Stoichiometric characteristics of different organs-litter-soil in subalpine coniferous forests in Chagangliang nature reserve

Abies faxoniana Rehd. and Picea asperata Mast. in the subalpine region of Chagangliang, Gansu Province, were taken as research objects, and the C, N, P, and K contents in different organs, litter, and soil of the two coniferous forests were measured to investigate their stoichiometric characteristics and their interactions, aiming to elucidate the mechanisms underlying their ecological adaptations.

Using community ecology methods, three 50 m×50 m fixed plots were established in each forest type. C, N, P, and K contents in different organs, litter, and soil layers were analyzed, and their correlations were examined.

1) The organic C, total N, total P, and total K contents in fir leaves were higher than those in the roots and stems. For spruce, the organic C content was highest in the leaves, while the total N, total P, and total K contents were highest in the stems; 2) In both coniferous forests, the organic C, total N, and total P contents were highest in the surface soil layer (0-10 cm) and gradually decreased with increasing soil depth. The total K content, however, showed little variation across different soil layers. Among the forest components, woody debris had the lowest organic C content but the highest N content, whereas mosses exhibited the highest C content. In litter, the total N and total P contents increased as decomposition progressed. The C∶N ratio was highest in the undecomposed litter layer and lowest in CWD. Mosses had the highest C∶P ratio, followed by CWD, while the undecomposed litter layer (K₁) had the smallest C∶K ratio, and CWD showed the largest C∶K ratio; 3) In P. asperata forests, soil organic C was significantly positively correlated with soil N and P (P≤0.01), soil N with P (P≤0.05), and soil P with K (P≤0.05). In A. faxoniana forests, soil organic C was positively correlated with soil P (P≤0.01) but negatively correlated with leaf P, K, and litter N and P (P≤0.05). Soil N and litter N were significantly negatively correlated (P≤0.01), while soil P and K showed a significant positive correlation (P≤0.01).

The growth of P. asperata is constrained by limitations in N, P, and K availability, coupled with factors such as slow litter decomposition and low accumulation of organic carbon in its leaves. In contrast, A. faxoniana exhibits higher organic carbon accumulation in its leaves and thrives in environments with more abundant N, P, and K. Therefore, in future vegetation restoration efforts, prioritizing the establishment of A. faxoniana forests is recommended. This approach will better support the region’s vegetation recovery and contribute to maintaining water conservation functions and overall ecosystem stability.