The Editorial Board of the Journal of Range Management invited James E. Ellis and David M. Swift to prepare this synthesis paper in recognition of their many, valuable contributions tu understanding of the ecology of grazing systems. Their work is characterized by a high level of imagination, by a steady commitment to thoroughness, and by distilled, clear thinking. JIM ELLIS took undergraduate work in animal husbandry at the University of Missouri and also obtained his Master of Science degree there studying wildlife biology. In 1970, he received his Ph.D. in Zoology at the University of California at Davis, where he was a National Institute of Health trainee in systems ecology. Shortly thereafter, he held a National Science Foundation postdoctoral fellowship at the University of Bristol working on systems analysis of mammalian social systems. He joined the Natural Resource Ecology Laboratory of Colorado State University as a Research Ecologist in 1971. He is currently the Associate Director of the Laboratory. Jim has enjoyed immense success in developing research programs; during the last decade he directed or played a major role in 12 successful proposals, collectively exceeding three milliondollaninsuppott. He has publishedextensively, withmost of his work focussing on processes regulatinggrazing systems. Jim has served as a consultant to the U.S. Senate, as well as the govcmmcnt of Saudi Arabia and the Norwegian Agency for International Development. His must recent project uses a systems approach to understand the controls on stability and persistence of a pastoral ecosystem in East Africa.

No abstract

No abstract

Since the turn of the century, African pastoralists have been held responsible for overuse of woody plants and for the degradation and desertification of many arid and semiarid lands. We analyzed the impacts of pastoral nomads and their livestock on the recruitment (establishment to first reproduction) of Acacia tortilis, a dominant tree in the dry woodlands of South Turkana, Kenya, where Acacia seedpods make up an important part of livestock diets. Seed density averaged over 85 times higher in bush‐fenced livestock corrals than in the surrounding environment. The survival and growth of 14 cohorts of trees ranging in age from 1 to 39 yr were investigated comparing tree stands originating inside livestock corrals with those originating outside. Corral soils contained nine times more C, three times more N, and six times more P than adjacent noncorral soils immediately following corral abandonment. Corral soils also retained more moisture than noncorral soils after rainfall. These soil conditions accelerated seedling emergence in corrals, and enhanced survival and growth of 1st‐yr seedlings. Survival of older trees in corral stands was not significantly different from those established outside corrals during this study. However, comparison of tree densities over time suggests that corral stands thin more rapidly than noncorral stands, probably because of crowding. The early survival and growth advantages of the corral environment appear to stabilize the reproductive patterns of A. tortilis in this arid ecosystem, where successful recruitment in noncorral sites may be restricted to the few years with high rainfall. Contrary to the conventional wisdom, pastoralists may be improving rangelands in South Turkana by enhancing recruitment reliability in this important tree species.

No abstract

No abstract

No abstract

Breath analysis is a promising method for rapid, inexpensive, noninvasive disease diagnosis and health monitoring owing to the correlative relationship between breath biomarker concentrations and abnormal health conditions. However, current methods to identify and quantify breath components rely on large, bench‐top analytical instruments. Carbon nanotube (CNT)‐based gas sensors are desirable candidates to replace benchtop instruments because of their sensitive chemical‐to‐electrical transducer capability, high degree of chemical functionality options, and potential for miniaturization. This review seeks to give an overview of the synthetic methods used to functionalize CNT‐based gas sensors, specifically those sensors that target biologically relevant breath markers. Specific examples are provided to highlight the sensing mechanisms behind different classes of CNT hybrid composites. Finally, the current challenges and prospective solutions of applying CNT‐based sensors to breath analysis are discussed.