# The Carbon Dynamics of Dry Tropical Afromontane Forest Ecosystems in the Amhara Region of Ethiopia
## Materials
### Forest Data  
Forest data in the four study areas were collected based on a systematic grid sampling approach (Figure 1, Table 1). The grid size of the systematic sampling within each of the four study areas differed according to the size of the forest. Slope, aspect, latitude and elevation were recorded for each plot. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Study Area** & **Forest Area (ha)** & **Grid Size (m)** & **\(N\)** & **Elev.** & **Stem C** & **NPP** \\  & **Area (ha)** & **Grid Size (m)** & **SI (\(\mathbf{c}\))** & **(\(\mathbf{t}\)\(\mathbf{c}\)\(\mathbf{a}\)\(\mathbf{-1}\))** & **(\(\mathbf{g}\)\(\mathbf{c}\)\(\mathbf{m}^{-2}\) year\(\mathbf{-1}\))** \\ \hline Gelavdivros & 68 & \(250\times 250\) & 33 & 2487 & 10–40 & \(60.4\pm 46.5\) & \(640\pm 425\) \\ Katassi & 553 & \(300\times 300\) & 56 & 2150 & \(1–36\) & \(41.2\pm 34.3\) & \(490\pm 327\) \\ Mehabreselessie & 19,162 & \(3000\times 3000\) & 19 & 863 & 3–41 & \(13.0\pm 5.5\) & \(150\pm 63\) \\ Taragedam & 324 & \(250\times 250\) & 36 & 2325 & 1–43 & \(19.9\pm 19.5\) & \(431\pm 333\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Overview of the forest areas of the four study areas Gelavdiwos, Katassi, Mehabreselessie and Tarageedam. The four sites cover different agro-ecological zones. Area refers to the forest area in hectares, for which the sampling point grid design was applied, Grid size refers to the distance between sampling points, \(N\) is the number of sample plots, Elev: the elevation, SI: the slope, C: the mean of the periodic (2005–2014) mean annual above ground carbon content of the vegetation in tons per hectare and NPP: the mean of the periodic mean annual NPP for 2005 to 2014 plus the corresponding standard deviations. Figure 2: Walter/Lieth climate diagram ([PERSON], 1960) for the four study areas (dotted areas indicate dry periods, hatched area humid periods and black areas wet periods). The graphs also show elevation, climate data recorded period, the mean annual temperature and the mean total annual precipitation. Since average stand density varied by study area but forest inventories require a certain average minimum number of trees per plot, we varied the plot size by study area. In Gelawdiwos and Taragedam, information for trees with a DBH (diameter at breast height) >10 cm was collected on plots with a 10 m radius, while for Mahibeselassie and Katzsi a plot size radius of 15 m was chosen. On these plots, the following tree information was recorded: tree species, tree location, DBH, crown width in the four cardinal directions, tree height and height to live crown base. In addition, increment core data were collected by major species groups on each sampling plot and for each \"central stem\". The term \"central stem\" refers to the 60 th percentile of the DBH distribution and follows a suggested procedure by [36], which showed that the central stem represents the \"mean tree\" (=quadratic mean DBH) on a given plot. In addition, for trees with DBH <10 cm and a height >1.5 m, the same set of tree variables (except the increment cores) was collected on subplots with a radius of 4 m. All trees (from plots and subplots) with a DBH \(\geq\)2.5 cm were used for deriving vegetation carbon and carbon increment. Missing tree heights H were derived from the Petterson height-diameter curve [37]:  
\[\mathrm{H}=\frac{1}{\left(\mathrm{a}+\frac{\mathrm{b}}{\mathrm{DBH}}\right)^{2 }}+1.3 \tag{1}\]  
where the parameters a and b were derived for the twenty most important tree species in the study areas [38]. Above ground carbon vegetation C\({}_{\mathrm{veg}}\) was calculated according to the following formulation [39]:  
\[\mathrm{C}_{\mathrm{veg}}=\mathrm{e}^{-2.922+0.99\times\mathrm{In}\left( \mathrm{DBH}^{2}\times\mathrm{H}\times\mathrm{q}\right)\times 0.5} \tag{2}\]  
where DBH and H are as previously defined and 9 is the mean wood density of African tree species set equal to 0.614 g cm\({}^{-3}\)[40]. The carbon content was assumed to be 50% of the biomass [41; 42; 43].