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Soil resources in parts of Tanzania are rapidly being depleted by increased rates of soil erosion and downstream sediment transport, threatening ecosystem health, water and livelihood security in the region. However, incomplete understanding to what effect the dynamics of soil erosion and sediment transport are responding to land‐use changes and climatic variability are hindering the actions needed to future‐proof Tanzanian land‐use practices. Complementary environmental diagnostic tools were applied to reconstruct the rates and sources of sedimentation over time in three Tanzanian river systems that have experienced changing land use and climatic conditions. Detailed historical analysis of sediment deposits revealed drastic changes in sediment yield and source contributions. Quantitative sedimentation reconstruction using radionuclide dating showed a 20‐fold increase in sediment yield over the past 120 years. The observed dramatic increase in sediment yield is most likely driven by increasing land‐use pressures. Deforestation, cropland expansion and increasing grazing pressures resulted into accelerating rates of sheet erosion. A regime shift after years of progressive soil degradation and convergence of surface flows resulted into a highly incised landscape, where high amounts of eroded soil from throughout the catchment are rapidly transported downstream by strongly connected ephemeral drainage networks. By integrating complementary spatial and temporal evidence bases, this study demonstrated links between land‐use change, increased soil erosion and downstream sedimentation. Such evidence can guide stakeholders and policy makers in the design of targeted management interventions to safeguard future soil health and water quality. [ABSTRACT FROM AUTHOR]

Water bodies in Tanzania are experiencing increased siltation, which is threatening water quality, ecosystem health, and livelihood security in the region. This phenomenon is caused by increasing rates of upstream soil erosion and downstream sediment transport. However, a lack of knowledge on the contributions from different catchment zones, land‐use types, and dominant erosion processes, to the transported sediment is undermining the mitigation of soil degradation at the source of the problem. In this context, complementary sediment source tracing techniques were applied in three Tanzanian river systems to further the understanding of the complex dynamics of soil erosion and sediment transport in the region. Analysis of the geochemical and biochemical fingerprints revealed a highly complex and variable soil system that could be grouped in distinct classes. These soil classes were unmixed against riverine sediment fingerprints using the Bayesian MixSIAR model, yielding proportionate source contributions for each catchment. This sediment source tracing indicated that hillslope erosion on the open rangelands and maize croplands in the mid‐zone contributed over 75% of the transported sediment load in all three river systems during the sampling time‐period. By integrating geochemical and biochemical fingerprints in sediment source tracing techniques, this study demonstrated links between land use, soil erosion and downstream sediment transport in Tanzania. This evidence can guide land managers in designing targeted interventions that safeguard both soil health and water quality. [ABSTRACT FROM AUTHOR]

Soil resources in East Africa are being rapidly depleted by erosion, threatening food, water and livelihood security in the region. Here we demonstrate how the integration of evidence from natural and social sciences has supported a community‐led change in land management in an agro‐pastoral community in northern Tanzania. Geospatial analysis of erosion risk and extent (based on a drone survey across a 3.6 km2 sub‐catchment) revealed that recently converted land had ca 12‐times greater rill density than established slow‐forming terraced plots (987 ± 840 m2 ha−1 vs. 79 ± 110 m2 ha−1). Slope length and connectivity between plots were key factors in the development of rill networks rather than slope per se wherein slope length was augmented by weak boundaries between newly formed plots. Erosion evidence, supported by communication of 'process' and 'structural' hydrological connectivity, was integrated with local environmental knowledge within participatory community workshops. Demonstration of the critical time window of hillslope‐scale rill erosion risk during early phases of slow‐forming terrace development catalysed a community‐led tree planting and grass seed sowing programme to mitigate soil erosion by water. This was grounded in an implicit farmer understanding of the need for effective governance mechanisms at both community and District levels, to enable community‐led actions to be implemented effectively. The study demonstrates the wide‐reaching impact of integrated and interdisciplinary 'upslope‐downslope' thinking to tackle global soil erosion challenges. [ABSTRACT FROM AUTHOR]

Increased soil erosion is one of the main drivers of land degradation in East Africa's agricultural and pastoral landscapes. This wicked problem is rooted in historic disruptions to co-adapted agro-pastoral systems. Introduction of agricultural growth policies by centralised governance resulted in temporal and spatial scale mismatches with the complex and dynamic East African environment, which subsequently contributed to soil exhaustion, declining fertility and increased soil erosion. Coercive policies of land use, privatisation, sedentarisation, exclusion and marginalisation led to a gradual erosion of the indigenous social and economic structures. Combined with the inability of the new nation-states to provide many of the services necessary for (re)developing the social and economic domains, many communities are lacking key components enabling sustainable adaptation to changing internal and external shocks and pressures. Exemplary is the absence of growth in agricultural productivity and livelihood options outside of agriculture, which prohibits the absorption of an increasing population and pushes communities towards overexploitation of natural resources. This further increases social and economic pressures on ecosystems, locking agro-pastoral systems in a downward spiral of degradation. For the development and implementation of sustainable land management plans to be sustainable, authorities need to take the complex drivers of increased soil erosion into consideration. Examples from sustainable intensification responses to the demands of population increase, demonstrate that the integrity of locally adapted systems needs to be protected, but not isolated, from external pressures. Communities have to increase productivity and diversify their economy by building upon, not abandoning, existing linkages between the social, economic and natural domains. Locally adapted management practices need to be integrated in regional, national and supra-national institutions. A nested political and economic framework, wherein local communities are able to access agricultural technologies and state services, is a key prerequisite towards regional development of sustainable agro-pastoral systems that safeguard soil health, food and livelihood security. [ABSTRACT FROM AUTHOR]

Extensive land degradation is a global problem that presents a critical threat to pastoralists' welfare in East Africa and beyond. Although the reasons for this environmental problem are complex, it is likely to be exacerbated by communal land management practices that have become suboptimal due to changes in land access and population growth. In the present paper we make initial steps towards addressing the problem by exploring socio-psychological predictors of willingness to protect communal land from degradation among Maasai pastoralists in Northern Tanzania. Based on the social identity approach and existing evidence for the role of group processes in pro-environmental action, we have developed and tested a path model predicting willingness to protect communal land. The results demonstrate that community identification is linked to willingness to act via perceived development of action-consistent group and personal norms. In addition, multiple groups analysis demonstrated a number of gender differences within the model. The results are broadly consistent with the existing social identity models of pro-environmental action, extending them into a novel context, and offering practical implications for addressing the issue of pastoralist land degradation. • We conducted a survey of 297 Maasai pastoralists in Northern Tanzania. • It explored predictors of willingness to protect communal land from degradation. • A path model based on the social identity approach was tested. • Community identification was linked to willingness to act via norms. • Multiple groups analysis demonstrated a number of gender differences. [ABSTRACT FROM AUTHOR]