This study assessed provisioning and cultural ecosystem services (ES) provided by natural wetlands and rice fields in two Kenyan wetlands; Ombeyi natural wetland and rice fields in Kore Irrigation ...Scheme. Data was collected through household questionnaire survey of 151 randomly selected farmers and 1 focus group discussion. The provisioning ES assessed included fibre; papyrus mats, reeds and thatching grass; fish and rice while cultural ES were religious/spiritual, eco-tourism, educational excursions and recreational use. The provisioning ES were quantified in terms of biophysical quantities and monetary value while cultural ES were graded per level of utilisation as low, medium and high. The study revealed that rice fields have enhanced food production (rice) in the area in addition to their higher value in terms of provisioning ES; rice (USD 602.49) and fish (USD 1039.50), and cultural ES (religious/spiritual and recreational use). In the natural wetland, both provisioning and cultural ES have declined over the past 20 years. The annual monetary value of USD 397.40 and 683.50 were observed for papyrus mats and fish production respectively in the natural wetland. Although rice fields seem to have higher value compared to the natural wetland sustainable utilisation of both systems is crucial in enhancing livelihoods.
•Conversion of natural wetlands into rice fields enhances food production.•Rice fields have a higher value in terms of provisioning and cultural ES.•Supply of ES in the rice fields are partially dependent on the natural wetlands.•Natural wetlands provide fibre; grass, papyrus and reeds, and fish.•Sustainable utilisation of ES in both natural wetlands and rice fields is vital.
Rice is an important food crop in Kenya and it is ranked third most consumed cereal crop after maize and wheat. The amplified demand for rice has resulted to conversion of wetlands to rice paddies ...and increased use of fertilizer, thus reducing wetlands ability to carbon sequestration. Consequently, there is enhanced emission of three potent greenhouse gases (GHGs); methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). This study assessed the impact of fertilizer application on GHGs emission and the nutrient stocks in rice paddies. The study was carried out from September 2018 to January 2019 in papyrus dominated wetland in Western Kenya. Sampling was done on a weekly basis for the first two months, and thereafter twice per month in Anyiko rice paddies located in river Nzoia basin, Kenya. Two replicates of three treatments; standard, control and under fertilization were assigned randomly in six plots. Static chamber method was used to collect GHGs and analysed by gas chromatography. Soil samples were collected and analysed for nitrogen and carbon stocks. There was no significant difference in carbon and nitrogen stocks among the three fertilization scenarios (One-way ANOVA, F (2,33)=0.219, P>0.05 for carbon and F(2,33)=0.134, P>0.05 for nitrogen). The amount of NO3-N and NH4-N were not significantly different across all the fertilization scenarios (Kruskal-Wallis, P>0.05). Kruskal-Wallis test (P>0.05) indicated that there was no significant difference in the mean fluxes of CH4 and CO2 among the three fertilization scenarios. However, for N2O the mean fluxes differed significantly (P<0.05). The mean fluxes indicated that under-fertilized plot was a probable sink for N2O (- 0.59±0.45 µgm-²h-¹) and a source for CH4 (6.93±2.42 mgm-²h-¹) and CO2 (208.81±36.20 mgm-²h-¹). Standard-fertilized plot was source for N2O, CO2 and CH4 (4.37±3.18 µgm-²h-¹, 248.29±41.22 mgm-²h-¹, 4.00±6.34 mgm-²h-¹,) respectively. The control plot acted as sink for N2O (-3.59±2.56 µgm-²h-¹) and a source for CH4 (8.30±4.79 mgm-²h-¹) and CO2 (174.80±26.81 mgm-²h-¹). In this study, different fertilization scenarios had positive effect on N2O emission but no effect on CO2 and CH4 emission and also on nutrient stocks.
In East Africa, wetlands are steadily converted to agriculture for food security reasons. This study analyzed high spatial resolution panchromatic and color photographs in the Anyiko wetland in Kenya ...to reveal wetland conversions between 1966 and 2018. In addition, socio-economic determinants of land use/cover change are assessed in the Anyiko wetland. Socio-economic data was collected through a questionnaire survey of 226 households. A CHi- squared Automatic Interaction Detector (CHAID) decision tree approach is utilized to assess determinants of wetlands conversion. The results showed that between 1966 and 2018, the wetland area reduced by 55%, mostly attributed to agricultural development. Households were more likely to cultivate the wetland if they did not harvest papyrus for artisanal products, were male-headed and lacked alternative sources of income. The perceptions that wetland is “wasteland” and conversion to agriculture provides higher net monetary benefit did not influence wetland cultivation. Hence, the conversion of the wetland was determined by the socio-economic status of the households rather than perceptions on its value.
Tropical wetlands are important climate regulators. However, their climate regulating function is at risk by land-use conversion for agricultural purposes. In sub-Saharan Africa, studies ...investigating the effect of land-use change in wetlands and associated soil greenhouse gas (GHG) emissions remain limited. Moreover, the influence of season in GHG emissions with land-use change has hardly been studied. Therefore, we investigated methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emissions from a Kenyan wetland and adjacent areas converted to farmland during the dry and rainy seasons. Moreover, we assessed which soil parameters drive the variations in GHG emissions. The GHG samples were collected by the static chamber method and analyzed by gas chromatography. For data analysis, we employed an explorative-statistical approach to explain the emission rates' variation and determine which parameters influence the GHG emissions, both as main and interaction effects. The results showed that regardless of the season, there were CH4 emissions (>0.50 mg m−2 h−1) from the wetland when soil organic carbon content was high and uptake (<0.001 mg m−2 h−1) when both soil organic carbon content and soil moisture were low. In the farmland, there was CH4 uptake when soil nitrate‑nitrogen content was high. CO2 emissions did not vary significantly between the land-use types. Instead, emission rates were primarily governed by season. The highest emissions (>175 mg m−2 h−1) during the dry season were attributed to high soil organic carbon content. During the rainy season, emissions hardly exceeded 175 mg m−2 h−1. Regarding N2O, we detected the highest emissions (>5 μg m−2 h−1) from the farmland during the dry season. Overall, this study shows that wetland conversion to farmland encourages CH4 uptake regardless of the season and increases N2O emissions during the dry season. Based on the respective GHG global warming potential, these patterns may pose an increased environmental threat.
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•CO2 emissions are influenced by season and not land-use change.•Conversion of wetlands to farmland promotes CH4 uptake regardless of the season.•Conversion of wetlands to farmland increases N2O emissions during the dry season.•Beyond season and land-use, analyses reveal the effects of soil parameters on emissions.•Wetland conversion to farmland jeopardizes climate change mitigation.
River systems have undergone a massive transformation since the Anthropocene. The natural properties of river systems have been drastically altered and reshaped, limiting the use of management ...frameworks, their scientific knowledge base and their ability to provide adequate solutions for current problems and those of the future, such as climate change, biodiversity crisis and increased demands for water resources. To address these challenges, a socioecologically driven research agenda for river systems that complements current approaches is needed and proposed. The implementation of the concepts of social metabolism and the colonisation of natural systems into existing concepts can provide a new basis to analyse the coevolutionary coupling of social systems with ecological and hydrological (i.e., ‘socio-ecohydrological’) systems within rivers. To operationalize this research agenda, we highlight four initial core topics defined as research clusters (RCs) to address specific system properties in an integrative manner. The colonisation of natural systems by social systems is seen as a significant driver of the transformation processes in river systems. These transformation processes are influenced by connectivity (RC 1), which primarily addresses biophysical aspects and governance (RC 2), which focuses on the changes in social systems. The metabolism (RC 3) and vulnerability (RC 4) of the social and natural systems are significant aspects of the coupling of social systems and ecohydrological systems with investments, energy, resources, services and associated risks and impacts. This socio-ecohydrological research agenda complements other recent approaches, such as ‘socio-ecological’, ‘socio-hydrological’ or ‘socio-geomorphological’ systems, by focusing on the coupling of social systems with natural systems in rivers and thus, by viewing the socioeconomic features of river systems as being just as important as their natural characteristics. The proposed research agenda builds on interdisciplinarity and transdisciplinarity and requires the implementation of such programmes into the education of a new generation of river system scientists, managers and engineers who are aware of the transformation processes and the coupling between systems.
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•River systems have been massively transformed and are socio-ecohydrological systems.•A socio-ecohydrologically driven approach provides insights into coevolutionary processes.•Social metabolism and the colonisation of natural systems are underlying concepts.•Four research clusters analyse the transformation and coupling of society and nature.•Interdisciplinary and transdisciplinary approaches support the operationalization of the research agenda.
The development of and access to freshwater resources in East Africa is fundamental to the region's sustainable development goals. Following vision documents for regional development and working with ...local stakeholders, we developed water scenarios up to 2050 that inform the hydro-economic modeling analysis of the extended Lake Victoria Basin, the headwaters of the Nile River. Water scenarios that take an integrated approach to assessing the combined effects of climate change, land use, and increasing human water use suggest that the flow regime of the Nile may remain relatively stable. However, if this stability is to be achieved, while at the same time sufficient water is preserved for healthy freshwater ecosystems, a large fraction of water infrastructure must rely on advanced, often costly technologies and management. Interconnected analyses of both upstream and downstream water resources over time, guided by co-developed scenarios, are indispensable for planning sustainable water-development pathways.
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•We developed a novel East Africa regional vision scenario for the water sector•Co-development is central to scenario building and analysis•A hydro-economic modeling framework integrates natural and human system trends•We assess links among climate change, water and land use, and environmental water needs
Water is critical for leveraging development opportunities in East Africa. Identifying sustainable water-development pathways in the context of climate change and environmental protection is imperative for water security. We co-developed regional water scenarios together with local stakeholders. A hydro-economic assessment of the headwaters of the Nile River revealed the upstream-downstream linkages and interconnections among socio-economic development, climate change, and the environment. Although annual freshwater resources are abundant, in an increasing number of months and sub-basins, advanced water-saving technologies and management are needed to avoid local hotspots of water scarcity. More support is needed to increase access to existing water resources for future sustainable development. We recommend that greater emphasis be put on scenario co-development to build joint research and solution implementation teams with strong ownership by policymakers and practitioners.
Water is critical for leveraging development opportunities in East Africa. Identifying sustainable water-development pathways in the context of climate change and environmental protection is imperative for water security. We co-developed regional water scenarios together with local stakeholders. A hydro-economic assessment of the headwaters of the Nile River revealed interconnections among socio-economic development, climate change, and the environment. In an increasing number of months and sub-basins, advanced water-saving technologies and management are needed to avoid local water-scarcity hotspots.
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