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Stable isotope ecology in the Ituri Forest
Thure E Cerling1, John A Hart, Terese B Hart
1Department of Geology and Geophysics, Department of Biology, University of Utah, Salt Lake City, UT 84112, USA. tcerling@mines.utah.edu
Oecologia
|October 8, 2003
Summary
The Ituri Forest exhibits extreme carbon-13 depletion, impacting plant and mammal diets. Subcanopy browsers show more negative carbon isotope values, reflecting their food sources within the forest ecosystem.
Area of Science:
- Ecology
- Stable Isotope Biogeochemistry
Background:
- The Ituri Forest in the Democratic Republic of Congo is a closed-canopy ecosystem.
- Previous research indicates potential carbon-13 (¹³C) depletion in this environment.
Purpose of the Study:
- To investigate carbon-13 (¹³C), nitrogen-15 (¹⁵N), and oxygen-18 (¹⁸O) stable isotope variations in plants and animals within the Ituri Forest.
- To understand how different forest strata (canopy, gaps, subcanopy) influence isotopic signatures and food web dynamics.
Main Methods:
- Analysis of delta (δ) ¹³C, δ¹⁵N, and δ¹⁸O values in plant and animal (tooth enamel) samples.
- Comparison of isotopic values across different forest strata and dietary guilds (browsers, frugivores, folivores, omnivores).
Main Results:
- Plants in the Ituri Forest show extreme ¹³C depletion, with subcanopy plants exhibiting the most negative δ¹³C values.
- Mammalian herbivores display δ¹³C values that correlate with their feeding strata, indicating dietary partitioning.
- Nitrogen isotope (δ¹⁵N) values in plants did not significantly differ across forest strata.
- Oxygen isotope (δ¹⁸O) values in surface waters and tooth enamel were also analyzed.
Conclusions:
- The extreme ¹³C depletion in the Ituri Forest significantly influences the isotopic signatures of its fauna.
- Stable isotope analysis reveals distinct dietary niches and trophic relationships within the forest ecosystem based on carbon isotopes.