodlands: A literature review

Hydrologic processes in the pinyon-juniper woodlands of the western region of the United States are variable because of the inherent interactions among the occurring precipitation regimes, geomorphological settings, and edaphic conditions that characterize the ecosystem. A wide range of past and present land-use practices further complicates comprehensive evaluations of these hydrologic processes. Heterogeneous vegetative covers make it even more difficult to generalize hydrologic processes and the effects of land management practices on the water balance. Nevertheless, estimates of interception, infiltration, evapotranspiration, soil moisture storage, and hillslope soil erosion of these on-site hydrologic processes have been obtained in plot studies. Estimates of off-site streamflow volumes, sediment yields and transport, and quality of streamflow water are available from the results of watershed-level investigations. Estimates of these respective hydrologic processes are presented in this general technical report.

Mesquite removal and mulching impacts on herbage production on a semidesert grass-shrub rangeland

The objectives of our study were to determining the effects of velvet mesquite (Prosopis velutina) removal, control of the resulting basal sprouts, and mulching treatments on herbage production (standing biomass) and selected soil chemicals (nutrients) shown to affect herbage production on the Santa Rita Experimental Range. Mesquite control treatments consisted of overstory removal by chain saw with and without control of the resulting basal sprouts. Mulching treatments were applications of mesquite wood chips, commercial compost, or lopped-and-scattered mesquite branchwood. Mesquite removal resulted in increases for total herbage production and the production of native herbaceous species. Production of the nonnative Lehmann lovegrass (Eragrostis lehmanniana), the dominant herbaceous species, was unchanged. The mulching treatments did not affect herbage production. None of the treatments affected soil chemical properties thought to influence herbage production.

Changes in Transpiration by Emory Oak Following Tree Harvesting

Transpiration by mature- and sprout-forms of Emory oak (Quercus emovyi) was estimated bv the saptlow velocity method on two adjacent sites, one unharvested and the other harvested for filelwood, in the oak woodlands of southeastern Arizona. There were few differences in daily tl-anspiration between mature trees on either site; however, there were differences in transpiration between the mature trees on the two sites and the post-harvesting stump sprouts on the harvested site. The importance of these differences is shown by translating the estimates of transpiration by individual trees to a stand-basis through extrapolations of the results to inventories of stocking conditions in the vicinity of the sites sampled. On a per-hectare basis, about 1,900 liters of water were transpired by mature Emory oak on the unharvested site, while 3,150 liters of water were transpired annually by the mature trees and post-harvesting stump sprouts. One factor contributing to the greater transpiration of Emory oak in the harvested stand is likely the occurrence of a large number of vigorous post-harvesting sprouts.