**Abstract**

Worldwide agroforestry has been recognized as a potential greenhouse gases mitigation strategy under Kyoto protocol. And this is due to its potential in carbon sequestration. There are several agroforestry technologies with different rate in carbon sequestration. In that respect carbon sequestration can depend on type of technology, climate, time since land use change and previous land use. Our knowledge in this topic from the tropical countries such as Tanzania is how ever very limited. To address this challenge this study was undertaken in Kilombero District where the local community are practicing various agroforestry technologies. The objective of this study was to understand the carbon sequestration in different trees species in agroforestry technologies and also to understand which agroforestry technology provide the greatest benefit in term of carbon sequestration. Ecological survey was conducted and a total of 90 plot engaged in different agroforestry technologies were randomly selected from three villages of different altitudinal range. Pivot table was used in analysis and allometric equation was used for computing biomass and carbon. The result shows that *Mangifera indica* contributed highest carbon over all the tree species encountered during ecological survey with 189.88 Mg C ha−1. Home garden, Mixed intercropping, Parkland and Boundary with 19 514.19 MgCha−1, 648.44MgCha−1,144.79 MgCha−1 and 139.29 Mg C ha−1 respectively were the agroforestry technology practiced in Kilombero. From the results Home garden contributed more to carbon sequestration and this study results can be used to inform practitioners and policy makers on the most effective agroforestry technologies for carbon sequestration since agroforestry technologies are expected to play important role as climate change mitigation strategy.

**Keywords:** agroforestry technology, carbon sequestration, mitigation, climate change, carbon stock

## **1. Introduction**

Agroforestry have been considered as a viable alternative to prevent and mitigate the climate change. Using trees as means of mitigating climate change have been achieved by maintaining the existing once on farm land and or by increasing the plantation of short rotation or increasing fast growing trees on the farm fields [1]. Mitigating climate change through increased carbon sequestration in the soil can

particularly become useful especially when addressed in combination with other challenges that affect the people livelihood such as reverting land degradation and ensuring food security [2, 3].

Usually potential in carbon sequestration may occur in different land uses including Agricultural land use and forest land through improved land use management and convention to land use with higher carbon storage in harvested product [4]. On other hand IPCC recognized agroforestry having high potential for sequestering carbon under climate change mitigation strategies [1]. Within agroforestry carbon can be stored above and below ground biomass [5]. In that respect agroforestry practices accumulate more carbon than forest and pasture because they have both forestry and grassland sequestration and storage pattern active [6, 7] but, sequestration potential of agroforestry depend on plant characteristics, tree species, age, crop, biodiversity and tree density. Also depend on structural arrangement, management factor such as fertilization, residual, and harvesting regime. This factors together with agroecological condition as well as soil characteristics in the area where the agroforestry is implemented influence the above and below ground carbon sequestration [5, 8–10]. Jose and Bardhan [8] also pointed that if the agroforestry technologies is to be used for climate change mitigation through carbon sequestration, then better information is required about above and below ground biomass and carbon stock. The aim of this study was to determine the carbon stock in different agroforestry technologies and also to determine which technology has the best potential for long term carbon sequestration.
