Stable isotopic studies of earthworm feeding ecology in tropical ecosystems of Puerto Rico

✍ Scribed by Paul F. Hendrix; Sharon L. Lachnicht; Mac A. Callaham Jr.; Xiaoming Zou

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 60 KB
• Volume: 13
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19990715)13:13<1295::aid-rcm605>3.0.co;2-9

✦ Synopsis

Feeding strategies of earthworms and their influence on soil processes are often inferred from morphological, behavioral and physiological traits. We used 13 C and 15 N natural abundance in earthworms, soils and plants to explore patterns of resource utilization by different species of earthworms in three tropical ecosystems in Puerto Rico. In a high altitude dwarf forest, native earthworms Trigaster longissimus and Estherella sp. showed less 15 N enrichment ( 15 N = 3-6%) than exotic Pontoscolex corethrurus ( 15 N = 7-9%) indicating different food sources or stronger isotopic discrimination by the latter. Conversely, in a lower altitude tabonuco forest, Estherella sp. and P. corethrurus overlapped completely in 15 N enrichment ( 15 N = 6-9%), suggesting the potential for interspecific competition for N resources. A tabonuco forest converted to pasture contained only P. corethrurus which were less enriched in 15 N than those in the forest sites, but more highly enriched in 13 C suggesting assimilation of C from the predominant C 4 grass. These results support the utility of stable isotopes to delineate resource partitioning and potential competitive interactions among earthworm species.