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Paper No. 231-5
Presentation Time: 9:00 AM-6:30 PM
LIFE IMPACTS ON LANDSCAPE: WORMS DISPERSE PARTICLES AND AERATE TROPICAL SOILS
Earthworms are among the most important soil fauna in tropical soils due to their impacts on soil structure, their ability to break down organic matter, and their extensive collective biomass. Previous workers [1] calculated that “66% of the litter decay in the tabanuco forest is due to faunal effects alone; mainly due to earthworms” and that the number of earthworms correlates positively with the amount of macropores in the soil [2]. In the Luquillo Critical Zone Observatory (LCZO) studies are currently underway that attempt to understand the erosional processes that are shaping the landscape in El Yunque National Forest. Despite the crucial role of the earthworm in shaping the soil, it is rare that a geomorphological study takes the perspective of soil fauna. We hypothesize that the creation of macropore tunnel networks allows for better drainage of the soil, aiding the erosion processes that shape the landscape. This lab study focuses on the effects of earthworm tunneling on the volume, bulk density, and infiltration capacity of soil collected from the Tabanuco forest in the LCZO. To quantify these effects, eleven worms were collected and individually housed in 5”x7”x2mm glass cases specially designed to be the width of the worms. This design forced the worms to tunnel in a two dimensional space in order to allow visual documentation of their excavation habits. Repeat photography and image analysis were used to map the surface area of the total soil in each case as well as the surface area of the tunnels, which was multiplied by the width of the case to calculate the total volume and volume excavated. After two weeks, the worms were removed; and the soil infiltration capacity and bulk density were measured.
[1] Gonzalez and Seastedt, 2001. Soil fauna and plant litter decomposition in tropical and subalpine forests. Ecology.
[2] Ehlers, W., 1975. Observations on earthworm channels and infiltration on tilled and untilled loess. Soil Science.