Soil stoichiometric characteristics and influencing factors in karst forests under micro-topography and microhabitat scales

Abstract. To quantitatively evaluate the stoichiometric characteristics of karst forest soils and their response mechanisms to complex microenvironments, the study systematically investigated soil stoichiometric traits and influencing factors across micro-topography and microhabitat scales in the Maolan karst forest. Key findings include: (1) Soil nutrients (organic carbon, total nitrogen, hydrolyzable nitrogen, available phosphorus, available potassium, total calcium, exchangeable calcium, and exchangeable magnesium) exhibited strong variability with significant spatial heterogeneity; (2) Microhabitat factors significantly influenced nutrient accumulation, though different elements showed distinct response patterns to microhabitat variations; (3) Micro-topographic parameters (slope gradient, aspect, and position) exerted indirect effects through gravity, light exposure, and erosion, driving the formation of gradient patterns in soil stoichiometry; (4) Differential response mechanisms of nutrients to abiotic factors, combined with the differential nutrient regulation and absorption strategies of various plant life forms, collectively shaped the complex stoichiometric characteristics. Synergistic interactions were observed among microhabitat-micro-topography-plant life form factors, with geomorphological abiotic factors playing predominant roles at this scale. Although biotic factors like plant life forms showed relatively weaker direct influences, their regulatory effects were closely interrelated with microhabitat-topographic factors. This multi-dimensional feedback mechanism between biotic and abiotic factors reflects the complexity of nutrient cycling in karst ecosystems.