2. Soil Bulk Density, Total Pore Space, and Compaction Due to Human Foot Traffic Jessie Meeks and Ali Theuer, 2001

3. Contents : ïPurpose and Objectives ïSites ïMethods ïData ïDiscussion ïWrapping up

4. We explored the relationship between calculated soil bulk density (g/cc) and estimated amounts of human foot traffic. ïSoil compaction increases bulk density and decreases pore space. ïA decrease in pore space leads to increased erosion and decreased soil productivity. ïLogging trucks are a known hazard, what can feet do?

5. Site 1: located on the Brook Trail, visited by less than 1,000 people annually (thatís 2,000 feet every year) Site 2: located along the river trail, visited by just over a thousand people annually Site 1 Site 2

6. Site 3: located along the main loop trail, over 10,000 visitors per year Site 4: located along a side trail with about 10,000 visitors per year

7. What did we do?

8. Soil samples were obtained by hammering a can of known volume into the ground, both on and off trail at all four sites. We took keen and meticulous notes and observations.

9. Samples were taken back to the lab and weighed.

10. The shape of some of the cans was compromised while hammering them into the soil. The new volume of each can was determined using a graduated cylinder.

11. What did we find?

12. Bulk Density Data

14. What does it mean?

15. ïAn average difference in bulk densities of 25.76% between on trail and off trail was calculated ïAs bulk density increases, pore space decreases ïBulk density was greater on trail than off trail, therefore pore space is less on trail ïSoil bulk density reaches a maximum, leveling off (i.e most of the pore space is compacted) ïLess pore space results in increased soil erosion and decreased soil productivity ïRelationships among the number of hammer blows, crumpling of cans, and the calculated bulk density were observed

16. Summary Higher bulk densities on trails suggest that their soils are less productive and more susceptible to erosion than their off trail counterparts Error: a loss of soil mass may have ensued in the Transporting of samples from container to container Study Improvements: continue the study over several years, varying the levels of foot traffic at the sample locations, and tracking the bulk density and total pore space over time.

17. Thanks!