Seasonal variation in <i>δ</i>¹³C and <i>δ</i>¹⁸O of cellulose from growth rings of <i>Pinus radiata</i>

Abstract

Abstract Seasonal variation in δ 13 C and δ 18 O of cellulose ( δ 13 C c and δ 18 O c ) was measured within two annual rings of Pinus radiata growing at three sites in New Zealand. In general, both δ 13 C c and δ 18 O c increased to a peak over summer. The three sites differed markedly in annual water balance, and these differences were reflected in δ 13 C c and δ 18 O c . Average δ 13 C c and δ 18 O c from each site were positively related, so that the driest site had the most enriched cellulose. δ 13 C c and δ 18 O c were also related within each site, although both the slope and the closeness of fit of the relationship varied between sites. Supporting the theory, the site with the lowest average relative humidity also had the greatest change in δ 18 O c ‰ change in δ 13 C c . Specific climatic events, such as drought or high rainfall, were recorded as a peak or a trough in enrichment, respectively. These results suggest that seasonal and between‐site variation in δ 13 C c and δ 18 O c are driven by the interaction between variation in climatic conditions and soil water availability, and plant response to this variation.