Terrestrial Consumers / Trophic Interactions

Structure-Function-Biodiversity

LTER VI Planning Workshop1 September 2007Anthony Joern

Primary system drivers and grassland consumers?

Prairie Structure& Function

Consumers

Grassland Drivers

Konza Prairie Consumers …

• Focus of many long-term core data sets• Major contributors to site biodiversity• Highly variable dynamics, especially densities• Major participants in food webs, contributing to

community & ecosystem dynamics • Serve as key indicator species for understanding

global environmental change• Major foci of conservation biology

Integration of LTER Research at Konza PrairieNew LTER Initiatives

Season of Fire

Fire Reversal Exp.

Insect Biodiversityand Ecology $

Fire

Grazing

Climate

Spatial and TemporalHeterogeneity

Tallgrass Prairie• Genes• Organisms• Populations• Communities• Ecosystems• Landscapes

Management IssuesBison/Cattle Grazing $

Restoration $

Land Use / LandCover Change $

Water Quality $

Climate Change

Climate GradientStudies

Flux TowersCO2, H20 $

ExperimentalStream Studies $

RainfallManipulations $

Plot-LevelMechanistic Studies

BelowgroundExp. Plots

Irrigation Transects

P AdditionExperiment

Mycorrhizae &Soil C Exp $

LINX Studies $

Extending the InferenceOf Konza StudiesBud Bank

Demography $Invasive Species

Cross-Site, Network & International Studies

EcologicalGenomics $

• Long-term LTER core data• Landscape scale habitat use• Long-term lekking activity• Landscape-scale experiments

Avian DynamicsBrett Sandercock, Kim With

Frequency of dry years0.20 0.25 0.30 0.35 0.40 0.45

Sto

chas

tic g

row

th ra

te (l

ogλ )

-0.05

0.00

0.05

0.10

0.15 Rapid dryingGradual dryingIncreased variability

Peromyscus leucopus

Year1980 1985 1990 1995 2000 2005

Tota

l Num

ber C

augh

t

0

20

40

60

80

100

120

140

Small Mammal Dynamics

Blarina hylophaga

Year1980 1985 1990 1995 2000 2005

Tota

l Num

ber C

augh

t0

20

40

60

80

100

120

D. Kaufman, G. Kaufman

• Long-term core data on small mammals• Temporal dynamics of core species• Responses to key ecosystem drivers

& land cover change• Dynamic responses to climate change

Peromyscus maniculatus

Small Mammal Responses to Climate and Habitat Drivers

Four Research Phases in Konza LTER (since 1981)

I Magnitude & causes in temporal/ spatial variationII Season of annual fire effects on populationsIII Impact of woody invasion (ongoing direction)IV Deer mouse demography (new direction)

Key Points & Rationale• Relevant to climate change themes• Woody invasion/ habitat shifts changing communities• Long term population trends provide baseline to link with

additional • Critical vertebrate component of trophic structure

Aquatic Consumers

N1B

Dis

char

ge

0.001

0.01

0.1

1

10

Cat

ch P

er U

nit E

ffort

0.0001

0.001

0.01

0.1

1

Year98 99 00 01 02 03 04 05

Dis

char

ge

0.001

0.01

0.1

1

10C

atch

Per

Uni

t Effo

rt

0.0001

0.001

0.01

0.1

1

Phoxinus

Semotilis

95 96 97 98 99 00 01 02 03 04 05

Abu

ndan

ce

(num

ber/

min

ute

e-fis

hing

)

0.01

0.1

1

10

100Stoneroller S. redbelly daceOrangethroated darter Creek chub

Experimental Steams

• Long-term core data on fish• Focus on stream permanence • Impact of disturbance• Stream macroinvertebrates & fish• Links to ecosystem processes evident

K. Gido, C. Paukert, & M. Whiles

Julian Day (1995)

60 80 100 120 140 160 180 200 220

Mea

n di

scha

rge

(m3 /

s)

0.0

0.2

0.4

0.6

0.8

1.0

Julian Day (1995)

60 80 100 120 140 160 180 200 220

Mea

n di

scha

rge

(m3 /

s)

02468

101214

Ric

hnes

s (#

taxa

)

0

5

10

15

20

25

Ric

hnes

s (#

taxa

)

0

5

10

15

20

25Intermittent Reach Perennial Reach

Dry

Dry

Macroinvertebrates

N fl

ux (g

N m

-2)

0.00

0.05

0.10

0.15

0.20

0.25

Burned UnburnedMowed Unmowed

FertCont FertCont FertCont FertContMowed Unmowed

Bio

mas

s (g

AFD

M m

-2)

0.0

0.5

1.0

1.5

2.0

C. calliopeT. aurifera

Terrestrial Arthropods & Nematodes • Grasshoppers: Long-Term Core Data

• Responses to Prairie Drivers• Food Webs & Trophic Cascades• Parasitic hymenoptera biodiversity

J. Blair, A. Joern, T. Todd, M. Whiles, G. Zolnerowich

KPBS LTER Acridids

1980 1985 1990 1995 2000 2005

Abu

ndan

ce (#

/ 200

sw

eeps

)

0

50

100

150

200

250

Core Long-Term RecordsAnalyses of long-term data are showing interesting insights

with respect to role of key grassland drivers

• Grasshoppers: (Jonas & Joern. 2007. Oecologia 153: 699-711)– Dynamics affected by fire, bison and weather at local and

regional scales (see Jonas & Joern poster; 25 years)• Fish: (Franssen et al. 2006. Freshwater Biology 51: 2072-2086)

– Seasonality rather than disturbance from floods is best predictor of stream fish assemblages

• Birds: (Powell. Auk 123: 183-197)– Variable species-specific responses to annual burning and bison

grazing significant; heterogeneous landscape best approach.• Small Mammals: Matlack et al. 2002. Journal of Mammalogy 83:280-

289; Rehmeier et al. 2005. Journal of Mammalogy, 86:670-676. – Strong weather signal and woody vegetation determines temporal

dynamics; variable species responses to fire and grazing for spatial variation.

Andropogon gerardii

% F

olia

r N

0.0

0.5

1.0

1.5

2.0

% F

olia

r N

0.0

0.5

1.0

1.5

2.0

2.5(a) (b)Solidago missouriensis

P-Fertilzer (g/m2)0 2 4 6 8 10

% F

olia

r P

0.00

0.05

0.10

0.15

0.20

0.25 0gN10gN

P-Fertilizer (g/m2)0 2 4 6 8 10

% F

olia

r P

0.00

0.04

0.08

0.12

0.160gN10gN

P-Fertilization (g/m2)-2.5 0.0 2.5 5.0 7.5 10.0

Gra

ssho

pper

Den

sity

(#/m

2 )

0

5

10

15

200gN/m2

10gN/ m2

Andropogon gerardii

0 2 4 6 8 10

Per

cent

age

Leaf

Dam

age

0

10

20

300gN10gN

Solidago missouriensis

P-Fertilizer (g/m2)0 2 4 6 8 10

Per

cent

age

Leaf

Dam

age

0

10

20

30

0gN10gN

Stoichiometric responses(Viviana Loaiza REU)• N is key, little support for role of P

in grasshoppers in P-plots• Useful to extend stoichiometric

approach to understand dynamics of trophic interactions

Some New Directions & Syntheses• Synthesize scale-dependent processes affecting

consumer responses to canonical prairie drivers• Develop detailed scale-dependent understanding of

effects of bison foraging on heterogeneity of vegetation structure, food quality, nutrient cycling, and plant species availability

• Determine the critical elements of habitat heterogeneity in response to grazing-fire-climate interactions that underlie different consumer dynamics

• Further define the functional contributions of consumers in tallgrass prairie, and their trophic interactions

• Develop detailed demographic studies of targeted taxa to track consequences of climate and habitat change

• Plant species richness• Vegetation height• Foliar nutritional quality• Variable microclimates &

structural microhabitats for smaller consumers

Bison Create Habitats & Heterogeneity

1-year burn

4-year burn

Ungrazed GrazedN1B-N Transect 2005

Distance Along Transect (m)0 50 100 150 200

Veg

etat

ion

Hei

ght (

cm)

0

10

20

30

40

50

601D Transect 2005

Distance Along Transect (m)0 50 100 150 200 250 300

Veg

etat

ion

Hei

ght (

cm)

0

10

20

30

40

50

N4D-E Transect 2005

Distance Along Transect (m)0 50 100 150 200 250 300

Veg

etat

ion

Hei

ght (

cm)

0

10

20

30

40

50

60K4B-E frass

Distance Along Transect (m)0 50 100 150 200 250

Veg

etat

ion

Hei

ght (

cm)

0

20

40

60

Vegetation Height

Consumer responses to heterogeneity induced by fire & grazing?

Remote sensing & forage quality

Characterizing & Scaling Effects of Habitat Heterogeneity

Grasshopper

BisonDistribution of depends on bison, fire, soil nutrients

Rabbits?Voles?Birds?

Hierarchical, scale- and size-dependent responses to habitat quality & structure?

OR

Ongoing: Konza-Kruger study of top-down effects of grazers/ browsers on vegetation dynamics and plant community(Knapp, Smith, Collins, Blair)

Some Theory: size-dependent fractal relationships of habitat/ resource use by consumers (Ritchie & OLff 1998)

Variable heterogeneity determines diversity

Spatial Heterogeneity# S

pp/ I

ndiv

idua

ls

?

Small herbivores more likely limited by food quality & habitat structure (ectotherms), large herbivores by quantity

Link Dynamics of Aboveground andBelowground Trophic Structure

• Use long-term belowground plot experiment to work out role of bottom-up processes determining trophic structure

• Link aboveground and belowground dynamics• Have most resources needed to proceed – need conceptual

framework and explicit hypotheses• Stable isotope technology may be useful

(Jonas Thesis, In prep)

Precipitation

Topography& Edaphic

FireFrequency

Grazing

Landscape/Management/ State Local Conditions

PlantSpecies

Vegetation Structure

Temperature FoliarQuality

Spiders

NutrientsConsumed

Grasshoppers

PlantBiomass

Climate change affects biotic interactions: consumer responses

Mid-Summer

Early Summer

Upper Limit

Lower Limit

Time of Day

Late Spring/ Early Summer

Integrate Understanding of Dynamics in Terrestrial & Aquatic Habitats

• Multiple approaches• Can these be profitably linked?

Shredders

1o Production

Wood

CBOM

FBOM SPOM

Invert predators

Gatherers FilterersScrapers

Crayfish

Vertebrate predators

87

225

77182164 7

24

17

342

3

30

95

12

10

1

(Stagliano and Whiles 2002) (Joern 2005)

Terrestrial Consumers / Trophic Interactions

Structure-Function-Biodiversity

LTER VI Planning Workshop1 September 2007Anthony Joern