Austin, A. T., and O. E. Sala., 1999. Foliar d15N is negatively correlated with ranfall along the IGBP transect in Australia. Australian Journal of Plant Physiology 26:293-295.

------A simple correlative analysis between annual precipitation and foliar d15N indicates a highly significant (p<0.0001, r = -0.64) negative linear relationship between foliar d15N and median annual precipitation. With increasing annual rainfall, there is a systematic decrease in the foliar d15N signatures. More than 40% of the variance in this data set is explained by the relationship of foliar d15N with annual precipitation. The correlation of precipitation and d15N suggests that annual rainfall input may be an important component controlling ecosystem nitrogen cycling. There are a number of interrelated mechanisms at work that will determine the ecosystem d15N signature -- a net result of all factors affecting the inputs, outputs, and internal fractionations of 15N over 14N. In addition to the direct effects of precipitation on short-term turnover, long-term losses affecting ecosystem nitrogen pools are reflected in the d15N values. The increasingly depleted foliar 15N in wetter sites suggests that in spite of potentially more rapid turnover, accumulated losses of nitrogen relative to ecosystem nitrogen pools are greater in the drier sites. While the magnitude of both input and output will increase with increasing rainfall, the ratio of loss relative to intrasystem turnover will become smaller, such that increased water availability will result in a systematically less open cycle. This pattern of decreasing d15N with rainfall suggests that the integrated effect of increased rainfall on nitrogen cycling is a decrease in the openness of the cycle itself. For every unit of nitrogen that moves through the plant-soil-microbial components of an ecosystem, the potential for loss from that system is greater in sites of lower rainfall. ------The long-term effects of the openness of the nitrogen cycle on the carbon-nutrient balance could be important. While water availability would continue to be the most frequent limitation to ecosystem production, nitrogen availability could become limiting in wet periods. The greater potential for losses would maintain these systems in a state of nitrogen limitation, in spite of relatively lower nitrogen demand. Thus, openness of nitrogen cycling may help to explain the persistence of nitrogen limitation in some terrestrial ecosystems.