Stoichiometric properties of soil and microbial carbon, nitrogen, and phosphorus on the Jingpohu lava plateau.

The Jingpo Lake lava plateau is a distinctive volcanic ecosystem with complex microtopography, low water retention, and severe nutrient deficiency, making it an ideal natural laboratory for investigating vegetation-soil-microbial interactions during ecological succession. Knowledge of soil-microbial stoichiometric coupling and nutrient limitation in volcanic landscapes remains limited. To address this gap, we investigated soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), microbial biomass (MBC, MBN, MBP), microbial entropy (qMBC, qMBN, qMBP), and stoichiometric imbalance (C:Nimb, C:Pimb, N:Pimb) across five vegetation types-grassland (GL), shrubland (SL), deciduous broad-leaved forest (DB), coniferous and broad-leaved mixed forest (CB), and coniferous forest (CF). The results showed that the soil TN and TP contents in SL were significantly higher than those in forest vegetation types (p < 0.05), likely attributable to its litter's low C:N ratio and low lignin content, which may facilitate accelerated N and P mineralization. Conversely, CF accumulated more SOC, potentially due to litter enriched in recalcitrant compounds exhibiting greater resistance to decomposition. Stoichiometric imbalance was pronounced in CB, which showed the lower qMBC but higher C:Nimb, C:Pimb, and N:Pimb values, indicating poor soil quality and reduced microbial growth efficiency. Redundancy analysis confirmed that C:Nimb and C:Pimb were the principal drivers of microbial entropy. Consistently high soil C:N and C:P ratios, together with low N:P ratios, indicate that vegetation growth on the lava plateau is primarily limited by nitrogen. These results provide empirical insights that may inform nutrient management and ecological restoration strategies in volcanic ecosystems.