Stable Isotopes in Tree Rings of Tropical Forests

Abstract

AbstractThe study of stable isotopes in tree rings is relatively new, but growing research field in tropical forests. In this chapter, we review 53 studies that measured stable isotopes of C, O and/or N in tree rings of a total of 83 tropical tree species. Tree growth in tropical forests is generally determined by seasonality of precipitation, and not temperature. Consequently, temporal variation in both δ13C and δ18O has often been correlated to precipitation and variability of the El Niño Southern Oscillation (ENSO), which can affect weather systems throughout the tropics and subtropics. Currently, stable isotopes research in the tropics has mainly focused on (i) quantifying the effects of rising atmospheric CO2 concentration and climate change on tree physiology, (ii) identifying the drivers of growth variability and reconstruction of past climate, and (iii) the identification of annual rings in wood lacking anatomically distinct growth boundaries. In addition, some initial studies used tree-ring δ15N as a tool to assess anthropogenic change of the nitrogen cycle in tropical forests. Although stable isotope analyses in the tropics still faces methodological and interpretation issues, it is becoming an important tool for understanding the functioning of tropical forests and their resilience to global change.