Miombo woodlands are extensive dry forest ecosystems in central and southern Africa covering ≈2.7 million km2. Despite their vast expanse and global importance for carbon storage, the long-term carbon stocks and dynamics have been poorly researched. The objective of this paper is to present and summarize the evidence gathered on above- and belowground (root and soil) carbon stocks of miombo woodlands from the 1960s to mid-2018 through a review. We analyzed data to answer: (1) What is the range of aboveground and belowground carbon stocks found in miombo woodlands over the last six decades? (2) Are there differences in carbon stocks based on land-management categories? (3) Does precipitation influence aboveground carbon stocks in old-growth miombo? (4) Do differences in cover type, age and region influence carbon stocks? (5) How does previous land-use affect carbon stocks in re-growth miombo? A literature review protocol was used to identify 56 publications from which quantitative data on aboveground and soil carbon pools were extracted. We found that the mean aboveground carbon stock in old-growth miombo was 30.83±16.76 Mg C ha-1 (range 1.48—107.24 Mg ha-1). Old-growth miombo had an average calculated root carbon stock of 16.49±9.18 Mg C ha-1 (range 0.8—57.81 Mg ha-1). Soil carbon stocks in old-growth miombo varied widely, between 8.75 and 134.6 Mg C ha-1 while in re-growth miombo they varied between 10.73 and 52.2 Mg C ha-1. It must be noted these soil data are given only for information; they inconsistently refer to varying soil depths and are thus difficult to interpret. The wide range reported suggests a need for further studies, much more systematic in methods and reporting. Other limitations of the dataset include the lack of systematic sampling and lack of data in some countries, viz. Angola and Democratic Republic of the Congo.

The carbon stocks in the forests originated from the atmosphere and are accumulated in the organic matter of trees and soils. Forests play major roles in providing ecosystem services like climate change mitigation through carbon sequestration and nutrient flow dynamics. Therefore, the major objective of this study was to estimate carbon stocks of Biteyu forest by quantifying the aboveground biomass of trees, belowground carbon, soil carbon, and carbon stocks of litter pool. Systematic sampling technique was employed for vegetation and carbon data collection. The total of 10 line transects were laid along elevational gradients. The transects were 500 m apart and sampling plots were 300 m apart from each other. Each transect has comprised of a minimum of 4 plots to a maximum of six totaling 50 plots representing the forest for the investigation. A square sample plot of 900 m2 was used to collect vegetation data with a DBH ≥ 2.5 cm and a height of 2 m and above. To sample herbaceous vegetation in the forest floor, five smaller subplots of 1 m x 1 m = 1 m2 (four at the corner and one at the centre of the main plot) were established. The disturbance level was also determined using the cattle interference and selective cutting of trees. The appropriate allometric models were applied for both aboveground and belowground biomass estimations. The findings showed that cattle interference affects the forest understory from growing and recruitment. The mean of cattle interference was 4.77±2.12 per ha and the mean of wood stump was 26.67±9.37 per ha. The size class analysis showed that the smallest diameter class (2.5-10 cm) in the forests represented 37.05% of the total stem density. The diameter classes between 10 and 30 cm comprised a stem density of 41.08%. It was estimated that the total carbon stock of Biteyu forest was about 166.67 ± 16.4 ha-1. The carbon stock in AGB and BGB was estimated to be 87.13 ± 11.80 t ha-1 and 22.94 ± 2.84 t ha-1, respectively. Moreover, the contribution of soil and litter carbon pools to the total carbon in the forest ecosystem were 56.37 ± 1.73 and 0.26 ± 0.01 t ha-1 , respectively. From the present study it can be concluded that estimated mean carbon stock of the forest is smaller than that of other similar forests in the dry evergreen montane forest, which was attributed to the higher anthropogenic disturbances. Therefore, the interventions, which reduce the climate change effect, would be very important in the maintenance of forest ecosystem functioning.