Wetlands in Khalong-la-Lithunya catchment in Lesotho: Soil organic carbon contents, vegetation isotopic signatures and hydrochemistry

There is sparse information on the characteristics of the wetlands in the Khalong-la-Lithunya catchment (KLC), Lesotho in terms of physico-chemical properties, soil organic pools and vegetation isotopic signatures and hydrochemistry of surface waters after five years of rehabilitation. At the KLC two transects of length 250m–700m were chosen and soil observations made at intervals of 50m and at these points, piezometers were installed in duplicates and water samples were collected from Jan to Dec for four years (2009–2012). Soil samples were collected in duplicate from excavated mini-pits (0.50m). Vegetation samples were collected monthly (Jan, Apr and Aug) of 2010 from these transects (upper slope, middle and toe-slopes) on which δ15N isotope was applied. Samples (soil, water and plant) collected were properly labelled and transported to the laboratory. Samples were analysed after standard method. Results showed that soil organic carbon varied significantly across mini-pits, and transects. These ranged from 15.50gkg−1 with a mean of 28.61gkg−1 (Transect-1) to between 34.60 and 53.50gkg−1 with a mean of 43.24gkg−1 (Transect-2). Majority (or 78%) of the pedons in Transect-1 are strongly weathered, while in Transect-2, majority of the pedons (i.e. 73%) were classified as non- or weakly weathered using soil organic matter: silt+clay ratio. Results of the cluster analysis showed that clusters 1, 2, 3 and 4 were related to the water holding capacity, the soil weatherability, the soil ability to store carbon (carbon mitigation) and the soil's acidity. Results of the δ13C data for both transects varied slightly with slope positions though not significantly different (p81.50±8.5 to >32.8±2.2gkg−1.•Isotopic δ15N ranged from −2.52‰ to −2.93‰ with a mean of −2.81‰.•Higher water soluble p