Research has been lacking on the influence of honey mesquite (Prosopis glandulosa Torr.) on forage production in the Chihuahuan desert, In 1964 honey mesquite was controlled (65% kill) with the herbicide, Monuron, on portions of the New Mexico State University College Ranch. Both herbicide treated and nontreated areas occur within the same pasture on similar soils and have similar grazing histories (continuous grazing, conservative stocking rate). This has resulted in areas with moderate and low levels of mesquite (16% and 9% mesquite canopy cover, respectively). We evaluated relationships among forage standing crop, vegetation canopy cover, mesquite density, mesquite height, mesquite diameter, and mesquite volume on areas with low and moderate mesquite levels in fall 1992 and spring 1993. Regression analyses showed forage standing crop and canopy cover generally were not (P > 0.10) associated with mesquite height, mesquite diameter, canopy volume, and mesquite density on either low or moderate mesquite areas. Honey mesquite canopy cover on the non-treated area was nearly double that on the treated area. Data from long term permanent transects (1968-1992) showed no differences (P > 0.10) in total forage production behveen low and moderate mesquite areas in fall of 1992. On these transects mesquite increases in cover and density were over 3 times greater on the low compared to moderate mesquite areas in the 1982 to 1992 period. Our data indicate mesquite density and cover increase rapidly after herbicidal mesquite control even under conservative stocking. However at canopy cover levels below 17% honey mesquite appeared to have little effect on forage production. Potential maximum canopy cover of mesquite on these tvnes of sites is about 37%. Our data show that under Loss of forage from honey mesquite (Prosopis glandulosa Ton-.) invasion of desert grasslands is an important concern of range managers. Problems with animal distribution and handling can also occur with increased mesquite density. Herbicidal control of mesquite has long been advocated as a quick means to increase forage production and improve range condition on arid rangelands in Texas, Arizona, and New Mexico (Norris et al. 1963, Valentine 1970, Abdulla 1980, McDaniel et al. 1982, Gibbens et al. 1992). Research has shown mesquite control can increase forage production for 5 to 10 years post treatment (Herbel et al. 1983, Gibbens et al. 1986). However studies on long term (lo-30 years) effects of mesquite control on forage production are lacking. The primary objective of our study was to evaluate the influence of honey mesquite density, height, diameter, canopy cover, and volume on forage standing crop and cover in the Chihuahuan desert of southcentral New Mexico. The areas selected for study had similar terrain, distance to water, soils, precipitation, and grazing history. Low honey mesquite (herbicidal control of mesquite in 1964) and moderate honey mesquite (no or limited mesquite control) areas were selected for study. Low and moderate honey mesqui...

History tells us that dams can bring many benefits to society but there is also a long history of ‘near-miss’ incidents and failures that, in some cases, have led to great loss of life. The investigation of incidents and failures around the world has led to improvements in the design and construction of dams with the aim of reducing the risk of failure. By illustration of a number of examples and case studies, the objective of this paper is to explain the role of the investigating dam engineer in understanding the factors that contribute to dam safety incidents. The paper concludes that there is a role for more effective sharing of information both nationally and internationally to improve dam design and construction and reduce the risk of failure. The paper outlines how this might be achieved.

Ultrastructure observation on the cells at different life history stages of Cryptocaryon irritans (Ciliophora: Prostomatea), a parasitic ciliate of marine fishes. Parasitology.

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