Soils of southern South America, including Patagonia, have endured disturbances from volcanic eruptions, earthquakes, landslides, and erosion. Also, massive fires in the mid-20th century were set to forests in order to promote colonization. In 2010, another 17,000 acres of Patagonia burned, fueling an international reforestation effort. Although the young soils of Patagonia may contain high phosphorus levels, the element is tightly bound to the soil. How can local plants take root and access that phosphorus?

Soils of southern South America, including Patagonia, have endured a high frequency of disturbances from volcanic eruptions, earthquakes, landslides, and erosion. In addition, massive fires in the mid-20th century were set to forests in the region in an effort to promote colonization. In 2010, another 17,000 acres of Patagonia burned, fueling an international reforestation effort. Although the young soils of southern South America may contain high phosphorus levels, the element is tightly bound to the soil, offering limited phosphorus available to plants.

In contrast to previous studies of Proteaceae in Australia and South Africa, the best-fit model for predicting the number of cluster roots in this study did not contain any soil P factor; foliar P levels correlated with cluster root formation. The number of cluster roots was significantly higher in large seedlings, yet biomass investment in cluster roots was greater for small seedlings.

Piper found that cluster roots mediate a decoupling of foliar P from soil P concentrations for small seedlings. This enabled small seedlings to maintain adequate foliar P levels, critical to their ontogenetic growth. The relative investment in cluster roots was directly linked to both low soil N and leaf P. Seedlings from sites with lower total soil N had more cluster roots, regardless of other soil characteristics. The cluster root adaptation is very sensitive and highly expressed at low total soil N levels but rapidly disappears as soil N levels increase. The investment in cluster roots declines after seedling establishment, most likely as aerial growth is increasingly important for light competition

Source:
http://www.sciencedaily.com/releases/2014/01/140123222338.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Fplants_animals%2Fsoil_types+%28Soil+Research+News+–+ScienceDaily%29