Assessing the impact of historic pollution and restoration efforts on soil invertebrates

Historic pollution from local mining and smelter operations have significantly reduced lake water quality and ground cover diversity in the area surrounding Sudbury, Ontario, Canada. Soil invertebrates are important components of an ecological system and have not been examined as thoroughly as other local organisms in terms of the effects from the historic pollution on their community dynamics or their response to restoration efforts. Pitfall traps were used to collect insects from five sites along a disturbance gradient and two sites that have had physically improved through restoration efforts. Preliminary results show that insect diversity at the family level does not follow the same pattern of diversity as the local vegetation where naturally recovering sites show significantly lower diversity at the family level than sites further away from the pollution source. The restored sites show contradicting results. One restored site is not significantly higher in diversity of herbivores than its natural counterpart (p>0.05) and another is (p<0.0001). This suggests that restoration attempts may not have reached the soil insect level of the ecosystem. An important focus should be on species composition of soil insects where specialists for seed dispersal or herbivory can be important factors in the recovery of disturbed sites. Soil insects can significantly improve soil quality and aid in colonization of desired vegetation. Current local restoration efforts include liming the soil and seeding or planting vegetation. Future designs of restoration efforts in disturbed ecosystems should include a focus for soil invertebrates that can enhance their habitat structure.