are plants enough: the relative importance of plants and nutrients to insect communities

Chelse Prather, PhD

•  Grew up in Northern Kentucky •  BS, biology, University of Kentucky •  PhD, biology, University of Notre Dame, research

in the rainforest in Puerto Rico •  Previous Postdoc, biology/history/philosophy,

Florida State University •  Now Research Faculty at University of Houston

Prairie restoration and management

•  Focus on restoring and managing for diverse native plant communities or creating habitat for game, migratory and threatened species.

•  What about the smaller animals—the invertebrates?

•  Butterflies, the “pretty” invertebrates have been mentioned.

•  What about all the others?

Outline 1.  Why care about invertebrates?

Invertebrates and humans 2.  Research question: What

determines invertebrate herbivore community structure in coastal tallgrass prairies?

3.  Other projects 4.  How to use this information?

Outline 1.  Why care about invertebrates?

Invertebrates and humans 2.  Research question: What

determines invertebrate herbivore community structure in coastal tallgrass prairies?

3.  Other projects 4.  How to use this information?

Invertebrates: •  Represent over 80% of all known

eukaryotic species •  Fill a vast array of ecological

niches • Attain high biomass in most

ecosystems.

Do insects affect humans?

Ecosystem services: Benefits from ecosystems that support human life and well-

being

Some%invertebrates%cause%problema2c%disservices%

The little things that run the world

E. O. Wilson

“…If invertebrates were to disappear, I doubt that the human species would last more than a few months.”%

Invertebrates, ecosystem

services, climate change

Chelse M. Prather, Shannon Pelini, Angela Laws, Emily Rivest, Megan Woltz, Christopher P. Bloch, Izzy Del

Torro, Chuan-Kai Ho, John Kominoski, T. A. Scott Newbold, Sheena Parsons.

2012. Biological Reviews, in press.

Goal: Evaluate invertebrate influences on ecosystem services and how these

influences may be altered by climate change

-On the National Bison range, it’s estimated that grasshoppers eat more vegetation than all the large vertebrates combined (Belovsky 2002).

Invertebrate effects on ecosystem services

- Can eat 0-100% of plant biomass in

an ecosystem

- 11,000 species of

myrmechores

-3/4 of all plants and 1/3 of all crops

by volume are pollinator-

dependent

%

!Dung&beetles&that&decompose&feces&are&worth&es6mated&at&$454&million&in&the&US&

%

!Emerging&insect&cause&huge&changes&in&available&nutrients%

!Invertebrate&frass&can&increase&or&decrease&nutrients&to&plants%

%

%

%

%

%

%

%

Invertebrate effects on ecosystem services%

Food web stability

%

In summary:

•  Invertebrates provide or indirectly influence all ecosystem services.

•  They are the major providers of a few services, and influence most of the others to a great degree.

•  BUT: the basic science has not been done to evaluate their relative importance.

Outline 1.  Why care about invertebrates?

Invertebrates and humans 2.  Research question: What

determines invertebrate herbivore community structure in coastal tallgrass prairies?

3.  Other projects 4.  How to use this information?

Fundamental question in ecology:

What is the relative importance of factors that affect the abundance and

diversity of organisms?

Why grasshoppers?

•  One of the major herbivores in most prairies across the US

•  Can eat more than ungulate herbivores combined

•  Relatively easy to sample

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass Plant diversity Plant micro-

nutrients Plant macro-

nutrients

P L A N T Q U A L I T Y

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Predator pressure &

Parasite load

X

X

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass Plant diversity Plant micro-

nutrients Plant macro-

nutrients

P L A N T Q U A L I T Y

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Predator pressure &

Parasite load

X

X

Pristine prairie Restored prairie

Shell-rich area Invasive forest

Measured grasshopper diversity and density, and possible predictors across 3 habitats (n=12).

Predators  Wolf spider density

Soil  Moisture

 Oyster shell content  pH

Plant community  Biomass  Diversity  Water

 Plant height  Macro-nutrients

(N, P)  Micro-nutrients (Ca, Cu, Fe, K, Mg,

Mn, Na, S, Zn)  Root biomass  Root moisture

0%

2%

1% 2%

Herbivores%(orthopterans)%

df%=%22%t%=%=2.54%

P%=%<%0.019%%%

0%

5%

1% 2%

Detri2vores%(isopods)%df%=%22%t%=%=2.00%

P%=%<%0.058%%%

0%

1%

2% Omnivores%(crayfish)%

df%=%22%t%=%5.79%

P%=%<%0.001%%%

0%

0.08%

0.16%

1% 2%

Predators%(wolf%spiders)%df%=%22%t%=%=6.92%P%=%%0.496%%%

Nu

mb

er o

f in

div

idu

als

pe

r m2

Shell-rich areas Pristine prairie Density of food web members

Significant drought event in 2011 Herbivore

abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass Plant diversity Plant micro-

nutrients Plant macro-

nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Predator pressure &

Parasite load

X

X

Results

Precipitation &

temperature

Soil moisture

Single-factor, bivariate

relationships; build up to multiple

factors.

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass Plant diversity Plant micro-

nutrients Plant macro-

nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Predator pressure &

Parasite load

X

X

Predator pressure &

Parasite load

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant diversity Plant biomass Plant micro-

nutrients Plant macro-

nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

X

X

Predator pressure &

Parasite load

Plant biomass

Results

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass Plant diversity

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

X

X

Predator pressure &

Parasite load

Plant diversity

Nitrogen

Results Phosphorus

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant biomass

Plant diversity

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

X

X

Predator pressure &

Parasite load

Plant macro-nurients

Results Calcium Potassium

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

X

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Sodium Sulfur

Plant micronutrients X

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

Site characteristics

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

X

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & management

Fragment size

Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & manage-

ment Fragment

size Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Results

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & manage-

ment Fragment

size Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Dependent variable

Predictors (coefficent)

R2 P F

Density P (0.456) Soil moisture (-0.866)

Fe (-0.564) N (-0.649)

Veg height (-0.219) Plant diversity (0.501)

Ca (0.478)

0.48 <0.001 11.59

Richness K(0.920) S (-0.687)

0.35 <0.001 7.653

Dependent variable

Predictors (coefficent)

R2 P F

Grass-feeder density

N:P 0.221 0.006 5.105

Mixed-feeder density

Ca (0.014) Roots (-0.229)

Zn (0.734)

0.732 <0.001 30.755

Forb-feeder density

Ca (1.453) P (-0.561) Na (0.475) Zn (-0.322)

0.791 <0.001 4.763

CONCLUSION: What is the relative importance of factors that affect the abundance

and distribution of prairie herbivores?

Herbivore abundance

Herbivore community characteristics

Herbivore diversity

Plant community characteristics

Plant micro-nutrients

Plant macro-nutrients

Precipitation &

temperature

C L I M A T E

Soil macro-nutrients

Soil micro-

nutrients

G E O L O G Y

Land use & manage-

ment Fragment

size Time since restoration

H U M A N I N F L U E N C E S

Top down controls

Plant biomass

Plant diversity

Predator pressure &

Parasite load

Conclusions: If you build it, will they come?

Katydid: Orchelimum

vulgaris

Grasshopper: Melanoplus

femurrubrum

Grasshopper: Metataplea brevicornis

Katydid: Concephalus

strictus

Species%specific%effects%

=100%

=50%

0%

50%

100%

=100%

=50%

0%

50%

100%

Grass%feeders% Mixed%feeders%

2%Grass% 2%Mixed%Both%

Grasshopper%diversity%conclusions%

•  The%number%of%species%doesn’t%necessarily%maSer,%but%the%iden2ty%of%the%species%you%have%maSers.%

•  Next—bigger%experiment%at%more%sites.%

**Disclaimer: understanding of what controls communities, not to be used to manage insects with current results**