It is becoming increasingly important to monitor biodiversity in the extensive Australian rangelands; currently however, there is no method capable of achieving this goal. There are two potential sources of relevant data that cover the Australian rangelands, and from which measures of biodiversity might be extracted: traditional field-based methods such as quadrat surveys have collected flora and fauna species data throughout the rangelands, but at fine scale; satellite remote sensing collects biologically relevant, spatially comprehensive data. The goal of this thesis was to provide the spatially comprehensive measure of biodiversity required for informed management of the Australian rangelands. The study specifically focused on the Stony Plains in the South Australian rangelands. To that end the thesis aimed to develop indices capable of measuring and/or monitoring biodiversity from vegetation quadrat survey data and remotely sensed data. The term biodiversity is so all-encompassing that direct measurement is not possible; therefore it is necessary to measure surrogates instead. Total perennial vegetation species richness (y-diversity) is a sound surrogate of biodiversity: the category of species is well defined, species richness is measurable, and there is evidence that vegetation species richness co-varies with the species richness of other taxonomic groups in relation to the same environmental variables. At least two broad scale conventional vegetation surveys are conducted in the study region; the Biological Survey of South Australia; and the South Australian Pastoral Lease Assessment. Prior to the extraction of biodiversity data the quality of the BSSA, the best biodiversity survey, was evaluated. Analysis revealed that false-negative errors were common, and that even highly detectable vegetation species had detection probabilities significantly less than one. Without some form of correction for detectability, the species diversity recorded by either vegetation survey must be treated with caution. Informed by the identification of false-negative errors, a method was developed to extract y-diversity of woody perennials from the survey data, and to remove the influence of sampling effort. Data were aggregated by biogeographic region, rarefaction was used to remove most of the influence of sampling effort, and additional correction removed the residual influence of sampling effort. Finally, additive partitioning of species diversity allowed extraction of indices of a-, β- and y-diversity free from the influence of sampling effort. However, this woody perennial vegetation y-diversity did not address the need for a spatially extensive, fine scale measure of biodiversity at the extent of the study region. The aggregation of point data to large regions, a necessary part of this index, produces spatially coarse results. To formulate and test remotely sensed surrogates of biodiversity, it is necessary to understand the determinants of and pressures on biodiversity in the Australian rangelands. The most compelling explanation for the distribution of biodiversity at the extensive scales of the Australian rangelands is the Productivity Theory, which reasons that the greater the amount and duration of primary productivity the greater the capacity to generate and support high biodiversity. The most significant pressure on biodiversity in the study area is grazing-induced degradation, or overgrazing. Two potential spatially comprehensive surrogates of pressure on biodiversity were identified. The first surrogate was based on the differential effect of overgrazing on waterenergy balance and net primary productivity: water-energy balance is a function of climatic variables, and therefore a measure of potential or expected primary productivity; net primary productivity is reduced by high grazing pressure. The second surrogate was based on the effect of grazing-induced degradation on the temporal variability of net primary productivity: overgrazing reduces mean net primary productivity and rainfall use efficiency, and increases variation in net primary productivity and rainfall use efficiency. The two surrogates of biodiversity stress were derived from the best available remotely sensed and climate data for the study area: actual evapotranspiration recorded by climate stations was considered an index of water-energy balance; net primary productivity was measured from NOAA AVHRR integrated NDVI; rainfall use efficiency (biomass per unit rainfall) was calculated from rainfall data collected at climate stations and the net primary productivity measure. Finally, the surrogates were evaluated against the index of woody perennial a-, β- and y-diversity, on the assumption that prolonged biodiversity stress would reduce vegetation species diversity. No link was found between Surrogate 1 and woody perennial a-, β- or y-diversity. The relationship of Surrogate 2 to woody perennial diversity was more complex. Only some of the results supported the hypothesis that overgrazing decreases y-diversity and average NPP and RUE. Importantly, none of the results supported the most important part of the hypothesis that the proposed indices of biodiversity pressure would co-vary with woody perennial a-diversity. Thus, the analysis did not reveal a convincing link between either surrogate and vegetation species diversity. However, the analysis was hampered to a large degree by the climate data, which is interpolated from a very sparse network of climate stations. This thesis has contributed significantly to the measurement and monitoring of biodiversity in the Australian rangelands. The identification of false-negative errors as a cause for concern will allow future analyses of the vegetation survey data to adopt methods to counteract these errors, and hence extract more robust information. The method for extracting sampling effort corrected indices of a-, β- and y-diversity allow for the examination and comparison of species diversity across regions, regardless of differences in sampling effort. These indices are not limited to rangelands, and can be extracted from any vegetation quadrat survey data obtained within a prescribed methodology. Therefore, these tools contribute to global biodiversity measurement and monitoring. Finally, the remotely sensed surrogates of biodiversity are theoretically sound and applicable in any rangeland where over-grazing is a significant source of degradation. However, because the evaluation of these surrogates in this thesis was hampered by available data, further testing is necessary. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1346544 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008

The purpose of this study was to assess the present land resource surveying methods and techniques used in Eritrea, to evaluate different methods and techniques of land resource surveying which are currently in use in various parts of the world, to design improved methods and techniques of land resource surveying for Eritrea and to indicate the importance of cost-effective ways of land resource surveying in achieving optimal land use. A literature survey of methods and techniques of soil, rangeland, and agro-climatic survey was done in-depth. An analysis was conducted on the present resource surveying methodologies and techniques used in Eritrea. International publications on land resource surveying methods and techniques were studies and evaluation of their appropriateness for Eritrea was conducted. Finally an appropriate and affordable set of land resource surveying methodologies and techniques are proposed for Eritrea. The main conclusion of the study is to adapt international methods and techniques of resource surveying which are appropriate under the country’s socio-economic and technical conditions. Developing local methods and techniques under present condition is not possible due to various reasons. / Dissertation (M Inst Agrar (Land-use Planning))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

Thesis (M. Sc. Agriculture (Soil Science)) -- University of Limpopo, 2021 / Globally and in most parts of South Africa, there is a trend of increasing shrub encroachment in savanna rangelands. A number of studies have investigated the impact of shrub encroachment on soil organic carbon content (SOC) and soil organic carbon stocks (SOCs) in savannas. So far there is no clear consensus on whether shrub encroachment increases or decreases the level of SOC and SOCs, especially in semi arid savanna grasslands. Furthermore, knowledge on the effects of shrub encroachment on SOCs is largely restricted to the topsoil, as this is the part of the profile influenced by inputs and losses of soil organic matter. How shrub encroachment affects the vertical distribution of SOCs is rarely considered in the existing literature and the edaphic factors controlling SOCs with depth are poorly understood. The objectives of this study were (i) to quantify the vertical distribution of SOC and SOCs and (ii) to identify the edaphic factors controlling the vertical distribution of SOC and SOCs in a shrub-encroached savanna grassland sited on shallow plinthic soil. To achieve the objectives, a vegetation and soil survey of the savanna grassland was conducted whereby sampling areas were demarcated and characterized into open and shrub encroached grassland plots. In each encroachment level, three pits were randomly dug to the limiting layer on plots sited on the same soil type and similar topographic position. Soil samples were collected from the pits at depth intervals of 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 and 60-70 cm. The collected soil samples were analyzed for chemical and physical properties in the laboratory. Correlation analysis was carried out to determine the relationship between SOC and SOCs, which were the variables of interest in this study and related controlling soil physicochemical properties. The results showed that SOC was significantly greater (P<0.05) in the shrub-encroached grassland compared to open grassland. Furthermore, the results revealed that SOC was on average 19 and 13% greater in the topsoil (0-20 cm) and subsoil (20-70 cm) of shrub encroached grassland compared to open grassland. The greater SOC in the topsoil of the shrub-encroached grassland was mainly attributed to higher SOC inputs from plant litter and detritus derived from trees and grasses, which are the dominant plant life forms in savannas. In the topsoil, SOC and SOCs were positively correlated with extractable phosphorus (P) (r = 0.60; P < 0.05), while in the subsoil they were positively correlated ix with extractable phosphorus (r = 0.54), soil porosity (r = 0.52), extractable copper (r = 0.46), extractable zinc (r = 0.41), exchangeable calcium (r = 0.37) and negatively correlated with mean weight diameter (r = -0.43). Overall, SOC and SOCs under both shrub-encroached and open grasslands vertically decreased with soil depth. The results obtained highlighted that the factors controlling the level of SOC and SOCs differs in the topsoil and subsoil of the studied shrub encroached grassland. These findings suggest that in the shallow plinthic soil investigated in this study, SOC in the topsoil is controlled by the macronutrient P, while in the subsoil it is physically protected by soil aggregates and chemically stabilized via complexation interactions with exchangeable cations and heavy metals. In-depth understanding of the physico-chemical factors controlling SOC storage is critical to foster management practices that will improve the cycling of SOC in shrub-encroached savanna grasslands.

This paper deals with a study of the rangelands in Coleman County just west south and west of the Western Cross Timbers of Texas. This problem consists of classifying certain rangelands in this area according to whether they are excellent, fair, good, or poor, the chief basis for which is their deterioration.

Thesis (MScConEcol )--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Over 70% of South Africa is too arid for crop farming and is used for commercial livestock ranching, communal livestock ranching, or game ranching. These management systems differ from each other in a number of aspects, e.g. herbivore species, stocking rate, grazing regime, and management structure. The main question addressed in this study is: to what extent do the three management systems affect rangeland condition? Following the equilibrium paradigm of vegetation dynamics, communal livestock ranches are expected to have a greater detrimental effect on rangeland condition than other management systems because stocking densities and, consequently, herbivore impacts, are usually far higher than under the other two management systems. However, recent nonequilibrium theories argue that vegetation dynamics in arid systems are mainly driven by rare and stochastic rainfall events. Biotic factors, such as grazing and herbivore diversity, are predicted to have little effect on rangeland condition. This leads to the prediction that herbivore impacts on arid ecosystems are not density-dependent and, consequently, the high stocking densities commonly recorded on communal livestock ranches will not cause more rangeland degradation than other management systems. Arid and semi-arid rangelands are characterised by high inherent spatial and temporal variation in vegetation and soil parameters. Hence, differentiating between the effects of grazing management systems and natural variability caused by abiotic factors, such as rainfall, is difficult. This problem can be circumvented by examining gradients of grazing intensity radiating from water-points (= piospheres). I examined changes in vegetation and soil parameters along 500 m-Iong grazing gradients on ranches in the semi-arid Northem Cape province, South Africa, with the three abovementioned management systems. Analysis of the vegetation on these ranches demonstrated the existence of grazing gradients around the water-points. Two characteristic zones described in other studies were identified, namely the sacrifice zone (almost complete denudation of the vegetation close to the water-point) and the dense shrub zone (distal to the sacrifice zone). Communal livestock ranching had a greater negative effect on rangeland vegetation than the two other ranching systems, particularly with regard to annual grass species diversity, percentage of bare soil, and shrub density. Within 100 m of the water-points, soil quality was negatively affected by commercial cattle ranching. Contrastingly, there were no significant effects of the other two management systems on soil quality in the piosphere. The feeding of supplemental forage and nutrients may explain the greater impact of commercial cattle farming on soil quality. The results of this study are consistent with the predictions of the equilibrium theory of vegetation dynamics because grazing impacts were density-dependent in these semi-arid rangelands. However, the results presented here also indicate that forage supplementation alters the spatial and temporal distribution of livestock in a manner that may have greater negative impacts on soil quality than density of livestock per se. / AFRIKAANSE OPSOMMING: Meer as 70% van Suid-Afrika is te droog vir gewasverbouing en word gebruik vir kommersiële veeboerdery, gemeenskaplike veeboerdery of wildboerdery. Die bestuur van dié verskillende boerderytipes verskil wesentlik van mekaar in verskeie opsigte, ondermeer herbivoorspesies, veeaanskaffingstempo, weidingstipe en bestuurstruktuur. Die belangrikste vraag wat aangespreek word in die studie is die volgende: Tot watter mate affekteer die drie verskillende boerderybestuurstipes die toestand van weivelde? Gesien teen die agtergrond van die ekwilibriumparadigma van plantedinamika, word verwag dat gemeenskaplike veeboerdery 'n groter impak op die toestand van weiveld sal hê as ander boerderytipes, omdat veedigtheid en gevolglik herbivoor-impak gewoonlik veel hoër is as met die ander twee boerderytipes. Onlangse nie-ekwilibria-teorië voer egter aan dat plantedinamika in ariede gebiede gedryf word deur seldsame en buitengewone reënvalgebeure. Biotiese faktore, soos weiding en herbivoor diversiteit sal na verwagting min effek hê op die toestand van weiveld. Hieruit volg die voorspelling dat herbivoorimpak op ariede ekosisteme nie afhanklik is van digtheid nie, en dat hoë veedigtheid algemeen aangeteken vir gemeenskaplike boerderye, nie rede sal wees vir groter ver1iese in weiveld nie. Ariede en semi-ariede weivelde word gekenmerk deur 'n hoë ruimtelike en tydelike veranderinge in plant- en grondparameters. Gevolglik is dit moeilik om te onderskei tussen die effekte van weidingsbestuur en natuur1ike veranderings wat veroorsaak word deur nie-biotiese faktore, soos reënval. Dié probleem kan oorbrug word deur gradiënte van weidingsintensiteit, wat vanaf waterpunte uitstraal, te ondersoek. Vervolgens het ek binne al drie bg. boerderybestuursisteme veranderinge in plant- en grondparameters langs SOOm-lange weidingsgradiënte ondersoek op plase in die semiariede Noord-Kaap provinsie van Suid-Afrika. Plantegroei-analise het getoon dat 'n weidingsgradiënt rondom waterpunte voorkom. Twee kenmerkende sones is in ander studies geïdentifiseer, nl., 'n opofferingsone (waar amper alle plantegroei naby waterpunte uitgetrap is) en die digte, struik-sone (distaal to die opofferingsone). Gemeenskapsveeboerdery het 'n groter negatiewe effek op plaasgewasse as die ander twee boerderytipes, veral waar dit betrekking het op grasspesie-diversiteit, persentasie grond sonder plantbedekking en struikdigtheid. Binne 100m vanaf waterpunte, is grondkwaliteit merkbaar negatief geaffekteer deur kommersiële veeboerdery. Daarteenoor, was daar geen merkbare effek op die grondkwaliteit naby waterpunte van die ander twee boerderytipes nie. Aanvullingsvoer kan moontlik die rede wees vir die waargenome, groter impak van kommersiële veeboerdery op grondkwaliteit. Die resultate van die studie strook met voorspellings van die ekwilibria-teorie van plante-dinamika, daarin dat weidingsimpak digtheidsafhanklik is in hierdie semiariede plaasgebiede. Die resultate toon ook egter, dat voedingsaanvullings die ruimtelike en tydelike verspreiding van vee in so 'n wyse verander, dat dit moontlik 'n veel groter negatiewe uitwerking op grondkwaliteit het as veedighteid per se.

Thesis (PhD (Agronomy))--University of Stellenbosch, 2006. / Vegetation dynamics and restoration strategies of degraded rangeland were investigated near a watering point in the Allaidege communal grazing area in Administrative Zone 3 of the Afar Region in the northeastern lowlands of Ethiopia. The degradation gradient formed by grazing pressure in the study area was stratified into four different areas based on the vegetation cover; severely degraded (SD), moderately to severely degraded (MSD), moderately degraded (MD) and lightly degraded (LD) areas. The study was initiated at the start of the rainy season in June 2003 and lasted untill December 2004. The objectives were to study the effects of the grazing pressure on plant species composition; on plant biomass production and basal cover; on rangeland forage quality; on the rangeland soil status and to determine and quantify viable restoration strategies for forage species in severely degraded rangelands. The botanical composition of the different degradation areas was determined by making a 250 point wheel point method survey in each of four 30 m x 30 m quadrats in each degradation area using the nearest plant approach. The botanical composition of each degradation area was determined by measuring the frequency of occurrence of the different life forms (perennial grasses, annual grasses and forbs) of the species recorded in the field. Accordingly, a significant interaction was observed in both seasons between the different degradation areas and life forms considered. A high abundance of annual grasses was evident in SD and MSD areas in both seasons. In the MD and LD areas, a three-fold increase in frequency was recorded for perennial grasses compared to the MSD area in 2003. In 2004, the frequency of annual grasses, forbs and perennial grasses in the MD area was almost similar to that of the LD area. The abundance of perennial grasses in the MD and LD areas was two- and five-fold higher compared to perennial grasses in the MSD and SD areas respectively. Biomass production was recorded by cutting the vegetation in 1 m x 1 m quadrats in each grazing area at ground level. The dry matter content of subsamples was determined in order to calculate the dry matter production of the quadrat. The differences in dry matter yield recorded in the different degraded areas was not significant for the 2003 season, although an increasing trend in yield was observed from the SD to MD areas. Significant yield differences were however recorded when one outlier in the data was excluded from the analysis. The significant differences occurred between the MD and SD areas where the MD area produced 2.4 t ha-1 more dry matter than the SD area. Similarly, in 2004 no significant yield difference was observed between the degradation areas. However, the contribution of different species to dry matter yield varied in the different degradation areas. Setaria verticillata, Sporobolus ioclados and Paspalidium desertorum were found to be the major species contributing to the dry matter producion in the SD area, S. verticillata and P. desertorum in the MSD area, Chrysopogon plumulosus and P. desertorum in the MD area and C. plumulosus and Panicum coloratum in the LD area. The percentage basal cover was calculated from the number of basal strikes recorded at 1 000 points in each plot of each degradation area using the wheel point method. The total basal cover percentage did not significantly change along the degradation gradient in any of the seasons. However, data for both seasons showed an increasing trend of total basal cover percentage closer to the watering point compared to areas further away from the watering point, except for the SD area, which had the lowest basal cover percentage. The contribution to percentage basal cover by some species decreased while it increased for some other species in grazing areas near the watering point. Forage quality was investigated by analysing sub-samples of the forage samples taken to determine biomass production. The forage samples were analysed for neutral detergent fibre (NDF), acid detergent fibre (ADF), crude protein (CP), lignin, in vitro dry matter digestibility (IVDMD), phosphorus (P), and calcium (Ca) content. The forage showed a decrease in NDF and ADF content in areas close to the watering point in both seasons. This decrease in fibre content was accompanied by an increase in CP content close to the watering point. The increase in CP was significant for the SD area in both seasons. Although a similar trend was observed in both seasons, the CP content was found to be significantly higher in 2004 than in 2003. The results of the lignin analysis were inconclusive if the data of both seasons are considered. It does appear however as if the lignin content of the forage was generally higher in 2003. The 2 years pooled average of P content of the forages showed insignificant variation along the degradation gradient. However, an increase in P concentration of the forages was evident in areas far from the watering point. Contrary to this, Ca concentration was significantly higher in the SD area compared to areas further away from the watering point. Hand clipped forage samples and esophageal collected forage samples were analysed to compare the quality of the samples. Due to the fact that only two animals were available for esophageal collection, differences were in most cases not significant at the 5% level, but trends indicate that animals select higher quality forage than what is assumed based on hand clipping. Organic carbon (OC) content, total nitrogen (N) content, available phosphorus (P) content, available potassium (K) content, exchangeable calcium (Ca) and magnesium (Mg) contents, cation exchange capacity (CEC), total exchangeable bases (TEB), exchangeable sodium percentage (ESP), soil acidity (pH) and base saturation of soils in the different degradation areas were determined by means of acknowledged laboratory methods. No significant differences in OC, N, P, K, Ca, Mg and K content of soil in the different degradation areas could be observed. There was however an increasing trend for OC and N content with distance from the watering point. Sodium concentration and pH increased significantly in areas close to the watering point. Cation exchange capacity content of the soil was variable and no clear trend could be established. Significantly higher TEB and ESP contents were observed in the SD area. In general, the differences in plant biomass production and basal cover, botanical composition, forage quality and soil status over the degradation gradient clearly implicates the negative impact of unrestricted grazing pressure on the rangeland around the watering points. In the rangeland restoration trial, establishment of three local and three exotic grass species in the SD area was investigated. Treatments applied included application of inorganic fertilizer, dry dung organic manure and grass mulch. The mulch treatments caused a significant yield increase for all the sown species. Among all the species, Ischaemum afrum and Tragus berteronianus performed better and produced significantly higher dry matter yields than Enteropogon rupestris, Chloris gayana and Panicum coloratum. In general the study indicated the importance of mulching when planning to restore degraded rangeland under arid environmental conditions.

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.

Watersheds in the Southwest, particularly the San Simon Watershed in Arizona, have been experiencing degradation since the turn of the century through processes of erosion and vegetation change. Mitigation and management actions rely on long-term assessment of landcover change; however, traditional methods of ground assessment are time-consuming and specific to particular sites. Remote sensing techniques can be an alternative method to assess landcover change over extensive areas. Forage inventory surveys and historical monitoring data were assessed for utility in landcover change detection. The contemporary remotely-sensed classifications included 2001 SwReGAP data and a CART classification of 2010 Landsat TM data. The CART classification was aided by shrub cover analysis of NAIP aerial photography. It was found that 1930s Grazing inventories were compatible with contemporary satellite image classifications for large-scale landcover change detection.

One of the most fascinating subjects in all American history is the story of the great cow country. Its heyday was the twenty-year period from 1868 to 1888. It extended from below the Rio Grande on the south to well up in Saskatchewan in western Canada on the north. East and west it reached from the Rocky Mountains to about the Missouri- Arkansas border. It occupied a region nearly 2,000 miles long and from 200 to 700 miles wide--almost a million square miles in one vast open range. For countless years this region had been the home of millions of wild buffaloes, but in a very short time after 1868 it was transformed into a gigantic cattle kingdom. After two decades of spectacular existence, it just as suddenly passed away, and the cattle industry entered a new and in many ways an entirely different era. Texas cattle and Texas cattlemen played leading roles in this great drama of the West. The warm southern plains of Texas were the breeding place-the "incubator"-f or thousands of longhorn cattle, the broad prairies to the north were their feeding grounds, and the newly established railroad towns in Kansas and other states were the shipping points.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, .Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy. / An Index of Biological Integrity (IBI) has been developed for rangeland condition assessment in arid northwestern Namibia. The usefulness of termites as bio-indlcators has been tested and reliable sampling protocol for termite diversity in an arid ervlronrnent has been developed. The study was conducted mainly at a high- and low-intensity site on each of three farms. Two of the farms were communally owned; the other was commercially owned. (Abbreviation abstract) / Andrew Chakane 2019