Invertebrates as Indicators of Human Impact on Soil “How do invertebrate populations change with soil compaction?”

My First Model Initial Question: How are surface and underground bug populations different in areas that have experienced industrial pollution versus areas that have experienced mild human development and areas relatively undeveloped and not exposed to recent pollution or human activity? Human Impact As Bug Species Diversity Exposure to Pollution And

Ratified Ideas Failure to collect sufficient data indicating site pollution history combined with faulty data collection techniques Resulted in a revised question and model

Revised Model: Question: Are insect populations different in habitats characterized by serious, moderate and minimal soil compaction? Which insects survive better in areas with soil compaction? Human Activity Soil Compaction Aeration Drainage Nutrient Content Insect Population/ Diversity

Assumptions 1. Invertebrates could be used as an indicator species for soil compaction 2. Soil density is a measure of compaction 3. Soil sample collection method is accurate enough to determine relative density of various soil samples

A little background… In a study by Lindo and Visser it was determined that certain species of micro-arthropods could be used as an indicator species for human disturbance in the form of forest clear cutting and that the factors most likely influencing the changes in species diversity and abundance are soil compaction and changes in food availability In a study by Lindo and Visser it was determined that certain species of micro-arthropods could be used as an indicator species for human disturbance in the form of forest clear cutting and that the factors most likely influencing the changes in species diversity and abundance are soil compaction and changes in food availabilitySignificance… Study findings may support assumption #1 that invertebrates can be used as an indicator of soil compaction Study findings may support assumption #1 that invertebrates can be used as an indicator of soil compaction

Site Selection Three locations at Discovery Park suspected of having different soil densities were selected for this experiment. Three locations at Discovery Park suspected of having different soil densities were selected for this experiment. Site #1on a main path leading from the visitor’s center to the loop trail Site #1on a main path leading from the visitor’s center to the loop trail Site #2 on a less popular path leading behind the visitor’s center Site #2 on a less popular path leading behind the visitor’s center Site #3 located 30 paces off the path containing site #2 Site #3 located 30 paces off the path containing site #2

Location Selection 2 data collection locations and 1 soil density control location are selected for each site. 2 data collection locations and 1 soil density control location are selected for each site. At sites 1 & 2 the data collection locations are placed off center of the path to prevent foot traffic interference. At sites 1 & 2 the data collection locations are placed off center of the path to prevent foot traffic interference. Control locations are 2 paces off the path for sites 1 & 2 and 2 paces from one of the data collection locations for site 3. Control locations are 2 paces off the path for sites 1 & 2 and 2 paces from one of the data collection locations for site 3.

Determining Soil Density/Compaction Insert a standard bulb planting tool into the soil up to the 2” mark Insert a standard bulb planting tool into the soil up to the 2” mark Place soil from bulb planting tool into a standard 1 gallon freezer bag Place soil from bulb planting tool into a standard 1 gallon freezer bag Weigh soil samples using a triple beam balance Weigh soil samples using a triple beam balance Density=Mass/Volume Density=Mass/Volume Density can be compared via mass measurements because all volumes should be constant Density can be compared via mass measurements because all volumes should be constant

Soil Densities by Site

Insect Collection Procedures 1 pint glass jars are buried in the soil with lip even to the ground 1 pint glass jars are buried in the soil with lip even to the ground Leaves are tented over the jar opening to prevent outside interference in data collection Leaves are tented over the jar opening to prevent outside interference in data collection Jars are left in place for 96 hour periods and checked for insects every 48 hours Jars are left in place for 96 hour periods and checked for insects every 48 hours Boat-backed Beetle Common Black Ground Beetle

Invertebrates by Location

What it all means… Is there a connection between soil density and invertebrate populations size and diversity? YES!

Conclusions: 1. Soil density has a visible effect on invertebrate populations. Human Activity Density Soil Compaction Aeration Drainage Nutrient Content Insect Population/ Diversity

Conclusions: 2. For soil compaction to affect insect populations, the compacted area must be larger than the width of the paths chosen for this study. 3. The insect populations sampled for this study most likely reflect the populations found in areas with soil compaction equivalent to the control areas.