Ecuador, Perú Cuyabeno-Güeppí (2008) Ecuador, Perú : Cuyabeno-Güeppí ecuadorpercuyab202008alve Year: 2008 Fig. 32. Formation and redistribution of Andean gravels and sands into soils and stream systems of the Cuyabeno-Güeppí region. Erosion slowly deepens the valleys while processes of bioturbation (mixing caused by burrowing organisms) integrate gravels into the hilltop soils. Gravels remain in stream beds because the streams do not flow fast enough to transport them. many soils derived from rock or sands rich in weatherable minerals, the clays forming the base of the Cuyabeno and th
Ecuador, Perú Cuyabeno-Güeppí (2008) Ecuador, Perú : Cuyabeno-Güeppí ecuadorpercuyab202008alve Year: 2008 Fig. 32. Formation and redistribution of Andean gravels and sands into soils and stream systems of the Cuyabeno-Güeppí region. Erosion slowly deepens the valleys while processes of bioturbation (mixing caused by burrowing organisms) integrate gravels into the hilltop soils. Gravels remain in stream beds because the streams do not flow fast enough to transport them. many soils derived from rock or sands rich in weatherable minerals, the clays forming the base of the Cuyabeno and the Giieppi are relatively infertile and likely to limit ecosystem productivity (Fig. lOA). However, through time, organic matter works into the soil via plant growth, tree falls, and processes of bioturbation caused by ant mounds, worm tunnels, and burrowing mammals like armadillos and anteaters (Fig. 33). In contrast to weathered clays, organic matter has a high cation-exchange capacity. When organic matter accumulates in inert clays, the soil as a whole increases in fertility. The formation of organic-rich soils through time depends on plant growth, which in turn depends on an adequate nutrient source. The nutrient source of early infertile soils likely included inputs from precipitation (Zimmermann et al. 2007), atmospheric and volcanic dust, and any transport of nutrients into the system by animals (Fig. 33). A story from the memory of the Cofan highlights the importance of bioturbation in creating soil fertility. The story, as translated in 'The Old People Told Us' (R. Borman pers. comm.) is as follows: The world came to an end by an earthquake. When the earthquake ended it, all the people died except for three survivors. Then everything became like a river. They all clung to floating trees. Clinging, the people went. Then this one thought, 'I'm alone.' He began walking and searching. There was no jungle, just sand. Everything was cleaned and there was no earth
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