Human Impacts on Soil Health

Are the Bugs Bugged?

The Effect of Deforestation on Land Dwelling Arthropods

BackgroundInsects perform critical functions in our environment- nutrient recycling--plant, animal, and dung

decomposition, and fungi dispersal- plant propagation- food for higher animals- maintenance of plant and animal

communities

Background

Their presence is needed for a healthy environment

If they are absent, an inference can be made on the health of the land

Because of this, Conservation biologists use insects for environmental monitoring

Also, they are easy and inexpensive to study

Initial Model

Arthropods

Humans

Development/Deforestation

Determine the level and location

Affects the lives (breeding locations, food, growth media) of

Create a habitable environment for

Breaks down

Gives convenience to their lives

Contribute to food sources for

Portion included in this study

AssumptionsInsects do describe the health of the land

The more insects there are, and the more diverse the present species, the healthier the land

Insects at one site would be similar to a nearby site if their environments were made the same

Insects present during the fall describe the insect population of the land

Methods

Chose sites

Collected arthropods- Dug hole size of spaghetti sauce jar- Placed jar in hole- rim flush with ground- Left for 72 hours- Collected jars, counted, and identified

trapped arthropods

Site 1

Highly Deforested

Previous location of McD’s building

Site 2

Mild Deforestation

Front yard in

Wallingford

Site 3

Little/No Deforestation

Water Shed near NSCC

DataInsect Abundance Across Sites

02468

10121416

High Mild Low

Level of Deforestation

Nu

mb

er

of

Sp

eci

me

ns

Species Diversity

0

2

4

6

8

10

High Mild Low

Level Of Deforestation

Nu

mb

er

of

Sp

eci

es

DataSite Kind of Species Found NicheHighlyDeforested Site

Very small, unidentifiablearthropod(nickname, “Sim”)

Unknown

MildlyDeforested Site

3 Arachnids6 Pill bugs6 Earwigs (Dermaptera)13 “Sims”1 Campodea (Diplura)

PredatorHerbivoreHerbivoreUnknownHerbivore

LowDeforested Site

2 Beetle3 Earwigs1 Milipede1 “Sim”1 Pillbug3 Mites3 Campodea

UnknownHerbivoreUnknownUnknownHerbivoreUnknownHerbivore

Conclusions and ClaimsSpecies diversity, and diverse niches filled decreases with increased deforestation

Deforestation disturbs insect populations

The disturbed insect population cannot support the land for higher animals and plants

Deforested areas are unable to support plant and animal life

One result as deforestation occurs; animal populations are forced to move, impeding on the population’s growth and survival

Revised model

Arthropods

Humans

Development/Deforestation

Determine the level and location

Affects the lives (breeding locations, food, growth media) ofDecreasing species diversity and ecological functions performed

Create a habitable environment for

Breaks down

Gives convenience to their lives

Contribute to food sources for

More QuestionsWhat would these sites look like in the spring or summer?

What other kinds of insects are present that I couldn’t catch?

Which insects are most helpful in nutrient recyling in our area?

Which insects support the lives of vertebrates most?

Can the introduction of insects be used in restoration of land?

The end of the Bug tale for now.

What is the relationship What is the relationship between bugs and the between bugs and the nutrients in the soil in nutrients in the soil in

compost piles?compost piles?Rachelle LoukRachelle Louk

Edtep 586Edtep 586

Autumn 2004Autumn 2004

Initial ModelInitial Model

Niche differentiationNiche differentiation Niche interaction Niche interaction Differential Differential

distribution of distribution of speciesspecies

Species vary with Species vary with level of level of decompositiondecomposition

About compost piles:About compost piles:

The interior of a compost pile is warmer The interior of a compost pile is warmer than the exteriorthan the exterior

The top of a pile is less compact than the The top of a pile is less compact than the bottombottom

Level of decomposition increases towards Level of decomposition increases towards the bottom of a pilethe bottom of a pile

As decomposition progresses, organic As decomposition progresses, organic compounds will be returned to the soil - compounds will be returned to the soil - nitrogen in particularnitrogen in particular

Definition of bug:Definition of bug:

I am using the word ‘bug’ to include all I am using the word ‘bug’ to include all of the macro-invertebrates that I of the macro-invertebrates that I observed. This includes organisms observed. This includes organisms from the phyla:from the phyla:ArthropodaArthropodaAnnelidaAnnelidaNematodaNematoda

AssumptionsAssumptions

That bugs would be present in all samplesThat bugs would be present in all samples(this turned out to be problematic)(this turned out to be problematic)

That a given level of a pile is homogeneous That a given level of a pile is homogeneous enough to yield representative samplesenough to yield representative samples

Level of decomposition and position in pile are the Level of decomposition and position in pile are the main factors affecting bug distribution and main factors affecting bug distribution and abundanceabundance(materials in pile affect bugs present)(materials in pile affect bugs present)(pH affects the bacteria/fungi present, which (pH affects the bacteria/fungi present, which

affect bugs that graze on bacteria/fungi)affect bugs that graze on bacteria/fungi)

MethodsMethods

Collect samples of compost from top, middle, Collect samples of compost from top, middle, and bottom of piles using 4 fl.oz. plastic and bottom of piles using 4 fl.oz. plastic containercontainer

Use a dissecting scope to search a petri dish Use a dissecting scope to search a petri dish full of compost from each samplefull of compost from each sample

Isolate bugs in vials with ethanolIsolate bugs in vials with ethanol Identify bugs and research nichesIdentify bugs and research niches Test samples for N content using Rapitest® Test samples for N content using Rapitest®

soil kitsoil kit

Some of the cool bugs I Some of the cool bugs I found...

PseudoscorpionPseudoscorpion Oribatidae MiteOribatidae Mite

Collembola (aka springtails)Collembola (aka springtails)

CentipedeCentipede

Niches of the bugs:Niches of the bugs:

The detritivores I The detritivores I found include:found include: collembola (a.k.a. collembola (a.k.a.

springtails)springtails) isopods (a.k.a. potato isopods (a.k.a. potato

bugs)bugs) dipluransdiplurans millipedesmillipedes annelids (a.k.a. earth annelids (a.k.a. earth

worms)worms)

The predators I The predators I found include:found include: pseudoscorpionspseudoscorpions oribatidae mitesoribatidae mites staphylinidae beetlesstaphylinidae beetles centipedescentipedes fly larvaefly larvae nematodes (a.k.a. round nematodes (a.k.a. round

worms)worms)

Most of the bugs I found were generalists and Most of the bugs I found were generalists and mostly competing for the same food sources. This mostly competing for the same food sources. This data refutes my initial hypothesis that competition data refutes my initial hypothesis that competition

would be minimized by niche differentiation.would be minimized by niche differentiation.

Bug population composition Bug population composition across UW greenhouse pileacross UW greenhouse pile

0

5

10

15

20

25

30

35

40

top middle bottom

Location of sample in pile

Nu

mb

er

of

bu

gs

worm

millipede

centipede

isopods

orobatidae

collembola

More bugs and more types of bugs mid- More bugs and more types of bugs mid- pile, least number of bugs at the bottompile, least number of bugs at the bottom

Bug population composition Bug population composition across horse manure across horse manure

compostcompost

More bugs at the bottom/oldest part of the pileMore bugs at the bottom/oldest part of the pile

0

5

10

15

20

25

30

top (7-9 mos) middle(12mos)

bottom(15mos)

Location and Age of Sample

Nu

mb

er

of

bu

gs

earth worms

nematodes

fly larvae

pseudoscorpion

orobatidae mites

collembola

Bug population distribution in 15 Bug population distribution in 15 month old piles of varying month old piles of varying

compositioncomposition

More bugs, and types of bugs, in mixed More bugs, and types of bugs, in mixed compostcompost

0

10

20

30

40

50

60

chickenmanure

horse manure horse manure+ garden

wasteComposition

Nu

mb

er

of

Bu

gs

fly larvae

pseudoscorpion

earthworm

nematodes

oribatidae mites

staphylinidae beetle

dipluran

collembola

isopods

Bug distribution across piles and positions

Some groups have nearly ubiquitous distribution, and Some groups have nearly ubiquitous distribution, and some show localized distribution. However, the some show localized distribution. However, the distribution of most of these bugs do not suggest distribution of most of these bugs do not suggest differential distribution within compost piles. differential distribution within compost piles.

0102030405060

Nu

mb

er

of

bu

gs millipede

centipede

fly larvae

nematodes

annelids

pseudoscorpions

diplura

staphylinidae

oribatidae

collembola

isopods

greenhousegreenhouse Chicken manureChicken manure Horse manureHorse manure

Relative nitrogen levels Relative nitrogen levels across piles and locationsacross piles and locations

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gree

nous

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p of

pile

gree

nhou

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bott

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fpi

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2 yr

chi

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+di

rt

7-9

mos

hors

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op

12 m

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man

ure,

Re

lati

ve N

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ntr

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Concentrations were compared to N2=adequate, N3=sufficient, N4=surplus. Concentrations were compared to N2=adequate, N3=sufficient, N4=surplus. Concentrations higher than N4 were assigned a level relative to other readingsConcentrations higher than N4 were assigned a level relative to other readingswith an increasing scale of 0.5 determined arbitrarily. with an increasing scale of 0.5 determined arbitrarily. Nitrogen concentrations generally increased with the Nitrogen concentrations generally increased with the age of the sample.age of the sample.The starting material of the pile affected the The starting material of the pile affected the concentration of nitrogen. concentration of nitrogen.

Evidence & Final ClaimsEvidence & Final Claims

Most of the bugs I found were generalists and Most of the bugs I found were generalists and mostly competing for the same food sources, mostly competing for the same food sources, refuting a hypothesis of niche differentiation.refuting a hypothesis of niche differentiation.

I found no conclusive evidence of differential I found no conclusive evidence of differential distribution of bugs within piles. distribution of bugs within piles.

More bugs, and types of bugs, in compost of mixed More bugs, and types of bugs, in compost of mixed composition. The materials in the environment composition. The materials in the environment influence the presence of bugs.influence the presence of bugs.

Nitrogen concentrations generally increased with Nitrogen concentrations generally increased with the age of the sample and was effected by the the age of the sample and was effected by the composition of the pile. composition of the pile.

Revised ModelRevised Model

Future Questions...

Were my samples representative?I’d like to do it again taking multiple

samples at every level.

Did pH, or any other nutrient effect the bugs present?

Does population composition vary seasonally?

I want to thank:

UW Biology Department:Eileen O’Connor for helping me arrange lab

time and equipmentEvan Sugden for identifying bugs for me

Good entomology websites at:University of MissouriUniversity of Nebraska - Lincoln

My colleagues for academic and emotional support!

Invertebrates as Indicators of Human Impact on Soil

“How do invertebrate populations change with soil compaction?”

My First ModelInitial 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?

Hum

an Impact

As

Bug S

pecies Diversity

Exposure to P

ollution

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

Significance…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.

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 #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.

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.

Determining Soil Density/Compaction

Insert a standard bulb planting tool into the soil up to the 2” markPlace soil from bulb planting tool into a standard 1 gallon freezer bagWeigh soil samples using a triple beam balanceDensity=Mass/VolumeDensity can be compared via mass measurements because all volumes should be constant

Soil Densities by Site

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50

100

150

200

250

Soil by Site

Ma

ss

in

Gra

ms

Insect Collection Procedures

1 pint glass jars are buried in the soil with lip even to the groundLeaves 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

Boat-backed Beetle

Common Black Ground Beetle

Invertebrates by Location

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16

Boa

t-B

acke

d B

eetle

s

Com

mon

Bla

ck B

eetle

s

Cau

lum

bula

Sm

all S

pide

r

Mill

iped

e

Ear

wig

Uni

dent

ified

Ann

alid

Tot

al S

peci

min

s

Com

mon

Bla

ck B

eetle

Ear

thw

orm

Uni

dent

ified

Inse

ct

Sm

all S

pide

r

Uni

dent

ified

Bee

tle

Slu

g

Tot

al S

peci

min

s

Uni

dent

ified

Inse

ct

Sm

all S

pide

r

Mill

iped

e

Tot

al S

peci

min

s

Site 1 Site 2 Site 3

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

DensitySoil 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.