Physicochemical soil characterisation and nutritional associations of Laccopetalum giganteum (Wedd) Ulbr. (Ranunculaceae) in its high-Andean habitat: a baseline for conservation

Abstract

Background: Laccopetalum giganteum (Wedd.) Ulbr. is an endemic species of the Peruvian Andes classified as Critically Endangered. Its conservation is constrained by limited knowledge of its soil requirements. This study aimed to characterise soil physicochemical properties in their natural habitat and evaluate their relationships with plant biometric and nutritional traits to support conservation strategies. Methods: A total of 24 soil–plant pairs were collected from high-Andean populations near Lake Pelagatos, Ancash, Peru (4,567 m a. s. l.). Soil variables (pH, electrical conductivity, texture, macronutrients, micronutrients, and carbonates) were evaluated as independent variables, while plant variables (biometry, dry matter, and mineral composition) were considered response variables using descriptive statistics, generalised linear models (GLM), and generalised linear mixed models (GLMM). Results: Soils were slightly alkaline (pH 7.73 ± 0.41), with moderate carbonate content (9.22 ± 4.76%), electrical conductivity of 17.8 ± 5.4 mS·m⁻¹, and predominantly sandy texture (73.5 ± 10.4%). Plant growth showed significant negative associations with exchangeable calcium (β = −0.12) and carbonates (β = −0.06). Positive associations were observed with zinc (β = 0.10), manganese (β = 0.29), and silt content (β = 0.12). Above-ground tissues contained 22.1 mg·kg⁻¹ Zn and 24.2 mg·kg⁻¹ Mn, with bioaccumulation factors of 5.8 and 43.2, respectively. Conclusions: L. giganteum shows low affinity for calcareous soils and persists in marginal environments through efficient micronutrient acquisition. These findings provide a quantitative basis for substrate selection in ex situ propagation (pH 6.2–6.8; CaCO3 < 2%; Zn and Mn supplementation) and for identifying priority microsites for in situ conservation