2.2. Experimental design and sampling
In October 2018, six forest stands (1) A. nepalensis- early regeneration (AER) forest, (2) A. nepalensis -late regeneration (ALR) forest, (3) A. nepalensis -planted by the forest department in the degraded forest (APDF) (4) A. nepalensis - mature oak mixed (AMOM) forest, (5) A. nepalensis - mix with rhododendron (AMR) forest, and (6) A. nepalensis –mix with old oak (AMOO) forest in a chronosequence of A. nepalensis forest stands were randomly selected from the entire area of the Kedarnath valley. Proportion to the total basal area of A. nepalensis of the stand was the primary criteria for stands selection. In each sampling stand, three 0.1 ha plots were established using a stratified random sampling design. Each plot was subdivided into ten (10 m x 10 m sized) quadrats for biomass and carbon inventory. Species density and tree diameter at breast height (DBH) were recorded in each plot. Tree biomass, including the biomass of bole, branch, twig, foliage, catkin, stump root, lateral root, and fine roots was estimated in plots by already developed allometric equations (Rawat, & Singh, 1988; Adhikari, 1994; Sharma &Ambhasht 1990; Sharma, 2011). Three 5 m x 5 m quadrats were layed to study Shrubs and three 1 m x 1 m sized quadrats were used for herbs and litter Shrubs were harvested and separated into branches, roots, and leaves; herbs were harvested and separated into above-and belowground components from each subplot. Components of shrubs, herbs, and litter were brought to the laboratory and oven-dried at 64 °C for 48 h and weighed to estimate the ratio of fresh weight to dry biomass (Mg ha-1). The total vegetation C stock was computed by assuming that carbon content is 47.4% of the total biomass (Martin and Thomas, 2011). Soil samples were randomly collected with soil corers (diameter, 5 cm) at up to maximum soil depths (0-10 cm in AER, 0-30 cm in APDF, 0-100 cm in ALR, AMOM, AMR and AMOO plots) and divided in 0-10, 10-20, 20-30, 30-50, 50-80 and 80-100 cm. The soil samples were placed in plastic bags and brought to the laboratory.  The soil sample was air-dried, and visible plant debris and stones were removed and ground to pass through a 2-mm sieve to perform organic carbon analysis. Soil organic carbon (SOC) was calculated using K2Cr2O7-H2SO4oxidation (Nelson & Sommers, 1996). Bulk density was estimated for each soil depth by weighting the whole sample and oven-dried at 105 °C for 48 h.
Soil carbon stock (SOCS) was calculated according to the following equations:
\begin{equation} \text{SOC\ stock\ }\left(\text{Mg\ ha}^{1}\right)=SOC\ x\ BD\ x\ D\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (1)\ \nonumber \\ \end{equation}
Where SOC (%) is soil organic carbon, D is the sampling depth (cm), BD is the bulk density (g cm-3) and SCFs is the mass of proportion of coarse fragments content (% of volume) using an average rock density of 2.65 g cm-3.
Topographic feature (slope aspect, elevation, slope position, slope angle) of each plot was measured and slope correction was applied for final biomass estimation. Stands located on slope >10%, slope correction was applied using the following equation:
\begin{equation} L=Ls\ x\ Cos\ S\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\nonumber \\ \end{equation}
Where L is the true horizontal distance of forest stands Ls is the standard distance measured in the field along the slope and S is the slope in degrees. The area of the sampled stands was then calculated as: Area= stands width × calculated true stands length (L).