An audio report from the environmental science podcast 'Andean Eco-Innovations' features a discussion on restoring high-altitude peatlands in South America:
'Welcome back to Andean Eco-Innovations. In this segment, field hydrologist Mateo Salcedo explains the ongoing remediation of degraded bofedales—high-altitude wetland ecosystems situated above 4,000 meters in Bolivia's Apolobamba range. Over past decades, unmanaged drainage ditches accelerated water loss and exposed subterranean peat layers to severe erosion. To reverse this degradation, the engineering team designed low-profile check dams along key tributary gullies. While conventional civil projects typically rely on imported cement barriers or synthetic geotextile sheets, the researchers opted for a localized bio-composite: tightly compressed blocks of native tola shrub roots bound with local volcanic ash clay. Hydrological monitoring showed that these organic dams successfully slowed downstream runoff by 65 percent, facilitating sediment accumulation and raising the local water table by 35 centimeters. Furthermore, as the tola root matrix slowly biodegrades, it releases natural humic compounds that promote the rapid re-establishment of native Distichia cushion plants across the bog floor.'
Based on the audio report, what specific material did the engineering team use to construct the low-profile check dams?
- APermeable sheets of synthetic geotextiles reinforced with imported cement
- Compressed blocks of native tola shrub roots bound with volcanic ash clayAnswer
- CTransplanted mats of living Distichia cushion plants secured with wooden stakes
- DCompacted volcanic basalt boulders lined with synthetic rubber barriers