The Effects of Ragweed (Ambrosia artemisiifolia L.) on Nutrient Cycling in a 1st-year Old-field

The potential effects of common ragweed {Ambrosia artemisiifolia) on nutrient loss from a recently disturbed old-field in Indiana were assessed by measuring nitrogen and phosphorus uptake and by comparing soil nitrogen concentrations in bare and vegetated plots. Bare plots had soil nitrate concentrations, 4.6 times higher than those in plots with ragweed-dominated natural vegetation. A total of 2.49 g/m2 of nitrogen were taken up by ragweed in the 1 st-year field, and 12% of this total was stored in seeds. The remainder of the nitrogen taken up was in more readily decomposed vegetative tissues. Thus ragweed could reduce nitrogen losses very early in succession by taking up and storing nitrogen. Most of the nitrogen taken up is probably readily available to plants in subsequent years.