Impact of sediment load on Cyperus papyrus growth in Lake Tana buffer zone, Northwest Ethiopia

Abstract

Cyperus papyrus is the cornerstone of Lake Tana’s buffer zone, a vital ecosystem supplying the Blue Nile. However, this critical area is under siege from excessive sediment runoff, primarily due to deforestation and unsustainable agricultural practices in the surrounding watershed. The lack of research on papyrus’s response to varying sediment levels has hindered restoration efforts. To address this knowledge gap, a study was conducted between May and October 2020 near Lake Tana. Twelve experimental wetlands were constructed, each divided into four sediment treatments: control (0 cm), low (1 cm), medium (5 cm), and high (10 cm). Papyrus growth parameters, including height, diameter, new shoot count, and above and below-ground biomass, were monitored every two weeks. Results unequivocally indicate that sediment load significantly impacts papyrus growth. Plants subjected to high sediment levels exhibited stunted growth, with reduced height, diameter, and new shoot production compared to those in lower sediment or control conditions. Biomass measurements also revealed a substantial decline in both above and belowground plant matter under high sediment stress. These findings highlight the urgent need for sediment management strategies to protect and restore the papyrus-dominated wetlands of Lake Tana.