Terrestrial Consumers / Trophic Interactions - - PowerPoint PPT Presentation

Terrestrial Consumers / Trophic Interactions

Structure-Function-Biodiversity

LTER VI Planning Workshop 1 September 2007 Anthony 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 Prairie

New LTER Initiatives

Season of Fire Fire Reversal Exp. Insect Biodiversity and Ecology $

Fire Grazing Climate

Spatial and Temporal Heterogeneity

Tallgrass Prairie

• Genes
• Organisms
• Populations
• Communities
• Ecosystems
• Landscapes

Management Issues

Bison/Cattle Grazing $ Restoration $ Land Use / Land Cover Change $ Water Quality $

Climate Change

Climate Gradient Studies Flux Towers CO2, H20 $ Experimental Stream Studies $ Rainfall Manipulations $

Plot-Level Mechanistic Studies

Belowground

• Exp. Plots

Irrigation Transects P Addition Experiment Mycorrhizae & Soil C Exp $ LINX Studies $

Extending the Inference Of Konza Studies

Bud Bank Demography $ Invasive Species Cross-Site, Network & International Studies Ecological Genomics $

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

Avian Dynamics

Brett Sandercock, Kim With

Frequency of dry years

0.20 0.25 0.30 0.35 0.40 0.45

Stochastic growth rate (logλ)

• 0.05

0.00 0.05 0.10 0.15

Rapid drying Gradual drying Increased variability

Peromyscus leucopus

Year

1980 1985 1990 1995 2000 2005

Total Number Caught

20 40 60 80 100 120 140

Small Mammal Dynamics

Blarina hylophaga

Year

1980 1985 1990 1995 2000 2005

Total Number Caught

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 variation II Season of annual fire effects on populations III 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

Discharge

0.001 0.01 0.1 1 10

Catch Per Unit Effort

0.0001 0.001 0.01 0.1 1

Year

98 99 00 01 02 03 04 05

Discharge

0.001 0.01 0.1 1 10

Catch Per Unit Effort

0.0001 0.001 0.01 0.1 1

Phoxinus Semotilis

95 96 97 98 99 00 01 02 03 04 05

Abundance (number/ minute e-fishing)

0.01 0.1 1 10 100

Stoneroller

• S. redbelly dace

Orangethroated 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

Mean discharge (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

Mean discharge (m3/s) 2 4 6 8 10 12 14 Richness (# taxa) 5 10 15 20 25 Richness (# taxa) 5 10 15 20 25

Intermittent Reach Perennial Reach

Macroinvertebrates

N flux (g N m-2)

0.00 0.05 0.10 0.15 0.20 0.25

Burned Unburned

Mowed Unmowed

Fert Cont Fert Cont Fert Cont Fert Cont

Mowed Unmowed

Biomass (g AFDM m-2)

0.0 0.5 1.0 1.5 2.0

• C. calliope
• T. 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

Abundance (#/ 200 sweeps)

50 100 150 200 250

Core Long-Term Records

Analyses 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

• f 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

% Foliar N

0.0 0.5 1.0 1.5 2.0

% Foliar N

0.0 0.5 1.0 1.5 2.0 2.5

(a) (b)

Solidago missouriensis

P-Fertilzer (g/m2)

2 4 6 8 10

% Foliar P

0.00 0.05 0.10 0.15 0.20 0.25 0gN 10gN

P-Fertilizer (g/m2)

2 4 6 8 10

% Foliar P

0.00 0.04 0.08 0.12 0.16

0gN 10gN

P-Fertilization (g/m2)

• 2.5

0.0 2.5 5.0 7.5 10.0

Grasshopper Density (#/m2)

5 10 15 20

0gN/m2 10gN/ m2

Andropogon gerardii

2 4 6 8 10

Percentage Leaf Damage

10 20 30 0gN

10gN Solidago missouriensis P-Fertilizer (g/m2)

2 4 6 8 10

Percentage Leaf Damage

10 20 30

0gN 10gN

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

• f 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 Grazed

N 1 B

• N

T ra n s e c t 2 5 D is ta n c e A lo n g T ra n s e c t (m )

Vegetation Height (cm)

D is ta n c e A lo n g T ra n s e c t (m )

Vegetation Height (cm)

• E

T ra n s e c t 2 5

D is ta n c e A lo n g T ra n s e c t (m )

Vegetation Height (cm)

• E

fra s s

D is ta n c e A lo n g T ra n s e c t (m )

Vegetation Height (cm)

Vegetation Height

Consumer responses to heterogeneity induced by fire & grazing?

Remote sensing & forage quality

Characterizing & Scaling Effects of Habitat Heterogeneity

Grasshopper

Bison

Distribution 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 # Spp/ Individuals ?

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

Link Dynamics of Aboveground and Belowground Trophic Structure

• Use long-term belowground plot experiment to work out role
• f 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 Fire Frequency Grazing Landscape/ Management/ State Local Conditions Plant Species Vegetation Structure Temperature

Foliar

Quality Spiders Nutrients Consumed Grasshoppers Plant Biomass

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 Filterers Scrapers Crayfish Vertebrate predators

87 22 5 77 182164 7 24 17 34 2 3 30 95 1 2 10 1 (Stagliano and Whiles 2002) (Joern 2005)

Terrestrial Consumers / Trophic Interactions

Structure-Function-Biodiversity

LTER VI Planning Workshop 1 September 2007 Anthony Joern