Soil degradation and associated socio-ecological impacts in the drylands of Nakasongola district, Central Uganda

Word processed copy.Includes bibliographical references (p. 219-236).This study investigated the causes, magnitude and selected socio-ecologlcal effects of soil degradation, with the ultimate goal of explaining and mapping the spatial and temporal variations of degradation in the dryland area of central Uganda

Recent glacial recession in the Rwenzori Mountains of East Africa due to rising air temperature

Based on field surveys and analyses of optical spaceborne images (LandSat5, LandSat7), we report recent decline in the areal extent of glaciers in the Rwenzori Mountains of East Africa from 2.01 +/- 0.56 km(2) in 1987 to 0.96 +/- 0.34 km(2) in 2003. The spatially uniform loss of glacial cover at lower elevations together with meteorological trends derived from both station and reanalysis data, indicate that increased air temperature is the main driver. Clear trends toward increased air temperatures over the last four decades of similar to 0.5 degrees C per decade exist without significant changes in annual precipitation. Extrapolation of trends in glacial recession since 1906 suggests that glaciers in the Rwenzori Mountains will disappear within the next two decades

FORMATION AND DISTRIBUTION OF THE VALLEY SIDE GULLIES IN CENTRAL UGANDA

The dry subhumid area of Central Uganda forms part of the ‘cattle dry corridor’ characterized by relatively low but unpredictable rains, poor resource development, high livestock population and increasing human population densities leading to environmental degradation problems including gully erosion. This paper examines the characteristics of gullies and the main intrinsic and extrinsic variables affecting their spatial distribution in the central drylands of Uganda. A field survey was used. Preliminary studies were done covering two sub counties in the district of Nakasongola, and then more detailed studies narrowed to 2 sub catchments close to Migera town. Ten gullies were sampled for detailed measurements. The spatial distribution of all gully scars were identified in the field and their positions recorded using a Global Position System. This data was imported in Geographical Information System in ILWIS 3.2 environment. Field measurement of gully dimensions (lengths, width and depth) was done and the data used for computing the volume of soil loss from gully erosion. Results revealed that in general land degradation by gullies in this dry sub humid area is an increasing problem, which is mainly attributed to human activities of livestock grazing and movement. The extent and magnitude of erosion by gullies, however, is controlled by soil characteristics and topographic variations. The gullies were largely discontinuous, dominantly of linear pattern and rarely exceeded 2 m depth. There is urgent need to address the problem of degradation by gullies, while taking into consideration the controlling factors, in order to ensure sustainable rangeland management

Horticulture in Mountain Agro-Ecosystems of Uganda: Environmental and Socio-Economic Threats and Opportunities

Horticultural crops have gained importance over the recent years as a strategy for addressing livelihood improvement particularly amongst both the rural and urban poor in high- and low- mountain areas. Mountain ecosystems in Uganda, however, are under pressure driven by increasing population, urbanisation and globalization.  This has resulted into widely reported environmental degradation. Environmental and social concerns are a reality that needs to be underpinned if sustainable use of these ecosystems is to be achieved. This paper examined the socio-ecological problems, challenges posed by increased shift to horticultural farming and opportunities in mountain ecosystems of Uganda, using a case study of Mt Elgon. Data collection was obtained largely through household surveys, focus group discussions and field observations. Results revealed that household economic gain and unsustainable traditional crop production systems were the main drivers for the recent shift to intensive horticultural system. These changes have caused environmental and social concerns particularly accelerated erosion, health risks associated with increased use of chemical inputs, and conflict largely attributed to encroachment on conservation areas for farming and staking materials.  The study recommends for pro-active measures (e.g. increased investment in horticultural value chain) in mitigating environmental and social problems if future sustainability of the mountain ecosystems are to be attained

Climate change and the aquatic ecosystems of the Rwenzori Mountains, Uganda

The Rwenzori Mountains are home to one of the last remaining tropical icefields outside of the Andes. Over the last century, equatorial icefields of the East African highlands have been steadily shrinking but the precise climate tropical alpine glaciers remain unclear. More than a decade had passed since the last detailed measurements of glacial cover were made in the Rwenzori Mountains. Recent evidence from Kilimanjaro suggests that its icecap will disappear entirely by the year 2020(1). The Rwenzori glaciers contribute meltwater flows to aquatic ecosystems of the Rwenzori Mountains National Park, a Word Heritage Site featuring spectacular, rare Afroalpine flora and fauna, and are headwaters of the River Nile. With the overall aim of assessing the impact of recent climate change on alpine aquatic ecosystems of the Rwenzori Mountains, a collaborative, international research team led by the University College London (United Kingdom) and Makerere University (Uganda), and involving the Institut für Geographie from the University of Innsbruck (Austria) and Water Resources Management Department (Uganda) was assembled in order to pursue three primary scientific objectives: • to assess the magnitude of current glacial recession; • to assess the impact of glacial recession on alpine riverflow; and • to assess recent environmental change from observational datasets and available, environmental archives stored in lake sediment and glacial ice

LAND USE/COVER CHANGE PATTERNS IN HIGHLAND ECOSYSTEMS OF LAKE BUNYONYI CATCHMENT IN WESTERN UGANDA

Land use and cover changes influence the livelihood and degradation of fragile ecosystems. The extents of these changes in pattern were investigated in Lake Bunyonyi Catchment which lies in the South Western Highlands of Uganda. The dynamics and magnitude of land use and cover changes were assessed using Landsat (TM/ETM+) satellite images and collection of socio-economic data through interviews. The images were processed and analysed using the mean-shift image segmentation algorithm to cluster and quantify the land use and cover features. The study noted that in the assessment period 1987-2014, the small-scale farmlands, open water and grasslands remained quasi constant; while the woodlots followed a quadratic trend, with the lowest acreage experienced in 2000. The tropical high forests and wetlands cover types experienced significant decline over the years (P<0.05). Patches of small-scale farmlands, woodlots, and wetland interchangeably lost or gained more land dependant on climate variability. Even though the tropical high forest lost more than it gained, it only gained and lost to small scale farmland and woodlots; while grassland mainly lost to small scale farmland and woodlots.L\u2019occupation du sol et les changements de couverture influencent la subsistance et la d\ue9gradation des \ue9cosyst\ue8mes fragiles. La tendance des niveaux de ces changements \ue9taient \ue9valu\ue9e dans le basin versant du lac Bunyonyi qui relie les r\ue9gions montagneuses du Sud-Ouest d\u2019Ouganda. Les dynamiques et l\u2019 envergure d\u2019utilisaton de la terre et les changements de couverture \ue9taient \ue9valu\ue9es en utilisant les images du satellite Landsat (TM/ETM+) et la collecte des donn\ue9es socio-\ue9conomiques \ue0 travers des interviews. Les images \ue9taient trait\ue9es et analy\ue9es en utilisant l\u2019algorithme de segmentation de passage-moyen-d\u2019image pour grouper et quantifier les occupations du sol et les caract\ue9ristiques de la couverture. L\u2019\ue9tude a montr\ue9 que dans la p\ue9riode d\u2019\ue9valuation de 1987-2014, la petite \ue9tendue de terres cultivables, l\u2019eau libre et les prairies sont demeur\ue9es quasi constantes; tandis que les terres bois\ue9es ont suivi une tendance quadratique, avec la plus petite superficie observ\ue9e en l\u2019an 2000. Les grandes for\ueats tropicales et les zones humides ont exp\ue9riment\ue9 un d\ue9clin significatif au cours des ann\ue9es (P<0.05). Les petites parcelles de terres agricoles, les terres bois\ue9es, et les zones humides indistinctement ont perdu et gagn\ue9 plus de terres d\ue9pendamment de la variabilit\ue9 climatique. Bien que la grande for\ueat tropicale aie perdu plus qu\u2019elle en a gagn\ue9e; elle a seulement perdu de tr\ue8s petites \ue9tendues de terres agricoles et bois\ue9es; alors que les prairies ont principalement perdu de tr\ue8s petites \ue9tendues de terres agricoles et bois\ue9es

Catalyzing Transformations to Sustainability in the World's Mountains

Mountain social‐ecological systems (MtSES) are vital to humanity, providing ecosystem services to over half the planet's human population. Despite their importance, there has been no global assessment of threats to MtSES, even as they face unprecedented challenges to their sustainability. With survey data from 57 MtSES sites worldwide, we test a conceptual model of the types and scales of stressors and ecosystem services in MtSES and explore their distinct configurations according to their primary economic orientation and land use. We find that MtSES worldwide are experiencing both gradual and abrupt climatic, economic, and governance changes, with policies made by outsiders as the most ubiquitous challenge. Mountains that support primarily subsistence‐oriented livelihoods, especially agropastoral systems, deliver abundant services but are also most at risk. Moreover, transitions from subsistence‐ to market‐oriented economies are often accompanied by increased physical connectedness, reduced diversity of cross‐scale ecosystem services, lowered importance of local knowledge, and shifting vulnerabilities to threats. Addressing the complex challenges facing MtSES and catalyzing transformations to MtSES sustainability will require cross‐scale partnerships among researchers, stakeholders, and decision makers to jointly identify desired futures and adaptation pathways, assess trade‐offs in prioritizing ecosystem services, and share best practices for sustainability. These transdisciplinary approaches will allow local stakeholders, researchers, and practitioners to jointly address MtSES knowledge gaps while simultaneously focusing on critical issues of poverty and food security