The encroachment of rangelands by woody plants causes an imbalance in the grass:bush ratio leading to decline in ecosystem services including grazing capacity, biodiversity, and water yield. This study assessed the historical changes in woody cover, and the effects of bush clearing on water loss, atmospheric carbon uptake, herbaceous vegetation, and soil seed bank (SSB) dynamics. The study was conducted at Makapanstad (Radi and Maseding) and Kgomokgomo rangelands, North-West Province, South Africa. Landsat imagery was used to assess woody cover over 34 years (1984 - 2018) in a total area of 16 397 ha. Evapotranspiration (ET) and gross primary productivity (GPP) were assessed in cleared sites and their adjacent uncleared sites from 2013 to 2018. Woody plant densities, herbaceous composition, ground cover and biomass production were assessed in 24, 5×5-m plots distributed equally in three 2500-m2 bush-encroached blocks in each rangeland in February 2016. Three samples for soil nutrient analysis were collected 20-cm deep in each plot. Thereafter, half (1250-m2) of each block was mechanically cleared to make three replicates of cleared and uncleared microsites. Post-treatment survey of vegetation was conducted in February 2017. SSB was assessed for samples collected in April 2016 before bush clearing and in August, October and December 2016, and April and August 2017 in paired microsites. In 1984, herbaceous cover (humid + arid grasslands) dominated, accounting for 36% of the total area followed by woody cover (shrublands + bushlands) and unvegetated cover (bare soils + abandoned croplands), with respective proportions of 33 and 31%. There were substantial land cover changes over time, with shrub cover increasing linearly (r2 = 0.94, p < 0.05) at a rate of 0.26% year-1, increasing the total woody cover (TWC) to 38% in 2018. Cropland abandonment was the main driver of increase in shrub cover in the study area. Herbaceous cover declined with increase in TWC (r2 = 0.69), whereas bare soil cover increased (r2 = 0.70) with TWC over time. The main encroachers were Vachellia tenuispina at Radi, Vachellia tortilis at Maseding and Dichrostachys cinerea and V. tortilis at Kgomokgomo. Most of the woody species correlated with total N and clay content (r = 0.96; p < 0.05) in black vertic clay soils of Radi and Maseding, whereas non-leguminous species correlated with total N and C:N in the red-yellow apedal soils of Kgomokgomo. ET and GPP varied interannually in all rangelands and both declined significantly (p < 0.05) after bush clearing at Radi and Kgomokgomo but not at Maseding. ET increased with GPP in cleared (r2 = 0.50-0.59) and uncleared sites (r2 = 0.82-0.93) at Radi and they showed a strong relationship (r2 >0.70) in both sites at Maseding and Kgomokgomo. ET ranged from 0.26-0.46 and 0.48-0.97 Kg H2O m-2 day-1 in cleared and uncleared sites, respectively, at Radi and from 0.44-0.98 and 0.63-1.24 Kg H2O m-2 day-1 at Kgomokgomo. Total SSB densities (constituted mostly by early successional species) increased significantly (p < 0.05) to 2470, 1872 and 693 seeds m-2 at Radi, Maseding and Kgomokgomo, respectively, in cleared microsites in August 2017. Similarly, biomass production (BP) and basal cover (BC) were highest in cleared relative to uncleared microsites. Overall, increase in woody cover reduced herbaceous cover and this calls for bush control in the studied rangelands. The decline in ET after bush clearing suggested that bush clearing could be used to increase rangeland water yield. Increased SSB densities, BP and BC indicated that bush clearing facilitates passive restoration. / Thesis (PhD (Pasture Science))--University of Pretoria, 2020. / Agricultural Research Council / National Research Foundation / Plant Production and Soil Science / PhD (Pasture Science) / Unrestricted

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19221号 / 理博第4113号 / 新制||理||1592(附属図書館) / 32220 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 伊谷 原一, 教授 幸島 司郎, 教授 村山 美穂 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Thesis (M.Sc. (Horticulture)) --University of Limpopo, 2007 / Bush tea (Athrixia phylicoides DC) has been used for many years by the people of South Africa for medicinal purposes. The herbs was only harvested from the wild, therefore data on the effects of mineral nutrition on total antioxidant activity had not been established. The objective of this study was to determine the seasonal effect of nitrogen (N), phosphorus (P) and potassium (K) nutrition on total antioxidant activity (TAA) in cultivated bush tea leaves. Treatments consisted of 0, 100, 200, 300, 400 or 500 kgha-1 N, P or K in a randomized complete block design with four replications under 50 % shade nets. Three (N, P and K) parallel trials were conducted per season (autumn, winter, spring and summer). TAA was determined using 2,2-diphenyl-1-picrylhydrazyl-hydrate (DPPH) method and analyzed in a spectrophotometer. Results of this study demonstrated that regardless of season, the application of N, P and K fertilizers increased quadratically levels of TAA in bush tea with most of the increase occurring between 0 and 300 N, 300 P and 200 K kgha-1. Therefore, for improved total antioxidant content in bush tea leaves, 300 N, 300 P and 200 K kgha-1 N are recommended. / National Research Foundation (NRF), Agricultural Research Council(ARC-LNR)

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No / The dichotomy between prohibitive law and moral responsibility is at the centre of debates about the legitimacy of humanitarian intervention. However, political interests remain an important factor not only in determining and tempering the humanitarian impulses of states, but also for gauging their more general adherence to the rule of law. The humanitarian intervention debate only has meaning in a context in which there is general, routine adherence to the non-interventionist norm of the international system, codified as Article 2(4) of the UN Charter. The `Bush Doctrine¿ of pre-emptive self-defence alters the political and politico-legal context that has until now given the humanitarian intervention debate its meaning and importance. Given this, together with a more general loosening of the strictures prohibiting or limiting the use of force, there is good cause for concern about the foundations of the post-1945 international order. The debate about humanitarian intervention can no longer abstract the tension between law and morality from a political arena that is facing such profound challenges.

By 2001, the al-Qaida movement had evolved into a transnational revolutionary movement with an eschatological dimension, facilitating the 9/11 attacks to gain religious support and incite a strong reaction. The Bush administration was particularly tough in its response, terminating the Taliban regime and then declaring the right of pre-emption against a wider axis of evil, which led on to regime termination in Iraq and the intended constraining of Iran. In the event, regime termination in Iraq and Afghanistan resulted in protracted wars that were intensely costly in human and resource terms, and Iranian influence actually increased. The al-Qaida movement was dispersed while being transformed into a potent idea with little in the way of an organised structure, yet was effective in catalysing movements from South Asia through the Middle East to sub-Saharan Africa. Analyses of events in Iraq and Afghanistan point to deep misconceptions over the potential for the use of military force and of imposed state building. After more than a decade after 9/11, there has been a re-orientation away from large-scale occupations towards more remote means of maintaining control, with an emphasis on armed drones, special forces and privatised military companies. This approach appears initially appropriate and attractive but may be as counterproductive as the previous approach.