Brush encroachment is a serious problem on pastures in Western Canada. It results in a loss of productivity and habitat for wildlife. Sixty-seven pastures were visited in Manitoba, Saskatchewan and Alberta. Approximately half were privately owned lands and the remainder were public lands. Each field sampled was divided into grass, shrub and forest strata, within each stratum vegetation cover was noted and biomass and soil samples were taken. A historical reconstruction was created using aerial photos dating back to the 1940s up until most recent photos available. Six cover classes were delineated and patch statistics were calculated. Information on historical management practices were obtained also. It was determined that woody encroachment is occurring on pastures, but no significant trends found between environmental factors and encroachment. Therefore it was concluded that management probably has the greatest impact on the occurrence and extent of woody encroachment.

Brush encroachment is a serious problem on pastures in Western Canada. It results in a loss of productivity and habitat for wildlife. Sixty-seven pastures were visited in Manitoba, Saskatchewan and Alberta. Approximately half were privately owned lands and the remainder were public lands. Each field sampled was divided into grass, shrub and forest strata, within each stratum vegetation cover was noted and biomass and soil samples were taken. A historical reconstruction was created using aerial photos dating back to the 1940s up until most recent photos available. Six cover classes were delineated and patch statistics were calculated. Information on historical management practices were obtained also. It was determined that woody encroachment is occurring on pastures, but no significant trends found between environmental factors and encroachment. Therefore it was concluded that management probably has the greatest impact on the occurrence and extent of woody encroachment.

The genus Dorycnium L. consists of a number of species of perennial leguminous shrubs known to be relatively drought tolerant. Low rainfall areas (i.e <600 mm annually) of Australia under agricultural use are subject to periods of feed shortage during summer and autumn, and hence animal production is limited at this time. Dorycnium spp. have been identified as having the potential to be integrated into Australian grazing systems as a source of forage when little or no other feed is available. This project was established to further investigate a number of key issues related to the agronomic and forage characteristics of this potentially important genus. Research was undertaken into Dorycnium spp. to examine three important factors associated with the evaluation of a legume, seed germination characteristics, the nutritional value of the forage, and rhizobial associations. Dorycnium hirsutum Ser. accessions TAS1002 and TAS2001 were subjected to a range of germination experiments examining the level of pod maturity, harvest season, and the effect of pre-germination treatments. The seed coat of D. hirsutum was found to influence germination behaviour, with the use of pre-germination scarification treatments improving germination behaviour by increasing the percentage germination (PG) and lowering the mean time to complete germination (MTG) and percentage hard seed. Mechanical scarification of TAS2001 for 20 seconds was found to increase (P<0.05) PG from 86 to 96 %, lower the MTG from 6.0 to 2.7 days, and reduce the percentage hard from 13.6 to 1.9 % in relation to untreated seed. Mechanical and chemical scarification techniques were found to be the most effective in promoting rapid and uniform germination, were simple to apply and were repeatable. In general, inherent differences in seed lot germination characteristics were believed to be associated with the influence of environmental factors and the natural characteristics of selected accessions with indeterminate flowering. Established plots of D. rectum Ser., D. hirsutum and D. pentaphyllum Scop. were sampled along with an area of lucerne (Medicago sativa L.) on a regular basis throughout the spring/summer period of 2001/2002. Samples were analysed using near infrared reflectance spectroscopy (NIRS) and wet chemistry for crude protein (CP), neutral detergent fibre (NDF) and dry matter digestibility (DMD) and metabolisable energy (ME). Over the course of the sampling period forage of Dorycnium spp. generally displayed decreases in CP, ME, DMD and increases in NDF. Typical CP values ranged from 4 - 18 % of dry matter (DM), NDF 21 - 72 % of DM, DMD 32 - 75 %, and ME 4.1 - 11.0 MJ/Kg/DM. The nutritive value of Dorycnium spp. forage appeared to be influenced by environmental and developmental characteristics, with the growth stage identified as a useful tool for predicting forage quality. Although Dorycnium plants were of lower forage value than lucerne, their forage can provide livestock with an important source of nutrition in areas of low rainfall and during periods where there are feed gaps. Experimental plots of Dorycnium spp. at three Tasmanian sites were sampled every six weeks throughout the spring/summer period of 2002/2003 and analysed using a modified butanol-HCl method for condensed tannins (CT). The CT content of D. hirsutum was found to fluctuate from 3.2 to 16.6 % of the DM. Dorycnium rectum and D. pentaphyllum were found to contain CT levels of at least 7.7 and 6.8 % of DM respectively during the sampling period. The CT levels observed were considered to be high in general, with only D. hirsutum containing levels that may be considered to be low and possibly beneficial at certain stages of development. Increases in CT levels were associated with the initiation of flowering, and interactions between the environment and species were observed, although no common factor was identified as influencing CT levels. A glasshouse experiment was undertaken to assess the nitrogen fixing ability of the commercial Lotus corniculatus L. inoculant SU343 with Dorycnium spp. against a range of alternative inoculants. The host/rhizobia interactions of Dorycnium spp. along with six important pasture legumes and a range of inoculants was assessed. Strains WSM1284, WSM2323 and WSM2338, along with SU343 were found to be suitable inoculants for Dorycnium spp. examined. However, negative interactions between these inoculants and important pasture legumes were identified. Inoculant strains, WSM1284, WSM2323, WSM2338 and SU343 were selected to undergo evaluation under Tasmanian field conditions with D. hirsutum and D. rectum. In the field all strains were found to fix adequate amounts of atmospheric nitrogen. Inoculant SU343 was confirmed to be a suitable inoculant for D. rectum in terms of performance and commercial viability, however, WSM2338 and WSM1284 were found to be equally suitable. The inoculation of Dorycnium hirsutum with the Tasmanian isolate WSM2323, was found to be a significantly (P<0.05) superior strain to SU343 in terms of nitrogen fixation. The inoculation of D. hirsutum did not affect (P>0.05) plant DM production in the field. The ability of the inoculants to compete with a background population of root nodule bacteria was found to be of concern, and may have serious implications for the long-term performance from a single inoculation event. It was proposed that a combination of rhizobial strains may be more effective as a commercial inoculant rather than relying on the single L. corniculatus inoculant SU343.

Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Dennis Cash. Includes bibliographical references (leaves 100-106).

Inaug.--Diss. (Dr. agr.)--Rheinisch-Friedrich-Wilhelms-Universität zu Bonn. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 116-129).

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1941. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 59-63.

Quantities of herbaceous vegetation of Sahelian rangelands in Niger and Mali were compared to vegetation indices (VI) derived from Landsat MSS and NOAA AVHRR LAC images. Field data was collected in 1985,1988 and 1989 in Niger and an appropriate sampling scheme for the study area was developed. Herbaceous vegetation could be estimated to within t 150 kgha 1 at an 80% confidence level up to 1300 kgha -1. Establishing site positions was found to be a primary obstacle when selecting suitable sampling areas. Suggested is the use of Landsat MSS image hard-copies in combination with a global positioning system. Landsat MSS and NOAA AVHRR LAC data were available for dates corresponding to field surveys of 1985 and 1988. While Landsat MSS scenes were geometrically corrected to maps, NOAA AVHRR images were registered to Landsat MSS with a simulated resolution of 1.1 km. Data from both satellites were radiometrically corrected and standardized to atmospheric conditions to the image with the highest relative scene contrast for each study area. These reference images were identified on the basis of bare soil spectral reflectance values and a binary decision tree. Five methods of resampling image data to represent field sites were applied. - The image data sampling methods were found to have a significant influence on spectral reflectance values attributed to a site and, consequently, on the relationship between ground and satellite VIs. Ratio, normalized difference and perpendicular VIs (RVI, NDVI and PVI) were computed for each step of pre-processing procedures. For Landsat MSS VIs were also derived from average spectral reflectance values of bands 3 and 4 to simulate NOAA AVHRR channel 2. VIs were compared for the same sensor, between sensors and related to field data by using linear and logarithmic regression analyses. RVIs and NDVIs achieved very similar results, while PVIs showed a more variable relationship to ground data. Overall, VIs from simulated NOAA AVHRR channel 2 values were found to be not superior to those derived from just band 4. NOAA AVHRR VIs could be related to Landsat MSS ratio VIs by a single regression line for 1985 and 1988 growing seasons for Niger and Mali survey sites. For the inter-calibration a simulation of the NOAA AVHRR pixel size was found to be better suited than the high resolution Landsat MSS data.

Orientador: Ana Cláudia Ruggieri / Coorientador: Gabriel Maurício Peruca de Melo / Banca: Valdo Rodrigues Herling / Banca: Paola Pedroso Vantini / Banca: Ricardo Andrade Reis / Banca: Wanderley José de Melo / Resumo: O manejo adequado tem a finalidade de obter pastos persistentes, que forneçam forragem em quantidade e qualidade para os ruminantes. Assim, o manejo das pastagens deve considerar, entre outros fatores, a intensidade de pastejo adotada, a estrutura do dossel forrageiro, o sistema radicular das plantas e as características do solo. O objetivo deste trabalho foi estudar o efeito de diferentes ofertas de forragem nos compostos de reservas das plantas e atividade enzimática no solo de pastos de cultivares de Brachiaria manejados sob lotação rotacionada. O experimento foi conduzido no setor de Forragicultura da FCAV/UNESP, Jaboticabal/SP, no período de novembro de 2008 a junho de 2009. O delineamento utilizado foi inteiramente casualizado com quatro tratamentos (ofertas de forragem de 4, 7, 10 e 13% do peso corporal animal) e três repetições. No estudo dos compostos de reserva a coleta de dados foi dividida em quatro ciclos de pastejo (CP) e no estudo da atividade enzimática no solo a coleta de dados englobou, além dos CP, uma amostragem em julho, sendo dividida em dias de avaliação (1, 21, 42, 63 e 183 dias). O aumento das ofertas de forragem (OF) proporcionou maiores alturas do dossel comprimido ao longo do período experimental. Em todas as cv. de Brachiaria estudadas, verificou-se que o último CP apresentou maior altura. A massa seca de raízes da cv. Marandu foi menor (P>0,05) em relação às outras gramíneas. A menor (P>0,05) massa seca de parte aérea foi observada na OF de 4% e as maiores (P<0,05) massas nas cv. Xaraés e Mulato. Os teores de nitrogênio (N) total nas raízes nas OF de 4, 7 e 13% não diferiram (P>0,05) no decorrer dos CP. O teor de N total na parte aérea foi maior (P<0,05) no CP 3 para todas OF e cv. O teor de N em aminoácidos (aa) nas raízes nas quatro OF e três cv. foi maior (P<0,05)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The adequate management has the objective to provide a persistent grassland with forage availability and quality for ruminants. Thus, the pasture management should consider, among other factors, the intensity of grazing adopted, the structure of the sward, the root system of plants and soil characteristics. This study aimed to analyze the effect of different forage alowance in the pastures of Brachiaria cultivars (Marandu, Xaraés and Mulato) managed under rotational stocking. The experiment was carried out at FCAV / UNESP, Jaboticabal/SP, from November 2008 to June 2009. The design was completely randomized design with four treatments (forage allowances of 4, 7, 10 e 13% of animal body weight) and three replications. The data collection to study of compounds of reserves was divided into four grazing cycles (GC) and data collection to enzyme activities in the soil had extra sampled in July and was divided into days assessment (1, 21, 42, 63 and 183 days). The different forage alowance (FA) treatment resulted in higher heights compressed canopy over the trial period. In all Brachiaria cultivars (cv) studied, it was found that the last GC had a higher heights. The dry mass of roots of Marandu cv was lower (P>0,05) compared to other grasses. The dry mass of the shoots of the FA 4% was lower (P>0,05) than the others FA and Xaraés and Mulato cv had greater (P<0,05) shoot mass. The nitrogen (N) total contents in the in FA 4, 7 and 13% did not differ (P>0,05) during the GC. The N total content in shoots was higher (P<0,05) in GC 3 for all FA and cultivars. The N aminoacids (aa) content of roots in four FA and three cv was higher (P<0,05) in the first GC. The highest N-NH4 + concentrations were observed after nitrogen fertilization that occurred after the second grazing. The NNH4 + and N-NO3 - levels in roots and shoots... (Complete abstract click electronic access below) / Doutor

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