3.1. Tree and understory components C, N, and P concentrations and stoichiometry
The C concentrations of boles ranged from 515.4 ± 6.2 to 461.2 ± 8.2 g kg -1 and were in the following order: Q. leucotrichophora > other associated species (L. ovalifolia , P. pashia , M. esculenta , S. paniculata , L. umbrosa ) > R. arboreum > A. nepalensis, while the N concentrations of leaf ranged from 33.7 ± 3.4 to 17.3 ± 4.3 g kg-1 and followed the order: A. nepalensi > associated species> Q. leucotrichophora > R. arboreum . P concentrations of R. arboreum (0.24 ± 0.02 g kg-1) in leaf and litter were significantly (P < 0.05) greater than other plant species (Figure 1). A significant variation in C:N:P ratio was detected among the different tree components. The estimated branch, twig, leaf, fine root, course root, and litter C:N:P ratios of A. nepalensis were 979:22:1, 760:17.2:1, 578:40:1, 460:17:1, 623:12:1, 494:44:1, respectively and were lower than the other co-occurring tree species (Table 2). The C:N ratios of tree components ranked in the following order: bole > stump root > coarse root > fine root > branch > twig > litter > leaf. The C:N ratios of Q. leucotrichophora in bole (117 ± 9.3), stump root (98.5 ± 6.4), and coarse root (88.1 ± 5.3) was significantly greater than the bole, stump root, and coarse root of the other tree species (Figure 1). The C:P ratio of A. nepalensisand associated species in bole (2254.6 ± 22.2 and 1839.3 ± 15.2 respectively) and stump root (1646 ± 21.1 and 2213.3 ± 34 respectively) were significantly greater than the bole and stump root in comparison to other tree species. The N:P ratio of A. nepalensis and associated species in the litter (44.2 ± 3.2 and 81.2 ± 5.4, respectively) and leaf (44.7 ± 7.4 and 78.3 ± 8.9, respectively) were significantly greater than the litter and leaf of the other tree species (P < 0.05).
The C content (g kg-1) in different above and below-ground shrub components ranked in the following order: stem > root > leaf, while the shrub N and P concentrations (g kg-1) followed order: leaf > stem > root. The highest (465.53 ± 2.06) and the lowest (435.68 ± 2.15) C concentrations were measured in shrub stem and shrub leaf, respectively (Figure 1), while the highest (18.98 ± 3.03) and the lowest (12.21 ± 2.04) N concentrations were found in shrub leaf and shrub root, respectively. The highest (3.07 ± 0.02) P content was found in the leaf and the lowest (0.30 ± 0.02) in the root. The average C, N, and P concentrations (g kg-1) of herb aboveground component ranged from 448.8 ± 2.30 for C, 15.10 ± 1.02 for N, and 1.21 ± 0.06 for P. The concentration of C, N, and P (g kg-1) of herb belowground component ranged from 424.94 ± 2.34 for C, 8.92 ± 0.49 for N, and 0.61 ± 0.02 for P. The C:N, N:P and C:P ratio of shrubs ranked in the following order: root > stems > leaf, and the C: N, C:P and N:P ratio of herb ranked in the following order: herbs belowground > herb aboveground. The C:N ratio of herb roots was 1.17 times greater than the shrub roots. However, the C:P ratio of shrub roots was 2.08 times higher than the herb roots. The N:P ratio of shrub roots was 2.87 times greater than herbs roots.