Resource Utilization by Native and Invasive Earthworms and Their Effects on Soil Carbon and Nitrogen Dynamics in Puerto Rican Soils

Abstract

Resource utilization by earthworms affects soil C and N dynamics and further colonization of invasive earthworms. By applying ¹³C-labeled Tabebuia heterophylla leaves and ¹⁵N-labeled Andropogon glomeratus grass, we investigated resource utilization by three earthworm species (invasive endogeic Pontoscolex corethrurus, native anecic Estherella sp, and native endogeic Onychochaeta borincana) and their effects on soil C and N dynamics in Puerto Rican soils in a 22-day laboratory experiment. Changes of ¹³C/C and ¹⁵N/N in soils, earthworms, and microbial populations were analyzed to evaluate resource utilization by earthworms and their influences on C and N dynamics. Estherella spp. utilized the ¹³C-labeled litter; however, its utilization on the ¹³C-labeled litter reduced when cultivated with P. corethrurus and O. borincana. Both P. corethrurus and O. borincana utilized the ¹³C-labeled litter and ¹⁵C-labeled grass roots and root exudates. Pontoscolex corethrurus facilitated soil respiration by stimulating ¹³C-labeled microbial activity; however, this effect was suppressed possibly due to the changes in the microbial activities or community when coexisting with O. borincana. Increased soil N mineralization by individual Estherella spp. and O. borincana was reduced in the mixed-species treatments. The rapid population growth of P. corethrurus may increase competition pressure on food resources on the local earthworm community. The relevance of resource availability to the population growth of P. corethrurus and its significance as an invasive species is a topic in need of future research.

Citation

Huang, Ching-Yu; Gonzalez, Grizelle; Hendrix, Paul F. 2016. Resource Utilization by Native and Invasive Earthworms and Their Effects on Soil Carbon and Nitrogen Dynamics in Puerto Rican Soils. Forests, Vol. 7(11): 277-.