Cultivation Suitability Assessment of Ainsliaea acerifolia Based on a Composite Suitability Index (CSI) and Maximum Limiting Factor Method (MLFM)

This study aimed to develop a quantitative Cultivation Suitability Index (CSI) and identify growth-limiting environmental factors for the stable cultivation of Ainsliaea acerifolia, an understory perennial native to the southern and south-central mountainous regions of Korea. Climatic conditions, site topography, microenvironment, soil physicochemical properties, vegetation structure, and plant growth indices were investigated at six representative natural habitats. The soils were generally acidic and nutrient-limited, with low available phosphorus and low exchangeable Ca and Mg. Community diversity indices indicated stable understory assemblages across sites. Thirteen environmental indicators were normalized and weighted to construct the CSI, and suitability classes were defined as highly suitable (≥0.75), suitable (0.5–0.75), potential (0.25–0.5), and unsuitable (<0.25). The Maximum Limiting Factor Method (MLFM) was applied to identify site constraints, yielding a Limiting Factor Index (LFI) of 0.29–0.42, with light, humidity, temperature, EC, Ca and Mg emerging as dominant limiting factors. CSI and LFI exhibited a negative linear relationship (R2 = 0.6353), demonstrating that alleviation of limiting conditions directly improves site suitability. Optimal cultivation environments were characterized by moderately acidic soils, adequate Ca and Mg availability, moderate shade, and improved moisture balance. From a management perspective, maintaining soil pH around 4.5–5.0, supplementing Ca and Mg, enhancing drainage, and applying organic mulching or clay amendments to coarse textured soils are recommended. The CSI–MLFM framework provides a practical and transferable tool for selecting suitable cultivation sites and establishing sustainable understory and ecological mountain cultivation systems for A. acerifolia.