
TY  - JOUR
A1  - Handley, L. L. 
A1  - Austin, A. T. 
A1  - Stewart, G. R. 
A1  - Robinson, D. 
A1  - Scrimgeour, C. M. 
A1  - Raven, J. A. 
A1  - Heaton, T. H. E. 
A1  - Schmidt, S. 
T1  - The <emph type="7">15</emph>N natural abundance (&#948;<emph type="7">15</emph>N) of ecosystem samples reflects measures of water availability
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1999
VL  - 26
IS  - 2
SP  - 185
EP  - 199
KW  - 
UR  - https://doi.org/10.1071/PP98146 
N2  - We assembled a globally-derived data set for site-averaged foliar &#948;15N, the &#948;15N of whole surface mineral soil and corresponding site factors (mean annual rainfall and temperature, latitude, altitude and soil pH). The &#948;15N of whole soil was related to all of the site variables (including foliar &#948;15 N) except altitude and, when regressed on latitude and rainfall, provided the best model of these data, accounting for 49% of the variation in whole soil &#948;15N. As single linear regressions, site-averaged foliar &#948;15N was more strongly related to rainfall than was whole soil &#948;15N. A smaller data set showed similar, negative correlations between whole soil &#948;15N, site-averaged foliar &#948;15N and soil moisture variations during a single growing season. The negative correlation between water availability (measured here by rainfall and temperature) and soil or plant &#948;15N fails at the landscape scale, where wet spots are &#948;15N-enriched relative to their drier surroundings. Here we present global and seasonal data, postulate a proximate mechanism for the overall relationship between water availability and ecosystem &#948;15N and, newly, a mechanism accounting for the highly &#948;15N-depleted values found in the foliage and soils of many wet/cold ecosystems. These hypotheses are complemented by documentation of the present gaps in knowledge, suggesting lines of research which will provide new insights into terrestrial N-cycling. Our conclusions are consistent with those of Austin and Vitousek (1998) that foliar (and soil) &#948;15N appear to be related to the residence time of whole ecosystem N. 
ER  -

