STABLE CARBON-ISOTOPE RATIO OF TREE LEAVES, BOLES AND FINE LITTER IN A TROPICAL FOREST IN RONDONIA, BRAZIL

Leaves of 208 trees were collected for isotopic analysis together with wood from 36 tree boles and 18 samples of fine litter from a terra-fi rme forest located at Samuel Ecological Reserve, Rondonia State, in th e southwestern Amazon region. The range of delta(13)C values in leaves was from -28 to -36 parts per thousand, with an average (+/-1 SD) of -32.1 +/- 1.5 parts per thousand, which was more negative than the del ta(13)C values Of bole samples (-28.4 +/- 2.0 parts per thousand) and fine litter (-28.7 +/- 2.0 parts per thousand). These values are withi n the range found for tropical and subtropical forests. Pooling the de lta(13)C values for leaf samples from trees of the same height gave av erages which were positively correlated with plant height at a highly significant level, with a slope of 0.06 and an intercept of -33.3 part s per thousand and a correlation coefficient r(2) = 0.70 (P < 0.001).