Estimating the potential for natural ecosystem recovery at the Pietersielieskloof palmiet wetland, Western Cape.

Abstract

Recent research has highlighted the importance of cut-and-fill cycles in valley-bottom wetlands. This study considers the impact of longitudinal and lateral sediment connectivity on the natural recovery potential of valley-bottom wetlands. Pietersielieskloof is a Prionium serratum (commonly known as palmiet) dominated discontinuous valley-bottom wetland. P. serratum is considered to be a peat-forming ecosystem engineer that enhances sediment infill in valleybottom wetlands. Due to its ecological importance and potential as a carbon store, this wetland has been earmarked for rehabilitation by Working for Wetlands. The study ascertains the importance of including sedimentological and geomorphological input in wetland rehabilitation and management strategies. A study of wetland geomorphology was conducted to develop an understanding of the natural dynamic of cut-and-fill processes as context for recent erosion and deposition events. Sediment samples from gully walls and cores were collected for organic content and particle size analysis and five sediment samples predating the current phase of erosion were radiocarbon dated. The valley form was surveyed using cross-sections and long profiles, and historical change was digitised using 30 m – 5 to 30 mm resolution aerial imagery from 1938-2016 in ArcMap.