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Understanding the Causes of Bush Encroachment in Africa: The Key to Effective Management of Savanna Grasslands

The increase in biomass and abundance of woody plant species, often thorny or unpalatable, coupled with the suppression of herbaceous plant cover is a widely recognized form of rangeland degradation. Bush encroachment therefore has the potential to compromise rural livelihoods in Africa, as many depend on the natural resource base. The cause of bush encroachment phenomenon is not without debate, but fire, herbivory, nutrient availability and rainfall patterns have been shown to be the key determinants of savanna vegetation structure and composition. In this paper, these determinants are deliberated upon, with particular reference to arid and semi-arid environments of Africa. To improve our current understanding of causes of bush encroachment, an integrated approach, involving ecological and indigenous knowledge systems, is proposed. Only through our knowledge of causes of bush encroachment, both direct and indirect, can better livelihood adjustments be made, or control measures and restoration of savanna ecosystem functioning be realized

Understanding the savanna dynamics in relation to rangeland management systems and environmental conditions in semi-arid Botswana

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

Agro-pastoralists’ determinants of adaptation to climate change

Purpose – The purpose of this study is to analyze smallholder farmers’ perceptions on climate change and its stressors, their adaptation strategies and factors that influence their adaptation to climate change. Design/methodology/approach – The study was conducted in Kweneng district, located in the south eastern part of Botswana. Multi-stage sampling was used to obtain a representative sample from three sub-districts in the district. A structured questionnaire was used to collect data by using face-to-face interviews. Findings – Majority of farmers perceived an increase in mean annual temperature and the number of hot days and a decrease in mean annual rainfall and the number of rainfall days over the past 10 years as indicators of climate change. The prominent adaptation strategies included changes in planting dates for crops and supplementary feeding for livestock. The logistic regression results show that gender, age, household size, poverty, shortage of land, mixed farming and knowledge about climate change significantly influence adaptation. Practical implications – The findings indicate that climate change policy should target agricultural diversification at the household level and dissemination of information on climate change and adaptation strategies. Originality/value – Policy recommendations can be suggested: government climate change interventions should target agricultural diversification at the household level, and this study provides insights on what influences adaptation strategies and what should be targeted to build resilience in the agricultural sector

Effect of Housing Design and Location on Production and Economic Performance of Broiler Chickens during Summer in Botswana

ABSTRACT Botswana experiences long, hot summer periods which negatively affect broiler productivity and results in economic losses. To determine these negative effects, two parallel broiler production studies were conducted in the North eastern (NE) and South eastern (SE) regions. In each region, three large scale commercial broiler farms were randomly selected based on similarities in bird management and housing systems. In each farm, one house type (Gable, Hoop and See-saw) was selected for long term flock monitoring (1 to 35 days) over three production cycles. Results showed that the production performance of the broilers in the SE region was superior to that in the NE region, with temperatures on being average higher in the NE than in the SE. The European Production Efficiency Factor (EPEF) was significantly higher (p0.05) between the regions at 9.0% and 7.4% for the NE and SE, respectively. In the NE, the Gable structure had the highest profitability and economic efficiency and was thus superior in comparison to the other house structures

Effects of management regimes on structure, composition and diversity of seasonally inundated herbaceous communities in the Mkomazi National Park, Tanzania

The effects of management regimes on structural composition and diversity of seasonally inundated herbaceous communities were investigated in the Mkomazi National Park, Tanzania. Three sites were selected based on management regimes, that is "fire-grazing" (FG), "fire-no grazing" (FNG) and "no fire-no grazing" (NFNG), and sampled in the 2015 wet season. The studied vegetation parameters resulted significantly different across the sites, with the exceptions of species abundance between NFNG versus FG and NFNG versus FNG sites and species evenness, which remained constant among sites. A significantly higher species richness, Shannon diversity Index, standing biomass and percentage vegetation cover was detected at FNG site, than in the other sites. No significant differences arose when comparing FG and NFNG sites. Although the responses we found may in part be caused by confounding underlying variables such as variation in soil type, soil moisture or elevation, the patterns found may contribute to a more general understanding of the effects of management regimes in seasonally inundated savannah, as well as to sound approaches in environmental conservation and management. However, further research is needed to support our findings, replicating the study in other areas under the same or similar management conditions and in a wider array of ecosystems. 2018 John Wiley & Sons Ltd

Understanding the causes of bush encroachment in Africa: The key to effective management of savanna grasslands

The increase in biomass and abundance of woody plant species, often thorny or unpalatable, coupled with the suppression of herbaceous plant cover, is a widely recognized form of rangeland degradation. Bush encroachment therefore has the potential to compromise rural livelihoods in Africa, as many depend on the natural resource base. The causes of bush encroachment are not without debate, but fire, herbivory, nutrient availability and rainfall patterns have been shown to be the key determinants of savanna vegetation structure and composition. In this paper, these determinants are discussed, with particular reference to arid and semi-arid environments of Africa. To improve our current understanding of causes of bush encroachment, an integrated approach, involving ecological and indigenous knowledge systems, is proposed. Only through our knowledge of causes of bush encroachment, both direct and indirect, can better livelihood adjustments be made, or control measures and restoration of savanna ecosystem functioning be realized.</p

The impact of livestock grazing management systems on soil and vegetation characteristics across savanna ecosystems in Botswana

The objective of this study was to determine the impact of livestock grazing management systems on soil and vegetation dynamics under different environmental conditions of Botswana. Soil and vegetation were randomly sampled along transects located in three ranches and adjacent communal grazing land in 2009 and 2010. Our results showed that grazing management systems did not consistently affect soil texture, organic carbon, pH and bulk density. The soil characteristics such as soil carbon and clay content were strongly associated with variation in rainfall, and contributed to improved rangeland condition characterised by high herbaceous biomass and low bush encroachment. Livestock grazing management systems do not impact soil and vegetation properties differently as indicators of degradation are observed in both grazing systems. Thus, there is a need to develop a sustainable land management model that will improve soil carbon, increase herbaceous biomass and generally improve the condition of rangelands in Botswana.Keywords: cattle, grassland, grazing, land degradation, rangeland conditio

Pastoralists' Perception and Ecological Knowledge on Savanna Ecosystem Dynamics in Semi-arid Botswana

We investigated vegetation dynamics in relation to livestock grazing as perceived by pastoral farmers in different regions of Botswana. A structured questionnaire was used to collect farmers' understanding of vegetation changes and causes within three different grazing lands. The pastoral farmers' description of dominant vegetation differed significantly both at the local and district level, which suggests that rangelands consist of patches dominated by different grasses and woody vegetation. Most pastoralists indicated that grass composition has undergone changes, and unpalatable grasses such as Aristida congesta and Megaloprotachne albescens are increasing. The different factors perceived by pastoral farmers to cause changes in vegetation composition included rainfall, overgrazing, and fire. Bush encroachment is considered to be more common in communal grazing land than in ranches. According to pastoral farmers, the ranching system is less degrading to the environment and more sustainable for livestock production than is communal grazing