Exudation of (±)-catechin by the invasive plant, Centaurea maculosa, increases phosphorus availability.
Thorpe, Andrea*,1, Archer, Vincent1, 2, Deluca, Thomas1, Callaway, Ragan1, 1 University of Montana, Missoula, MT, USA2 USDA Forest Service, Boise, ID, USA
ABSTRACT- As novel, and often dominant components of plant communities, invasive plants can have strong and unique effects on soil nutrient cycles. We found evidence that Centaurea maculosa (spotted knapweed) has strong, direct effects on soil nutrient cycling, at least partially due to exudation of the polyphenol, (±)-catechin. In the field, P concentration in C. maculosa shoots was more than twice that of three native species (Pseudorogneria spicata, Festuca idahoensis, and Lupinus sericeous). In the greenhouse, even at very low levels of soil P availability, uptake of P by C. maculosa was six times greater than that by the native, Lupinus argenteus. However, soil P levels were higher in areas with living C. maculosa compared to where the weed had been eliminated by herbicide, the opposite of what is expected if root or mycorrhizal uptake were responsible for the P efficiency of C. maculosa. In the laboratory, application of (±)-catechin, a putative metal chelate, to soils invaded by C. maculosa results in a similar, three-fold increase in soluble P. Centaurea maculosa appears to drive dramatic changes in fundamental ecosystem properties in addition to its powerful biotic effects.
Key words: Centaurea maculosa, phosphorus, catechin, invasive plant
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