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Item Open Access IMPACT OF ALTITUDINAL VARIATION ON SELECTED SOIL PROPERTIES AND CARBON DYNAMICS IN THE ALPINE WETLANDS OF LESOTHO(2025-07-01) Mochala, MThe study entitled, “Impact of Altitudinal Variation on Selected Soil Properties and Carbon Dynamics in the Alpine Wetlands of Lesotho” was conducted in the on-going project entitled, “Carbon Modelling and Omics Approaches for Screening of Soil Microbes for Climate Change Adaptation in the Alpine Wetlands of Lesotho,” initiated in November, 2024. The study was designed in blocks (sub-catchments) with six altitudinal variations (from 2500 to 3155 m a.s.l), equivalent to alpine wetlands from three sub-catchments (Senqunyane, Khubelu and Sani) as follows: Khorong (2500-2550 m a.s.l) and Tenesolo (2552-2600 m a.s.l) in Senqunyane; Khamoqana (2839-2880 m a.s.l) and Khalong-la- Lichelete (2891-29950 m a.s.l) in Sani; and Lets’eng-la-Likhama (3040-3080 m a.s.l) and Koting-Sa-ha Ramosetsana (3087-3155 m a.s.l) in Khubelu. Each treatment was replicated four times. The soil texture was loam to sandy loam across the alpine wetlands. The alpine wetland soils were slightly acidic and non-saline. The findings of the study revealed that bulk density (BD) decreased with increasing altitude 0-15 cm soil depth and was significantly lower (1.08 Mg m-3) in Koting-Sa- ha Ramosetsana (KSHM) compared to other wetlands. The KSHM also showed significantly higher infiltration rate (IR) of 2.17 cm hr-1, maximum water holding capacity (MWHC) of 57.51% and saturated hydraulic conductivity (Ksat) of 2.70 cm hr-1 Ksat at 0-15 cm soil depth whereas, Tenesolo recorded the higher BD and the least IR, MWHC and Ksat. Soil organic carbon (SOC) and Calcium (Ca) were significantly higher in KSHM and increased with increasing altitude, except Khorong (KRN) which did not follow this increasing trend, i.e., KRN (2500-2550 m a.s.l) was exhibited with higher contents of SOC and Ca. The electrical conductivity, cation exchange capacity and macronutrients (nitrogen, phosphorus and potassium) availability of the soil were non-significant. Soil enzyme activities declined significantly with increase in altitude due to lower temperatures at higher elevations, limiting microbial activity. The dehydrogenase, fluorescein di-acetate and β-galactosidase activities were 3.92 and 45.33%, 1.82 and 32.20% and 9.29 and 15.11% lower in KSHM (3087-3155 m a.s.l) compared to Tenesolo (2552-2600 m a.s.l) and Khorong (2500-2550 m a.s.l), respectively. Higher carbon pools viz., very labile (CVL), labile (CL), less labile (CLL) and non-labile (CNL) and total organic carbon (TOC) were recorded under KSHM compared to all other wetlands at varied altitudes. Passive pool of carbon (CPSV) was dominant over active carbon pool (CACT) with 75–79% contribution towards TOC. Both CPSV and CACT were higher in KSHM (higher elevation site). The Soil Quality Index (SQI) was enhanced (42.54% and 42.51%) at both upper (Koting-sa-ha Ramosetsana) and lower (Khorong) elevation wetlands, indicating that altitude alone does not fully determine soil quality. Instead, wetland condition, vegetation cover, and site-specific environmental factors are critical in shaping soil functionality and regulating carbon processes in alpine wetland ecosystem. Therefore, further research needs to consider synergistic factors including the slope, topography and soil degradation level in addition to the altitude.