Natural Sciences

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Above-ground biomass and carbon stocks of different land cover types in Mt. Elgon, Eastern Uganda
(International Journal of Research on Land-use Sustainability, 2014) Buyinza, Joel; Balaba Tumwebaze, Susan; Namaalwa, Justine; Byakagaba, Patrick
This research applied selected allometric models to estimate the total above ground biomass (TAGB) and carbon stocks in the different land-use/ land cover (LULC) types in Mt. Elgon National Park, in Eastern Uganda. The LULC types identified for the study were – tropical high forest (THF) - normal, THF- degraded and grasslands. The vegetation in each land cover type was assessed at four levels i.e. the mature trees, poles, saplings and undergrowth. Tree diameter and height of each sampled tree were also measured. In each plot, one sapling was randomly selected, uprooted and sub-samples of the foliage, bole and root components were collected, and their fresh weight was determined in the field. Calculation of the Mean Squared Error (MSE), Prediction Sum of Squares (PRESS) statistic and Predicted R2 values of the selected equations was done to establish the most appropriate equation for biomass and carbon estimation. The TAGB was 652.15t/ha, 55.16t/ha and 41.7t/ha in the THF-Normal, THF-Degraded and Grasslands respectively. The carbon stocks in the THF-normal were 293.65tC ha-1, 25 tC ha-1 in the THF-degraded and 18.76 tC ha-1 in the grasslands. Over 90% of sequestered carbon was lost due to land cover change from THF-Normal to THF-Degraded. This calls for policy makers to urgently come up with interventions to address forest degradation.
Abundance and Diversity of Native Forage Species in Pastoral Karamoja Sub-Region, Uganda
(African study monographs, 2015) Egeru, Anthony; Wasonga, Oliver; MacOpiyo, Laban; Mburu, John; Majaliwa Mwanjalolo, G.J
Low input pastoral production systems rely exclusively on natural forage resources in space and time. Information on the abundance and diversity of such pastures is vital in improving livestock production and managing the biodiversity of grazing landscapes. This study documented grass and browse forage species utilised in pastoral Karamoja, and determined their relative abundance by district, season and grazing land cover. Up to 65 grass and 110 browse species were utilised in Karamoja Sub-region. In-situ assessments revealed that Chloris, Hyparrhennia, Sporobolus, Pennisetum, Aristida, Cynodon, Eragrostis, Setaria, and Panicum grasses had higher relative abundance. Triumfetta annua, Indigofera erecta, Acacia drepanolobium, Grewia holstii, Acacia kirkii, Acacia mellifera, Acacia tortolis, Maerua pseudopetalosa, Acacia oerfota, and Ocimmum canum woody species were the most abundant. From the community assessment, Hyparrhennia, Chloris, Panicum, Bracharia, Eragrostis, and Setaria grasses and Acacia mellifera, Cadaba farinose, Acacia oerfota, Acacia drepanolobium, Caparis tormentosa, Maerua pseudopetalosa and Hisbiscus micrantha woody plants were identified as the most abundant among the grazing land cover. The grass and browse forage species varied by season, location, and land cover type. The study also found detailed local knowledge of grass and browse forage species in the community. This study has shown the existence of high diversity among grass and browse forage species with differentiated relative abundance across space and time. This, and the detailed communal cultural knowledge, form a basis for the improvement of livestock production as well as biodiversity conservation in Karamoja sub-region.
Abundance, movements and habitat use by African Grey Parrots (Psittacus erithacus) in Budongo and Mabira forest reserves, Uganda
(Journal of African Ornithology, 2007) Amuno, John B.; Massa, Renato; Dranzoa, Christine
Populations of African Grey Parrots are threatened by increased forest loss and the pet trade. Budongo forest reserve has, for over 60 years, been subjected to selective logging. Mabira forest reserve faces human pressures characterised by extractive disturbances, and agricultural activities with increased boundary settlements. We estimated parrot populations using the ‘forest limiting circumference’ method, and ‘encounter rate approach’ for general abundance and forest type associations, respectively. Counts were conducted on flyways in the morning and evening of one day, and observations on food tree location and preference were made by forest type and time of day. Total parrot populations were estimated at 714 in Budongo and 342 in Mabira. Mean numbers of flocks observed per flyway were 4.18 ± 4.33 and 4.70 ± 2.71 for Budongo and Mabira, respectively. Similarly, flock sizes varied from 2.59 ± 2.95 in Budongo to 2.87 ± 3.06 in Mabira forest. High encounter rates were recorded in disturbed/secondary forests during foraging activities and these coincided with areas of abundant fruiting trees. Movements into and out of main forests followed regular flyways and inter-forest movements increased with forest fragmentation. However, the presence of forest strips seemed to enhance the stability of flyways. While African Grey Parrots in Budongo may benefit from its large size, the Mabira population is likely to face a greater threat of further decline. More protected areas are needed to maintain viable populations, and future research should focus on breeding ecology, population monitoring and the impact of trade activities on this species.
Active restoration facilitates bird community recovery in an Afrotropical rainforest
(Biological Conservation, 2016) Latja, Pirita; Valtonena, Anu; Malinga, Geoffrey M.; Roininen, Heikki
Active restoration of rainforests is essential in enhancing the recovery of biodiversity in many tropical regions suffering from deforestation. However, the value of actively restored rainforests for birds is still relatively poorly understood because of the short history of active restoration programs. Here, we studied the recovery of bird communities in Kibale National Park, Uganda.Wesampled birds along a restoration gradient consisting of six restoration areas (3–16 years old) and used five primary forests as reference areas. We found that bird community compositions changed in an orderly fashion along the restoration gradient. The abundance of arboreal insectivore frugivores and forest specialists increased, while that of foliage-gleaning insectivores, granivores and forest visitors decreased towards older sites. The similarity of the bird communities of the restored forests to those of the nearby primary forests increased linearly with time. If this recovery rate is extrapolated to the future, the bird communities could reach a pre-disturbance state after only approximately 20 years of active restoration. However, previous studies have shown that recovery is typically a non-linear process, and the time needed for bird communities to recover is more likely longer than this. Nevertheless, our study provides evidence that bird communities benefit from active rainforest restoration after human-induced deforestation.
Adaptation To Climate Change In Uganda: Evidence From Micro Level Data
(Global environmental change, 2011) Hisali, Eria; Birungi, Patrick; Buyinza, Faisal
This study employed data from the 2005/06 Uganda national household survey to identify adaptation strategies and factors governing their choice in Uganda's agricultural production. Factors that mediate or hinder adaptation across different shocks and strategies include age of the household head, access to credit and extension facilities and security of land tenure. There are also differences in choice of adaptation strategies by agro-climatic zone. The appropriate policy level responses should complement the autonomous adaptation strategies by facilitating technology adoption and availing information to farmers not only with regard to climate related forecasts but available weather and pest resistant varieties.
Adaptation to Climate Change in Uganda: Evidence from Micro Level Data
(Global environmental change, 2011) Hisali, Eria; Birungi, Patrick; Buyinza, Faisal
This study employed data from the 2005/06 Uganda national household survey to identify adaptation strategies and factors governing their choice in Uganda's agricultural production. Factors that mediate or hinder adaptation across different shocks and strategies include age of the household head, access to credit and extension facilities and security of land tenure. There are also differences in choice of adaptation strategies by agro-climatic zone. The appropriate policy level responses should complement the autonomous adaptation strategies by facilitating technology adoption and availing information to farmers not only with regard to climate related forecasts but available weather and pest resistant varieties.
Adaptive Party Choice of Low-Ranking Males in Fission–Fusion Dynamics of Chimpanzees in Kalinzu Forest Reserve, Uganda
(MDPI AG, 2022-08) Shibata, Shohei; Furuichi, Takeshi; Hashimoto, Chie
Several studies have examined factors that regulate fission–fusion dynamics (FFD) in chimpanzee communities, such as receptive females, predation risks, and food availability. However, the effects of these factors vary between populations. In this study, we conducted focal animal observations of adult males in the M group in Kalinzu to examine the influence of male dominance rank, aggression from other males, the presence of females exhibiting maximum sexual swelling (MS), and fruit abundance on male tendencies of party attendance. We found that low-ranking males spent more time alone than other males when females with MS were absent. In contrast, when females with MS were present, males of all ranks showed a similar tendency of party attendance. We also found that the aggressive interactions increased with the number of males irrespective of the presence or absence of females with MS, and low-ranking males attracted aggression more frequently than higher-ranking males. These results suggest that low-ranking males frequently ranged alone to avoid aggression from other males unless they attended parties to seek mating opportunities. We conclude that low-ranking males have alternative tactics to balance the costs and benefits incurred or gained when attending parties.
Adoption Patterns and Intensity for Multiple BananaTechnologies in Uganda
(MDPI AG, 2022-12) Stella Kiconco; Suresh Chandra Babu; Kenneth Akankwasa
The adoption of improved technologies is widely recognized as key to improving agricultural productivity in Sub-Saharan Africa. This study analyzes adoption patterns and intensity of multiple banana technologies in Uganda which have been promoted over time. We used primary data collected from 383 banana farmers sampled using a multi-stage sampling procedure. Multivariate probit (MVP) and ordered probit analyses were applied to establish the adoption patterns and adoption intensity, respectively, and any factors affecting them. The findings highlight that 15 pairwise correlation coefficients among banana technologies were statistically significant implying that banana farmers adopt technologies simultaneously. The household size, total banana area, ecological location, membership to farmer groups, access to formal credit sources, and the type of market accessed had significant effects on household adoption patterns and intensity. Thus, it is recommended that such factors should be seriously considered in addition to technology characteristics when planning promotion programs. Simultaneous adoption implies that each of the technologies should be considered as a package which contributes to the increased farmer options and maximum synergistic effects among them. This study contributes to the existing literature by highlighting the key variables which affect the pattern and intensity of adopting technological packages involving both input intensification and low-external-input technologies in Uganda.
Adsorbed complex and laboratory geotechnics of Quarry Dust (QD) stabilized lateritic soils
(Environmental Technology & Innovation, 2018) Onyelowe, Kennedy
The effect of ordinary Portland cement, OPC+Quarry Dust, QD on the adsorbed moisture, diffused double layer (DDL), dielectric constant, density and repulsion potential (RP) of treated lateritic soil was investigated through laboratory tests. The preliminary tests showed that the natural soil was an A-2-7 soil, according to the AASHTO classification system, highly plastic soil and high swelling potentials. The soil was treated with a fixed 5% OPC and varying proportions of QD at 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by weight of the dry soil. The stabilization results showed that the compaction properties improved consistently, with the addition of the QD. Also, the addition of the QD reduced the adsorbed moisture and consequently reduced the double diffused layer and the repulsion potential, which constitute the properties investigated within the adsorbed complex in the stabilization operation. These observations brought about the cation exchange reaction between the metallic ions that were attracted to the adsorption complex, resulting to densification, flocculation from the natural state of dispersion of particles and strength gain in the stabilization procedure. Results also showed that the repulsion potential increased in magnitude with the distance between the reactive particles and the clay surface and reduced with increased proportions of QD. The dielectric constant also reduced considerably with adsorbed moisture, which indicated that the dielectric was affected by the moisture and the ions released within the adsorbed complex.
African food insecurity in a changing climate: The roles of science and policy
(Food and Energy Security, 2019) Onyutha1, Charles
African population is projected to double to 2.48 billion people by 2050. The population increase poses a serious challenge of increasing food supply to meet the future demand. This challenge is compounded by climate change impacts on agriculture. In this paper, how poverty contributes to household food insecurity is explored and measures suggested to help address this challenge. To plan adaptation measures, linkages among food insecurity, poverty, and illiteracy should be considered. For the sub-Saharan Africa (SSA), adaptation (focused on poverty alleviation) should be prioritized and preferred to mitigation. Enhancement of adaptive capacity should not only be tailored toward empowerment of women but also made highly localized to household levels. Generally, efforts could be geared toward yield gap closure, addressing challenges regarding food distribution, promoting non-farm income-generating activities, and unification of government priorities in agriculture and food security. Government in each country of the SSA should ensure that governance strongly embraces transparency, accountability, and integrity otherwise as it is said a fish rots from the head down. Estimates of uncertainty in predicting future climate and their implications on expenditure related to adaptation should to always be made in an integrated way and reported to support actionable policies. To increase credibility in climate prediction especially at local scales, advances toward improving climate models (for instance by refining spatiotemporal scales, enhancing models’ capacity to reproduce observed natural variability in key climatological variables like rainfall) should be made, and this requires support from the investment in climate science. Science–policy interfacing is required in planning and implementation of measures for adapting to climate change impacts. In summary, food insecurity and persistent poverty especially in the SSA should be of direct relevance and concern at a global scale. Thus, global collaboration in science is key to achieve food security in the SSA.
Age validation, growth and mortality of introduced Tilapia zillii in Crater Lake Nkuruba, Uganda
(Fisheries Management and Ecology, 2016) Efitre, J .; Murie, D . J .; Chapman, L . J .
Periodicity and timing of opaque zone formation in otoliths of introduced redbelly tilapia, Tilapia zillii (Gervais), in Crater Lake Nkuruba, Uganda, were validated using marginal increment. Age and growth were assessed through readings of biannuli in thin-sectioned sagittal otoliths. Deposition of opaque zone formation in T. zillii otoliths was bimodal (March–May and September–November), corresponding to two seasonal peaks of precipitation characteristic of this equatorial region. Ages of T. zillii ranged from 2 to 8 years, with fish gillnetted offshore having a faster growth and attaining larger size-at-age than fish captured inshore in minnow traps, suggesting that use of multiple gears is needed when estimating the growth of T. zillii. Total instantaneous mortality (Z), estimated using catch curve analysis, was 0.74 for gillnetted fish and 0.71 for trapped fish. These estimates were at the low end of the total mortality reported for other tilapia species. Natural mortality (M) was estimated as 0.52–0.54 by applying Rikhter and Efanov’s maximum age at maturity and Hoenig’s maximum age methods, respectively. Fishing mortality (F) in Lake Nkuruba was 0.17–0.22, indicating a low exploitation level in the lake.
An age-structured mathematical model for the within host dynamics of malaria and the immune system
(Springer, 2007) Luboobi, L. S.; Tumwiine, J.; Luckhaus, S.; Mugisha, J. Y. T.
In the paper, we use a mathematical model to study the population dynamics of replicating malaria parasites and their interaction with the immune cells within a human host. The model is formulated as a system of age-structured partial differential equations that are then integrated over age to obtain a system of nonlinear delay differential equations. Our model incorporates an intracellular time delay between the infection of the red blood cells by the merozoites that grow and replicate within the infected cells to produce new merozoites. The infected red blood cells burst approximately every 48 h releasing daughter parasites to renew the cycle. The dynamical processes of the parasites within the human host are subjected to pressures exerted by the human immunological responses. The system is then solved using a first-order, finite difference method to give a discrete system. Numerical simulations carried out to illustrate stability of the system reveal that the populations undergo damped oscillations that stabilise to steady states.
Agricultural expansion as risk to endangered wildlife: Pesticide exposure in wild chimpanzees and baboons displaying facial dysplasia
(Science of the Total Environment, 2017) Krief, Sabrina; Berny, Philippe; Gumisiriza, Francis; Gross, Régine; Demeneix, Barbara; Baptiste Fini, Jean; Chapman, Colin A.; Chapman, Lauren J.; Seguya, Andrew; Wasswa, John
Prenatal exposure to environmental endocrine disruptors can affect development and induce irreversible abnormalities in both humans and wildlife. The northern part of Kibale National Park, a mid-altitude rainforest in western Uganda, is largely surrounded by industrial tea plantations and wildlife using this area (Sebitoli) must cope with proximity to human populations and their activities. The chimpanzees and baboons in this area raid crops (primarily maize) in neighboring gardens. Sixteen young individuals of the 66 chimpanzeesmonitored (25%) exhibit abnormalities including reduced nostrils, cleft lip, limb deformities, reproductive problems and hypopigmentation. Each pathology could have a congenital component, potentially exacerbated by environmental factors. In addition, at least six of 35 photographed baboons from a Sebitoli troop (17%) have similar severe nasal deformities. Our inquiries in villages and tea factories near Sebitoli revealed use of eight pesticides (glyphosate, cypermethrin, profenofos, mancozeb, metalaxyl, dimethoate, chlorpyrifos and 2,4-D amine). Chemical analysis of samples collected from 2014 to 2016 showed that mean levels of pesticides in fresh maize stems and seeds, soils, and river sediments in the vicinity of the chimpanzee territory exceed recommended limits. Notably, excess levels were found for total DDT and its metabolite pp′-DDE and for chlorpyrifos in fresh maize seeds and in fish from Sebitoli. Imidacloprid was detected in coated maize seeds planted at the edge the forest and in fish samples from the Sebitoli area, while no pesticides were detected in fish from central park areas. Since some of these pesticides are thyroid hormone disruptors, we postulate that excessive pesticide use in the Sebitoli area may contribute to facial dysplasia in chimpanzees and baboons through this endocrine pathway. Chimpanzees are considered as endangered by IUCN and besides their intrinsic value and status as closely related to humans, they have major economic value in Uganda via ecotourism. Identifying and limiting potential threats to their survival such be a conservation priority.
Agrobiodiversity of homegardens in a commercial sugarcane cultivation land matrix in Uganda
(International Journal of Biodiversity Science, Ecosystem Services & Management, 2016) Mwavu, Edward N.; Ariango, Esther; Ssegawa, Paul; Kalema, Vettes N.; Bateganya, Fred; Waiswa, Daniel; Byakagaba, Patrick
ABSTRACT Understanding biodiversity in homegardens embedded in landscapes dominated by commercial monoculture agriculture is critical for sustainable management of agrobiodiversity and meeting rural households’ needs in the face of global changes. We assessed agrobiodiversity in the 120 homegardens and its contribution to rural household livelihood strategies within a commercial monoculture sugarcane cultivation land matrix in eastern Uganda. We recorded a total of 68 plant species from 46 genera representing 27 families. Species richness spanned 6 to 19 species, and α-diversity (H’) ranged from 0.6 to 2.3; with 86.67% of the homegardens having H’ >1. Species composition differed significantly (global RANOSIM = 0.153, p < 0.001) among the villages. The most important and commonly maintained plants were those that provided food, fuelwood and money income and included Zea mays L., Manihot esculenta, Phaesolus spp., Coffea sp., Musa spp., Ipomea batatus and Artocarpus heterophyllus. Most of the crops cited as useful by households were also frequent and visible in many of the homegardens. Although homegardens still hold some valuable plants, there is also loss of important plants from the agricultural system including cowpeas, soya beans, bambara groundnuts, finger millet, cotton, aerial yams and oysternut essential for sustaining household livelihoods. This loss, precipitated by increased land-use/cover change to commercial sugarcane plantations threatens agrobiodiversity conservation and the benefits households derive from homegardens. Our findings underline the importance of homegardens in the conservation of indigenous agrobiodiversity, and indicate that with the continued expansion of commercial sugarcane cultivation this opportunity may be lost.
Air pollution and mobility patterns in two Ugandan cities during COVID‑19 mobility restrictions suggest the validity of air quality data as a measure for human mobility
(Environmental Science and Pollution Research, 2022) Galiwango, Ronald; Bainomugisha, Engineer; Kivunike, Florence; Kateete, David Patrick; Jjingo, Daudi
We explored the viability of using air quality as an alternative to aggregated location data from mobile phones in the two most populated cities in Uganda. We accessed air quality and Google mobility data collected from 15th February 2020 to 10th June 2021 and augmented them with mobility restrictions implemented during the COVID-19 lockdown. We determined whether air quality data depicted similar patterns to mobility data before, during, and after the lockdown and determined associations between air quality and mobility by computing Pearson correlation coefficients ( R ), conducting multivariable regression with associated confidence intervals (CIs), and visualized the relationships using scatter plots. Residential mobility increased with the stringency of restrictions while both non-residential mobility and air pollution decreased with the stringency of restrictions. In Kampala, PM2.5 was positively correlated with non-residential mobility and negatively correlated with residential mobility. Only correlations between PM2.5 and movement in work and residential places were statistically significant in Wakiso. After controlling for stringency in restrictions, air quality in Kampala was independently correlated with movement in retail and recreation (− 0.55; 95% CI = − 1.01– − 0.10), parks (0.29; 95% CI = 0.03–0.54), transit stations (0.29; 95% CI = 0.16–0.42), work (− 0.25; 95% CI = − 0.43– − 0.08), and residential places (− 1.02; 95% CI = − 1.4– − 0.64). For Wakiso, only the correlation between air quality and residential mobility was statistically significant (− 0.99; 95% CI = − 1.34– − 0.65). These findings suggest that air quality is linked to mobility and thus could be used by public health programs in monitoring movement patterns and the spread of infectious diseases without compromising on individuals’ privacy.
Air quality management strategies in Africa: A scoping review of the content, context, co-benefits and unintended consequences
(Environment International, 2022) Okello, Gabriel; Nantanda, Rebecca; Awokola, Babatunde; Thondoo, Meelan; Okure, Deo; Tatah, Lambed; Bainomugisha, Engineer; Oni, Tolu
One of the major consequences of Africa’s rapid urbanisation is the worsening air pollution, especially in urban centres. However, existing societal challenges such as recovery from the COVID-19 pandemic, poverty, intensifying effects of climate change are making prioritisation of addressing air pollution harder. We undertook a scoping review of strategies developed and/or implemented in Africa to provide a repository to stakeholders as a reference that could be applied for various local contexts. The review includes strategies assessed for effectiveness in improving air quality and/or health outcomes, co-benefits of the strategies, potential collaborators, and pitfalls. An international multidisciplinary team convened to develop well-considered research themes and scope from a contextual lens relevant to the African continent. From the initial 18,684 search returns, additional 43 returns through reference chaining, contacting topic experts and policy makers, 65 studies and reports were included for final analysis. Three main strategy categories obtained from the review included technology (75%), policy (20%) and education/ behavioural change (5%). Most strategies (83%) predominantly focused on household air pollution compared to outdoor air pollution (17%) yet the latter is increasing due to urbanisation. Mobility strategies were only 6% compared to household energy strategies (88%) yet motorised mobility has rapidly increased over recent decades. A cost effective way to tackle air pollution in African cities given the competing priorities could be by leveraging and adopting implemented strategies, collaborating with actors involved whilst considering local contextual factors. Lessons and best practices from early adopters/implementers can go a long way in identifying opportunities and mitigating potential barriers related to the air quality management strategies hence saving time on trying to “reinvent the wheel” and prevent pitfalls. We suggest collaboration of various stakeholders, such as policy makers, academia, businesses and communities in order to formulate strategies that are suitable and practical to various local contexts.
Alpine grassland palaeoecology of the Virunga Volcanoes, East Africa: A new phytolith record from Mt. Muhavura
(Quaternary International, 2017) Murungi, May L.; McGlynn, Gayle; Lejju, Julius B.
This study presents a first attempt at using phytoliths from a high-altitude crater lake as a palaeoecological tool at a tropical montane site. Mt. Muhavura (4127 m asl) at the border of Uganda and Rwanda is part of the Virunga volcanoes located in the Albertine Rift, one of the most biodiverse areas in Africa. To investigate the potential of phytoliths to record grassland history in an Afroalpine environment, a unique and little studied ecosystem, we analysed the phytolith content of 37 sediment samples from a 159 cm sediment core from the crater lake at the summit of Mt. Muhavura representing the last ca. 2400 years BP. Ten plant species from the Alpine belt were also analysed for their main phytolith morphotypes. Phytoliths from the sediments were grouped into 12 main categories and the most frequently occurring individual morphotypes were bilobate (33%), oblong (16%), elongate (17%) and globular psilate (13%). The phytolith assemblage consists predominantly of phytoliths characteristic of grasses (70%). A literal interpretation of the results would be that Panicoideae grasses (mainly C4) that are characteristic of warm and wet climate and C3 Pooideae subfamily grasses characteristic of cold climate/ high altitude have co-existed throughout the late Holocene in this belt. As only C3 cold climate grass subfamilies are known to occur at this altitude today, the abundance of short cell phytoliths (bilobates) typical of Panicoideae grasses in the lake sediments at this altitude presents a new perspective to the phytolith discussion. The C3 Pooideae grasses analysed did not produce bilobates. In this study, the phytolith index, Ic that is used as a proxy of past grass subfamily dominance is not representative of the taxonomic significance for which it is known. This study suggests that caution needs to be taken when using bilobate morphotypes and the Ic as indicators of grass subfamily dominance at high altitude on East African mountains as the bilobates may not be taxonomically representative of the grasses for which they are typically known. This highlights the inherent problem of phytolith redundancy even at an altitude where C3/C4 grass distribution is better delineated.
Amending Soils with Hydrogels Increases the Biomass of Nine Tree Species under Non-water Stress Conditions
(Clean–Soil, Air, Water, 2009) Orikiriza, Lawrence J. B.; Agaba, Hillary; Tweheyo, Mnason; Eilu, Gerald; Kabasa, John David; Huttermann, Aloys
The classical aim of the application of super absorbent polyacrylate (SAPs) hydrogels is the prolonging of plant survival under water stress. Their effect on plant growth during non-water stress conditions is not known. This study examined the root and shoot biomass of seedlings of nine tree species; Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba. The seedlings were potted in five soil types; sand, sandy loam, loam, silt loam and clay. These were amended at two hydrogel levels: 0.2 and 0.4% w/w and grown under controlled conditions in a green house. Root and shoot growth responses of the seedlings were determined by measuring the dry weight of the roots, stems, leaves and twigs. The addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in a significant increase of the root dry weight (p a 0.001) in eight tree species compared to the controls after 8 wk of routine watering. Also, the dry weight of stems and leaves and twigs were significantly (p a 0.001) higher in the nine tree species potted in hydrogel amended soil types than in the hydrogel free controls. These results suggested that hydrogel amendment enhances the efficiency of water uptake and utilization of photosynthates of plants grown in soils which have water contents close to field capacity.
Analyses of community willingness-to-pay and the influencing factors towards restoration of River Malaba floodplains
(Environmental Challenges, 2021) Mubialiwo, Ambrose; Abebe, Adane; Onyutha, Charles
The high productivity of soils along River Malaba floodplains and various functions (like, transport and recreation) increase the desire for humankind settlement adjacent to floodplain corridors. However, human life and property have unceasingly been destroyed by floods. Strategies have been established to deal with floods but the problem still exists. This study employed the double-bound dichotomous choice contingent valuation method to quantify the community willingness-to-pay (WTP) and associated influencing factors for restoration of River Malaba floodplains. Reconnaissance surveys, focus group discussions, key informant interviews, observations study, and household questionnaires from 498 out of the targeted 550 respondents were employed in data collection. Among the adaptation strategies at household and community level, the post-flood strategies were more efficient than those practiced before- and during-floods. Among the suggested structural and non-structural strategies, “embankment/river training structures” and “flood forecasting and early warning” were highly preferred, respectively. The results revealed that 55% of the households expressed WTP an individual amount between Uganda shillings (UGX) 5,000 (United States Dollar, US$ 1.35) to UGX 500,000 (US$ 135.14), with a monthly average of UGX 97,080 (US$ 26.24). Total monthly amount would be UGX 38,249,500 (US$ 10,333.70) considering the 498 households. Among the factors analysed, age, gender, marital status, education level, occupation, household income, business affected, lost property due to floods, flooding a major problem had significant (p<0.01) positive impact on WTP. This study findings are pertinent in supporting stakeholders’ decision regarding predictive planning of flood adaptation strategies in the study area.
Analyses of Precipitation and Evapotranspiration Changes across the Lake Kyoga Basin in East Africa
(Water, 2020) Onyutha, Charles; Acayo, Grace; Nyende, Jacob
This study analyzed changes in CenTrends gridded precipitation (1961–2015) and Potential Evapotranspiration (PET; 1961–2008) across the Lake Kyoga Basin (LKB). PET was computed from gridded temperature of the Princeton Global Forcings. Correlation between precipitation or PET and climate indices was analyzed. PET in the Eastern LKB exhibited an increase (p > 0.05). March–April–May precipitation decreased (p > 0.05) in most parts of the LKB. However, September–October–November (SON) precipitation generally exhibited a positive trend. Rates of increase in the SON precipitation were higher in the Eastern part where Mt. Elgon is located than at other locations. Record shows that Bududa district at the foot of Mt. Elgon experienced a total of 8, 5, and 6 landslides over the periods 1818–1959, 1960–2009, and 2010–2019, respectively. It is highly probable that these landslides have recently become more frequent than in the past due to the increasing precipitation. The largest amounts of variance in annual precipitation (38.9%) and PET (41.2%) were found to be explained by the Indian Ocean Dipole. These were followed by precipitation (17.9%) and PET (21.9%) variance explained by the Atlantic multidecadal oscillation, and North Atlantic oscillation, respectively. These findings are vital for predictive adaptation to the impacts of climate variability on water resources.

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