Relationships between on-farm tree stocks and soil organic carbon along an altitudinal gradient, Mount Kilimanjaro, Tanzania

Understanding above-ground tree biomass carbon (AGC) and relationships to soil organic carbon (SOC) stocks across a landscape provide opportunities for better management of the carbon pools. This study determined relationships between on-farm AGC and SOC stocks along an altitudinal gradient on the slopes of Mount Kilimanjaro. Fifty plots (100 × 100 m) were established, whereby all trees ≥5 cm dbh, were recorded. Soil samples from top (0–20 cm) and subsoils (21–50 cm) were collected at the centre of the plots using four subplots. Tree inventory and soil analyses were performed and statistical tests were conducted to understand relationships between AGC and SOC stocks. Results indicated that stem density increased with altitude, however the upland and the midland did not differ significantly while the lowland differs with both the midland and the upland. A similar pattern was observed for basal area and above-ground tree biomass (AGB), with no significant difference between the midland and upland whereas the lowland differed significantly from both the upland and the midland. SOC stocks varied significantly, being the largest in the upland, amounting to almost twice the size recorded in the midland or the lowland. SOC stocks indicated poor correlation (Pearson’s: r = 0.327, df = 47, p = 0.023) and poor interaction (Wald = 0.0008, df = 1, p = 0.977) with AGC. This study concludes that the relationship between AGC and SOC stocks was masked by other factors including soil types, precipitation and land management. The protocol used to test the relationships might also have contributed further to current observation. Overall, the lowland area, having low AGC and SOC stocks, requires management interventions aimed at increasing SOC stocks

Relationships between on-farm tree stocks and soil organic carbon along an altitudinal gradient, Mount Kilimanjaro, Tanzania

Understanding above-ground tree biomass carbon (AGC) and relationships to soil organic carbon (SOC) stocks across a landscape provide opportunities for better management of the carbon pools. This study determined relationships between on-farm AGC and SOC stocks along an altitudinal gradient on the slopes of Mount Kilimanjaro. Fifty plots (100 × 100 m) were established, whereby all trees ≥5 cm dbh, were recorded. Soil samples from top (0–20 cm) and subsoils (21–50 cm) were collected at the centre of the plots using four subplots. Tree inventory and soil analyses were performed and statistical tests were conducted to understand relationships between AGC and SOC stocks. Results indicated that stem density increased with altitude, however the upland and the midland did not differ significantly while the lowland differs with both the midland and the upland. A similar pattern was observed for basal area and above-ground tree biomass (AGB), with no significant difference between the midland and upland whereas the lowland differed significantly from both the upland and the midland. SOC stocks varied significantly, being the largest in the upland, amounting to almost twice the size recorded in the midland or the lowland. SOC stocks indicated poor correlation (Pearson’s: r = 0.327, df = 47, p = 0.023) and poor interaction (Wald = 0.0008, df = 1, p = 0.977) with AGC. This study concludes that the relationship between AGC and SOC stocks was masked by other factors including soil types, precipitation and land management. The protocol used to test the relationships might also have contributed further to current observation. Overall, the lowland area, having low AGC and SOC stocks, requires management interventions aimed at increasing SOC stocks

Land Use and Environmental Gradients Influence on Riparian Woody Plant Diversity and Structure in Lake Manyara Watershed Ecosystem, Tanzania

This research article was published in Open Journal of Ecology, Volume 13, 2023.Riparian vegetations are important in supporting ecological connectivity between aquatic and terrestrial ecosystems. The structure and species composition of riparian woody plants have been subjected to multiple forces with varying degree of influences. This study examined the influence of land use and environmental gradient to the structure and composition of the riparian woody plants in northern Tanzania. A total of 270 plots were surveyed for woody plant species in the riparian ecosystems and later analysed to determine the influence of land use categories (homegarden, crop field, woodlot, open canopy forest, and closed canopy forest) and environmental variables (temperature, precipitation, elevation and slope) to the species richness, abundance, and stand parameters. Basal area was higher in woodlots, homegardens and crop fields than in the open and closed canopy forests; and as expected the reverse was true for the number of stocking density. Correlation among stand parameters with environmental variables varied significantly. Species richness and species abundance were negatively correlated to precipitation, temperature and elevation, while stocking density and basal area were positively correlated to precipitation. The study recommends continual retentions of trees on farm, further promoting of agroforestry interventions and sustainable utilization of woody plants in open and close canopy forests

Variability of Soil Micronutrients Concentration along the Slopes of Mount Kilimanjaro, Tanzania

Soil micronutrients are important elements for plant growth despite being required in small quantities. Deficiency of micronutrients can result in severe crop failure while excess levels can lead to health hazards; therefore, investigating their status in agricultural land is crucial. Fifty plots were established along an altitudinal gradient from 680 to 1696 m a.s.l. on the slopes of Mount Kilimanjaro, Tanzania. Soils were sampled at the top- (0–20 cm) and subsoils (21–50 cm) in four locations within each plot. Fourier Transform Mid-Infrared (FT-MIR) spectroscopy and wet chemistry were used for soil analysis. Results indicated that the mean concentrations of the micronutrients in the topsoil were Fe (130.4±6.9 mgkg−1), Mn (193.4±20.5 mgkg−1), Zn (2.8±0.2 mgkg−1), B (0.68±0.1 mgkg−1), and Cu (8.4±0.8 mgkg−1). Variations of the micronutrients were not statistically different by elevation (df = 41, p>0.05) and by soil depth (df = 49, p>0.05). Correlations among micronutrients were significant for Fe versus Mn (r=0.46, p<0.001), B versus Zn (r=0.40, p=0.003), B versus Cu (r=0.34, p=0.013), and Cu versus Zn (r=0.88, p<0.001). The correlated micronutrients implied that they were affected by similar factors. Soil pH correlated positively with B, Fe, and Mn and negatively with Cu and Zn, hence probably influencing their availability. Therefore, the need for sustaining micronutrient at sufficient levels is crucial. Management interventions may include moderating soil pH by reducing acidity through liming in the higher elevations and incorporation of organic matter in the lowlands

Forests, Farms, and Fallows: The Dynamics of Tree Cover Transition in the Southern Part of the Uluguru Mountains, Tanzania

This research article was published by MDPI, 2021Forests and woodlands remain under threat in tropical Africa due to excessive exploitation and inadequate management interventions, and the isolated success stories of tree retention and tree cover transition on African agricultural land are less well documented. In this study, we characterize the status of tree cover in a landscape that contains forest patches, fallows, and farms in the southern part of Uluguru Mountains. We aimed to unveil the practices of traditional tree fallow system which is socially acceptable in local settings and how it provides a buffering effects to minimize forest disturbances and thus represents an important step towards tree cover transition. We assessed land cover dynamics for the period of 1995 to 2020 and compared tree stocking for forest patches, fallows, and farms. We found that tree biomass carbon stocks were 56 ± 5 t/ha in forest patches, 33 ± 7 t/ha in fallows, and 9 ± 2 t/ha on farms. In terms of land cover, farms shrank at intensifying rates over time for the entire assessment period of 1995–2020. Forest cover decreased from 1995–2014, with the reduction rate slowing from 2007–2014 and the trend reversing from 2014–2020, such that forest cover showed a net increase across the entire study period. Fallow consistently and progressively increased from 1995–2020. We conclude that traditional tree fallows in the study site remain a significant element of land management practice among communities, and there appears to be a trend towards intensified tree-based farming. The gains in fallowed land represent an embracing of a traditional land management system that supports rotational and alternate uses of cropping space as well as providing a buffering effect to limit over-exploitation of forests. In order to maximize tree cover and carbon stocks in the farm landscape, this well-known traditional tree fallow system can be further optimized through the incorporation of additional innovations

Evidence-based opportunities for out-scaling climate-smart agriculture in East Africa

Climate-smart agriculture (CSA) is being widely promoted as a solution for food insecurity and climate change adaptation in food systems of sub-Saharan Africa, while simultaneously reducing the rate of greenhouse gas emissions. Governments throughout Africa are writing policies and programs to promote CSA practices despite uncertainty about the ability for practices to meet the triple CSA objectives of CSA. We conducted a systematic review of 175 peer-reviewed and grey literature studies, to gauge the impact of over seventy potential CSA practices on CSA outcomes in Tanzania and Uganda. Using a total of 6,342 observations, we found that practice impacts were highly context (i.e. farming system and location) specific. Nevertheless, practice effect across CSA outcomes generally agreed in direction. While our results suggest that CSA is indeed possible, lack of mitigation data precludes a more conclusive statement. Furthermore, the inclusion of potential adoption rates changes the potential of CSA practices to achieve benefits at scale. Given the uncertainty and variable impacts of practices across regions and outcomes, it is critical for decision makers to prioritize practices based on their desired outcomes and local context

REVIEW OF CLIMATE CHANGE MITIGATION IN AGRICULTURE IN TANZANIA

This report assesses and identified policies, strategies and initiatives led by the Tanzanian government towards addressing the impact of climate change in agriculture. Supporting 80% of the population, agriculture is still the main stay of the economy, and hence any negative impact originating from climate change to this sector has significant effect to the country economy and community livelihoods. The commitments of the Tanzanian government towards combating climate change at national, international and local level have been exemplary. Furthermore, due to less mechanized form of agriculture which also a rainfed, less input in terms of inorganic fertilizer and chemical pesticides, the country is still contributing less to the emission of the greenhouse gases (GHG). GHGs emission in Tanzania is reported mainly to be from land use change and forestry by 87.33%, energy and agriculture ranking second and third by contribution 6.39% and 5.68% respectively. This information gives an impression that despite less emission of GHGs in agriculture compared to other sectors, special attention needs to be paid on soil and livestock in order to reduce the emission from agriculture. The expected growth in agricultural sector may trigger acceleration of GHGs emission which might surpass other sectors, currently the conversion of natural forests and woodlands into agricultural fields is at alarming rate, the current rate of deforestation that have been reported by the government stands at 400,000 ha/year, agricultural sector is said to be the key contributor of deforestation. The REDD+ readiness phase is the most significant mitigation program, the readiness phase has been implemented through the UN-REDD and the NICFI programme with a total budget of over 100mil USD. The readiness phase has laid down a foundation to most ground work to support accounting on GHGs emission. Moreover, the readiness phase gave set up of the MRV system together with a road map for RL/REL. currently the ability of the nation to collect emission data (NFI) is much enhanced than before. Institutional arrangement and coordination for Carbon monitoring is well underway through the NCMC. However the development of MRV system in Tanzania is still at infancy stage as many of the key issues are not in place viz. NFMS, RL/REL and the definition of forest. Tanzania has a good foundation of policy framework to address adaptation and mitigation of climate change in agriculture. It needs very complex and accommodating methods and tools that will capture differences in agro-ecologies farming systems, agricultural input levels and other land management.The document is also available ttp://www.fao.org/climatechange/micca/en/) .Government of Finland

Variability of Soil Micronutrients Concentration along the Slopes of Mount Kilimanjaro, Tanzania

Soil micronutrients are important elements for plant growth despite being required in small quantities. Deficiency of micronutrients can result in severe crop failure while excess levels can lead to health hazards; therefore, investigating their status in agricultural land is crucial. Fifty plots were established along an altitudinal gradient from 680 to 1696 m a.s.l. on the slopes of Mount Kilimanjaro, Tanzania. Soils were sampled at the top- (0–20 cm) and subsoils (21–50 cm) in four locations within each plot. Fourier Transform Mid-Infrared (FT-MIR) spectroscopy and wet chemistry were used for soil analysis. Results indicated that the mean concentrations of the micronutrients in the topsoil were Fe (130.4±6.9 mgkg−1), Mn (193.4±20.5 mgkg−1), Zn (2.8±0.2 mgkg−1), B (0.68±0.1 mgkg−1), and Cu (8.4±0.8 mgkg−1). Variations of the micronutrients were not statistically different by elevation (df = 41, p>0.05) and by soil depth (df = 49, p>0.05). Correlations among micronutrients were significant for Fe versus Mn (r=0.46, p<0.001), B versus Zn (r=0.40, p=0.003), B versus Cu (r=0.34, p=0.013), and Cu versus Zn (r=0.88, p<0.001). The correlated micronutrients implied that they were affected by similar factors. Soil pH correlated positively with B, Fe, and Mn and negatively with Cu and Zn, hence probably influencing their availability. Therefore, the need for sustaining micronutrient at sufficient levels is crucial. Management interventions may include moderating soil pH by reducing acidity through liming in the higher elevations and incorporation of organic matter in the lowlands