Soil Nutrient Profiles in Three Types of Rocky Fissure Network Habitats of Typical Karst Formations in China: A Maolan World Heritage Perspective

Abstract

Amid global desertification, this study investigates karst ecosystems; analyzing soil’s physiological and ecological properties within intricate fissure networks supporting plant root growth. This study investigates soil nutrients in three types of rocky fissure network habitats in Maolan, through field surveys and experimental measurements. Significant variability was found across habitats. The quantities of organic carbon, total nitrogen, available nitrogen, available phosphorus, and available potassium were highest in Type I soil, followed by Type III; and were lowest in Type II. Total phosphorus was highest in Type III, intermediate in Type I, and lowest in Type II; while total potassium content was highest in Type III, moderate in Type II, and lowest in Type I. Based on nutrient participation in C, N, P, and K cycles, Type I habitats had the highest levels, Type III had moderate levels, and Type II had the lowest levels; while potassium-related nutrients were highest in Type III. The nutrient ratios C/K, N/K, P/K, and N/P were highest in Type I, moderate in Type II, and lowest in Type III. C/N was highest in Type II, moderate in Type III, and lowest in Type I; while C/P was highest in Type II, moderate in Type I, and lowest in Type III. A comprehensive nutrient evaluation ranked Type I as the best, Type III as moderate, and Type II as the worst. Key factors such as average trace length, areal density, and integration significantly influence soil nutrients by impacting humus and soil storage, and the growth space for plant roots within rocky habitats. Additionally, the orientation of fissures primarily impacts nutrient cycling, while both the angles and lacunarity significantly affect the stoichiometric ratios of nutrients. Rocky habitat networks characterize soil quality. A comparison of existing studies reveals stoichiometric differences between karst and non-karst regions. Effective ecological restoration in karst areas requires targeted strategies that consider the specific attributes of different rocky habitats. This study enhances understanding of soil nutrients in karst forest ecosystems and proposes new approaches for soil’s ecological restoration and combating global desertification.