Question

Listen to the following excerpt from an oral presentation about environmental conservation in South America:

"Welcome, everyone. Today I want to share the recent conservation efforts undertaken by the indigenous communities surrounding Lake Titicaca. Over the past five years, water pollution and unregulated harvesting have degraded nearly thirty percent of the native totora reed population. In response, local environmental groups partnered with university researchers in 2024 to implement a community-led reforestation initiative. Specifically, community volunteers planted over fifty thousand native totora saplings along the southern shoreline to filter pollutants and restore aquatic habitats. In addition to planting, the project established three designated protected zones where all commercial cutting is strictly prohibited. While some proposed introducing foreign aquatic plant species to speed up water purification, the leadership firmly decided to rely exclusively on indigenous plant varieties to preserve ecological balance. Recent monitoring indicates that local fish populations in the reforested zones have already increased by fifteen percent."

Based on the presentation, which specific action did the community volunteers carry out along the southern shoreline?