14 pp. / A primary expression of stocking levels on rangeland vegetation is utilization defined as the proportion or degree of current years forage production that is consumed or destroyed by animals (including insects). Utilization may refer either to a single plant species, a group of species, or the vegetation as a whole. Utilization is an important factor in influencing changes in the soil, water, animal, and vegetation resources. The impact of a specific intensity of use on a plant species is highly variable depending on past and present use, period of use, duration of use, inter-specific competition, weather, availability of soil moisture for regrowth, and how these factors interact. Utilization data can be used as a guideline for moving livestock within an allotment with due consideration to season, weather conditions and the availability of forage and water in pastures scheduled for use during the same grazing season. In combination with actual use and climatic data, utilization measurements on key areas and utilization pattern mapping are useful for estimating proper stocking levels under current management. Utilization studies are helpful in identifying key and problem areas, and in identifying range improvements needed to improve livestock distribution.

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The objective of this work is to estimate the effect of floods on the riparian vegetation communities of the Gila Box, Arizona, based on historical maps, satellite images, and GPS-referenced airborne video. The condition and extent of selected riparian vegetation communities in 1973, 1982, and 1991 are documented. Changes in riparian vegetation communities for the time period from 1973 to 1982 and from 1982 to 1991 are analyzed to assess the potential effect of floods that occurred in 1978 and 1983, respectively. The results indicate that the floods in 1978 and 1983 may have had an impact on the mesquite riparian community. The effect of floods on riparian vegetation is most apparent in the downstream portion of the Gila River. The information collected and presented in this work can be used to formulate effective management plans to the Gila Box area.

A case study is used to illustrate and assess the applicability of participatory democracy theory to public participation in public land decision-making. In this case, public outcry against a Bureau of Land Management acquisition plan resulted in adoption of a coordinated resource management process, an application of participatory democracy theory which is purported to improve public acceptance of administrative decisions by providing improved access and representation, information exchange and learning, continuity of participation, and shared decision-making authority. The study suggests that in order to satisfy the public, a participatory democracy approach to public participation should give participants tangible evidence that their input will influence agency decisions, preferably by giving them the authority to collectively make decisions that will be binding on all participants, including agencies. Furthermore, organizational and decision-making rules, as well as legal and bureaucratic limitations on the process, must be explicit.

The renewable natural resources (RNR) of Senegal form the basis of socioeconomic development for the population of this Sahelian country of West Africa. However, because of the current maladapted policies and practices, these resources are in a crisis that has led to a major degradation of the socioeconomic and environmental conditions. To solve these socioeconomic and environmental problems, many solutions have been developed and implemented. However, because of their disregard for both socioeconomic and traditional cultural values, these attempted solutions have often contributed to the problems. To resolve this crisis, Senegal needs to adopt a new integrated management approach along with new integrated natural resources tenure and decentralization policies. Considering the country's limited economic means, the urgent need for policy change, and the necessary progressive implementation of a new policy, this new natural resources policy will need to be developed incrementally. It should take into account the existing policies and examine different alternatives from the current ecological, economic, and sociocultural situation.

This thesis investigates the effects of rangeland management systems on savanna ecosystems under different environmental conditions in Botswana, Southern Africa. The soil sampling and vegetation assessment were conducted in twenty–three transects located in communal and ranching grazing lands across three sites. Pastoralists were also interviewed on vegetation change on their respective grazing lands. Soil texture, pH, bulk density and soil organic carbon differed between sites, but not between communal and ranching lands. Soil organic carbon was positively affected by soil clay content. The herbaceous vegetation composition showed heterogeneity between sites, but Matlolakgang and Xanagas rangelands were in poor condition, particularly the communal grazing land that had high cover of increasers II species. Higher herbaceous biomass was observed in ranches than communal lands and biomass also increased with increasing soil organic carbon. Bush encroachment was observed in communal and ranching grazing lands at Matlolakgang and Xanagas, but not Goodhope. Woody plant cover, density and diversity increased with decline in soil clay content, but not linearly. Pastoralists indicated that herbaceous vegetation compositions had changed in some areas, with increase of unpalatable grass species and bush encroachment especially in communal land. Pastoralists considered bush encroachment a problem as it suppress herbaceous vegetation productivity, but they also considered woody vegetation as a valuable grazing resource. The long-term indicators of ecosystem degradation (soil and woody cover) showed that communal and ranching grazing did not affect the savanna ecosystem differently. This is contrary to assumptions of Tribal Grazing Land Policy of Botswana, which promote ranching as a more sustainable management system. The results revealed that rainfall and soil clay strongly influence rangeland condition. These results have implications for the management policies of communal grazing lands throughout sub-Saharan Africa and in similar arid habitats across the world.

abstract: Rangelands are an extensive land cover type that cover about 40% of earth’s ice-free surface, expanding into many biomes. Moreover, managing rangelands is crucial for long-term sustainability of the vital ecosystem services they provide including carbon (C) storage via soil organic carbon (SOC) and animal agriculture. Arid rangelands are particularly susceptible to dramatic shifts in vegetation cover, physical and chemical soil properties, and erosion due to grazing pressure. Many studies have documented these effects, but studies focusing on grazing impacts on soil properties, namely SOC, are less common. Furthermore, studies testing effects of different levels of grazing intensities on SOC pools and distribution yield mixed results with little alignment. The primary objective of this thesis was to have a better understanding of the role of grazing intensity on arid rangeland soil C storage. I conducted research in long established pastures in Jornada Experimental Range (JER). I established a 1500m transect in three pastures originating at water points and analyzed vegetation cover and SOC on points along these transects to see the effect of grazing on C storage on a grazing gradient. I used the line-point intercept method to measure and categorize vegetation into grass, bare, and shrub. Since soil adjacent to each of these three cover types will likely contain differing SOC content, I then used this vegetation cover data to calculate the contribution of each cover type to SOC. I found shrub cover and total vegetation cover to decrease, while grass and bare cover increased with decreasing proximity to the water source. I found areal (g/m2) and percent (go SOC to be highest in the first 200m of the transects when accounting for the contribution of the three vegetation cover types. I concluded that SOC is being redistributed toward the water source via foraging and defecation and foraging, due to a negative trend of both total vegetation cover and percent SOC (g/g). With the decreasing trends of vegetation cover and SOC further from pasture water sources, my thesis research contributes to the understanding of storage and distribution of SOC stocks in arid rangelands. / Dissertation/Thesis / Masters Thesis Biology 2018

Diet selection and self-medication are fundamental to the survival of all species. The abilities to choose healthy foods in response to past consequences are basic elements of evolution. This study explores self-medication regarding tannins both as a medication and as a dietary challenge. In the first study, sheep with natural parasite infections were offered a low quality supplement containing a dose of tannins considered to be therapeutic (medicine), while the control infected lambs received the same supplement without tannins (placebo). This study included a group of parasite-free lambs. The parasitized lambs ate more of the tannin containing supplement than non-parasitized lambs for the first 12 d of the study, when parasite burdens were high, but differences became smaller and disappeared towards the end of the study when parasite burdens decreased. This result indicated lambs ability to detect the presence of internal parasites and to learn to ingest tannin when followed by relief from parasite burdens.In the second study, lambs grazed on pastures with forages containing saponins (alfalfa),iiialkaloids (endophyte-infected tall fescue) and tannins (birdsfoot trefoil). I observed the foraging behavior of groups of lambs after intra-ruminal infusions of tannins (treatment). Lambs that first received intraruminal infusions of tannins and then were offered 2-way choices between varieties of forages with high and low concentrations of either saponins, alkaloids, or tannins increased their preference for the high-saponin variety of alfalfa and the high-alkaloid variety of tall fescue relative to lambs not infused with tannins (controls). Lambs infused with tannins and offered choices among the 3 forages with high concentrations of secondary compounds also manifested higher preference for the high-alkaloid variety of tall fescue than control lambs. In contrast, lambs infused with tannin reduced their preference for the high-tannin variety of birdsfoot trefoil.This research has implications for many situations where forages with secondary compounds are available but underutilized. Landscapes where such forages are available could be used effectively with little or no harm to livestock if medicinal forages or supplements are made available and offered as alternatives so animals can learn about their benefits of chemical complementarities among different plant species.

A 4-year study was conducted on the Missouri Coteau in the Mixed Grassland Ecoregion of Saskatchewan to determine the effects of mowing to a 7.5 cm stubble height on the growth of <i>Festuca hallii</i> (Vasey) Piper and <i>Stipa curtiseta</i> (A.S. Hitch.) Barkworth. Green standing crop (GSC), dead standing crop (DSC) and above ground net primary production (ANPP) were compared to an unmowed control after a single mowing in April, May, June, July, August, September, October or November on 5 landforms including north aspect-concave-slope, north aspect-convex-slope, south aspect-concave-slope, south aspect-convex-slope and level upland. Mowing reduced GSC, DSC and ANPP with reductions varying among months of mowing and among landforms. Green standing crop, DSC and ANPP of <i>F. hallii</i> were greatest on the north aspects and least on south aspect-convex slope and ranged from 2 to 122 g m-2, 3 to 121 g m-2, and 8 to 122 g m-2, respectively. Mowing reduced GSC of <i>F. hallii</i> for 1 to 11 growing season months and DSC for 1 to >11 growing season months. Mowing in May or November reduced ANPP of <i>F. hallii</i> for 1 growing season, while mowing in other months reduced ANPP for 2 growing seasons. Green standing crop of <i>S. curtiseta</i>, ranging from 3 g m-2 to 55 g m-2, was least on the north aspects and greatest on the south aspect-convex slope and was reduced 1 to 5 growing season months following mowing. Mowing after June reduced DSC of <i>S. curtiseta</i>(5 to 58 g m-2) for 1 to 10 growing season months, and ANPP (6 to 64 g m-2) for 1 growing season. Generally, mowing reduced GSC, DSC and ANPP of <i>F. hallii</i> longer than <i>S. curtiseta</i>. Production of <i>F. hallii</i>- and <i>S. curtiseta</i>-dominated plant communities in the Northern Mixed Prairie will be maintained by providing rest periods between defoliation events based on the number of growing season months for <i>F. hallii</i> to recover production.