Stable isotope ecology in the Ituri Forest

The Ituri Forest, Democratic Republic of Congo (formerly Zaire) is an example of a closed canopy forest showing extreme depletion in ¹³C. δ¹³C values for plants from the canopy top, from gaps in the canopy, and from the subcanopy average −29.0±1.7‰, −30.4±0.9‰, and −34.0±1.5‰, respectively. The δ¹³C of forest mammals show these differences, with the subcanopy browsers (okapi, dwarf antelope) having δ¹³C values for tooth enamel much more negative than subcanopy frugivores who derive their food from the canopy top, and from folivores and omnivores living in gap or clearing areas. Nitrogen isotopes in plants from this ecosystem have an average δ¹⁵N value of 5.4±1.8‰ and do not show significant differences at the 95% confidence interval between plants from the canopy top, from gaps in the canopy, and from the subcanopy. The δ¹⁸OSMOW values of surface waters in the study area are between −2.0 and −2.7. The δ¹⁸OPDB for tooth enamel ranged from −3 to +7‰.