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Harvard Forest REU Symposium Abstract 2012

• Title: Effects of Warming on Slugs and Decomposition in Harvard Forest, MA
• Author: Katherine Davis (Duke University)
• Abstract:

  Slugs are well known as garden and agricultural pests, but also play important roles in forest ecosystems. Slugs can influence decomposition by consuming dead organic material, and ultimately make nutrients available to plants. Studies have also shown that fecal material from slugs, as well as the mucus they produce for movement, creates favorable conditions for bacteria, further contributing to decomposition. As the climate warms, it is important to understand how invertebrates and the ecosystem processes mediated by them will be affected. I investigated the response of Arion lusitanicus, a non-native slug common in central Massachusetts and their influence on decomposition under different warming treatments by placing slugs in heated open-top chambers at Harvard Forest, Massachusetts. Hot water was used to increase the air in each chamber, resulting in a temperature range of 0 to 5.5 C above ambient. I used two enclosures, one with three slugs and the other with no slugs, in each chamber. Each container had the same amounts of potting soil, leaf litter, and bran flakes (food for the slugs). Over the course of four weeks, I monitored slug mortality and the amount of food consumed in each chamber. I also weighed the leaf litter to determine decomposition rates and the slug weight at the beginning and end of the experiment in order and whether the slugs gained or lost weight. I expected to see an increase in slug food consumption due to higher metabolic rates in the warm chambers, and higher slug mortality in the warm chambers because of desiccation.
  
  Neither slug mortality rates nor slug weight changed across temperature treatments, but the slugs in warmer chambers consumed significantly less food than those in cooler chambers. This may be due to slugs’ preference for moist food items; if the food dried out faster in the warmer chambers, the slugs may have stopped eating it. Decomposition occurred at a faster rate in the warmer chambers, but was not affected by the presence or absence of slugs. More research is needed to understand how these slugs function in the forest and how that might change in the future.
  
  

• Research Category: Conservation and Management; Invasive Plants, Pests & Pathogens; Physiological Ecology, Population Dynamics, and Species Interactions