Physical and chemical characteristics of soils in Ephedra gerardiana and E. pachyclada habitats of Kali Gandaki Valley in Central Nepal

Abstract

In the Kali Gandaki Valley in Central Nepal, Ephedra gerardiana and E. pachyclada show species specificity for physical and chemical characteristics of soils. Here, the relationship between soil characteristics and ephedrine and pseudoephedrine contents was examined. E. gerardiana grew in moist alpine scrub and upper alpine meadow from 3735 to 4156 m a.s.l., while E. pachyclada grew in the lower Caragana steppe and dry alpine scrub from 2629 to 3671 m a.s.l. The soil texture of E. gerardiana and E. pachyclada collection sites were classified as loam or sandy loam mainly composed of sand and silt. Loss on ignition (%) of soil in E. gerardiana habitats (28.4–35.0%) was markedly higher than for that in E. pachyclada habitats (14.2–17.2%). E. pachyclada soil (pH 8.4–9.2) was more alkaline than that for E. gerardiana (pH 8.5). The five ions (Cl⁻, SO₄²⁻, Ca²⁺, Mg²⁺, and Na⁺) in soil of E. pachyclada (Cl⁻, 0.01–18.97 mmol/100 g dry soil weight; SO₄²⁻, 1.95–83.33; Ca²⁺, 3.79–77.91; Mg²⁺, 1.28–27.9; Na⁺, 0.94–34.49) were markedly higher than those of E. gerardiana (Cl⁻, 0.18–0.29; SO₄²⁻, 0.07–0.08; Ca²⁺, 4.19–4.59; Mg²⁺, 0.22–0.58; Na⁺, 0.93–1.40). The main factor contributing to strongly alkali soils for each species was different between E. gerardiana and E. pachyclada: CaCO₃ for E. gerardiana and CaSO₄, MgSO₄, NaCl, or a combination of these for E. pachyclada. The total ephedrine and pseudoephedrine content in E. gerardiana and E. pachyclada ranged from 1.67–1.88%DW and 1.95–4.80%DW, respectively. Both E. gerardiana and E. pachyclada were amenable for use a raw material source for extraction of ephedrine and pseudoephedrine, and the ephedrine content of both species showed a statistically significantly positive correlation with Mg²⁺ and Na⁺ contents of the soil.